87,339 results on '"FERROELECTRICITY"'
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2. Temperature dependent dielectric and ferroelectric properties of Sr2Na(1-x)K(x)Nb5O15 (0≤x≤0.07) Tetragonal Tungsten Bronze (TTB) ceramics
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Riaz, Muhammad Fahad, Hussain, Fayaz, and Chandio, Ali Dad
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- 2025
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3. Improving the thermal stability of 180° domain switching by engineering the ferroelectric/electrode interface
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Jeyaseelan, Antony, Vishwanath, Sujaya Kumar, Yoon, Sukeun, and Kim, Jihoon
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- 2025
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4. Tailoring La doping concentration for superior ferroelectric and energy storage performance in Bi2WO6 thin films
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Ahn, Yoonho and Son, Jong Yeog
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- 2025
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5. Investigating the photodetection performance of self-biased Au/PZT/ FTO and Au/PZT/Au/FTO UV photodetectors
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Ashtar, M., Marwat, M.A., Bentalib, A., Jumah, A.B., Yang, Y., Xue, W., and Cao, D.
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- 2025
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6. Freestanding ferroelectric thin film with robust ferroelectricity via inserted dielectric layers
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Dai, Liyufen, Yao, Dijie, An, Feng, Cheng, Mingqiang, Zhong, Xiangli, Tang, Zhenhua, and Zhong, Gaokuo
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- 2025
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7. Alternating multi-pulse atomic layer deposition for dopant tailoring in sub-10 nm ferroelectric thin films
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Wang, Ting-Yun, Chuang, Chun-Ho, Mo, Chi-Lin, Jiang, Yu-Sen, Shyue, Jing-Jong, Shieh, Jay, and Chen, Miin-Jang
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- 2025
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8. Surface-Induced effects in ferroelectric BaTiO3 thin films
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Kushwaha, Anoop Kumar, Khadka, Rajan, and Keblinski, Pawel
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- 2025
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9. Spin-coated BiFeO3 films on Si wafers: Low processing temperature but prominent piezoelectricity
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Yi, Jiaojiao, Zhai, Yining, Cheng, Yue-yu-shan, Shu, Liang, Zhang, Dawei, Li, Jing-Feng, and Liu, Lisha
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- 2025
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10. Large ferroelectric polarization and high dielectric constant in HfO2-based thin films via Hf0.5Zr0.5O2/ZrO2 nanobilayer engineering
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Liu, Lei, Jiang, Chengfeng, Yuan, Xi, Zhang, Yan, Chen, Haiyan, and Zhang, Dou
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- 2025
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11. Esterified phenylalanine supramolecular motion: Anion order–disorder rotation induced reversible phase transition and dielectric-ferroelectric properties
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Liu, Yang, Wang, Na, Yao, Yubing, Qi, Huanhuan, Hu, Hongzhi, Zhang, Tong, and Liu, Zunqi
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- 2025
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12. Heteroepitaxial growth of PMN-PT thin films on SrTiO3 buffered III-V semiconductor GaAs by pulsed laser deposition
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Du, Xiaona and Ning, Xin
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- 2025
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13. Chemically driven BaTiO3–CoFe2O4 nanocomposite with strong dielectric and low leakagecharacteristics for electrocatalytic water splitting reaction
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Singh, Purnima, Mahato, Anupama, Mondal, Debasish, Panda, Bholanath, Sahis, Amrit, Pramanik, Anup, and Dhak, Debasis
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- 2024
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14. Rapid microwave annealing of ferroelectric copolymer films for multifunctional perception
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Luo, Xingsheng, Yang, Jiang, Feng, Yirou, and Zhu, Guodong
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- 2024
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15. Enhanced magnetoelectric properties of the composite films of Bi0.5Na0.5Ti0.98Fe0.02O3-δ-NiFe1.98Nd0.02O4 with different deposition sequences
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Shi, Min, Du, Shushu, Chen, Wu, Chen, Hao, Xu, Yudong, Zuo, Ruzhong, and Bai, Tiancheng
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- 2024
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16. Phase field theoretical study of the electrocaloric effect in porous ferroelectric films.
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Liu, Zenghong, Xiang, Yuanjin, Zou, Xing, Zhu, Zhe, and Fang, Wenxiao
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PYROELECTRICITY , *ADIABATIC temperature , *FERROELECTRICITY , *CERAMICS , *THIN films , *FERROELECTRIC thin films - Abstract
It has been experimentally observed that changes in the nanopore structure have a great impact on the ferroelectric domain structure, and then, the ferroelectric polarization value of the film can be controlled to increase the response of the electrocaloric effect. This phenomenon has great application prospects in refrigeration applications. In this study, the evolution process of the domain structure of porous ferroelectric films of Pb0.7 Sr0.3TiO3 (PST) with different pore shapes was obtained through phase field simulation, and the influence of the pore shape on the performance of electrocaloric was predicted and analyzed. The results show that different shapes of pores can control the magnitude of the adiabatic temperature change. Among them, the anisometric ellipse shaped pore thin film can obtain a maximum adiabatic temperature change of 8 K, which is a significant improvement compared with traditional PST ceramics and PST non-porous films. This large adiabatic temperature change is due to the pore-induced domain switching. Therefore, controlling the pore shapes provides a new idea for optimizing the electrocaloric properties of porous ferroelectric thin films. [ABSTRACT FROM AUTHOR]
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- 2025
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17. Application of the Skanavi model to CaCu3Ti4O12 materials.
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Luo, Hao, Geng, Kejia, Qin, Xinrui, Kong, Cuncun, Liu, Xin, Su, Xueyan, Su, Yaoheng, Lu, Dingze, and Cheng, Pengfei
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ELECTRIC fields , *FERROELECTRICITY , *PERMITTIVITY , *OCTAHEDRA , *EQUATIONS - Abstract
In this paper, the optical and static permittivities of CaCu3Ti4O12 supercells are calculated based on the Skanavi model by decomposing the electric field of molecules into the electric field of ions. The results show that the Skanavi model's theoretical predictions are significantly more accurate than those of the Clausius–Mossotti equation and Born model and are in good agreement with the experimental data. In addition, the absence of ferroelectricity in CaCu3Ti4O12 is also revealed by investigating the changes in the structural coefficients of the effective electric field caused by the displacement of Ti4+ along the z-axis. Finally, by analyzing the contribution of TiO6 octahedra or CuO4 planar squares to the static permittivity, the main polarization unit in the structure of CaCu3Ti4O12 has been discovered. This study not only makes up for the insufficient research on the polarization mechanism of CaCu3Ti4O12 but also provides a new tool to explore the polarization mechanism of other materials. [ABSTRACT FROM AUTHOR]
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- 2025
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18. Modulation of flux-closure polar state for enhanced storage unit and thermal conductivity via dual-probe excitation.
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Luo, S. S., Hu, S. W., Shan, D. L., Liu, Y. Y., Lei, C. H., and Pan, K.
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NANOFILMS , *PIEZORESPONSE force microscopy , *FERROELECTRIC devices , *FERROELECTRIC materials , *FERROELECTRICITY - Abstract
Ferroelectric topological structures have broad application prospects for high-density information storage for long-term data retention via topological protection. However, the high-density memory component might generate tremendous power consumption, causing the failure of ferroelectric devices due to the severe thermal effect. There remains an emergent issue on the synchronous achievement of high-density data storage with the decreasing influences of the thermal effects in ferroelectric topological domain structures. Here, we introduce dual-probe excitation to control the symmetry of the electric field and integrate the phase field simulation for modulating the flux-closure ferroelectric domain configuration to simultaneously improve the memory storage unit and thermal conductivity at the nanoscale in PbTiO3 thin film under a piezoresponse force microscopy experiment. It is found that the grown flux-closure polar state in both in-plane directions encourages us to enhance the storage density during dual-probe excitation in topological ferroelectric memory devices. Moreover, the increased number of flux-closure polar states and the decreased density of the domain walls can be obtained by using dual-probe excitation. Finally, we figured out that both the double-staircase-like and paddle-like domain configurations exhibit large storage units and effective thermal conductivity simultaneously under dual-probe excitation. Our study gives a guideline to synchronously improve storage performance and thermal conductivity through multiple-probe excitations in topological ferroelectric materials and devices. [ABSTRACT FROM AUTHOR]
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- 2025
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19. General theory of cavity-mediated interactions between low-energy matter excitations.
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Sánchez Martínez, Carlos J., Lindel, Frieder, García-Vidal, Francisco J., and Feist, Johannes
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PROPERTIES of matter , *ELECTROMAGNETIC coupling , *DEGREES of freedom , *SUPERCONDUCTIVITY , *FERROELECTRICITY - Abstract
The manipulation of low-energy matter properties such as superconductivity, ferromagnetism, and ferroelectricity via cavity quantum electrodynamics engineering has been suggested as a way to enhance these many-body collective phenomena. In this work, we investigate the effective interactions between low-energy matter excitations induced by the off-resonant coupling with cavity electromagnetic modes. We extend a previous work by going beyond the dipole approximation accounting for the full polarization and magnetization densities of matter. We further include the often neglected diamagnetic interaction and, for the cavity, we consider general linear absorbing media with possibly non-local and non-reciprocal response. We demonstrate that, even in this general scenario, the effective cavity-induced interactions between the matter degrees of freedom are of electrostatic and magnetostatic nature. This confirms the necessity of a multimode description for cavity engineering of matter systems where the low-energy assumption holds. Our findings provide a theoretical framework for studying the influence of general optical environments on extended low-energy matter excitations. [ABSTRACT FROM AUTHOR]
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- 2024
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20. Harnessing room-temperature ferroelectricity in metal oxide monolayers for advanced logic devices.
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Naseer, Ateeb, Rafiq, Musaib, Bhowmick, Somnath, Agarwal, Amit, and Singh Chauhan, Yogesh
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FERROELECTRIC materials , *FIELD-effect transistors , *VALENCE bands , *LOGIC devices , *FERROELECTRICITY - Abstract
Two-dimensional ferroelectric materials are beneficial for power-efficient memory devices and transistor applications. Here, we predict out-of-plane ferroelectricity in a new family of buckled metal oxide (MO; M: Ge, Sn, Pb) monolayers with significant spontaneous polarization. Additionally, these monolayers have a narrow valence band, which is energetically separated from the rest of the low-lying valence bands. Such a unique band structure limits the long thermal tail of the hot carriers, mitigating subthreshold thermionic leakage and allowing field-effect transistors (FETs) to function beyond the bounds imposed on conventional FETs by thermodynamics. Our quantum transport simulations reveal that the FETs based on these MO monolayers exhibit a large ON/OFF ratio with an average subthreshold swing of less than 60 mV/decade at room temperature, even for short gate lengths. Our work motivates further exploration of the MO monolayers for developing advanced, high-performance memory and logic devices. [ABSTRACT FROM AUTHOR]
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- 2024
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21. Insights into the ferroelectric orthorhombic phase formation in doped HfO2 thin films.
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Wen, Yichen, Wu, Maokun, Cui, Boyao, Wang, Xuepei, Wu, Yishan, Li, Yu-Chun, Ye, Sheng, Ren, Pengpeng, Lu, Hong-Liang, Wang, Runsheng, Ji, Zhigang, and Huang, Ru
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CRITICAL temperature , *THIN films , *DOPING agents (Chemistry) , *FERROELECTRICITY , *TIMEKEEPING - Abstract
Despite the extensive research on HfO2-based thin films, the ferroelectric orthorhombic phase formation remains unclear. This work proposes a physical picture throughout the entire annealing process to describe the phase transition. Subsequently, the phase evolution at various doping and annealing temperatures is illustrated based on a kinetic model formalized from the classical nucleation theory. It is found that the formation of the ferroelectric orthorhombic phase depends not only on a modest doping concentration but also on the thermal activation of the t-to-o phase transition provided by a sufficient annealing temperature. In addition, phase transition rates correlated to the monoclinic phase formation are effectively suppressed by doping. The exploration of combined effects of annealing parameters indicates a more decisive role of the annealing temperature rather than the keeping time for induced ferroelectricity, and the doping impact becomes significant when a critical annealing temperature is reached. This work provides an understanding for exploring the kinetic effect on the phase transition in HfO2-based thin films, which helps improve ferroelectricity in doped HfO2 ferroelectric films. [ABSTRACT FROM AUTHOR]
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- 2024
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22. Ferroelectricity and nanotube-induced synthesis of one-dimensional group-Ⅳ monochalcogenide nanowires
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Guo, Jiasen, Li, Xinxin, Wang, Huijuan, Zhong, Chenghuan, Zheng, Xiaole, Chen, Ying, Yang, Dingyan, Xie, Shimao, and Li, Chunmei
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- 2023
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23. First-principles study of polar magnets corundum double-oxides Mn2FeMO6 (M = W and Mo)
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Ali, Akbar, Elsaeedy, H.I., Ullah, Sami, Ali Khan, Sayed, and Khan, Imad
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- 2022
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24. Ferroelectric proximity effects in two-dimensional FeSeTe.
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Disiena, Matthew N., Pandey, Nilesh, Luth, Christopher, Sloan, Luke, Shattuck, Reid, Singh, Jatin V., and Banerjee, Sanjay K.
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FERROELECTRICITY , *FERROELECTRIC materials , *SUPERCONDUCTING transitions , *PERMITTIVITY , *HYSTERESIS loop - Abstract
Recent studies have shown that proximity effects are able to substantially modulate the superconducting properties of various quasi-two-dimensional layered materials such as FeSe, FeSeTe, NbSe2, and NbS2. Due to their high surface charge concentration and high dielectric constants, ferroelectric materials provide an interesting avenue for inducing proximity effects in layered superconductors. In this study, we explore the interactions between FeSeTe and the two-dimensional ferroelectrics CuInP2S6 and CuInP2Se6. We found that contrary to the normal behavior of FeSeTe, FeSeTe/CuInP2S6, and FeSeTe/CuInP2Se6 heterostructures display a peculiar two-step superconducting transition. Further testing revealed a hysteresis loop in the IV curves of these samples when measured below the critical temperature indicating the presence of disorder and domains within FeSeTe. We conclude that these domains are responsible for the two-step transition in FeSeTe and hypothesize that they are induced by the domain structure of the aforementioned ferroelectric materials. [ABSTRACT FROM AUTHOR]
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- 2024
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25. Phase stability, piezoelectricity, and ferroelectricity in nitride short-period superlattices.
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Zhao, Ling-Xu and Liu, Jian
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PIEZOELECTRICITY , *FERROELECTRICITY , *NITRIDES , *SUPERLATTICES , *HETEROGENEITY - Abstract
Improving piezoelectric and ferroelectric responses of group III-nitrides is desired for their potential applications in the emerging microelectromechanical-based systems. One possible approach to realize the optimization and control of functionalities is to bring together compounds with different properties to form the ordered multilayer superlattices. In this work, we systematically investigate the phase stability, piezoelectricity, and ferroelectricity in a class of wurtzite-structure-derived nitride superlattices with a periodic alternation of chemically and/or structurally different layers. The structural heterogeneity and phase stability of the ordered wurtzite-structure-derived superlattices are intimately related to the ionic radii mismatch between the substitutional compounds and the parent nitrides. Moreover, the internal structural distortion of the nitride superlattices has a crucial impact on the ferroelectricity and piezoelectricity, namely, piezoelectric and ferroelectric responses become increasingly enhanced as the buckled atomic layers becomes flatter. This work offers fundamental physical insights into the structure–property relationships in nitride superlattices and may propose some material design strategies for achieving high-performance materials with desired responses. [ABSTRACT FROM AUTHOR]
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- 2024
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26. Influence of oxygen pressure on the ferroelectricity of pulsed laser deposition fabricated epitaxial Y-doped HfO2.
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Huang, Jia-hao, Yang, Lei, Wei, Lu-qi, Wang, Tao, Fan, Wen-cheng, Qu, Ke, Guan, Zhao, Chen, Bin-bin, Xiang, Ping-hua, Duan, Chun-gang, and Zhong, Ni
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PULSED laser deposition , *ATOMIC layer deposition , *FERROELECTRICITY , *FERROELECTRIC materials , *SPUTTER deposition , *PULSED lasers - Abstract
Ferroelectric properties of hafnium-based thin films have gained significant interest, yet the fundamental mechanisms responsible for the emergence of the ferroelectric phase continue to be inadequately investigated. In contrast with polycrystalline films fabricated by atomic layer deposition or sputter methods, which possess uncertainty in polarization orientation, epitaxial ferroelectric HfO2-based materials are less investigated, especially for factors such as electric field and oxygen vacancy, which are proposed and examined for their potential impacts on phase stability. In this study, Y-doped hafnium oxide (HYO) ferroelectric epitaxial films were fabricated using pulsed laser deposition, with variations in oxygen pressure during the deposition process. Structural and electrical analyses of HYO epitaxial ferroelectric films prepared under differing oxygen pressures revealed a correlation between the ferroelectric properties of the films and the oxygen content. An optimal selection of oxygen pressure was found to be conducive to the formation of HYO epitaxial ferroelectric films, presenting a promising avenue for future ferroelectric memory applications. [ABSTRACT FROM AUTHOR]
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- 2024
- Full Text
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27. Influence of oxygen pressure on the ferroelectricity of pulsed laser deposition fabricated epitaxial Y-doped HfO2.
