90 results on '"Xiangdong Ding"'
Search Results
2. Calix[4]arene-Decorated Covalent Organic Framework Conjugates for Lithium Isotope Separation
- Author
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Rui Ha, Fuzhu Liu, Jie Li, Meng He, Jianhui Lan, Bowei Wang, Jun Sun, Xue Liu, Xiangdong Ding, and Weiqun Shi
- Subjects
General Materials Science - Published
- 2023
3. Reducing Threshold of Ferroelectric Domain Switching in Ultrathin Two-Dimensional CuInP2S6 Ferroelectrics via Electrical–Mechanical Coupling
- Author
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Weijie Yang, Shengjie Chen, Xiangdong Ding, Jun Sun, and Junkai Deng
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General Materials Science ,Physical and Theoretical Chemistry - Published
- 2023
4. Lithium salt-regulated dual-stabilized elastomeric quasi-solid electrolyte for high-voltage lithium metal batteries
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Yali Liu, Youlong Xu, Jing Wang, Yao Niu, and Xiangdong Ding
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Renewable Energy, Sustainability and the Environment ,General Materials Science ,General Chemistry - Abstract
An elastomeric quasi-solid electrolyte was fabricated by the incorporation of LiDFOB. LiDFOB facilitated uniform lithium deposition morphology and decomposed to form a LiF-rich CEI to enhance the high-voltage (4.7 V) battery performance.
- Published
- 2023
5. Writing‐Speed Dependent Thresholds of Ferroelectric Domain Switching in Monolayer α ‐In 2 Se 3
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Weijie Yang, Bo Cheng, Jianhua Hou, Junkai Deng, Xiangdong Ding, Jun Sun, and Jefferson Zhe Liu
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General Materials Science ,General Chemistry - Published
- 2023
6. Coal‐Based Carbon Nanomaterials: En Route to Clean Coal Conversion toward Net Zero CO 2
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Mingjin Du, Paul A. Advincula, Xiangdong Ding, James M. Tour, and Changsheng Xiang
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Mechanics of Materials ,Mechanical Engineering ,General Materials Science - Published
- 2023
7. Tailoring Grain Size and Precipitation via Aging for Improved Elastocaloric Stability in a Cold-Rolled (Ni,Cu)-Rich Ti–Ni–Cu Alloy
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Pengfei Dang, Yumei Zhou, Xiangdong Ding, Jun Sun, Turab Lookman, and Dezhen Xue
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Mechanics of Materials ,General Materials Science - Published
- 2023
8. Giant energy storage of flexible composites by embedding superparaelectric single-crystal membranes
- Author
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Tian Wang, Xiaoming Shi, Ruobo Peng, Guohua Dong, Haixia Liu, Bohan Chen, Mengmeng Guan, Yanan Zhao, Bin Peng, Chao Zhou, Sen Yang, Wanbo Qu, Yang Zhang, Ziyao Zhou, Xiangdong Ding, Haijun Wu, Houbing Huang, and Ming Liu
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Renewable Energy, Sustainability and the Environment ,General Materials Science ,Electrical and Electronic Engineering - Published
- 2023
9. Avalanches during ferroelectric and ferroelastic switching in barium titanate ceramics
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Yangyang Xu, Guomang Shao, Jianbo Pang, Yumei Zhou, Xiangdong Ding, Jun Sun, Turab Lookman, E. K. H. Salje, and Dezhen Xue
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Physics and Astronomy (miscellaneous) ,General Materials Science - Published
- 2022
10. Unraveling the mechanism of optimal concentration for Fe substitution in Na3V2(PO4)2F3/C for Sodium-Ion batteries
- Author
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Youlong Xu, Xiangdong Ding, Rui Chang, Long Li, Chao Wang, and Shengnan He
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Materials science ,Renewable Energy, Sustainability and the Environment ,Fermi level ,Energy Engineering and Power Technology ,02 engineering and technology ,Activation energy ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Electric charge ,Cathode ,0104 chemical sciences ,Ion ,law.invention ,symbols.namesake ,Transition metal ,Chemical physics ,Atomic electron transition ,law ,symbols ,General Materials Science ,0210 nano-technology - Abstract
It is generally accepted that there is always an optimal concentration of transition metal substitution for the best possible electrochemical performance in cathode materials. This mechanism is crucial, yet normally overlooked. Herein we present a model based on Fe substitution in Na3V2(PO4)2F3 (Na3V2-2xFe2x(PO4)2F3), with the optimal stoichiometry at x=0.03, and discover this optimal concentration is mainly determined by the volcanic electronic conductivity and electron activation energy. Experimental measurements discover the electron charge transfer process from V to Fe ions. Initially, Fe ions hog the electrons upon increasing substitution, but gradually the overwhelming of the charge transfer leads to the drop of electron transition ability of the major V ions. First-principle calculations confirm the volcanic trend and charge transfer process in electronic properties, resulting in the Fermi level moves close to conduction band and then moves away in n-type Na3V2(PO4)2F3 crystal upon increasing substitution. Meanwhile, in situ electrochemical impedance spectroscopy detects the Na+ diffusivity increases monotonously upon increasing substitution. These findings unravel the mechanism for optimum transition metal substitution, providing a new understanding for similar phenomena in other cathode materials.
- Published
- 2021
11. Diverse electronic and magnetic properties of CrS2 enabling strain-controlled 2D lateral heterostructure spintronic devices
- Author
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Junkai Deng, Kaiyun Chen, Jefferson Zhe Liu, Yuan Yan, Jun Sun, Tieyan Chang, Sen Yang, Qian Shi, and Xiangdong Ding
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02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Condensed Matter::Materials Science ,QA76.75-76.765 ,Phase (matter) ,Antiferromagnetism ,General Materials Science ,Computer software ,Materials of engineering and construction. Mechanics of materials ,Nanosheet ,Spintronics ,business.industry ,Heterojunction ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Computer Science Applications ,Semiconductor ,Ferromagnetism ,Mechanics of Materials ,Modeling and Simulation ,TA401-492 ,Curie temperature ,Optoelectronics ,Condensed Matter::Strongly Correlated Electrons ,0210 nano-technology ,business - Abstract
Lateral heterostructures of two-dimensional (2D) materials, integrating different phases or materials into a single piece of nanosheet, have attracted intensive research interests for electronic devices. Extending the 2D lateral heterostructures to spintronics demands more diverse electromagnetic properties of 2D materials. In this paper, using density functional theory calculations, we survey all IV, V, and VI group transition metal dichalcogenides (TMDs) and discover that CrS2 has the most diverse electronic and magnetic properties: antiferromagnetic (AFM) metallic 1T phase, non-magnetic (NM) semiconductor 2H phase, and ferromagnetic (FM) semiconductor 1T′ phase with a Curie temperature of ~1000 K. Interestingly, we find that a tensile or compressive strain can turn the 1T′ phase into a spin-up or spin-down half-metal. Such strain tunability can be attributed to the lattice deformation under tensile/compressive strain that selectively promotes the spin-up/spin-down VBM (valence band bottom) orbital interactions. The diverse electromagnetic properties and the strain tunability enable strain-controlled spintronic devices using a single piece of CrS2 nanosheet with improved energy efficiency. As a demo, a prototypical design of the spin-valve logic device is presented. It offers a promising solution to address the challenge of high energy consumption in miniaturized spintronic devices.