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Huang, Jia-hao, Yang, Lei, Wei, Lu-qi, Wang, Tao, Fan, Wen-cheng, Qu, Ke, Guan, Zhao, Chen, Bin-bin, Xiang, Ping-hua, Duan, Chun-gang, and Zhong, Ni
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PULSED laser deposition ,ATOMIC layer deposition ,FERROELECTRICITY ,FERROELECTRIC materials ,SPUTTER deposition ,PULSED lasers - Abstract
Ferroelectric properties of hafnium-based thin films have gained significant interest, yet the fundamental mechanisms responsible for the emergence of the ferroelectric phase continue to be inadequately investigated. In contrast with polycrystalline films fabricated by atomic layer deposition or sputter methods, which possess uncertainty in polarization orientation, epitaxial ferroelectric HfO
2 -based materials are less investigated, especially for factors such as electric field and oxygen vacancy, which are proposed and examined for their potential impacts on phase stability. In this study, Y-doped hafnium oxide (HYO) ferroelectric epitaxial films were fabricated using pulsed laser deposition, with variations in oxygen pressure during the deposition process. Structural and electrical analyses of HYO epitaxial ferroelectric films prepared under differing oxygen pressures revealed a correlation between the ferroelectric properties of the films and the oxygen content. An optimal selection of oxygen pressure was found to be conducive to the formation of HYO epitaxial ferroelectric films, presenting a promising avenue for future ferroelectric memory applications. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
28. Atomic-Scale Scanning of Domain Network in the Ferroelectric HfO2 Thin Film
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Park, Kunwoo, Kim, Dongmin, Lee, Kyoungjun, Lee, Hyun-Jae, Kim, Jihoon, Kang, Sungsu, Lin, Alex, Pattison, Alexander J, Theis, Wolfgang, Kim, Chang Hoon, Choi, Hyesung, Cho, Jung Woo, Ercius, Peter, Lee, Jun Hee, Chae, Seung Chul, and Park, Jungwon
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Macromolecular and Materials Chemistry ,Chemical Sciences ,Engineering ,Physical Sciences ,Materials Engineering ,ferroelectricity ,HfO2 ,grain boundaries ,crystal structure ,domain network ,Nanoscience & Nanotechnology - Abstract
Ferroelectric HfO2-based thin films have attracted much interest in the utilization of ferroelectricity at the nanoscale for next-generation electronic devices. However, the structural origin and stabilization mechanism of the ferroelectric phase are not understood because the film is typically nanocrystalline with active yet stochastic ferroelectric domains. Here, electron microscopy is used to map the in-plane domain network structures of epitaxially grown ferroelectric Y:HfO2 films in atomic resolution. The ferroelectricity is confirmed in free-standing Y:HfO2 films, allowing for investigating the structural origin for their ferroelectricity by 4D-STEM, high-resolution STEM, and iDPC-STEM. At the grain boundaries of -oriented Pca21 orthorhombic grains, a high-symmetry mixed-(R3m, Pnm21) phase is induced, exhibiting enhanced polarization due to in-plane compressive strain. Nanoscale Pca21 orthorhombic grains and their grain boundaries with mixed-(R3m, Pnm21) phases of higher symmetry cooperatively determine the ferroelectricity of the Y:HfO2 film. It is also found that such ferroelectric domain networks emerge when the film thickness is beyond a finite value. Furthermore, in-plane mapping of oxygen positions overlaid on ferroelectric domains discloses that polarization is suppressed at vertical domain walls, while it is active when domains are aligned horizontally with subangstrom domain walls. In addition, randomly distributed 180° charged domain walls are confined by spacer layers.
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- 2024
29. Effect of fabrication parameters on the ferroelectricity of hafnium zirconium oxide films: A statistical study.
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Salcedo, Guillermo A., Islam, Ahmad E., Reichley, Elizabeth, Dietz, Michael, Schubert-Kabban, Christine M., Leedy, Kevin D., Back, Tyson C., Wang, Weisong, Green, Andrew, Wolfe, Timothy, and Sattler, James M.
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HAFNIUM oxide films , *FERROELECTRICITY , *HYDROFLUORIC acid , *ZIRCONIUM oxide , *HAFNIUM oxide - Abstract
Ferroelectricity in hafnium zirconium oxide (Hf1 − xZrxO2) and the factors that impact it have been a popular research topic since its discovery in 2011. Although the general trends are known, the interactions between fabrication parameters and their effect on the ferroelectricity of Hf1 − xZrxO2 require further investigation. In this paper, we present a statistical study and a model that relates Zr concentration (x), film thickness (tf), and annealing temperature (Ta) with the remanent polarization (Pr) in tungsten (W)-capped Hf1 − xZrxO2. This work involved the fabrication and characterization of 36 samples containing multiple sets of metal-ferroelectric-metal capacitors while varying x (0.26, 0.48, and 0.57), tf (10 and 19 nm), and Ta (300, 400, 500, and 600 ° C). In addition to the well-understood effects of x and Ta on the ferroelectricity of Hf1 − xZrxO2, the statistical analysis showed that thicker Hf1 − xZrxO2 films or films with higher x require lower Ta to crystallize and demonstrated that there is no statistical difference between samples annealed to 500 and 600 ° C, thus suggesting that most films fully crystallize with Ta ∼ 500 ° C for 60 s. Our model explains 95% of the variability in the Pr data for the films fabricated, presents the estimates of the phase composition of the film, and provides a starting point for selecting fabrication parameters when a specific Pr is desired. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
30. Advanced first principles-based study using berry polarization and wannier formulation to explore the promising ferroelectric material SnTiO3.
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Belboukhari, Aimad, Benchtia, Mohammed, Bakak, Abderrahim, Jallal, Said El, Koumina, My Abdelaziz, Bentaleb, Khaled Ait, Mezzane, Daoud, and Gagou, Yaovi
- Subjects
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FERROELECTRIC materials , *GEOMETRIC quantum phases , *CHEMICAL bonds , *FERROELECTRICITY , *BERRIES - Abstract
Ferroelectricity is a crucial property for numerous applications and is fundamentally important for exploring a significant class of smart materials. One of the primary objectives of many theoretical approaches is to efficiently predict new promising ferroelectric compounds by gaining deep insights into their behavior, thus optimizing their performance across various shapes, geometries, and scales. Among the most compelling and exciting approaches is the intimate combination of Berry phase and Maximally Localized Wannier formulation. Therefore, our study aims to leverage these theoretical advancements to systematically investigate the electronic, chemical bonding, ferroelectric, and piezoelectric properties of the promising hypothetical bulk system SnTiO3 by comparing it with its isomorph PbTiO3. Subsequently, we will expand our comparison to slab properties, such as the effects of slab thickness on electronic properties, employing the robust Wannier-based Tight Binding model. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
31. Advanced first principles-based study using berry polarization and wannier formulation to explore the promising ferroelectric material SnTiO3.
- Author
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Belboukhari, Aimad, Benchtia, Mohammed, Bakak, Abderrahim, Jallal, Said El, Koumina, My Abdelaziz, Bentaleb, Khaled Ait, Mezzane, Daoud, and Gagou, Yaovi
- Subjects
FERROELECTRIC materials ,GEOMETRIC quantum phases ,CHEMICAL bonds ,FERROELECTRICITY ,BERRIES - Abstract
Ferroelectricity is a crucial property for numerous applications and is fundamentally important for exploring a significant class of smart materials. One of the primary objectives of many theoretical approaches is to efficiently predict new promising ferroelectric compounds by gaining deep insights into their behavior, thus optimizing their performance across various shapes, geometries, and scales. Among the most compelling and exciting approaches is the intimate combination of Berry phase and Maximally Localized Wannier formulation. Therefore, our study aims to leverage these theoretical advancements to systematically investigate the electronic, chemical bonding, ferroelectric, and piezoelectric properties of the promising hypothetical bulk system SnTiO
3 by comparing it with its isomorph PbTiO3 . Subsequently, we will expand our comparison to slab properties, such as the effects of slab thickness on electronic properties, employing the robust Wannier-based Tight Binding model. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
32. Phase transitions in HfO2 probed by first-principles computations.
- Author
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Kingsland, Maggie, Lisenkov, S., Najmaei, Sina, and Ponomareva, I.
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PHASE transitions , *LANDAU theory , *ELECTRIC field effects , *DENSITY functional theory , *FERROELECTRICITY , *SPACE groups - Abstract
Ever since ferroelectricity was discovered in HfO 2 , the question of its origin remains controversial. Here, we probe this question using a combination of Landau theory of phase transitions and first-principles computations. In such an approach, the energy landscape associated with the phase transition between cubic and different experimentally demonstrated phases of HfO 2 (tetragonal, monoclinic, orthorhombic Pbca, orthorhombic Pnma, and orthorhombic Pca 2 1) is explored using density functional theory calculations. Computations revealed that stabilization of all but orthorhombic Pbca phase is driven by a single unstable zone-boundary antipolar mode X 2 −. When coupled with zone-center modes (Γ 1 + and Γ 3 +), it stabilizes the tetragonal phase. Coupling with four additional modes (Γ 5 + , X 3 − , X 5 − , X 5 +) results in the monoclinic phase, which is the ground state of the material. If, however, Γ 5 + mode is replaced with Γ 4 − mode, orthorhombic polar phase Pca 2 1 is stabilized. The application of this framework to examine the effect of electric field on the ferroelectric phase of hafnia reveals that the field of 5 MV/cm is capable of stabilizing ferroelectric phase over the monoclinic one at 0 K. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
33. Scalable ferroelectricity of 20 nm-thick (Al0.8Sc0.2)N thin films sandwiched between TiN electrodes.
- Author
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Ota, Reika, Yasuoka, Shinnosuke, Mizutani, Ryoichi, Shiraishi, Takahisa, Okamoto, Kazuki, Kakushima, Kuniyuki, Koganezawa, Tomoyuki, Sakata, Osami, and Funakubo, Hiroshi
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THIN films , *FERROELECTRICITY , *TITANIUM nitride , *ELECTRODES , *GAS mixtures , *ALUMINUM foam , *ZINC oxide films - Abstract
Ferroelectric (Al, Sc)N thin films have the potential for use in low-power memory applications. This study demonstrates the thickness scalability of ferroelectricity down to an approximately 20 nm-thick (Al0.8Sc0.2)N film sandwiched between microfabricable TiN electrodes. The impact of the deposition gas atmosphere during the sputtering process and the top electrode materials on the crystal structures and ferroelectric properties was investigated for 20–30 nm-thick (Al0.8Sc0.2)N thin films deposited on Si substrates covered with a TiN layer by radio frequency magnetron sputtering. The deposition atmosphere did not strongly affect the crystal structures of the 30 nm-thick (Al0.8Sc0.2)N films but significantly affected their ferroelectric properties. The leakage current density decreased for films deposited under pure N2 gas compared to the films deposited under a gas mixture of 0.67Ar + 0.33N2. The ferroelectric properties of 20 nm-thick (Al0.8Sc0.2)N films were changed by the top electrode materials; both the switching electric field and its maximum applicable electric field increased for the TiN top electrodes compared with the Pt top electrodes, improving the saturation characteristics of the remnant polarization (Pr) against the applied electric field. Consequently, the 20 nm-thick (Al0.8Sc0.2)N film sandwiched between the microfabricable TiN top and bottom electrodes showed ferroelectricity without noticeable degradation with decreasing film thickness; the film maintained large Pr values of over 100 μC/cm2 in the temperature range from room temperature to 150 °C. The present data open the door to scalable ferroelectric random-access memories using almost thickness-degradation-free thin (Al, Sc)N films with microfabricable TiN electrodes. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
34. Rate-independent model of ferroelectric materials: finite element and finite difference solution: Rate-independent model of ferroelectric materials: M. F. Alhasadi et al.
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Alhasadi, Mawafag F., Shahsavari, Leila, Sun, Qiao, and Federico, Salvatore
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FINITE difference method , *FINITE differences , *FERROELECTRIC materials , *DERIVATIVES (Mathematics) , *PIEZOELECTRIC materials - Abstract
Ferroelectric materials undergo a phenomenon called domain switching when subjected to electric fields exceeding a critical yielding value: an irreversible polarisation arises, that can be removed only by applying an appropriate electric field in the opposite sense. Under a cyclic electric field, this results in a hysteretic behaviour in the relation between the electric field and the polarisation. The hysteresis loop is a measure of the energy dissipated in the ferroelectric switching process. In this study, we introduce a rate-independent model of ferroelectricity, inspired by small-deformation elastoplasticity models. Analogously to the yielding surface in elastoplasticity, we define the switching surface, the boundary of the domain of the admissible states of the system. States in the interior of the domain are reversible, while states on the surface can be either reversible or irreversible, based on the relation between the electric field and the derivative of the yielding function with respect to the electric field. We solve a two-dimensional benchmark boundary-value problem by applying two numerical methods, Finite Differences and Finite Elements. Our results demonstrate the effectiveness of both methods in capturing the nonlinearities and reproducing the electrical hysteresis loops typical of ferroelectric materials. This work establishes a foundational framework for modelling rate-independent ferroelectricity and paves the way for future research on comprehensive elastoplastic-ferroelectric models for piezoelectric materials. [ABSTRACT FROM AUTHOR]
- Published
- 2025
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35. Improved Ferroelectric Effects and Gate Controllability in Hf0.5Zr0.5O2-Gated InAlGaN/GaN MIS-HEMTs Using ZrO2 Seed Layers: Improved Ferroelectric Effects and Gate Controllability in Hf0.5Zr0.5O2-Gated...: Tien-Han Yu et al
- Author
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Yu, Tien-Han, Chen, Yu-Lin, Tsao, Yi-Fan, Hsu, Chin-Tsai, Lu, Tsan-Feng, and Hsu, Heng-Tung
- Subjects
FERROELECTRICITY ,SEMICONDUCTOR technology ,STRAY currents ,THRESHOLD voltage ,POWER density ,MODULATION-doped field-effect transistors - Abstract
Scaling of GaN high-electron-mobility transistors (HEMTs) frequently leads to increased gate leakage current and increased risk of device breakdown when subjected to high-speed switching, ultimately resulting in a reduction of the maximum drain current and output power density. These issues can be effectively mitigated by incorporating a dielectric layer beneath the gate in HEMTs. This study delves into the performance enhancement of Hf
0.5 Zr0.5 O2 -gated InAlGaN/GaN metal–insulator–semiconductor (MIS) HEMTs that are grown on a ZrO2 seed layer. The implementation of ferroelectric Hf0.5 Zr0.5 O2 (HZO) stacks has been shown to significantly reduce gate leakage current and stabilize threshold voltage shifts. Furthermore, the positive bias transconductance peak shift enhances the overall electrical stability of the device. Our findings underscore the potential of using ferroelectric stacks in InAlGaN/GaN HEMTs to achieve higher efficiency and operational stability. These advancements make Hf0.5 Zr0.5 O2 -gated HEMTs particularly suitable for advanced high-power and high-frequency applications, demonstrating their capacity to deliver superior performance under challenging conditions. The results of this study highlight the critical role of dielectric engineering in optimizing GaN-based devices, paving the way for future innovations in semiconductor technology. [ABSTRACT FROM AUTHOR]- Published
- 2025
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- View/download PDF
36. Structural, Magnetic, and Ferroelectric Phase Transitions and Energy Storage Efficiency in Ba1-xLaxTi1-xFexO3 Ceramics.
- Author
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Hoang, T. P., Truong-Son, L. V., Phan, Lien, Nghiem, N. T., Truong-Tho, N., Tiep, N. H., Jabarov, S. H., Tien, D. P. T., Tran, T. A., Dang, N. T., Bich, D. D., and Khan, D. T.
- Subjects
PHYSICAL & theoretical chemistry ,PHASE transitions ,INORGANIC chemistry ,X-ray photoelectron spectroscopy ,ENERGY storage - Abstract
The co-substitution effect of La and Fe ions on structural characterization, ferroelectric and magnetic properties, and energy storage efficiency of multiferroics Ba
1-x Lax Ti1-x Fex O3 (0 ≤ x ≤ 0.20) was systematically studied utilizing a combination of x-ray diffraction, scanning electron microscopy, Raman spectroscopy, x-ray photoelectron spectroscopy (XPS), ferroelectric, and magnetic measurements. The results show a structural transformation from the P4mm tetragonal phase to the Pm-3m cubic one at x = 0.04, with no hexagonal phase across the entire large doping range, which differs from the results previously reported for BaTiO3 systems doped solely with Fe. The XPS results show single valence states of Ba, La, and Ti ions, alongside a mixed valence state of Fe in the investigated samples. Magnetic measurements indicate that the pristine sample (x = 0) exhibits weak ferromagnetic (FM) phases within a diamagnetic (DM) matrix. At x < 0.10, the FM and DM phases are suppressed while the paramagnetic phase becomes dominant, indicating no interaction between Fe ions and a reduction in lattice intrinsic defects such as O and Ti vacancies. For 0.10 ≤ x ≤ 0.15, Fe ions start to couple with each other, enhancing the ferromagnetism. However, as x = 0.20, the saturation magnetization is significantly reduced, indicating competition between FM and antiferromagnetic interactions between Fe ions. Ferroelectric measurements demonstrate the ferroelectric nature of the lightly doped samples (x ≤ 0.10) and the lossy improper ferroelectric nature of the samples with 0.15 ≤ x ≤ 0.20. The lossy improper ferroelectricity is related to electron hopping between the Fe3+ –Fe4+ interaction pathways. The coercive electric field, remnant polarization, and maximum polarization decrease with the increase of the porosity in the samples. Furthermore, Ba1-x Lax Ti1-x Fex O3 exhibits high energy storage efficiencies of up to ~ 77%. These findings demonstrate an effective way to make efficient energy storage materials through optimizing doping level and morphological properties in BaTiO3 and other ferroelectrics. [ABSTRACT FROM AUTHOR]- Published
- 2025
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37. On the giant deformation and ferroelectricity of guanidinium nitrate.