- Published
- 2021
12. An Ultra‐Thin, Ultra‐High Capacitance Density Tantalum Capacitor for 3D Packaging
- Author
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Jiping Zhao, Youlong Xu, Wenqiang Hou, Yizhuo Li, and Xiangdong Ding
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Mechanics of Materials ,General Materials Science ,Industrial and Manufacturing Engineering - Published
- 2023
13. Achieving stable actuation response and elastocaloric effect in a nanocrystalline Ti50Ni40Cu10 alloy
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Pengfei Dang, Yumei Zhou, Jianbo Pang, Xiangdong Ding, Jun Sun, Turab Lookman, and Dezhen Xue
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Mechanics of Materials ,Mechanical Engineering ,Metals and Alloys ,General Materials Science ,Condensed Matter Physics - Published
- 2023
14. Effects of chemical complexity on the initial oxidation resistance of HfC1−N ceramics
- Author
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Daming Yan, Yang Yang, Xiangdong Ding, Turab Lookman, Hongxiang Zong, and Jun Sun
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Computational Mathematics ,General Computer Science ,Mechanics of Materials ,General Physics and Astronomy ,General Materials Science ,General Chemistry - Published
- 2023
15. High local oxygen coverage causes initial oxidation of UN(001) surface
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Fuzhu Liu, Xiangdong Ding, and Jun Sun
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Nuclear and High Energy Physics ,Nuclear Energy and Engineering ,General Materials Science - Published
- 2023
16. Strain glass in Ti50-x-yNi50+yNby alloys exhibiting a boson peak glassy anomaly
- Author
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Hongji Lin, Shuai Ren, Pengfei Dang, Chunxi Hao, Xuefei Tao, Dezhen Xue, Yu Wang, Hongxiang Zong, Zhenxuan Zhang, Wenqing Ruan, Xiong Liang, Jiang Ma, Xiangdong Ding, and Jun Shen
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Mechanics of Materials ,Mechanical Engineering ,Metals and Alloys ,General Materials Science ,Condensed Matter Physics - Published
- 2023
17. Rationally optimized carrier effective mass and carrier density leads to high average ZT value in n-type PbSe
- Author
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Haijun Wu, Dongyang Wang, Xiangdong Ding, Yang Jin, Yu Xiao, Li-Dong Zhao, Wanbo Qu, Wei Liu, Jun Sun, Haonan Shi, Yang Zhang, and Sining Wang
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Range (particle radiation) ,Electron mobility ,Materials science ,Maximum power principle ,Renewable Energy, Sustainability and the Environment ,business.industry ,Doping ,General Chemistry ,Power factor ,Thermoelectric materials ,Effective mass (solid-state physics) ,Thermoelectric effect ,Optoelectronics ,General Materials Science ,business - Abstract
Among the intricately coupled thermoelectric parameters, carrier effective mass (m*) and carrier density (n) are two key parameters to determine the electrical transport properties. To enhance the broad-temperature thermoelectric performance in n-type PbSe, this work elaborately optimizes its power factor with the intrinsically proportional relationship between carrier effective mass and carrier density, n ∼ (m*)3/2. Herein, the carrier effective mass in n-type PbSe is first optimized with Sn alloying and undergoes a decrease from ∼0.34me in PbSe to ∼0.25me in Pb0.77Sn0.23Se because of band sharpening. This reduced carrier effective mass contributes to an obvious enhancement of carrier mobility, thereby boosting the maximum power factor from ∼16.8 μW cm−1 K−2 in PbSe to ∼20.5 μW cm−1 K−2 in Pb0.85Sn0.15Se. Moreover, to match the reduced carrier effective mass in n-type Pb0.85Sn0.15Se, its carrier density is well tuned with Ag counter doping, which further facilitates a high average power factor in the whole working temperature range. The average power factor in Pb0.85Sn0.15Se systems increases from ∼15.6 μW cm−1 K−2 with a carrier density of ∼6.21 × 1019 cm−3 to ∼17.6 μW cm−1 K−2 with a carrier density of ∼2.12 × 1019 cm−3 at 300–873 K. Finally, an average ZT (ZTave) of ∼0.95 is achieved in the n-type Pb0.85Sn0.15Se sample at 300–873 K, and the sample outperforms most other n-type PbSe-based thermoelectric materials.
- Published
- 2021
18. Van der Waals force-induced intralayer ferroelectric-to-antiferroelectric transition via interlayer sliding in bilayer group-IV monochalcogenides
- Author
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Bo Xu, Junkai Deng, Xiangdong Ding, Jun Sun, and Jefferson Zhe Liu
- Subjects
Mechanics of Materials ,Modeling and Simulation ,General Materials Science ,Computer Science Applications - Abstract
Two-dimensional materials with ferroelectric properties break the size effect of conventional ferroelectric materials and unlock unprecedented potentials of ferroelectric-related application at small length scales. Using first-principles calculations, a sliding-induced ferroelectric-to-antiferroelectric behavior in bilayer group-IV monochalcogenides (MX, with M = Ge, Sn and X = S, Se) is discovered. Upon this mechanism, the top layer exhibits a reversible intralayer ferroelectric switching, leading to a reversible transition between the ferroelectric and antiferroelectric states in the bilayer MXs. Further results show that the interlayer van der Waals interaction, which is usually considered to be weak, can actually generate an in-plane lattice distortion and thus cause the breaking/forming of intralayer covalent bonds in the top layer, leading to the observed anomalous phenomenon. This unique property has advantages for energy harvesting over existing piezoelectric and triboelectric nanogenerators. The interlayer sliding-induced big polarization change (40 μC cm−2) and ultrahigh polarization changing rate generate an open-circuit voltage two orders of magnitude higher than that of MoS2-based nanogenerators. The theoretical prediction of power output for this bilayer MXs at a moderate sliding speed 1 m s−1 is four orders of magnitude higher than the MoS2 nanogenerator, indicating great potentials in energy harvesting applications.
- Published
- 2022
19. High-Speed Impact Behavior and Microstructure Evolution of an Extruded Mg-7Sn-5Zn-3Al Alloy
- Author
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Xu Zuocheng, Fu Wei, Daqing Fang, J. L. Jiang, Tijun Chen, Guangli Bi, Xiangdong Ding, and Yuandong Li
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010302 applied physics ,Materials science ,Mechanical Engineering ,Alloy ,02 engineering and technology ,Split-Hopkinson pressure bar ,engineering.material ,Strain rate ,021001 nanoscience & nanotechnology ,Microstructure ,01 natural sciences ,Grain size ,Mechanics of Materials ,0103 physical sciences ,engineering ,Dynamic recrystallization ,General Materials Science ,Texture (crystalline) ,Composite material ,Elongation ,0210 nano-technology - Abstract
In this study, the high-speed impact behavior and microstructure evolution of an extruded Mg-7Sn-5Zn-3Al alloy were investigated under different strain rates (1626-4126 s−1) using a Split Hopkinson pressure bar. The experimental results indicated that the number of twins and dynamic recrystallization (DRX) increased, while the average grain size of the extruded alloy continuously decreased with the increase in the strain rates. In addition, the texture type of the extruded alloy transformed from (0001) to (11-20) during impacts. The high-speed impact behavior of the extruded alloy was found to strongly depend on the strain rate at room temperature. The strain rate sensitivity (SRS) changed from positive to negative with the increase in the strain rate. The negative SRS was mainly attributed to the DRX and the formation of micro-cracks at high strain rates (3712 s−1< $$\dot{\varepsilon }$$
- Published
- 2020
20. Design, Simulation and Experiment for a Vortex-Induced Vibration Energy Harvester for Low-Velocity Water Flow
- Author
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Xiangying Guo, Minghui Yao, Xiangdong Ding, and Dongxing Cao
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0209 industrial biotechnology ,Materials science ,Renewable Energy, Sustainability and the Environment ,Water flow ,Mechanical Engineering ,02 engineering and technology ,Mechanics ,021001 nanoscience & nanotechnology ,Industrial and Manufacturing Engineering ,Root mean square ,Vibration ,020901 industrial engineering & automation ,Flow velocity ,Vortex-induced vibration ,Management of Technology and Innovation ,General Materials Science ,0210 nano-technology ,Energy harvesting ,Beam (structure) ,Excitation - Abstract
Piezoelectric vibration energy harvesting has attracted considerable attention because of its prospects in self-powered electronic applications. There are a many low-velocity waters in nature, such as rivers, seas and oceans, which contain abundant hydrokinetic energy. In this paper, an optimal geometric piezoelectric beam combining magnetic excitation is identified and applied to a vortex-induced vibration energy harvester (ViVEH) for low velocity water flow, which is composed of a continuous variable-width piezoelectric beam carrying a cylindrical bluff body. The finite element simulation and experiment are first carried out to study the harvesting characteristics of the designed variable-width beam ViVEH without considering the magnetic excitation. The influence of the width-ratio and flow velocity on the harvesting voltage is studied in detail. The optimal structure, a ViVEH equipped with triangular piezoelectric beam, is then obtained by the superior energy harvesting performance for low velocity water flow. From the experimental results, at a flow velocity of 0.6 m/s, the highest root mean square (RMS) voltage and RMS voltage per unit area are 19.9 V and 0.07 V/mm2, respectively. Furthermore, magnetic excitation is introduced to improve the scavenging performance of the optimal triangular beam ViVEH, different polarity arrangements are compared, and the optimal case, the arrangement of horizontal repulsion and vertical attraction (HR-VA), is obtained. This case can scavenge the highest power of 173 μW at a flow velocity of 0.5 m/s, which is increased by 127% compared to a conventional constant-width beam ViVEH with no magnetic excitation.