- Author
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Szafrański, Marek and Katrusiak, Andrzej
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ELECTRIC conductivity ,ELECTRIC properties ,INELASTIC neutron scattering ,ANGULAR momentum (Mechanics) ,DIELECTRIC measurements ,FERROELECTRIC thin films ,PERMITTIVITY measurement ,FERROELECTRICITY ,TUNNEL junctions (Materials science) - Abstract
The article in Nature Communications discusses the properties of guanidinium nitrate (GN) and challenges the claims made by Karothu et al. regarding the ferroelectricity and semiconductivity of GN crystals. The authors present evidence from previous studies on the giant deformation, crystal structures, and dielectric properties of GN to refute the new properties claimed by Karothu et al. They conclude that GN does not exhibit ferroelectric properties and is unsuitable for certain applications proposed by Karothu et al. The study was supported by the Adam Mickiewicz University in Poznań and the authors declare no competing interests. [Extracted from the article]
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- 2025
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38. Coupled pyroelectric-photovoltaic effect in 2D ferroelectric α-In2Se3.
- Author
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Uzhansky, Michael, Rakshit, Abhishek, Kalcheim, Yoav, and Koren, Elad
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ENERGY harvesting ,SHORT-circuit currents ,THERMAL conductivity ,FERROELECTRICITY ,SOLAR energy - Abstract
Pyroelectric and photovoltaic effects are vital in cutting-edge broadband sensors and solar energy harvesting. Recent advances revealed great potential of the bulk photovoltaic effect in two-dimensional (2D) materials to surpass the Shockley-Queiseer limit. Moreover, the atomic thickness, high thermal conductivity and room-temperature ferroelectricity endow 2D ferroelectrics with a superior pyroelectric response. Herein, we combined direct pyroelectric-photovoltaic measurements in 2D α-In
2 Se3 . The results reveal a gigantic pyroelectric coefficient of ∼30.7 mC/m2 K and a figure of merit of ∼135.9 m2 /C. Moreover, a coupled pyroelectric-photovoltaic effect was demonstrated, where the pyroelectric current follows the temperature derivative, while the short-circuit current follows temperature. Finally, we utilized the intercoupled ferroelectricity of In2 Se3 to realize a non-volatile, self-powered photovoltaic memory operation, demonstrating stable short-circuit current switching with 103 ON-OFF ratio. The coupled pyroelectric-photovoltaic effect, along with reconfigurable photocurrent, pave the way for a novel integrated thermal and optical response, in-memory logic and energy harvesting. [ABSTRACT FROM AUTHOR]- Published
- 2025
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39. Mechanical force-induced interlayer sliding in interfacial ferroelectrics.
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Guan, Zhao, Wei, Lu-qi, Fan, Wen-cheng, Sun, Yi-chen, Cao, Wei, Tian, Ming, Wan, Neng, Tong, Wen-yi, Chen, Bin-bin, Xiang, Ping-hua, Duan, Chun-gang, and Zhong, Ni
- Subjects
FERROELECTRICITY ,FERROELECTRIC crystals ,TRIANGLES ,SUPERLATTICES - Abstract
Moiré superlattices in two-dimensional stacks have attracted worldwide interest due to their unique electronic properties. A typical example is the moiré ferroelectricity, where adjacent moirés exhibit opposite spontaneous polarization that can be switched through interlayer sliding. However, in contrast to ideal regular ferroelectric moiré domains (equilateral triangles) built in most theoretical models, the unavoidable irregular moiré supercells (non-equilateral triangles) induced by external strain fields during the transfer process have been given less attention. Manipulation of controllable polarization evolutions is also a big challenge due to an interlinked network of polarized domains. In this study, we employ a sliding-disturb measurement to examine and modulate these irregular moirés via mechanical force. By introducing a curved substrate, the irregular moirés are fabricated, and three distinct types of moiré domains with different patterns are identified and modulated by external mechanical force disturbing. They exhibit reduced pinning forces when the shear direction is not aligned with the strain direction. The shift of the moirés is observed to be orthogonal to the shear direction. This work offers an effective pathway for the controlled switch of the polarization in interfacial ferroelectricity. Manipulation of controllable polarization evolutions is a big challenge. The authors fabricate the irregular moirés, identifying three distinct types of moiré domains with different patterns, modulating them by external mechanical force disturbing. [ABSTRACT FROM AUTHOR]
- Published
- 2025
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40. Quantifying the pyroelectric and photovoltaic coupling series of ferroelectric films.
- Author
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Hu, Chaosheng, Liu, Xingyue, Dan, Huiyu, Guo, Chong, Zhang, Maoyi, Bowen, Chris R., and Yang, Ya
- Subjects
PHOTOVOLTAIC effect ,ENERGY harvesting ,FERROELECTRICITY ,REFERENCE sources ,PERFORMANCE theory - Abstract
The coupling of photovoltaic and pyroelectric effects is a common phenomenon in ferroelectric films and often results in coupling enhancements. Although the coupling effects of a variety of ferroelectric films have been examined in terms of improved performance, they have yet to be quantitatively ranked and assessed. Here, by taking the charge coupling factor, the Yang's charge, and output energy as metrics to evaluate the coupling performance, a methodology is developed for evaluating the performance of a range ferroelectric films when the pyroelectric and photovoltaic effects are coupled. By experimentally measuring and quantitatively ranking the evaluation metrics, the influence of coupling effects on the output charge and the energy harvesting capabilities of various ferroelectric films can be readily visualized. In addition, the analysis of the underlying reasons for the coupling enhancement enables optimization of the methods to quantify the charge coupling factor. This work provides a unique reference for the selection of materials, optimization of performance, and energy harvesting for coupled ferroelectric film-based generators. The Yang's charge is proposed as a metric for evaluating the coupling performance in this study. Compared to the conventional charge coupling factor which only considers the relative performance change, the Yang's charge also considers the absolute performance of the device. [ABSTRACT FROM AUTHOR]
- Published
- 2025
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41. Two-Dimensional Ferroelectric Materials: From Prediction to Applications.
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Jiang, Shujuan, Wang, Yongwei, and Zheng, Guangping
- Subjects
- *
FERROELECTRIC materials , *FERROELECTRIC crystals , *NONLINEAR optics , *FERROELECTRICITY , *CURIE temperature , *FERROELECTRIC devices - Abstract
Ferroelectric materials hold immense potential for diverse applications in sensors, actuators, memory storage, and microelectronics. The discovery of two-dimensional (2D) ferroelectrics, particularly ultrathin compounds with stable crystal structure and room-temperature ferroelectricity, has led to significant advancements in the field. However, challenges such as depolarization effects, low Curie temperature, and high energy barriers for polarization reversal remain in the development of 2D ferroelectrics with high performance. In this review, recent progress in the discovery and design of 2D ferroelectric materials is discussed, focusing on their properties, underlying mechanisms, and applications. Based on the work discussed in this review, we look ahead to theoretical prediction for 2D ferroelectric materials and their potential applications, such as the application in nonlinear optics. The progress in theoretical and experimental research could lead to the discovery and design of next-generation nanoelectronic and optoelectronic devices, facilitating the applications of 2D ferroelectric materials in emerging advanced technologies. [ABSTRACT FROM AUTHOR]
- Published
- 2025
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42. A ferroelectric helical polymer.
- Author
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Bandyopadhyay, Supriya, Barman, Shubhankar, Paul, Swadesh, Datta, Anuja, and Ghosh, Suhrit
- Subjects
- *
HYSTERESIS loop , *FERROELECTRICITY , *CHROMOPHORES , *TEMPERATURE - Abstract
This communication introduces helical polyacetylene (P1) with an appended acceptor (A)–donor (D)–acceptor (A) conjugated chromophore as a promising ferroelectric candidate. The helical conformation of P1 leads to a highly stable chiral assembly of the appended ADA chromophores. This results in prominent ferroelectricity as evident from the superior hysteresis loop at room temperature, exhibiting a saturation polarization (PS) value ∼2 μC cm−2 and remanent polarization (Pr) value ∼1.8 μC cm−2 at a low coercive field (Ec) of 5.2 kV cm−1, rarely reported before for purely organic systems. [ABSTRACT FROM AUTHOR]
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- 2025
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43. A bulk photovoltaic effect in a zero-dimensional room-temperature molecular ferroelectric [C8N2H22]1.5[Bi2I9].
- Author
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Zhibo Chen, Tianhong Luo, Jinrong Wen, Zhanqiang Liu, Jingshan Hou, Yongzheng Fang, and Ganghua Zhang
- Subjects
- *
PHOTOELECTRIC devices , *OPEN-circuit voltage , *SHORT-circuit currents , *HYSTERESIS loop , *FERROELECTRICITY , *PHOTOVOLTAIC effect , *OPTOELECTRONIC devices - Abstract
Non-toxic molecular ferroelectrics have attracted significant interest due to their unique flexibility, low costs, and environmental friendliness. However, such materials with narrow bandgaps and ferroelectricity above room temperature (RT) are still scarce. Herein, we present a brand-new lead-free molecular ferroelectric [C8N2H22]1.5[Bi2I9] synthesized hydrothermally. [C8N2H22]1.5[Bi2I9] features a zero-dimensional (0D) structure with a polar space group of Pc, as confirmed by single-crystal X-ray diffraction and second-harmonic generation (SHG) analyses. The RT hysteresis loop reveals the intrinsic ferroelectricity of [C8N2H22]1.5[Bi2I9] with a spontaneous polarization (Ps) of 1.3 μC cm−2. A visible-light optical bandgap has been confirmed by UV-vis spectroscopy and theoretical calculations. A notable ferroelectric photovoltaic (PV) effect has been revealed in [C8N2H22]1.5[Bi2I9]-based photoelectric devices with an open-circuit voltage (Voc) of 0.39 V and a short-circuit current density (Jsc) of 2.3 μA cm−2 under AM 1.5G illumination. The PV performance can be significantly enhanced by tuning the ferroelectric polarization, achieving a maximum Voc of 0.47 V and Jsc of about 50 μA cm−2. This study offers a novel member of the 0D lead-free hybrid organic–inorganic molecular ferroelectric family possessing great promise for optoelectronic devices. [ABSTRACT FROM AUTHOR]
- Published
- 2025
- Full Text
- View/download PDF
44. Heterojunction Ferroelectric Materials Enhance Ion Transport and Fast Charging of Polymer Solid Electrolytes for Lithium Metal Batteries.
- Author
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Shan, Jiayao, Gu, Rong, Xu, Jinting, Gong, Shuaiqi, Guo, Shuainan, Xu, Qunjie, Shi, Penghui, and Min, YuLin
- Subjects
- *
PIEZOELECTRICITY , *SOLID electrolytes , *FERROELECTRIC materials , *POLYELECTROLYTES , *FERROELECTRICITY , *FERROELECTRIC ceramics , *SUPERIONIC conductors - Abstract
Solid polymer electrolytes offer great promise for all‐solid‐state batteries, but their advancement is constrained due to the low ionic conductivity at ambient temperature and non‐uniform ion transport, which hampers fast‐charging capabilities. In this study, a ferroelectric heterojunction composite is incorporated into poly(vinylidene difluoride) (PVDF) based solid electrolytes to establish an interfacial electric field that enhances lithium salt dissociation and promotes uniform ion deposition. Electrospun 1D BaTiO3 nanofibers serve as a long‐range organic/inorganic (polymer/filler) interface for ion transport, while MoSe2 hydrothermally grown on BaTiO3 forms Li2Se‐rich high‐speed ion conductors. The piezoelectric effect of the ferroelectric material helps suppress lithium dendrite growth by reversing internal charges and reducing local overpotentials. Consequently, the PVBM electrolyte achieves a substantia ionic conductivity of 6.5 × 10−4 S cm−1 and a Li‐ion transference number of 0.61 at 25 °C. The LiFePO4/PVBM/Li solid‐state batteries demonstrate an initial discharge capacity of 146 mAh g−1 at 1 C, with a capacity preservation of 80.2% upon completion of 1200 cycles, and an initial discharge capacity of 110.7 mAh g−1 at 5 C. These findings highlight the prospect of ferroelectric ceramic fillers to significantly improve ion transport and fast‐charging performance in polymer electrolytes. [ABSTRACT FROM AUTHOR]
- Published
- 2025
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- View/download PDF
45. Cluster sliding ferroelectricity in trilayer Quasi-Hexagonal C60.
- Author
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Wang, Xuefei, Ren, Yanhan, Qiu, Shi, Zhang, Fan, Li, Xueao, Gao, Junfeng, Gao, Weiwei, and Zhao, Jijun
- Subjects
POLARIZATION (Electricity) ,BAND gaps ,CHEMICAL bonds ,FERROELECTRICITY ,FERROELECTRIC crystals - Abstract
Electric polarization typically originates from non-centrosymmetric charge distributions in compounds. In elemental crystalline materials, chemical bonds between atoms of the same element favor symmetrically distributed electron charges and centrosymmetric structures, making elemental ferroelectrics rare. Compared to atoms, elemental clusters are intrinsically less symmetric and can have various preferred orientations when they are assembled to form crystals. Consequently, the assembly of clusters with different orientations tends to break the inversion symmetry. By exploiting this concept, we show that sliding ferroelectricity naturally emerges in trilayer quasi-hexagonal phase (qHP) C
60 , a cluster-assembled carbon allotrope recently synthesized. Compared to many metallic or semi-metallic elemental ferroelectrics, trilayer qHP C60 's have sizable band gaps and several ferroelectric structures, which are distinguishable by measuring their second-harmonic generation (SHG) responses. Some of these phases show both switchable out-of-plane and in-plane polarizations on the order of 0.2 pC/m. The out-of-plane and in-plane polarizations can be switched independently and enable an easy-to-implement construction of Van der Waals homostructures with ferroelectrically switchable chirality. [ABSTRACT FROM AUTHOR]- Published
- 2025
- Full Text
- View/download PDF
46. A bulk photovoltaic effect in a zero-dimensional room-temperature molecular ferroelectric [C8N2H22]1.5[Bi2I9].
- Author
-
Zhibo Chen, Tianhong Luo, Jinrong Wen, Zhanqiang Liu, Jingshan Hou, Yongzheng Fang, and Ganghua Zhang
- Subjects
PHOTOELECTRIC devices ,OPEN-circuit voltage ,SHORT-circuit currents ,HYSTERESIS loop ,FERROELECTRICITY ,PHOTOVOLTAIC effect ,OPTOELECTRONIC devices - Abstract
Non-toxic molecular ferroelectrics have attracted significant interest due to their unique flexibility, low costs, and environmental friendliness. However, such materials with narrow bandgaps and ferroelectricity above room temperature (RT) are still scarce. Herein, we present a brand-new lead-free molecular ferroelectric [C
8 N2 H22 ]1.5 [Bi2 I9 ] synthesized hydrothermally. [C8 N2 H22 ]1.5 [Bi2 I9 ] features a zero-dimensional (0D) structure with a polar space group of Pc, as confirmed by single-crystal X-ray diffraction and second-harmonic generation (SHG) analyses. The RT hysteresis loop reveals the intrinsic ferroelectricity of [C8 N2 H22 ]1.5 [Bi2 I9 ] with a spontaneous polarization (Ps ) of 1.3 μC cm−2 . A visible-light optical bandgap has been confirmed by UV-vis spectroscopy and theoretical calculations. A notable ferroelectric photovoltaic (PV) effect has been revealed in [C8 N2 H22 ]1.5 [Bi2 I9 ]-based photoelectric devices with an open-circuit voltage (Voc ) of 0.39 V and a short-circuit current density (Jsc ) of 2.3 μA cm−2 under AM 1.5G illumination. The PV performance can be significantly enhanced by tuning the ferroelectric polarization, achieving a maximum Voc of 0.47 V and Jsc of about 50 μA cm−2 . This study offers a novel member of the 0D lead-free hybrid organic–inorganic molecular ferroelectric family possessing great promise for optoelectronic devices. [ABSTRACT FROM AUTHOR]- Published
- 2025
- Full Text
- View/download PDF
47. Investigating the Interplay of Polar Nanodomains and Superconductivity in Doped Strontium Titanate through Transmission Electron Microscopy.
- Author
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Salmani-Rezaie, Salva
- Abstract
The simultaneous presence of itinerant carriers and polar crystal distortions poses a persistent challenge, especially in polar superconductors such as doped strontium titanate (SrTiO3). This study employs scanning transmission electron microscopy (STEM) to investigate the interplay between ferroelectricity and superconductivity in SrTiO3. Contrary to conventional models, the ferroelectric transition in strained, undoped SrTiO3 exhibits pronounced order-disorder characteristics. Increasing carrier concentration disrupts polar nanodomains, with dopant atoms contributing to the suppression of the ferroelectric transition. The destruction of the global ferroelectric state correlates with the suppression of superconductivity in strained SrTiO3 films, emphasizing the essential role of polar order. The length scale of polar order emerges as a crucial parameter controlling superconductivity in SrTiO3, providing valuable insights into the competition between itinerant carriers and polar crystal distortions. [ABSTRACT FROM AUTHOR]
- Published
- 2025
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- View/download PDF
48. 1D Crystalline Assemblies Exhibiting Large Second Harmonic Generation Susceptibilities and Stacking‐/Polarization‐Driven Tunability.
- Author
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Yang, Jingyu, Pan, Jinbo, Zhang, Yan‐Fang, Wan, Guolin, Zhu, Yongqian, Wei, Zixuan, Li, Yuhui, and Du, Shixuan
- Subjects
- *
SECOND harmonic generation , *POLARIZATION (Electricity) , *NONLINEAR optics , *DATABASES , *FERROELECTRICITY - Abstract
Nonlinear optical (NLO) van der Waals (vdW) crystals containing 1D building blocks exhibit large NLO coefficients and birefringence that are crucial for their applications. In this work, 21 NLO 1D building blocks with large second harmonic generation (SHG) susceptibility from the Computational 1D Materials Database (C1DB) are screened. Among them, 14 are hitherto unreported and have SHG susceptibilities approaching theoretical upper limits. Forty‐five new vdW NLO crystals are then constructed by stacking one or two of the 21 building blocks. Eighteen of them inherit the large SHG susceptibilities of their corresponding 1D building blocks. Three stable crystals exhibit large SHG susceptibilities and birefringence, while one stable crystal possesses ferroelectricity. Interestingly, the SHG susceptibilities of the newly constructed NLO crystals are inversely proportional to the third power of their bandgaps. Further calculations show that the SHG susceptibilities of the vdW NLO crystals can be tuned either by stacking order or by reversing electric polarization, providing possibilities for their application in tunable nonlinear optics and NLO switches. [ABSTRACT FROM AUTHOR]
- Published
- 2025
- Full Text
- View/download PDF
49. 2D Ferroelectric Metal–Organic Frameworks for Ultralow Power Field Effect Transistors.
- Author
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Xian, Zhenhui, Li, Changjian, Dong, Yangda, Peng, Mengping, Yu, Ye, Zhang, Yuan, Huang, Boyuan, Zhong, Gaokuo, Xie, Shuhong, and Li, Jiangyu
- Subjects
- *
FIELD-effect transistors , *FERROELECTRICITY , *NONVOLATILE memory , *FERROELECTRIC crystals , *NANOSTRUCTURED materials - Abstract
2D ferroelectrics open a new realm of nonvolatile memory and computing devices, while metal–organic frameworks (MOF) offer tremendous possibilities to design and optimize ferroelectric performance. Integrating a MOF ferroelectric gate with a semiconducting channel provides new strategy toward ultralow power ferroelectric field effect transistors (FeFETs), yet no 2D MOF is experimentally demonstrated to be ferroelectric yet. Here, the study successfully develops 2D ferroelectric MOF nanosheets, {CuL2(H2O)2(NO3)2(H2O)1.5·(CH3OH)}∞ wherein L denotes PhPO(NH4Py)2, abbreviated as {CuIIL2}n‐MOF, and confirm its ferroelectricity down to 7 nm thickness. A large polarization of ≈14.2 µC cm−2, small coercive field of ≈33.3 V µm−1, and excellent endurability >106 cycles are found in 2D {CuIIL2}n‐MOF nanosheets. This enables to fabricate FeFETs using 2D {CuIIL2}n‐MOF as the gate and MoS2 as the channel, achieving an on/off ratio of 107 with ultralow off‐state current of 100 fA and tunable memory window, making it exceptional among known FeFETs and very promising for next‐generation ultralow power memories and computing devices [ABSTRACT FROM AUTHOR]
- Published
- 2025
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- View/download PDF
50. Discovery of a layered multiferroic compound Cu1-xMn1+ySiTe3 with strong magnetoelectric coupling.
- Author
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De, Chandan, Yu Liu, Ayyagari, Sai Venkata Gayathri, Boyang Zheng, Kelley, Kyle P., Hazra, Sankalpa, Jingyang He, Pawledzio, Sylwia, Mali, Subin, Guchaait, Samaresh, Suguru Yoshida, Yingdong Guan, Seng Huat Lee, Sretenovic, Milos, Xianglin Ke, Le Wang, Engelhard, Mark H., Yingge Du, Weiwei Xie, and Xiaoping Wang
- Subjects
- *
POLARIZATION (Electricity) , *TRANSITION metal chalcogenides , *REMANENCE , *MAGNETIC hysteresis , *FERROELECTRICITY , *MULTIFERROIC materials - Abstract
Multiferroic materials host both ferroelectricity and magnetism, offering potential for magnetic memory and spin transistor applications. Here, we report a multiferroic chalcogenide semiconductor Cu1-xMn1+ySiTe3 (0.04 ≤ x ≤ 0.26; 0.03 ≤ y ≤ 0.15), which crystallizes in a polar monoclinic structure (Pm space group). It exhibits a canted antiferromagnetic state below 35 kelvin, with magnetic hysteresis and remanent magnetization under 15 kelvin. We demonstrate multiferroicity and strong magnetoelectric coupling through magnetodielectric and magnetocurrent measurements. At 10 kelvin, the magnetically induced electric polarization reaches ~0.8 microcoulombs per square centimeter, comparable to the highest value in oxide multiferroics. We also observe possible room-temperature ferroelectricity. Given that multiferroicity is very rare among transition metal chalcogenides, our finding sets up a unique materials platform for designing multiferroic chalcogenides. [ABSTRACT FROM AUTHOR]
- Published
- 2025
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- View/download PDF
51. Impact of enhanced ferroelectric polarization through La doping on photovoltaic properties of BiFeO3 thin films on HOPG.
- Author
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Ahn, Yoonho and Son, Jong Yeog
- Subjects
- *
THIN films , *PYROLYTIC graphite , *BAND gaps , *SURFACE structure , *FERROELECTRIC thin films , *FERROELECTRICITY - Abstract
BiFeO3 (BFO) thin films are well‐known for their multiferroic and photovoltaic properties, driving extensive research into potential applications. Highly ordered pyrolytic graphite (HOPG) substrates, with a graphene‐like surface structure, provide an ideal platform for assessing the impact of graphene electrodes. This study investigates the photovoltaic properties of ITO/BFO/HOPG devices with La‐doped BFO thin films at concentrations of 5, 10, and 15 mol%. The polycrystalline BFO thin films exhibited a preferential (111) orientation, with the 10 mol% La‐doped thin films demonstrating optimal crystallinity and the highest remanent polarization of 50.8 µC/cm2. Photovoltaically, the 5 mol% La‐doped BFO thin film exhibited an open‐circuit voltage (
V oc) of 0.46 V and the highest short‐circuit current (J sc) of 0.38 mA/cm2. The 10 mol% La‐doped BFO thin film achieved the highestV oc of 0.57 V with aJ sc of 0.35 mA/cm2, likely because of enhanced ferroelectric polarization. In contrast, the 15 mol% La‐doped BFO thin film showed a reduced band gap but diminished photovoltaic performance. The minimal variation in the band gap (within 0.1 eV) suggests that the improved photovoltaic performance is primarily driven by increased polarization resulting from enhanced tetragonality. [ABSTRACT FROM AUTHOR]- Published
- 2025
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- View/download PDF
52. α-In2Se3/PtX2(X=S,Se,Te)异质结电子结构调控研究.
- Author
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韩善成, 李京杰, 王楠, 黄火林, and 郝松
- Subjects
BAND gaps ,SMART devices ,FERROELECTRIC materials ,ELECTRONIC equipment ,ENERGY bands - Abstract
Copyright of Journal of Dalian University of Technology / Dalian Ligong Daxue Xuebao is the property of Journal of Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2025
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53. Study of Di-/Ferro-/Piezoelectric Properties of Sm3+-Doped ZnO Nanoparticles.
- Author
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Verma, Radha, Goel, Sahil, Verma, Komal, Kant, Krishan, Kumar, Rajesh, Garg, Maneesha, and Gupta, Rashi
- Subjects
DIELECTRIC loss ,STRAY currents ,PERMITTIVITY ,STRAINS & stresses (Mechanics) ,ENERGY density - Abstract
Pristine ZnO and Sm-doped ZnO nanoparticles were synthesized using a wet chemical co-precipitation technique. The morphological and structural characteristics of pristine and Sm-doped ZnO were studied by field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) techniques. Increases in lattice parameters, interplanar spacing, and volume was observed from the XRD patterns compared to its JCPDS card. Crystallite size, dislocation density, deformation stress, lattice strain, and energy density for both pristine and Sm-ZnO nanoparticles were calculated using Scherrer and Williamson–Hall (W–H) methods. An energy bandgap reduction was observed in the Sm-doped ZnO (E
g ~ 2.7 eV), which played a crucial role in explaining the increased leakage currents in Sm-ZnO. The Sm-doped ZnO nanoparticles exhibited a remnant polarization (Pr ~ 0.163 µC/cm2 ) and a coercive field (Ec ~ 25.33 kV/cm). Current–voltage (I–V) characteristics show maximum current generated on applying varying voltages (Vmax = 40 V, Imax = ~600 μA). Frequency- and temperature-dependent dielectric studies were conducted to examine the change in the values of the dielectric constant and dielectric loss with the variation in frequency and temperature. The Sm-doped ZnO-based nanogenerator generated an output voltage ~ 400 mV at tapping force of ~ 0.02 kgf, which makes it a prominent candidate for self-powered devices. [ABSTRACT FROM AUTHOR]- Published
- 2025
- Full Text
- View/download PDF
54. Ambient Moisture‐Induced Self Alignment of Polarization in Ferroelectric Hafnia.
- Author
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Wei, Lu‐Qi, Guan, Zhao, Tong, Wen‐Yi, Fan, Wen‐Cheng, Mattursun, Abliz, Chen, Bin‐Bin, Xiang, Ping‐Hua, Han, Genquan, Duan, Chun‐Gang, and Zhong, Ni
- Subjects
- *
FERROELECTRIC materials , *FERROELECTRICITY , *ELECTRONIC equipment , *ELECTRIC fields , *FERROELECTRIC crystals - Abstract
The discovery of nanoscale ferroelectricity in hafnia (HfO2) has paved the way for next generation high‐density, non‐volatile devices. Although the surface conditions of nanoscale HfO2 present one of the fundamental mechanism origins, the impact of external environment on HfO2 ferroelectricity remains unknown. In this study, the deleterious effect of ambient moisture is examined on the stability of ferroelectricity using Hf0.5Zr0.5O2 (HZO) films as a model system. It is found that the development of an intrinsic electric field due to the adsorption of atmospheric water molecules onto the film's surface significantly impairs the properties of domain retention and polarization stability. Nonetheless, vacuum heating efficiently counteracts the adverse effects of water adsorption, which restores the symmetric electrical characteristics and polarization stability. This work furnishes a novel perspective on previous extensive studies, demonstrating significant impact of surface water on HfO2‐based ferroelectrics, and establishes the design paradigm for the future evolution of HfO2‐based multifunctional electronic devices. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
55. Machine learning–guided optimization of coercive field in Al1−xScxN thin films for nonvolatile memory.
- Author
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Das, Shaon, Garg, Prachi, and Mazumder, Baishakhi
- Subjects
- *
RANDOM forest algorithms , *FERROELECTRIC materials , *THIN films , *FERROELECTRICITY , *SCANDIUM - Abstract
This study employs a data‐driven machine learning approach to investigate specific ferroelectric properties of Al1−
x Scx N thin films, targeting their application in next‐generation nonvolatile memory (NVM) devices. This approach analyzes a vast design space, encompassing over a million data points, to predict a wide range of coercive field values that are crucial for optimizing Al1−x Scx N‐based NVM devices. We evaluated seven machine learning models to predict the coercive field across a range of conditions, identifying the random forest algorithm as the most accurate, with a testR 2 value of 0.88. The model utilized five key features: film thickness, measurement frequency, operating temperature, scandium concentration, and growth temperature to predict the design space. Our analysis spans 13 distinct scandium concentrations and 13 growth temperatures, encompassing thicknesses from 9–1000 nm, frequencies from 1 to 100 kHz, and operating temperatures from 273 to 700 K. The predictions revealed dominant coercive field values between 3.0 and 4.5 MV/cm, offering valuable insights for the precise engineering of Al1−x Scx N‐based NVM devices. This work underscores the potential of machine learning in guiding the development of advanced ferroelectric materials with tailored properties for enhanced device performance. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
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56. Electronic ferroelectricity in monolayer graphene moiré superlattices.
- Author
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Zhang, Le, Ding, Jing, Xiang, Hanxiao, Liu, Naitian, Zhou, Wenqiang, Wu, Linfeng, Xin, Na, Watanabe, Kenji, Taniguchi, Takashi, and Xu, Shuigang
- Subjects
POLARIZATION (Electricity) ,FERROELECTRIC materials ,CARRIER density ,NONVOLATILE memory ,FERROELECTRICITY - Abstract
Extending ferroelectric materials to two-dimensional limit provides versatile applications for the development of next-generation nonvolatile devices. Conventional ferroelectricity requires materials consisting of at least two constituent elements associated with polar crystalline structures. Monolayer graphene as an elementary two-dimensional material unlikely exhibits ferroelectric order due to its highly centrosymmetric hexagonal lattices. Here, we report the observations of electronic ferroelectricity in monolayer graphene by introducing asymmetric moiré superlattice at the graphene/h-BN interface, in which the electric polarization stems from electron-hole dipoles. The polarization switching is probed through the measurements of itinerant Hall carrier density up to room temperature, manifesting as standard polarization-electric field hysteresis loops. We find ferroelectricity in graphene moiré systems exhibits generally similar characteristics in monolayer, bilayer, and trilayer graphene, which indicates layer polarization is not essential to observe the ferroelectricity. Furthermore, we demonstrate the applications of this ferroelectric moiré structures in multi-state nonvolatile data storage with high retention and the emulation of versatile synaptic behaviors. Our work not only provides insights into the fundamental understanding of ferroelectricity, but also demonstrates the potential of graphene for high-speed and multi-state nonvolatile memory applications. Monolayer graphene, with its highly centrosymmetric hexagonal lattice, is typically not considered ferroelectric. Here, the authors observe ferroelectricity in monolayer graphene by introducing asymmetric moiré superlattices, where polarization arises from electron-hole dipoles. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
57. Strong Electrostatic Control of Excitonic Features in MoS2 by a Free‐Standing Ultrahigh‐κ Ferroelectric Perovskite.
- Author
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Pucher, Thomas, Puebla, Sergio, Zamora, Victor, Sánchez Viso, Estrella, Rouco, Victor, Leon, Carlos, Garcia‐Hernandez, Mar, Santamaria, Jacobo, Munuera, Carmen, and Castellanos‐Gomez, Andres
- Subjects
- *
BORON nitride , *BINDING energy , *OPTICAL communications , *OPTICAL devices , *FERROELECTRICITY - Abstract
Integrating free‐standing complex oxides with two‐dimensional (2D) materials has recently attracted great interest, due to the rich physics evolving from such structures. Enhancing and tuning the opto–electronic properties of these systems is of high importance for a multitude of applications, such as sensors, memory devices or optical communications. The electrostatic control of photoluminescence of monolayer MoS2 at room temperature via integration of free‐standing BaTiO3 (BTO), a ferroelectric perovskite oxide is presented. It is shown that the use of BTO leads to highly tunable exciton emission of MoS2 in a minimal range of gate voltages. Due to BTO's ferroelectric polarization‐induced doping, large peak emission shifts as well as a large and tunable A trion binding energy in the range of 40–100 meV are observed. These measurements are compared with those carried out when the BTO is replaced by a hexagonal boron nitride (hBN) dielectric layer, confirming BTO's superior gating properties and thus lower power consumption. Additionally, advantage of the ferroelectric switching of BTO is taken by fabricating devices where the BTO layer is decoupled from the gate electrode with a SiO2 layer. Choosing to isolate the BTO allows to induce large remanent behavior of MoS2's excitonic features. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
58. Buffer Layer Stabilized Single‐Unit Cell Ferroelectric Bi2TeO5.
- Author
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Li, Yunfei, Li, Alei, Wang, Cong, Han, Mengjiao, Zhu, Juntong, Zhong, Yunlei, Zhao, Pin, Song, Ge, Wang, Shun, Shen, Zongjie, Wang, Lin, Zhang, Hui, Zhou, Wu, You, Lu, Ji, Wei, Lin, Junhao, and Kang, Lixing
- Subjects
- *
FERROELECTRIC materials , *BUFFER layers , *NONVOLATILE memory , *FERROELECTRICITY , *DISCONTINUOUS precipitation - Abstract
Miniaturizing van der Waals (vdW) ferroelectric materials to atomic scales is essential for modern devices like nonvolatile memory and sensors. To unlock their full potential, their growth mechanisms, interface effects, and stabilization are preferably investigated, particularly for ultrathin 2D nanosheets with single‐unit cell thickness. This study focuses on Bi2TeO5 (BTO) and utilizes precise control over growth kinetics at the nucleation temperature to create specific interfacial reconfiguration layers. Ultrathin BTO nanosheets with planar ferroelectricity at a single‐unit cell thickness are successfully grown. Atomic‐scale characterization reveals a disordered distribution of elements in the interfacial layer, which buffers strain from lattice mismatch. The theoretical calculations support these observations. Furthermore, this strategy also can be extended to the growth of a variety of 2D ternary oxide nanosheets. This work contributes to a better understanding of growth and stability mechanisms in 2D ultrathin nanosheets. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
59. Interface‐Modulated Antiferroelectric‐to‐Ferroelectric‐Like Transition in Ultrathin Hf0.5Zr0.5O2 Films.
- Author
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Lu, Haoyu, Li, Yu, Han, Jiyuan, Huangfu, Geng, Feng, Guan, Yin, Shuaishuai, Wei, Yingfen, Jiang, Hao, Zheng, Changlin, Liu, Qi, and Liu, Ming
- Subjects
- *
THIN films , *FERROELECTRIC materials , *PHASE transitions , *FERROELECTRICITY , *LOW voltage systems - Abstract
The development of ultrathin (≤5 nm) hafnia‐based ferroelectric (FE) films is essential for achieving low operating voltages, facilitating their integration into advanced process nodes for low‐power and non‐volatile memory applications. However, challenges in ultrathin FE films arise from the depolarization field and interface‐related issues, leading to an antiferroelectric‐like (AFE‐like) polarization switching behavior and more significant wake‐up effects, causing operational inconvenience and reliability concerns. Here, interface‐modulated ferroelectricity is reported in 4 nm Hf0.5Zr0.5O2 (HZO) thin films, demonstrating excellent properties with low operating voltage, enhanced switching speed, and high reliability. Electrical and structural characterizations reveal that adjusting interface asymmetry may introduce a substantial built‐in field (
E bi) and an AFE‐like switching behavior can exhibit a robust FE‐like characteristic. This AFE‐to‐FE‐like transition is driven by switching kinetics rather than commonly proposed phase transitions. Furthermore, a comprehensive model is developed to elucidate the intricate physics of the modulation mechanism by asymmetric interfaces, emphasizing the critical roles of depolarizing effects andE bi on ferroelectricity. This work underscores the importance of interfaces in engineering ferroelectricity for advanced electronic applications. [ABSTRACT FROM AUTHOR]- Published
- 2024
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60. Hybrid improper ferroelectricity in a Si-compatible CeO2/HfO2 artificial superlattice.