- Published
- 2020
21. Knowledge-Based Descriptor for the Compositional Dependence of the Phase Transition in BaTiO3-Based Ferroelectrics
- Author
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Jinshan Li, Xiangdong Ding, Turab Lookman, Deqing Xue, Jun Sun, Ruihao Yuan, and Dezhen Xue
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Phase transition ,Materials science ,Composition dependence ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Thermodynamics ,General Materials Science ,Materials design ,Piezoelectricity ,Solid solution - Abstract
Descriptors play a central role in constructing composition-structure-property relationships to guide materials design. We propose a materials descriptor, δτ , for the composition dependence of the...
- Published
- 2020
22. Enhanced energy storage properties of Sr(Sc0.5Nb0.5)O3 modified (Bi0.47La0.03Na0.5)0.94Ba0.06TiO3 lead-free ceramics
- Author
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Lin Zhang, Zhonghua Dai, Xiangdong Ding, Jinglei Li, Fan Xing, Weiguo Liu, and Jinglong Xie
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Phase transition ,Materials science ,Mechanical Engineering ,Dielectric ,Microstructure ,Ferroelectricity ,Energy storage ,law.invention ,Capacitor ,Mechanics of Materials ,law ,Electric field ,visual_art ,visual_art.visual_art_medium ,General Materials Science ,Ceramic ,Composite material - Abstract
Excellent energy storage performance of dielectric capacitors is highly desired in all kinds of energy storage devices. In this study, Sr(Sc0.5Nb0.5)O3 was introduced to enhance the energy storage properties of (Bi0.47La0.03Na0.5)0.94Ba0.06TiO3 (BLNBT) ceramics. All ceramic samples were sintered densely, and the phase structure, microstructure, dielectric and ferroelectric properties were then systematically investigated. Two distinct dielectric anomaly peaks, which are detected from the dielectric properties as a function of temperature, suggest not only a phase transition, but also indicate typical relaxor features. The breakdown strength is significantly improved, and the polarization versus electric field hysteresis loops become slim with the increasing content of SSN. The optimum energy storage performance is achieved in 0.85BLNBT–0.15SSN ceramic with the recoverable energy density of 1.83 J/cm3 and energy efficiency of 82.32% under a moderate electric field of 185 kV/cm. The excellent energy storage performance of 0.85BLNBT–0.15SSN ceramic makes it a promising candidate material for advanced pulsed power capacitors.