- Author
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Kumar, Pawan and Lee, Jun Hee
- Subjects
PERMITTIVITY ,FERROELECTRIC devices ,FERROELECTRICITY ,DIELECTRIC properties ,ACTIVATION energy - Abstract
Hybrid improper ferroelectrics (HIFs), characterized by ferroelectric polarization arising from the rotation of two symmetry inequivalent antiferrodistortive modes, exhibit exotic properties such as T-independent dielectric constants and robustness against depolarizing field. Here, using first-principles simulations, we report a new P 2 1 phase in a Si-compatible CeO
2 /HfO2 superlattice that exhibits remarkably robust hybrid improper ferroelectricity, induced by the in-plane oxygen rotations of two antiferrodistortive distortion modes. These non-polar distortions are coupled with a polar distortion through a trilinear coupling in the superlattice, stabilizing ferroelectricity as the competing ground state with the assistance of epitaxial strain. The estimated out-of-plane polarization ( P = 30.3 μ C / c m 2 ) is switchable with a remarkably small energy barrier of 8.5 meV/atom and relatively smaller coercive field relative to bulk HfO2 , expected to reduce the operational voltage of ferroelectric devices. Our discovery may offer unexpected opportunities for innovating high-performance, low-voltage devices, and promising advancements in next-generation CMOS compatible oxide-based electronics. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
61. Evidence of multiferroic behavior in sintered BaTiO3 obtained from high-energy ball-milled powders.
- Author
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Reséndiz-Trejo, Y., Sánchez-De Jesús, F., Betancourt-Cantera, L.G., Reyes-Valderrama, M.I., Cortés-Escobedo, C.A., and Bolarín-Miró, A.M.
- Subjects
- *
MULTIFERROIC materials , *DIELECTRIC materials , *FERROELECTRIC materials , *PERMITTIVITY , *DIFFRACTION patterns - Abstract
Multiferroic BaTiO 3 exhibiting ferroelectric and ferromagnetic behavior was synthesized via the high-energy ball milling of pure BaTiO 3 (BTO) powders for durations ranging from 15 to 60 min, followed by pressing and sintering at 1200 °C X-ray diffraction patterns of all synthesized samples predominantly revealed a BTO phase with a tetragonal structure and a secondary Ba 12 Fe 28 Ti 15 O 84 (BFTO) phase. The BFTO phase was formed after milling for more than 30 min because of chemical interactions between the BTO powder and milling media. Vibrating sample magnetometry confirmed the ferromagnetic nature of the sintered pellets. The specific magnetization increased with increasing milling duration, reaching a maximum value of 1.15 emu/g after 60 min of milling. This increase can be attributed to the distortion of the crystal structure and presence of a secondary phase, as confirmed by scanning electron microscopy and energy-dispersive X-ray spectroscopy. Additionally, electrical characterization revealed the dielectric nature of the materials, with relative permittivity ranging from 500 to 1800, maximum spontaneous polarization from 9.77 to 11.31 μC/cm2, coercive field from 3.86 to 11.12 kV/cm, and AC conductivity from 1 × 10−6 to 1 × 10−3 S/cm. The method described in this study is a simple and cost-effective approach to produce multiferroic materials with ferroelectric and relaxor ferroelectric behavior at room temperature, broadening their potential for technological applications. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
62. Ferroelectricity in Ce0.2-HfO2 films around 500 nm in thickness.
- Author
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Wu, Yida, Xu, Junbo, Bai, Mei, Kang, Ruirui, Qiao, Wenjing, Gao, Yangfei, Hu, Yanhua, Wang, Danyang, Zhao, Jiantuo, Wang, Jiping, and Lou, Xiaojie
- Subjects
- *
CHEMICAL solution deposition , *CERIUM oxides , *HAFNIUM oxide , *HYSTERESIS loop , *FERROELECTRICITY , *FERROELECTRIC thin films - Abstract
CeO 2 -HfO 2 solid solution thin films (Hf 1-x Ce x O 2) were deposited on Pt(111)/TiO 2 /SiO 2 /Si(100) substrates using the chemical solution deposition method. This study investigates the influence of CeO 2 content and annealing temperature on the structure and ferroelectric properties of Hf 1-x Ce x O 2 films. Ferroelectric behavior is demonstrated in polycrystalline Hf 0.80 Ce 0.20 O 2 films with thicknesses ranging from 163 to 524 nm. And the structure of the films is analyzed using glancing incidence X-ray diffraction. The comprehensive results indicate that Hf 0.80 Ce 0.20 O 2 films annealed at 850 °C exhibit excellent ferroelectricity. Square hysteresis loops associated with the ferroelectric orthorhombic phase are observed, even in the 524-nm-thick film. The remnant polarization (P r) and coercive field (E c) range from 16 to 18 μC/cm2 and 1100–1250 kV/cm, respectively, under a maximum applied electric field of 2 MV/cm for all Hf 0.80 Ce 0.20 O 2 films. Furthermore, the film presents thickness-insensitive characteristic. The current work paves the new way to design high-performance thick HfO 2 -based ferroelectric films. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
63. Imaging of electric-field-induced domain structure in DyMnO3 nanocrystals.
- Author
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Najeeb, Mansoor A., Morrison, Robbie, Mokhtar, Ahmed H., Porter, Daniel G., Lichtenberg, Frank, Bombardi, Alessandro, and Newton, Marcus C.
- Subjects
THRESHOLD voltage ,MACHINE learning ,DYSPROSIUM ,FERROELECTRICITY ,MANGANITE - Abstract
Multiferroic materials that exhibit interacting and coexisting properties, like ferroelectricity and ferromagnetism, possess significant potential in the development of novel technologies that can be controlled through the application of external fields. They also exhibit varying regions of polarity, known as domains, with the interfaces that separate the domains referred to as domain walls. In this study, using three-dimensional (3D) bragg coherent diffractive imaging (BCDI), we investigate the dynamics of multiferroic domain walls in a single hexagonal dysprosium manganite (h-DyMnO 3 ) nanocrystal under varying applied electric field. Our analysis reveals that domain wall motion is influenced by the pinning effects, and a threshold voltage of +3 V is required to overcome them. Using circular mean analysis and phase gradient mapping, we identified localised phase realignment and high-gradient regions corresponding to domain walls, providing insights into the behaviour of multiferroic systems under external stimuli. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
64. Strain‐Driven Stabilization of a Room‐Temperature Chiral Multiferroic with Coupled Ferroaxial and Ferroelectric Order.
- Author
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Ren, Guodong, Jung, Gwan Yeong, Chen, Huandong, Wang, Chong, Zhao, Boyang, Vasudevan, Rama K., Hachtel, Jordan A., Lupini, Andrew R., Chi, Miaofang, Xiao, Di, Ravichandran, Jayakanth, and Mishra, Rohan
- Subjects
- *
FERROELECTRIC materials , *SCANNING transmission electron microscopy , *MIRROR symmetry , *SYMMETRY breaking , *FERROELECTRICITY - Abstract
Noncollinear ferroic materials are sought after as testbeds to explore the intimate connections between topology and symmetry, which result in electronic, optical, and magnetic functionalities not observed in collinear ferroic materials. For example, ferroaxial materials have rotational structural distortions that break mirror symmetry and induce chirality. When ferroaxial order is coupled with ferroelectricity arising from a broken inversion symmetry, it offers the prospect of electric‐field‐control of the ferroaxial distortions and opens up new tunable functionalities. However, chiral multiferroics, especially ones stable at room temperature, are rare. A strain‐stabilized, room‐temperature chiral multiferroic phase in single crystals of BaTiS3 is reported here. Using first‐principles calculations, the stabilization of this multiferroic phase having
P 63 space group for biaxial tensile strains exceeding 1.5% applied on the basalab ‐plane of the room temperatureP 63cm phase of BaTiS3 is predicted. The chiral multiferroic phase is characterized by rotational distortions of TiS6 octahedra around the longc ‐axis and polar displacement of Ti atoms along thec ‐axis. The ferroaxial and ferroelectric distortions and their domains inP 63‐BaTiS3 are directly resolved using atomic resolution scanning transmission electron microscopy. Landau‐based phenomenological modeling predicts a strong coupling between the ferroelectric and the ferroaxial order makingP 63‐BaTiS3 an attractive test bed for achieving electric‐field‐control of chirality. [ABSTRACT FROM AUTHOR]- Published
- 2024
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- View/download PDF
65. Superior Electrocaloric Performance Enabled by Highly Robust Monomorphic Ferrodistortion in NaNbO3‐Based Relaxor.
- Author
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Li, Feng, Ji, Xiaoli, Wang, Xiangjian, Dai, Changshun, Wang, Xuan, Chen, Siyu, Liu, Wei, Long, Mingsheng, Shan, Lei, Qi, He, Wang, Jianli, Wang, Chunchang, and Cheng, Zhenxiang
- Subjects
- *
PYROELECTRICITY , *FERROELECTRICITY , *FERROELECTRIC crystals , *COOLING , *ENTROPY - Abstract
A synergistic realization of high electrocaloric effect (ECE) and excellent temperature stability in ferroelectrics are foundation for practical applications, which is, however, a major challenge in ferroelectric cooling community thus far. In confront with this long‐standing issue, an emergent monomorphic ferrodistortion strategy in NaNbO3‐based relaxor is proposed with flexible tetragonal polar nanoregions immersing in short‐range oxygen octahedral tilt. This not only contributes to large quantities of polar entities to increase entropy change but also produces highly robust oxygen octahedral tilt to persist ferroelectricity and obstruct thermal agitations. Therefore, a high Δ
T of 0.96 K and an ultrawide temperature span ΔT span of 110 K with a record‐high figure of merit of 4.74 is achieved in Ta‐doped NaNbO3‐BaTiO3 ceramics and these superior EC performances present a remarkable breakthrough in ferroelectric bulks cooling. This work thus provides an innovative way of utilizing ferrodistortive relaxor feature with polar nanoregions immersing in oxygen octahedral tilt to simultaneously boost EC value and temperature stability and thus monomorphic ferrodistortion is proposed as an effective strategy to develop high‐performance entropy‐change materials. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
66. Nanoscale Engineering of Wurtzite Ferroelectrics: Unveiling Phase Transition and Ferroelectric Switching in ScAlN Nanowires.
- Author
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Wang, Ding, Wang, Ping, Mondal, Shubham, Hu, Mingtao, Wu, Yuanpeng, Wang, Danhao, Sun, Kai, and Mi, Zetian
- Abstract
The pursuit of extreme device miniaturization and the exploration of associated physical phenomena has spurred significant interest in crystallographic phase control and ferroelectric switching in reduced dimensions. The recently discovered wurtzite ferroelectrics offer intriguing piezoelectric and ferroelectric properties, CMOS compatibility, and seamless integration with mainstream semiconductor technology. In this study, we present a comprehensive investigation of the crystallographic phase transition of ScAlN nanowires across the full Sc compositional range. While a gradual transition from wurtzite to cubic phase was observed with increasing Sc composition, we further demonstrate that a highly ordered wurtzite phase ScAlN can be confined at the ScAlN/GaN interface for Sc contents surpassing what is possible in conventional films. We provide the first evidence of ferroelectric switching in ScAlN nanowires, a result that holds significant implications for future device miniaturization. Our demonstration of tunable ferroelectric ScAlN nanowires opens new possibilities for nanoscale, domain, alloy, strain, and quantum engineering of wurtzite ferroelectrics, representing a significant stride toward the development of next-generation, miniaturized devices based on wurtzite ferroelectrics. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
67. Ferroelectricity in CsPb2Nb3O10 and exfoliated 2D nanosheets.
- Author
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Li, Yan, Shimada, Masanari, Kobayashi, Makoto, Yamamoto, Eisuke, Canton-Vitoria, Ruben, Liu, Xiaoyan, and Osada, Minoru
- Subjects
- *
PIEZORESPONSE force microscopy , *FERROELECTRICITY , *PEROVSKITE , *FERROELECTRIC crystals , *NANOSTRUCTURED materials - Abstract
Pb-based perovskites play pivotal roles in ferroelectric research. In the search for new Pb-based ferroelectrics, we investigated the ferroelectric properties of Dion–Jacobson type CsPb2Nb3O10 and exfoliated 2D nanosheets. Ferroelectricity in CsPb2Nb3O10 was demonstrated for the first time. CsPb2Nb3O10 adopted a polar tetragonal structure with a modest TC = 260 °C and polarization PS = 7.93 μC cm−2; the polarization mainly arose from the out-of-plane displacements of Nb5+ ions and nearby oxygens. CsPb2Nb3O10 layered perovskite offers additional advantages for tailoring ferroelectric nanomaterials, as exfoliated 2D nanosheets provide novel platforms for investigating ferroelectric properties down to the 2D limit. Piezoresponse force microscopy confirmed stable ferroelectricity even in exfoliated 2D Pb2Nb3O10 nanosheets. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
68. Reconfigurable van der Waals Ferroionic Barristor for Multifunctional Nanoelectronics.
- Author
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Ding, Jiahui, Cheng, Ruiqing, Hou, Yutang, Wang, Yanrong, Yin, Lei, Wen, Yao, Wang, Zhenxing, Feng, Xiaoqiang, Zhai, Baoxing, Chang, Sheng, Wang, Fang, and He, Jun
- Subjects
- *
IONIC conductivity , *NANOELECTRONICS , *FERROELECTRICITY , *TRANSISTORS , *IONS - Abstract
2D materials have been interested in recent years due to their unique properties and enormous potential in various fields. In particular, 2D ferroionics with both ferroelectricity and ionic conductivity shed light on new possibilities for van der Waals nanoelectronics. Here, supported by theoretical calculations and electrical characterizations, the reconfigurable van der Waals ferroionic barristor that can be used in multifunctional electronics including resistive devices and steep‐slope transistors is reported. Large modulation on the device properties is achieved by electrically driven migration and redistribution of mobile ions. The memory device shows an unprecedented long‐term stability with a switching ratio of ≈1010. Utilizing this ferroionic nature, 2D transistors able to beat the Boltzmann tyranny, with different gate configurations, are designed. The subthreshold swing (SS) exhibits sub‐60 mV per decade values over five decades of the drain current with a minimum of 12.1 mV per decade. This work paves the way for investigating the symbiotic relationship of ferroelectricity and ionic activities in van der Waals ferroionics and highlights their applications in advanced nanoelectronics. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
69. Enhanced Ferroelectric Polarization in Au@BaTiO3 Yolk‐in‐Shell Nanostructure for Synergistic Boosting Visible‐Light‐ Piezocatalytic CO2 Reduction.
- Author
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Hu, Jun, Zhao, Rufang, Ni, Jingren, Luo, Wei, Yu, Hongjian, Huang, Hongwei, Wu, Boyuan, Wang, Yang, Han, Jie, and Guo, Rong
- Subjects
- *
POLARIZATION (Electricity) , *GOLD nanoparticles , *CHEMICAL energy conversion , *FERROELECTRICITY , *CHEMICAL energy , *IRRADIATION , *PHOTOREDUCTION - Abstract
Developing efficient photo‐piezocatalytic systems to achieve the conversion of renewable energy to chemical energy emerges enormous potential. However, poor catalytic efficiency remains a significant obstacle to future practical applications. Herein, a series of unique Au@BaTiO3 (Au@BT) yolk‐shell nanostructure photo‐piezocatalyst is constructed with single Au nanoparticle (Au NP) embedded in different positions within ferroelectric BaTiO3 hollow nanosphere (BT‐HNS). This special structure showcases excellent mechanical force sensitivity and provides ample plasmon‐induced interfacial charge‐transfer pathways. In addition, the powerful piezoelectric polarization electric field induced by the enhanced ferroelectric polarization electric field via corona poling treatment in BT‐HNS further promotes charge separation, CO2 adsorption and key intermediate conversion. Notably, BT with single Au NP encapsulated into hollow nanosphere shell with reinforced polarization (Au@BT‐1‐P) shows synergistically improved photo‐piezocatalytic CO2 reduction activity for producing CO with a high production rate of 31.29 µmol g−1 h−1 under visible light irradiation and ultrasonic vibration. This work highlights a generic tactic for optimized design of high‐performance and multifunctional nanostructured photo‐piezocatalyst. Meanwhile, these yolk‐in‐shell nanostructures with single Au nanoparticle as an ideal model may hold great promise to inspire in‐depth exploration of carrier dynamics and mechanistic understanding of the catalytic reaction. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
70. Supramolecular Rotor Assembly for the Design of a Hybrid Ferroelectric‐Antiferromagnetic Multiferroic Semiconductor.
- Author
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Wang, Na, Li, Hua‐Kai, Shen, Huai‐Yi, Ye, Le, Xu, Ze‐Jiang, Ren, Mei‐Ling, Yao, Nian‐Tao, Shi, Chao, Ye, Heng‐Yun, and Miao, Le‐Ping
- Subjects
- *
PHOTOELECTRIC devices , *ANTIFERROMAGNETISM , *FERROELECTRICITY , *FERROELECTRIC crystals , *SEMICONDUCTORS - Abstract
Ferroelectric (FE)‐antiferromagnetic (AFM) multiferroic materials have sparked growing interest due to their huge possibilities in energy‐saving, photoelectric devices, nonvolatile storage, and switches. However, realizing FE‐AFM properties in a hybrid molecular material is difficult because ferroelectric and magnetic orders are commonly mutually exclusive. Here, we report an FE‐AFM multiferroic semiconductor [NH4(18‐crown‐6)]2[Mn(SCN)4] (
NCMS ) by supramolecular assembly approach via molecular rotor synthon [NH4(18‐crown‐6)] and inorganic magnetic module [Mn(SCN)4]. Interestingly,NCMS shows good ferroelectricity with a spontaneous polarization (P s) of 5.94 μC cm−2 higher than most crown‐ether‐based ferroelectrics. Especially, the realization of antiferromagnetism is for the first time in the crown ether hybrid perovskite ferroic systems. Additionally, semiconductorNCMS displays an X‐ray radiation detection response with a large photo/dark current on‐off ratio (197). Our study not only gives a deep insight into understanding multiferroic properties but also provides a novel and efficient approach to realizing high‐performance hybrid multiferroic materials. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
71. Perspective on 2D perovskite ferroelectrics and multiferroics.
- Author
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Zhang, Junting, Xie, Yu, Ji, Ke, and Shen, Xiaofan
- Subjects
- *
FERROELECTRIC materials , *FERROELECTRIC crystals , *ELECTRONIC equipment , *FERROELECTRICITY , *ENERGY consumption - Abstract
Two-dimensional (2D) ferroelectrics and multiferroics have attracted considerable scientific and technological interest in recent years due to the increasing demands for miniaturization and low energy consumption of electronic devices. At present, the research on 2D ferroelectrics and multiferroics is still focused on van der Waals materials, while the known bulk ferroelectric and multiferroic materials are mostly found in perovskite systems. The ability to prepare and transfer 2D perovskite oxides has provided unprecedented opportunities for developing ferroelectrics and multiferroics based on 2D perovskites. In this Perspective, we review the research progress on 2D ferroelectrics and multiferroics in inorganic perovskites in terms of different ferroelectric and magnetoelectric coupling mechanisms. The improper ferroelectricity and novel magnetoelectric coupling mechanisms discovered in 2D perovskites are emphasized, and then, the main challenges and future development direction are put forward. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
72. Self-Powered Deep-Ultraviolet Photodetector Driven by Combined Piezoelectric/Ferroelectric Effects.
- Author
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Hoang Huy, Vo Pham and Bark, Chung Wung
- Subjects
- *
FERROELECTRICITY , *PIEZOELECTRICITY , *QUANTUM dots , *PHOTODETECTORS , *GALLIUM - Abstract
In this study, in situ piezoelectricity was incorporated into the photoactive region to prepare a self-powered deep-ultraviolet photodetector based on a mixture of polyvinylidene fluoride (PVDF)@Ga2O3 and polyethyleneimine (PEI)/carbon quantum dots (CQDs). A ferroelectric composite layer was prepared using β-Ga2O3 as a filler, and the β-phase of PVDF was used as the polymer matrix. The strong piezoelectricity of β-PVDF can facilitate the separation and transport of photogenerated carriers in the depletion region and significantly reduce the dark current when the device is biased with an external bias, resulting in a high on/off ratio and high detection capability. The self-powered PD exhibited specific detectivity (D* = 3.5 × 1010 Jones), an on/off ratio of 2.7, and a response speed of 0.11/0.33 s. Furthermore, the prepared PD exhibits excellent photoresponse stability under continuous UV light, with the photocurrent retaining 83% of its initial value after about 500 s of irradiation. Our findings suggest a new approach for developing cost-effective UV PDs for optoelectronic applications in related fields. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
73. Improved ferroelectricity and endurance in Ca doped Hf0.5Zr0.5O2 films.
- Author
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Yin, Lu, Li, Xinyu, Xiao, Duoduo, He, Sijia, Zhao, Ying, Peng, Qiangxiang, Yang, Qiong, Liu, Yunya, and Wang, Chuanbin
- Subjects
- *
CHEMICAL solution deposition , *STRAY currents , *HAFNIUM oxide , *SURFACE roughness , *FERROELECTRICITY - Abstract
Doped Hf 0.5 Zr 0.5 O 2 materials have drawn increasing attention due to the excellent ferroelectric properties, but the relevant research is just in the preliminary stage and the reported doped systems are rare. In this work, Ca doped Hf 0.5 Zr 0.5 O 2 (Ca:HZO) ferroelectric films were successfully fabricated via chemical solution deposition and investigated for the first time. It is observed that Ca doping induces a phase transformation from monoclinic to orthorhombic/tetragonal and then to monoclinic/tetragonal. The highest orthorhombic phase fraction is achieved in 2.5 mol% Ca doped HZO film, contributing to the optimum ferroelectric property with the largest remnant polarization of 14.00 μC/cm2 after 105 cycles. Additionally, the leakage current density is observed to decrease with increasing Ca content, which is mainly associated with the changes of grain size and surface roughness. As a result, the endurance is significantly improved in the Ca doped films, and an excellent endurance of 1010 cycles is achieved in the 2.5 mol% Ca doped film. These results suggest that Ca doping can enhance the ferroelectric and endurance properties of HZO films by optimizing the phase and morphological structure. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
74. Room temperature superparaelectric state in 20BaTiO3-60V2O5-20Bi2O3 glass for capacitive energy storage applications.
- Author
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El-Desoky, M. M., Morad, Ibrahim, Fareed, Shereef A., and Harby, Amany E.
- Subjects
- *
PHYSICAL & theoretical chemistry , *DIELECTRIC materials , *ENERGY density , *PERMITTIVITY , *FERROELECTRICITY - Abstract
Materials with high dielectric constant exhibit excellent charge storage capacity, making them favorable solutions for next-generation dielectric capacitors. The glass system with the composition of 20BaTiO3-60V2O5-20Bi2O3 was prepared by conventional melt quenching technique. The glassy nature of the sample was confirmed by using DSC and XRD measurement while the existence of nano polar cluster inside the glass matrix was confirmed using HRTEM. The real permittivity (ε\) value shows two peaks in which the dielectric constant gradually increases up to a maximum value (εm) with the increase in temperature, and then it smoothly decreases, suggesting two phase transitions around 180 and 280 ◦ C. The measurements of the P–E hysteresis loop illustrated energy storage density of 124 mJ/cm3 and energy storage efficiency about 84% at room temperature. The glass sample shows superparaelectric behavior confirmed by the dielectric and P-E loop measurements. For high-energy storage applications, dipolar glasses have more outstanding potential than conventional ceramic dielectrics. Eventually, the glass matrix maintains high breakdown strength and can effectively stabilize nanocluster phases. So, we consider the present glass sample to be a good candidate for capacitive energy storage applications. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
75. Mapping Sliding Ferroelectricity in Bulk (PbS)1.11VS2 Crystals.
- Author
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Antunes Corrêa, Cinthia, Volný, Jiří, Uhlířová, Klára, and Verhagen, Tim
- Subjects
- *
PIEZORESPONSE force microscopy , *DISLOCATION structure , *HYSTERESIS loop , *FERROELECTRICITY , *HETEROSTRUCTURES - Abstract
The recent discovery of sliding ferroelectricity opens up the field of 2D ferroelectricity. However, the limitation to switching the polarization due to the topological protection of the domain walls limits the potential of these heterostructures. Here, the switching of sliding ferroelectric bulk misfit layer compound (PbS)1.11VS2 crystals is studied using switching spectroscopy piezoresponse force microscopy. A large number of measured hysteresis loops can be efficiently analyzed using unsupervised machine‐learning tools. Different switching behavior of the domains is observed on different types of domain structures, and it is shown that full domain switching can be observed for the right type of dislocation structure in the PbS layer. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
76. Ferroelectricity‐Induced Surface Ferromagnetism in Core–Shell Magnetoelectric Nanoparticles.
- Author
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Canhassi, Carlos A. I., Chernozem, Roman V., Chernozem, Polina V., Romanyuk, Konstantin N., Zelenovskiy, Pavel, Urakova, Alina O., Gerasimov, Evgeny Y., Koptsev, Danila A., Surmeneva, Maria A., Surmenev, Roman A., Kholkin, Andrei L., and Kopelevich, Yakov
- Subjects
- *
MAGNETOELECTRIC effect , *PIEZORESPONSE force microscopy , *EXCHANGE bias , *MAGNETIC fields , *MAGNETIC force microscopy - Abstract
Magnetoelectric nanoparticles (NPs) present an important class of nanomaterials with a wide interest in piezocatalytic and biomedical applications. Herein, the results of magnetoelectric and magnetization measurements performed on core–shell NPs having magnetic core (MnFe2O4, MFO) and ferroelectric shell (Ba0.85Ca0.15Ti0.5Zr0.5O3, BCZT) synthesized by the microwave hydrothermal method are reported. Magnetic results are compared with the measurements on reference MFO NPs prepared under identical conditions. Detailed SQUID magnetometer measurements of the magnetization hysteresis loops M(H) down to 2 K reveal the existence of a clear exchange bias effect in pure MFO NPs attributed to the coexistence of ferromagnetic and antiferromagnetic short‐range interactions. When the magnetic core is covered by the thin ferroelectric BCZT shell, it is observed that 1) the shell suppresses the apparent bias effect and 2) induces an "extra" ferromagnetic magnetization at T < 20 K. The results indicate that this "extra" ferromagnetism has a 2D character and it is most likely related to the interface interactions between the MFO core and BCZT shell. Ferroelectric properties and strong magnetoelectric effect in core–shell NPs are revealed via piezoresponse force microscopy under magnetic field. The mechanisms of the observed effects are discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
77. The Directional Design of the Quasi‐Phase‐Matching Short‐Wave Ultraviolet Nonlinear Optical Crystal.
- Author
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Sha, Hongyuan, Yang, Dongling, Shang, Yanran, Wang, Zujian, Su, Rongbing, He, Chao, Su, Bin, Yang, Xiaoming, Long, Xifa, and Pan, Shilie
- Subjects
- *
NONLINEAR optical materials , *ATOMIC displacements , *HYSTERESIS loop , *PIEZOELECTRICITY , *FERROELECTRICITY - Abstract
Since the study of short‐wave ultraviolet nonlinear optical crystals based on the quasi‐phase‐matching principle will effectively expand the development field of nonlinear optical materials, it is urgent to achieve their directional design. Here, it is proposed and implemented on account of the hexagonal wurtzite structure. Thus, the LiRbSeO4 crystal is obtained with [SeO4] groups as the main tetrahedra and [LiO4] as the separation. It exhibits a wide transparency window (0.22–5.57 µm) and an excellent nonlinear optical effect (≈1.7 × KH2PO4), which originates from the synergy of distorted tetrahedral groups and their uniform arrangement. More importantly, the LiRbSeO4 crystal is confirmed to be a ferroelectric with a typical polarization‐electric field hysteresis loop (a coercive field of 27.71 kV cm−1, a remanent polarization of 8.60 µC cm−2 at 373 K). Its ferroelectricity is further identified by the domain engineering studies, involving piezoelectricity and the chirality. Besides, ferroelectricity is attributed to the ordered arrangement of tetrahedra with the polarization reversal involving atomic displacements. Therefore, the LiRbSeO4 crystal is a promising short‐wave ultraviolet nonlinear optical candidate based on the quasi‐phase‐matching principle. This work also provides a new horizon for the design of nonlinear optical crystals. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
78. Synthesis, morphological and optical properties impact on transition metal ion (Co and Mn)-doped barium strontium titanate (BST) ferroelectric ceramics towards enhanced optoelectronic device applications.
- Author
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Chaudhary, Mikanshi, Jindal, Shilpi, and Devi, Sheela
- Subjects
- *
BARIUM strontium titanate , *TRANSITION metal ions , *OPTICAL properties , *FERROELECTRICITY , *OPTOELECTRONIC devices - Abstract
Barium strontium titanate (BST) is a perovskite material, which is used directly in various applications including thermistors, electromechanical actuators, sensors and ceramic capacitors. Here, we have investigated the impact of dopant (Mn and Co) on synthesized BST nanoparticles and its morphological, structural, vibrational and optical properties have been investigated through scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence (PL), FTIR and Raman spectroscopies. SEM image showed the nearly spherical grain for pure BST and doped (Mn and Co) BST samples. The estimated particles were strongly influenced by different dopants, in addition, Mn-doped BST showed maximum grain growth for pure and Co-doped BST samples. XRD patterns have been employed to investigate the microstructural parameters (phase, lattice, crystallite size, strain, dislocation density, etc.). The crystallite sizes have been estimated using the Scherrer formula, showing maximum crystallite size for Mn-doped BST ceramics. Recorded FTIR spectra showed the transmission peak, which is centred at wavenumber of 470 cm−1 (pure BST), was shifted to 1250 cm−1 with Mn-doped BST. Raman spectra exhibited the increased number of modes from pure BST to Mn-doped BST sample. PL showed the emissions bands, which were observed at 602–659 nm. Here, the peak shifted towards higher wavelength from pure BST to Mn-doped BST (red shifting from pure to Mn-doped BST). It revealed that the prepared samples can be employed as suitable photoluminar material. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
79. Frozen in time: A review of non‐ergodic physical systems.
- Author
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Bossen, Aaron M. and Mauro, John C.
- Subjects
- *
FERROELECTRIC materials , *GLASS transitions , *FERROELECTRICITY , *THERMODYNAMICS , *FRUSTRATION - Abstract
The common feature of non‐ergodic systems is an internal timescale that greatly exceeds the external observational timescale tobs${t}_{obs}$. This kinetic state of broken ergodicity occurs in many systems, with profound thermodynamic implications. In this work, we present a review of non‐ergodic physical systems focused on the common origins of non‐ergodic behavior across diverse material systems. We begin with a theoretical discussion of energy landscapes and two treatments of thermodynamics in broken ergodic systems. We then discuss several characteristic material classes that exhibit non‐ergodic behavior, describing the process of ergodic breakdown and its signatures for each. The disordered nature and frustration of different energetic interactions in the example systems are discussed as the possible origin of non‐ergodic dynamics. We conclude with several considerations that can assist in the identification of non‐ergodic behavior. This review intends to unify the behavior of a diverse group of physical systems with a common description to aid future discussions between these fields of study. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
80. Strong ferroelectricity in one-dimensional materials self-assembled by superatomic metal halide clusters.
- Author
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Guo, Yu, Zhao, Yang, Ling, Qiao, Zhou, Si, and Zhao, Jijun
- Abstract
Cluster-assembled materials have long been pursued as they can create some unprecedented and desirable properties. Herein, we assemble a class of one-dimensional (1D) ReNX
4 (X = F, Cl, Br and I) and MF5 (M = V, Nb and Ta) nanowires by covalently linking their superatomic clusters. These assembled 1D nanowires exhibit outstanding energetic and dynamic stabilities, and hold sizable spontaneous polarization, low ferroelectric switching barriers and high critical temperature. Their superior ferroelectricity is originated from d0 -configuration transition metal ions generated by the hybridization of empty d orbitals of metal atoms and p orbitals of non-metal atoms. These critical insights pave a new avenue to fabricate 1D ferroelectrics toward the development of miniaturized and high-density electronic devices using building blocks as cluster with precise structures and functionalities. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
81. A Z/E isomeric cation designed organic-inorganic cadmium chloride ferroelectric with broadband white-light emission.
- Author
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Qi, Jun-Chao, Qin, Yan, Peng, Hang, Lv, Hui-Peng, Bai, Yong-Ju, Shen, Xin, Xia, Zhang-Tian, and Liao, Wei-Qiang
- Abstract
Hybrid organic-inorganic metal halides (HOMHs) have attracted tremendous interest in the past decades due to their diverse functional properties, such as ferroelectricity and luminescence. However, although a large number of ferroelectric HOMHs and luminescent HOMHs have been reported, the HOMH ferroelectrics with white-light emission remain very sparse. Here, for the first time, by using the Z/E isomeric organic cation, we designed a cadmium-based HOMH ferroelectric [EE-PMU]CdCl
4 (EE-PMU = pyridin-2-ylmethanamide muconate) with broadband white-light emission. In contrast to the [ZZ-PMU]CdCl4 with centrosymmetric crystal structure at room temperature, [EE-PMU]CdCl4 adopts the polar crystal symmetry, which shows piezoelectricity with a piezoelectric coefficient of d33 up to 19 pC/N and ferroelectricity with the saturated polarization of 1.52 µC/cm2 . Moreover, [EE-PMU]CdCl4 exhibits a broadband white-light emission with an ultra-high color rendering index of 91 under UV excitation, which is related to the severely distorted [CdCl4 ]2− tetrahedron in the structure. To our knowledge, [EE-PMU]CdCl4 is the first example of Z/E isomeric cation-designed HOMH ferroelectric and the first cadmium halide white-light emissive ferroelectric. This finding paves a new way for the design of organic-inorganic molecular ferroelectrics with white-light emission. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
82. Passive control strategy of inductive power transfer to microimplants based on ferroelectric dielectrics.
- Author
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Olsommer, Yves and Ihmig, Frank R.