- Published
- 2020
23. Improved Flow-Induced Vibration Energy Harvester by Using Magnetic Force: An Experimental Study
- Author
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Minghui Yao, Xiangdong Ding, Dongxing Cao, and Xiangying Guo
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0209 industrial biotechnology ,Materials science ,Renewable Energy, Sustainability and the Environment ,Water flow ,Mechanical Engineering ,Acoustics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Industrial and Manufacturing Engineering ,Sweep frequency response analysis ,Magnetic field ,Physics::Fluid Dynamics ,Vibration ,020901 industrial engineering & automation ,Flow velocity ,Vortex-induced vibration ,Management of Technology and Innovation ,Magnet ,General Materials Science ,0210 nano-technology ,Energy harvesting - Abstract
Vibration energy harvesting has attracted considerable attention because of its application prospects for charging or powering micro-electro-mechanical system. Abundant hydrokinetic energy of water at low velocity is contained in the fluid environment, such as rivers and oceans, which are widely existing in nature. In this paper, a flow-induced piezoelectric vibration energy harvester (PVEH) with magnetic force enhancement, which is integrated by piezoelectric beam, circular cylinder bluff body and magnets, is proposed and experimental investigated. It could transfer the hydrokinetic energy, both the vortex-induced vibration and magnetic force excitation underwater, into electricity. First, the frequency sweep experiment of the piezoelectric cantilever beam is carried out to determine the resonance frequency where the effect of magnetic force on the vibration characteristic is obtained. Furthermore, the flow-induced vibration experiment platform is setup and the energy harvesting performance of the PVEH is investigated in detail. The effects of the magnet property, flow velocity and the magnetic poles distance on the vibration frequency and the acquisition voltage are demonstrated and discussed. The results show that it could improve the harvesting performance by introducing magnetic force. It has advantages in higher output voltage for the flow-induced PVEH, especially in low velocity water flow, when the flow velocity is 0.35 m/s, the PVEH under attractive magnetic force with magnetic distance of 20 mm scavenges the higher acquisition voltage of 5.2 V, which is increased by 225% than the PVEH with non-magnetic. The results can be applied to guide further fabrication process and optimized design of the proposed flow-induced PVEH underwater with low flow velocity.
- Published
- 2020
24. An ultrathin two-dimensional vertical ferroelectric tunneling junction based on CuInP2S6 monolayer
- Author
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Min Zhao, Jun Sun, Gaoyang Gou, and Xiangdong Ding
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Materials science ,Condensed matter physics ,Graphene ,Oxide ,Heterojunction ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Ferroelectricity ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,symbols.namesake ,chemistry ,law ,Monolayer ,symbols ,General Materials Science ,Thin film ,van der Waals force ,0210 nano-technology ,Quantum tunnelling - Abstract
Ferroelectric (FE) materials, especially ABO3 FE perovskite oxides, have been extensively studied for their important applications in memory devices, electronics and sensors. However, the integration of FE perovskite oxides into miniaturized memory and electronic devices has been impeded by the critical thickness limitation, as out-of-plane ferroelectricity in most FE perovskite oxides will disappear when the oxide thin film thickness is below a critical value. On the other side, CuInP2S6 (CIPS) nano-flake, a prototypical two-dimensional (2D) FE material, has recently been demonstrated to display stable out-of-plane ferroelectricity at the atomic layer thickness by experiment, which offers a new candidate for developing FE devices in the 2D nanoscale regime. Herein, after investigation of the structural and ferroelectric properties of 2D CIPS layers, especially the interactions between out-of-plane polarization and the corresponding depolarization field using first-principles calculations, we reveal that out-of-plane ferroelectricity can even persist in the CIPS monolayer, which is only 3.4 A in thickness. Moreover, in order to explore the potential application of 2D FE CIPS layers as minimized FE devices, we design an ultrathin ferroelectric tunneling junction (FTJ) composed of a graphene/CIPS monolayer/graphene vertical van der Waals (vdW) heterostructure. Our transport simulations based on the non-equilibrium Green's function formalism predict that such an ultrathin FTJ device can still exhibit the typical tunneling electroresistance (TER) effect, where tunneling current strongly depends on the direction of FE polarization. Our work not only elucidates the origin of stable out-of-plane ferroelectricity appearing in 2D CIPS layers, but also demonstrates the practical application of a CIPS based 2D FTJ as a miniaturized, multi-functional and low-power consumption memory device for modern electronics.