- Subjects
FERROELECTRIC devices ,DIELECTRIC devices ,FERROELECTRICITY ,HYSTERESIS ,ELECTRIC potential - Abstract
In this study, a passive control strategy of inductive power transfer (IPT) using ferroelectric multilayer ceramic chip capacitors (MLCCs) is presented. The required system parameters, i.e., ferroelectric hysteresis, frequency of the IPT, and voltage range across the MLCCs are reported. The receiver circuit consists only of a parallel resonant circuit, a halfwave rectifier and a load; the passive control of the IPT is achieved exclusively by the nonlinear properties of the ferroelectric MLCCs. The stabilization of the secondary output voltage ULoad at constant load is experimentally evaluated for an inductive coupling factor k between 10 % and 30 % for three nonlinear MLCCs #1, #2 and #3. With our proposed passive control strategy ULoad is maintained at -1.2 % and +0.6 % around a median value of 17.3 V (17.1 - 17.4 V) for k ∈ [20 %, 30 %] using MLCC #1, ±0.9 % around a median value of 11.2 V (11.1 - 11.3 V) for k ∈ [10 %, 18 %] using MLCC #2, and -1.6% and +2.6 % around a median value of 5.03 V (4.95 - 5.16 V) for k ∈ [16 %, 30 %] using MLCC #3. The proposed control principle is particularly advantageous for highly miniaturized microimplants, as it allows IPT control without additional semiconductors, sensors and vulnerable communication channels. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
83. Memory State Dynamics in BEOL FeFETs: Impact of Area Ratio on Analog Write Mechanisms and Charging
- Author
-
Hannes Dahlberg, Oscar Kaatranen, Karl-Magnus Persson, Arto Rantala, Jacek Flak, and Lars-Erik Wernersson
- Subjects
BEOL integration ,CMOS ,FeFET ,ferroelectricity ,HZO ,non-volatile memory ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
This work presents dynamic state writing by combining ferroelectric (FE) polarization together with charge injection (CI) on Si-based ferroelectric MOSFETs as a novel approach for non-volatile memory design. FE capacitors are non-destructively integrated in the Back-End-of-Line (BEOL) with Si MOSFETs to create FE-Metal-FETs (FeMFETs). We explore the FE/MOS area ratio (AR) as a critical design parameter, particularly in the context of dynamic writing processes, where various voltage pulse trains are applied for analog potentiation and depression of the memory state. AR significantly influences both the electric field distribution over the FE and the extent of CI from the top electrode. Constant-pulse writing schemes enable analog threshold voltage modulation by considering the AR, with reduced voltages and faster operation for smaller ARs. Retention of intermittent states written by FE polarization combined with CI is demonstrated, illustrating the stability and effectiveness of FeMFET devices and AR optimization for memory applications.
- Published
- 2025
- Full Text
- View/download PDF
84. High field dielectric response in κ-Ga2O3 films.
- Author
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He, Fan, Jiang, Kunyao, Choi, Yeseul, Aronson, Benjamin L., Shetty, Smitha, Tang, Jingyu, Liu, Bangzhi, Liu, Yongtao, Kelley, Kyle P., Rayner Jr., Gilbert B., Davis, Robert F., Porter, Lisa M., and Trolier-McKinstry, Susan
- Subjects
- *
METAL organic chemical vapor deposition , *ATOMIC layer deposition , *PIEZORESPONSE force microscopy , *PERMITTIVITY , *ELECTRICAL resistivity , *FERROELECTRICITY - Abstract
κ-Ga2O3 has been predicted to be a potential ferroelectric material. In this work, undoped Ga2O3 films were grown by either plasma-enhanced atomic layer deposition (PEALD) or metal organic chemical vapor deposition (MOCVD) on platinized sapphire substrates. 50 nm thick PEALD films with a mixture of κ-Ga2O3 and β-Ga2O3 had a relative permittivity of ∼27, a loss tangent below 2%, and high electrical resistivity up to ∼1.5 MV/cm. 700 nm thick MOCVD films with predominantly the κ-Ga2O3 phase had relative permittivities of ∼18 and a loss tangent of 1% at 10 kHz. Neither film showed compelling evidence for ferroelectricity measured at fields up to 1.5 MV/cm, even after hundreds of cycles. Piezoresponse force microscopy measurements on bare κ-Ga2O3 showed a finite piezoelectric response that could not be reoriented for electric fields up to 1.33 MV/cm. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
85. Understanding the stress effect of TiN top electrode on ferroelectricity in Hf0.5Zr0.5O2 thin films.
- Author
-
Han, Runhao, Hong, Peizhen, Zhang, Bao, Bai, Mingkai, Hou, Jingwen, Yang, Jinchuan, Xiong, Wenjuan, Yang, Shuai, Gao, Jianfeng, Lu, Yihong, Liu, Fei, Luo, Feng, and Huo, Zongliang
- Subjects
- *
THIN films , *TITANIUM nitride , *FERROELECTRICITY , *LEAD titanate , *ELECTRODES , *PHASE transitions , *GRAIN size - Abstract
We conducted a comprehensive investigation on the influence of TiN thickness and stress on the ferroelectric properties of Hf 0.5 Zr 0.5 O 2 thin films. TiN top electrode layers with varying thicknesses of 2, 5, 10, 30, 50, 75, and 100 nm were deposited and analyzed. It was observed that the in-plane tensile stress in TiN films increased with the thickness of the TiN top electrode. This is expected to elevate the tensile stress in the Hf 0.5 Zr 0.5 O 2 film, consequently leading to an enhancement in ferroelectric polarization. However, the effect of stress on the ferroelectric behavior of Hf 0.5 Zr 0.5 O 2 films exhibited distinct stages: improvement, saturation, and degradation. Our study presents novel findings revealing a saturation and degradation phenomenon of in-plane tensile stress on the ferroelectric properties of polycrystalline Hf 0.5 Zr 0.5 O 2 films, thereby partially resolving the discrepancies between experimental observations and theoretical predictions. The observed phase transformation induced by tensile stress in Hf 0.5 Zr 0.5 O 2 films played a crucial role in these effects. Furthermore, we found that the impact of the TiN top electrode thickness on other factors influencing ferroelectricity, such as grain size and oxygen vacancies, was negligible. These comprehensive results offer valuable insights into the influence of stress and TiN top electrode thickness on the ferroelectric behavior of Hf 0.5 Zr 0.5 O 2 films. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
86. Tunable electrocaloric effect in selective ferroelectric bilayers via electrostatics for solid-state refrigeration and microelectronics thermal management.
- Author
-
Gupta, Sanju and Saxena, Avadh
- Subjects
- *
PYROELECTRICITY , *MORPHOTROPIC phase boundaries , *FERROELECTRICITY , *PHASE transitions , *ELECTROSTATICS , *LANDAU theory , *THERMOELECTRIC materials , *MAGNETOCALORIC effects - Abstract
Ferroelectric (FE) electrocaloric materials research has been blossoming worldwide for solid-state refrigeration and potential cooling systems replacing thermoelectric Peltier coolers in microelectronics. In this work, we report the outcomes from a systematic study of combined phase transition (thermodynamics) based on the phenomenological Landau theory and distributed electric field (electrostatics of thin film interfaces) in FE bilayer films. Specifically, the compositional variation of ferroelectric bilayers results in broken spatial inversion symmetry leading to asymmetric thermodynamic potentials due to a combination of normal (first- and second-order phase transition) and relaxor (dispersive dielectric constant) ferroelectric behaviors devised for efficient electrocaloric cooling effects. Extensive theoretical analyses conducted for bilayers consisting of insulating materials highlight modified phase transition temperature behavior and self-poling by effective electric field amplification arising due to bilayers' electrostatic coupling yielding significant changes in isothermal entropy (ΔS) and adiabatic temperature (ΔT). The theoretical calculation insights supported with experimental results signify, through case studies for a combination of materials experimental parameters, that amplification of the local electric field and materials engineering maximize the number of coexisting phases at or away from the morphotropic phase boundary of constituent layers in bilayer thin film architectures, which can be applicable toward other classes of materials and multilayer systems. These are effective ways for efficient cooling, in general, and for microelectronics thermal management either directly or by developing a thermal switch with phase change materials integrated with thermoelectric coolers for residual heat dissipation, both at the system and on-chip levels. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
87. Influence of moisture on the ferroelectric properties of sputtered hafnium oxide thin films.
- Author
-
Berg, Fenja, Kopperberg, Nils, Lübben, Jan, Valov, Ilia, Wu, Xiaochao, Simon, Ulrich, and Böttger, Ulrich
- Subjects
- *
HAFNIUM oxide films , *HAFNIUM oxide , *MONTE Carlo method , *FERROELECTRICITY , *REACTIVE sputtering - Abstract
While the influence of various fabrication parameters during deposition on the ferroelectricity of hafnium oxide has been extensively studied, the effect of different atmospheres on the actual switching process has not yet been investigated. In this work, we characterized the ferroelectric properties of undoped hafnium oxide prepared by reactive sputtering under three different atmospheres: dry oxygen/nitrogen, wet nitrogen, and vacuum conditions. We found a significant correlation between dry and wet atmospheres and resulting polarization. Specifically, we observed a direct effect on ferroelectric switching when the film was exposed to dry atmospheres and vacuum, resulting in a higher electric field necessary to initialize the wake-up effect due to an initial imprint effect. Increasing the amount of wet nitrogen during switching decreased the imprint and lowered the necessary voltage required for the wake up. We present a simple model that explains and discusses the incorporation of moisture and its resulting consequences on the ferroelectric properties of hafnium oxide. Additionally, kinetic Monte Carlo simulations showed that the addition of protons to the oxide thin film leads to a lowering of the potential and to a redistribution of protons and oxygen vacancies, which reduces the initial imprint. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
88. Regulating ferroelectricity in Hf0.5Zr0.5O2 thin films: Exploring the combined impact of oxygen vacancy and electrode stresses.
- Author
-
Bai, Mingkai, Hong, Peizhen, Han, Runhao, Chai, Junshuai, Zhang, Bao, Hou, Jingwen, Xiong, Wenjuan, Yang, Shuai, Gao, Jianfeng, Luo, Feng, and Huo, Zongliang
- Subjects
- *
OXYGEN electrodes , *THIN films , *FERROELECTRICITY , *PHASE transitions , *ELECTRODES - Abstract
Hf0.5Zr0.5O2 (HZO) is a promising candidate for low-power non-volatile memory due to its nanoscale ferroelectricity and compatibility with silicon-based technologies. Stress and oxygen vacancy (VO) are key factors that impact the ferroelectricity of HZO. However, their combined effects have not been extensively studied. In this study, we investigated the impact of the VO content on HZO thin films' ferroelectricity under different electrode stresses by using TiN and tungsten (W) top electrodes and controlling ozone dose time during HZO deposition. The HZO thin films with W top electrodes exhibit elevated stress levels and a greater abundance of orthorhombic/tetragonal phases, and the HZO thin films with TiN top electrode shows an increase in the monoclinic phase with increasing ozone dose time. The residual polarization (Pr) of the capacitors with TiN and W top electrodes displayed different or even opposing trends with increasing ozone dose time, and the VO content decreases with increasing ozone dose time for both sets of capacitor samples. We propose a model to explain these observations, considering the combined influence of electrode stresses and VO on the free and formation energy of the crystalline phase. Increasing the VO content promotes the transformation of the tetragonal phase to the orthorhombic phase in HZO films with TiN top electrodes, and with W top electrodes, a higher VO content prevents the tetragonal phase from transforming into the orthorhombic/monoclinic phase. Additionally, an alternative explanation is proposed solely from the perspective of stress. These findings provide valuable insights into the regulation of ferroelectricity in HZO thin films. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
89. Engineering Relaxor Behavior in (BaTiO3)n/(SrTiO3)n Superlattices
- Author
-
Lupi, Eduardo, Wexler, Robert B, Meyers, Derek, Zahradnik, Anton, Jiang, Yizhe, Susarla, Sandhya, Ramesh, Ramamoorthy, Martin, Lane W, and Rappe, Andrew M
- Subjects
Engineering ,Macromolecular and Materials Chemistry ,Materials Engineering ,Chemical Sciences ,BaTiO3 ,ferroelectricity ,relaxors ,SrTiO3 ,superlattices ,Physical Sciences ,Nanoscience & Nanotechnology ,Chemical sciences ,Physical sciences - Abstract
Complex-oxide superlattices provide a pathway to numerous emergent phenomena because of the juxtaposition of disparate properties and the strong interfacial interactions in these unit-cell-precise structures. This is particularly true in superlattices of ferroelectric and dielectric materials, wherein new forms of ferroelectricity, exotic dipolar textures, and distinctive domain structures can be produced. Here, relaxor-like behavior, typically associated with the chemical inhomogeneity and complexity of solid solutions, is observed in (BaTiO3 )n /(SrTiO3 )n (n = 4-20 unit cells) superlattices. Dielectric studies and subsequent Vogel-Fulcher analysis show significant frequency dispersion of the dielectric maximum across a range of periodicities, with enhanced dielectric constant and more robust relaxor behavior for smaller period n. Bond-valence molecular-dynamics simulations predict the relaxor-like behavior observed experimentally, and interpretations of the polar patterns via 2D discrete-wavelet transforms in shorter-period superlattices suggest that the relaxor behavior arises from shape variations of the dipolar configurations, in contrast to frozen antipolar stripe domains in longer-period superlattices (n = 16). Moreover, the size and shape of the dipolar configurations are tuned by superlattice periodicity, thus providing a definitive design strategy to use superlattice layering to create relaxor-like behavior which may expand the ability to control desired properties in these complex systems.
- Published
- 2023
90. First-principles property assessment of hybrid formate perovskites.
- Author
-
Popoola, Abduljelili, Ghosh, P. S., Kingsland, Maggie, Kashikar, Ravi, DeTellem, D., Xu, Yixuan, Ma, S., Witanachchi, S., Lisenkov, S., and Ponomareva, I.
- Subjects
- *
PEROVSKITE , *VALUATION of real property , *PERMITTIVITY , *DENSITY functional theory , *FERROELECTRICITY - Abstract
Hybrid organic–inorganic formate perovskites, AB(HCOO)3, are a large family of compounds that exhibit a variety of phase transitions and diverse properties, such as (anti)ferroelectricity, ferroelasticity, (anti)ferromagnetism, and multiferroism. While many properties of these materials have already been characterized, we are not aware of any study that focuses on the comprehensive property assessment of a large number of formate perovskites. A comparison of the properties of materials within the family is challenging due to systematic errors attributed to different techniques or the lack of data. For example, complete piezoelectric, dielectric, and elastic tensors are not available. In this work, we utilize first-principles density functional theory based simulations to overcome these challenges and to report structural, mechanical, dielectric, piezoelectric, and ferroelectric properties of 29 formate perovskites. We find that these materials exhibit elastic stiffness in the range 0.5–127.0 GPa; highly anisotropic linear compressibility, including zero and even negative values; dielectric constants in the range 0.1–102.1; highly anisotropic piezoelectric response with the longitudinal values in the range 1.18–21.12 pC/N; and spontaneous polarizations in the range 0.2–7.8 μC/cm2. Furthermore, we propose and computationally characterize a few formate perovskites that have not been reported yet. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
91. The effect of single-doping engineering on ferroelectric properties of α-In2Se2X: A density functional theory study.
- Author
-
Wen, Jun, Chen, Yi-Jie, Sun, Fu-Li, Lin, Cun-Biao, Zhang, Xian-Jie, Wang, Jia-Hao, Chen, Wen-Xian, and Zhuang, Gui-Lin
- Subjects
- *
DENSITY functional theory , *FERROELECTRIC materials , *CHARGE carrier mobility , *DOPING agents (Chemistry) , *MONOMOLECULAR films , *ENGINEERING , *PHONON scattering , *FERROELECTRICITY - Abstract
Tailoring the specific properties to practical applications by structural modification is of vital importance for the envisioned development of two-dimensional ferroelectric materials. Herein, a comprehensive investigation on the effects of single doping on the ferroelectric properties and electronic transport in a monolayer of α-In2Se3 was carried out via the combination of first-principles density functional theory calculations and electron–phonon coupling simulations. Our results show that single-doping in In2Se3 can reduce effective mass of carriers and thereby enhance the high carrier mobility potential of the material. Moreover, the ferroelectric phonon mode in single-doped In2Se2X features a lower scattering rate, associating with the single-doping atom, and indicates reduced hindrance to carrier transport during ferroelectric switching. Compared to pristine In2Se3, the obtained smaller ferroelectric barriers (<1 eV) of single-doped ones promote more promising ferroelectricity from the analysis of the ferroelectric soft mode. Interestingly, the observed variations in ferroelectric behaviors resulting from doping of different elements highlight the significance of single-doping in modifying the ferroelectric properties of monolayers. Furthermore, strain engineering results reveal that single doping obviously affects the dependence of gap on strains: linear relationship for doping ones and nonlinearity for pristine one. Our study provides valuable insights into achieving higher carrier mobility in these critical materials. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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92. Field-induced reversible insulator-to-metal transition and the onset of ferroelectricity in molybdenum trioxide films.
- Author
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Dragoman, Mircea, Modreanu, Mircea, Sheehan, Brendan, Vulpe, Silviu, Romanitan, Cosmin, Aldrigo, Martino, Dinescu, Adrian, Serban, Andreea Bianca, and Dragoman, Daniela
- Subjects
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REVERSIBLE phase transitions , *TRIOXIDES , *MOLYBDENUM , *METAL-insulator transitions , *FERROELECTRICITY , *ELECTRIC fields - Abstract
This paper presents the experimental evidence of reversible insulator–metal transition (IMT) in thin-film amorphous molybdenum trioxide (MoO3) induced by electric fields of just a few volts. The presence of oxygen vacancies in MoO3 is considered to play a significant role in the reported reversible IMT. The oxygen vacancies not only impact MoO3 stoichiometry but also the optical bandgap. The subthreshold slope for IMT in 10 nm-thick MoO3-based devices is 48.3 mV/decade, which represents a transition from an insulator to a metallic state, and the electric field threshold for such a transition was found to be equal to 0.034 V/Å. Following the IMT in MoO3, there are six orders of magnitude differences between the resistivity of the insulator state (27.5 M Ω at −9 V) and the metallic state (80 Ω between +5 and +9 V). In addition, we reported stabilization of a nanocrystalline hexagonal MoO3 (h-MoO3) phase in thicker MoO3 (150 nm-thick) in the presence of oxygen vacancies that behave as a wide bandgap (3.1 eV) ferroelectric semiconductor with a coercive field of about 50 kV/cm, a saturation polarization of about 30 μC/cm2, and a remanent polarization of about 10 μC/cm2. This ferroelectricity in nanocrystalline h-MoO3 (150 nm-thick) remains stable even after 8 months of storage of the sample in ambient conditions, with remanent polarization increasing up to 20 μC/cm2. These are unexpected results from MoO3. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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93. Enhancement of ferroelectricity in perovskite BaTiO3 epitaxial thin films by sulfurization
- Author
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Xuan Luc Le, Nguyen Dang Phu, and Nguyen Xuan Duong
- Subjects
sulfurization ,perovskite oxides ,ferroelectricity ,epitaxy ,thin film ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Sulfur is a promising anion dopant for exploring exotic physical phenomena in complex perovskite oxides. However, sulfurization to the epitaxial single-crystal oxide thin films with high crystallinity is experimentally challenging due to the volatility of sulfur element; thus, sulfurization effects on the associated properties have been scarcely studied. Here, we demonstrate an enhancement of ferroelectric polarization of epitaxial BaTiO3 thin films by sulfur doping. Initially, the epitaxial BaTiO3 thin films with high crystallinity were grown by pulsed laser deposition (PLD). Then, sulfurization to epitaxial BaTiO3 films was performed using a precursor of thiourea (CH4N2S) solution via a spin-coating technique. The crystalline structure of sulfurized BaTiO3 films was identified by X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM). The structural distortion with the elongated out-of-plane lattice constant was observed in the sulfurized BaTiO3 films. Atomic force microscopy (AFM) analyses also confirmed the surface morphology of films after sulfurization. Interestingly, we found an enhanced ferroelectric polarization in sulfur-doped BaTiO3 films accompanying the improved tetragonality in the crystal structure after sulfurization. The increments in the remnant (~34.8%) and saturated (~30.6%) polarizations of sulfurized BaTiO3 films were obtained in comparison with pure BaTiO3 films. Our work could be a primary study for a thorough understanding of the sulfur doping effect in perovskite oxides, opening up the potential of oxysulfide materials.
- Published
- 2024
- Full Text
- View/download PDF
94. Revealing subterahertz atomic vibrations in quantum paraelectrics by surface-sensitive spintronic terahertz spectroscopy.
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Zhaodong Chu, Junyi Yang, Yan Li, Kyle Hwangbo, Jianguo Wen, Bielinski, Ashley R., Qi Zhang, Martinson, Alex B. F., Hruszkewycz, Stephan O., Fong, Dillon D., Xiaodong Xu, Norman, Michael R., Bhattacharya, Anand, and Haidan Wen
- Subjects
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QUANTUM theory , *SURFACE dynamics , *PHONONS , *SUPERCONDUCTIVITY , *FERROELECTRICITY - Abstract
Understanding surface collective dynamics in quantum materials is crucial for advancing quantum technologies. For example, surface phonon modes in quantum paraelectrics are thought to be essential in facilitating interfacial superconductivity. However, detecting these modes, especially below 1 terahertz, is challenging because of limited sampling volumes and the need for high spectroscopic resolution. Here, we report surface soft transverse optical (TO1) phonon dynamics in KTaO3 and SrTiO3 by surface-sensitive spintronic terahertz spectroscopy that can sense the collective modes only a few nanometers deep from the surface. In KTaO3, the TO1 mode softens and sharpens with decreasing temperature, leveling off at 0.7 terahertz. In contrast, this mode in SrTiO3 broadens substantially below the quantum paraelectric crossover and coincides with the hardening of a sub-milli-electron volt phonon mode related to the antiferrodistortive transition. These observations that deviate from their bulk properties may have implications for interfacial superconductivity and ferroelectricity. The developed technique opens opportunities for sensing low-energy surface collective excitations. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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95. Ultra-tunable dielectric capacitors enhanced by coupling ferroelectric field effect and semiconductor field effect.
- Author
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Mao, Feilong, Gui, Jiashu, Hou, Yongqi, Gao, Siyuan, Zeng, Haohan, Wang, Weibiao, Xu, Zhibin, Zhu, Yifan, Fan, Li, and Zhang, Hui
- Subjects
- *
FERROELECTRICITY , *FERROELECTRIC capacitors , *INFORMATION storage & retrieval systems , *INDUCTIVE effect , *MICROWAVE filters - Abstract
Tunable ferroelectric film capacitors play an important role in tunable microwave devices and filter systems due to their high dielectric constant, low loss, and high dielectric tunability. However, there is a trade-off between low loss and high tunability, which limits further enhancement of dielectric performance. Here, we propose an ultra-tunable capacitor by designing a Ba0.7Sr0.3TiO3 (BST)–semiconductor heterostructure. In the tunable capacitor, the BST film is fabricated directly on p-type silicon substrates by magnetron sputtering, and a heterostructure layer is constructed. The coupling effects between the semiconductor depletion layer capacitance and the BST capacitance produce higher capacitance tunability than a traditional sandwich BST capacitor. Based on the coupling effects, a metal–ferroelectric–semiconductor–ferroelectric–metal capacitor is developed, which enables the capacitor to operate under both negative and positive biases, which has an n value (n = C max / C min ) of 90 with 40 V bias voltage and a maximum Q of 1000. The results offer a potential approach to designing high-performance tunable capacitors on silicon with BST film that could build tunable filters for information processing in communication systems. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
96. Atomic-level direct imaging for Cu(I) multiple occupations and migration in 2D ferroelectric CuInP2S6.
- Author
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Guo, Changjin, Zhu, Jiajun, Liang, Xiali, Wen, Caifu, Xie, Jiyang, Gu, Chengding, and Hu, Wanbiao
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SCANNING transmission electron microscopy ,COPPER ,FERROELECTRIC materials ,LATTICE constants ,FERROELECTRICITY - Abstract
CuInP
2 S6 (CIPS) is an emerging 2D ferroelectric material known for disrupting spatial inversion symmetry due to Cu(I) position switching. Its ferroelectricity strongly relies on the Cu(I) atom/ion occupation ordering and dynamics. Nevertheless, the accurate Cu(I) occupations and correlated migration dynamics under the externally applied energy, which are key to unlocking ferroelectric properties, remain controversial and unresolved. Herein, an atomic-level direct imaging through aberration-corrected scanning transmission electron microscopy is performed to precisely trace the Cu(I) dynamic behaviours under electron-beam irradiation along (100)-CIPS. It clearly demonstrates that Cu(I) possesses multiple occupations, and Cu(I) could migrate to the lattice, vacancy, interstitial and interlayer sites between the InS6 octahedral skeletons of CIPS to form local Cux InP2 S6 (x = 2-4) structure. Cu(I) multi-occupations induced lattice stress results in a layer sliding along the b-axis direction generating a sliding size of 1/6 b lattice constant. The Cux InP2 S6 (x = 2-4) exists in a type of dynamic structure, only metastable with electron dose over 50 e− Å−2 , thus generating a dynamic process of C u x In P 2 S 6 (x = 2 − 4) ⇌ CuIn P 2 S 6 , a completely unreported phenomenon. These findings shed light on the unveiled mechanism underlying Cu(I) migration in CIPS, providing crucial insights into the fundamental processes that govern its ferroelectric properties. The authors demonstrate that Cu(I) possesses multiple occupations, and Cu(I) migrate to the lattice, vacancy, interstitial and interlayer sites between the InS6 octahedral skeletons of CuInP2 S6 to form local Cux InP2 S6 (x = 2-4) structure. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
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97. Ferroelectricity‐Tuned Band Topology and Superconductivity in 2D Materials and Related Heterostructures.
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Chen, Jianyong, Cui, Ping, and Zhang, Zhenyu
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SUPERCONDUCTIVITY , *FERROELECTRICITY , *HETEROSTRUCTURES , *TOPOLOGY , *DIODES - Abstract
Ferroelectricity, band topology, and superconductivity are respectively local, global, and macroscopic properties of quantum materials, and understanding their mutual couplings offers unique opportunities for exploring rich physics and enhanced functionalities. In this mini‐review, the attempt is to highlight some of the latest advances in this vibrant area, focusing in particular on ferroelectricity‐tuned superconductivity and band topology in 2D materials and related heterostructures. First, results from predictive studies of the delicate couplings between ferroelectricity and topology or superconductivity based on first‐principles calculations and phenomenological modeling are presented, with ferroelectricity‐enabled topological superconductivity as an appealing objective. Next, the latest advances on experimental studies of ferroelectricity‐tuned superconductivity based on different 2D materials or van der Waals heterostructures are covered. Finally, as perspectives, schemes are outlined that may allow to materialize new types of 2D systems that simultaneously harbor ferroelectricity and superconductivity, or that may lead to enhanced ferroelectric superconductivity, ferroelectric topological superconductivity, and new types of superconducting devices such as superconducting diodes. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
98. Unveiling the structural, optical, electrical, and ferromagnetic properties of Ca2+ doped mixed spinel ferrites for switching field high-frequency device applications.
- Author
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Jain, Prachi, Shankar, S., and Thakur, O.P.
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- *
FIELD emission electron microscopy , *SIZE reduction of materials , *MICROWAVE devices , *UNIT cell , *X-ray diffraction - Abstract
In this paper, the calcium-doped nickel-zinc nano-ferrites [Ni 0.5 Zn 0.5 Ca x Fe 2-x O 4 ; x = 0.00, 0.10, and 0.30] were prepared using the chemical co-precipitation synthesis route and studied for switching field high-frequency device applications. The structural analysis has been completed by analyzing X-ray diffraction (XRD) patterns. The Rietveld refined XRD patterns confirmed the formation of cubic spinel structure of Ca2+ substituted nickel-zinc ferrites. The detection of metal-oxygen bonds present at A and B lattice sites has been unveiled by Fourier transform infrared (FTIR) spectroscopy. The morphological studies obtained through FESEM (Field emission scanning electron microscopy) analysis showed a reduction in the particle size from 70 nm to 53 nm when the concentration of Ca2+ ions in Ni-Zn ferrites was increased. Energy dispersive spectra (EDS) confirmed the presence of elements present in the prepared composition. The structure of a cubic spinel-shaped unit cell has been verified from three active prominent Raman modes (A 1g , A 2g , and T 2g). Diffuse-reflectance spectroscopy (DRS) exhibits the increment in the bandgap values (from 1.55 eV to 1.63 eV) which helps fabricate highly efficient photovoltaic devices. The ferroelectric measurements yielded a rise in polarization values from 1.461 μC/cm2 to 18.228 μC/cm2 for 10 % Ca2+ ion substitution. The tangent loss values declined from 24 to 3 in Ni-Zn ferrites upon substituting Ca2+ ions. The Vibrating sample Magnetometer (VSM) technique found the increment in the saturation magnetization (M s) values from 34.724 emu/g to 54.662 emu/g on substituting up to 30 % Ca2+ ions in Ni-Zn ferrites. These obtained results support the material in switching field distribution for high-frequency applications. The results exhibited that the prepared samples can be applicable for switching devices, filters, and microwave absorption devices. The results revealed the maximum frequency between 12 and 18 GHz which is useful for Ku band absorption. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
99. Anomalous Polarons in Two‐Dimensional Organometallic Perovskite Ferroelectric.
- Author
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Yu, Junhong, Han, Yadong, Yang, Yunfan, Zhang, Hang, Liu, Yi, Xu, Jinlong, Sun, Zhihua, and Hu, Jianbo
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- *
LEAD halides , *PEROVSKITE , *FERROELECTRICITY , *PHYSICS , *METHYLAMMONIUM - Abstract
The concept of ferroelectric polarons is proposed to partially explain the exceptional optoelectronic properties observed in lead halide perovskites (LHPs). It is intriguing but unclear how this proposal, which involves local or transient polarizations, applies in general to 2D LHPs with long‐range ferroelectricity. Here, this work presents a pioneering time‐domain experimental investigation of polarons in ferroelectric (IA)2(MA)2Pb3Br10 (IMPB; IA is isoamylammonium and MA is methylammonium) using transient absorption spectroscopy. Compared to non‐ferroelectric LHPs, IMPB exhibits several distinct polaronic properties closely associated with macroscopic polarizations of ferroelectricity, including a prolonged polaron formation time (≈1.1 ps), a Stark splitting of the bleaching (≈63 meV), and a giant polaron Mott density (≈7.6 × 1018 cm−3). These findings broaden the realm of 2D polaron systems and reveal the decisive role of static/unidirectional polarizations on polaron physics in 2D LHPs. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
100. Transverse size effect of relaxor ferroelectric Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 film for one- and two-dimensional integrated sensors by simulation.
- Author
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Liang, Cao, Gong, Zhentao, Wang, Simin, Wei, Mianhao, Zhang, Qiaozhen, Duan, Zhihua, Wang, Tao, Tang, Yanxue, Zhao, Xiangyong, and Wang, Feifei
- Subjects
- *
PYROELECTRIC detectors , *PERMITTIVITY , *THIN films analysis , *FERROELECTRICITY , *SENSOR arrays - Abstract
In this work, the transverse size effect of the new-generation relaxor ferroelectric Pb(In 1/2 Nb 1/2)O 3 -Pb(Mg 1/3 Nb 2/3)O 3 -PbTiO 3 (PIMNT) thin film was studied by finite element method, aiming to revealing the lateral size and shape dependence of the piezoelectric, dielectric, and pyroelectric behavior for guiding one- and two-dimensional integrated array sensor applications. The results indicated that as the aspect ratio (width to thickness ratio) decreased from 100 to 0.01, for both one-dimensional rectangular and two-dimensional square PIMNT array elements, a sharp increase in piezoelectric and dielectric constants could be observed for the PIMNT with <001> direction while a slight increase could be found for those along <111> orientation, exhibiting a strong orientation dependence. In comparison, the PIMNT with <110> direction exhibited strong shape dependence. The piezoelectric and dielectric constants of <110>-oriented square element increased more remarkably than those of the rectangular one. The pyroelectric coefficients of PIMNT exhibited weak shape dependence, decreasing from 8.5 × 10−4 C/(m2·K) to about 8.0 × 10−4 C/(m2·K) for both element shapes with transverse size decreasing. These findings give insight into the transverse size and shape effect on the new-generation PIMNT thin film and provide a guide for its design in one- and two-dimensional piezoelectric and pyroelectric array sensor applications. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
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