- Published
- 2020
25. Charge doping induced reversible multistep structural phase transitions and electromechanical actuation in two-dimensional 1T′-MoS2
- Author
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Kaiyun Chen, Jefferson Zhe Liu, Xiangdong Ding, Qian Shi, Jun Sun, Junkai Deng, and Sen Yang
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Phase transition ,Materials science ,Condensed matter physics ,Doping ,Charge (physics) ,02 engineering and technology ,Electronic structure ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Distortion ,Phase (matter) ,Condensed Matter::Strongly Correlated Electrons ,General Materials Science ,Density functional theory ,0210 nano-technology ,Charge density wave - Abstract
The 1T′ phase of transition metal dichalcogenides (TMDs) is a low symmetry charge density wave (CDW) phase, which can be viewed as a periodically distorted structure (Peierls distortion) of the high symmetry 1T phase. In this paper, using density functional theory (DFT) calculations, we report that the positive charge (hole) injection is an effective method to modulate the Peierls distortion of MoS2 1T′ for a new CDW phase and superior electromechanical properties. A new stable CDW phase is discovered at a hole doping level of 0.10 h+ per atom, named 1T′t. Hole charging and discharging can induce a reversible phase transition of MoS2 among the three phases, 1T, 1T′ and 1T′t. Such a reversible phase transition leads to superior electromechanical properties including a strain output as high as −5.8% with a small hysteresis loop, multi-step super-elasticity, and multi-shape memory effect, which are valuable in active electromechanical device designs at the nanoscale. In-depth analysis of the change of the electronic structure under hole doping was performed to understand the new CDW phase and the observed phase transition. Using charge doping to modulate the Peierls distortion in two-dimensional materials can serve as a general concept for nano-active material designs.
- Published
- 2020
26. Correlating dislocation mobility with local lattice distortion in refractory multi-principal element alloys
- Author
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Bing Chen, Suzhi Li, Jun Ding, Xiangdong Ding, Jun Sun, and En Ma
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Mechanics of Materials ,Mechanical Engineering ,Metals and Alloys ,General Materials Science ,Condensed Matter Physics - Published
- 2023
27. Current vortices and magnetic fields driven by moving polar twin boundaries in ferroelastic materials
- Author
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Suzhi Li, Ekhard K. H. Salje, Guangming Lu, Xiangdong Ding, Jun Sun, Li, S [0000-0003-1113-6555], Ding, X [0000-0002-1220-3097], Salje, EKH [0000-0002-8781-6154], Apollo - University of Cambridge Repository, Li, Suzhi [0000-0003-1113-6555], Ding, Xiangdong [0000-0002-1220-3097], and Salje, Ekhard K. H. [0000-0002-8781-6154]
- Subjects
02 engineering and technology ,01 natural sciences ,5108 Quantum Physics ,Condensed Matter::Materials Science ,0103 physical sciences ,lcsh:TA401-492 ,639/301/357/997 ,General Materials Science ,Multiferroics ,010306 general physics ,lcsh:Computer software ,Physics ,Superconductivity ,639/301/1034/1035 ,Condensed matter physics ,Magnetic moment ,article ,021001 nanoscience & nanotechnology ,Computer Science Applications ,Vortex ,Magnetic field ,Dipole ,lcsh:QA76.75-76.765 ,Domain wall (magnetism) ,Mechanics of Materials ,Modeling and Simulation ,Polar ,lcsh:Materials of engineering and construction. Mechanics of materials ,0210 nano-technology ,51 Physical Sciences - Abstract
Ferroelastic twin boundaries often have properties that do not exist in bulk, such as superconductivity, polarity etc. Designing and optimizing domain walls can hence functionalize ferroelastic materials. Using atomistic simulations, we report that moving domain walls have magnetic properties even when there is no magnetic element in the material. The origin of a robust magnetic signal lies in polar vortex structures induced by moving domain walls, e.g., near the tips of needle domains and near domain wall kinks. These vortices generate displacement currents, which are the origin of magnetic moments perpendicular to the vortex plane. This phenomenon is universal for ionic crystals and holds for all ferroelastic domain boundaries containing dipolar moments. The magnetic moment depends on the speed of the domain boundary, which can reach the speed of sound under strong mechanical forcing. We estimate that the magnetic moment can reach several tens of Bohr magnetons for a collective thin film of 1000 lattice planes and movements of the vortex by the speed of sound. The predicted magnetic fields in thin slabs are much larger than those observed experimentally in SrTiO3/LaAlO3 heterostructures, which may be due to weak (accidental) forcing and slow changes of the domain patterns during their experiments. The dynamical multiferroic properties of ferroelastic domain walls may have the potential to be used to construct localized magnetic memory devices in future.
- Published
- 2021
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28. Rippling Ferroic Phase Transition and Domain Switching In 2D Materials
- Author
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Xiangdong Ding, Hongxiang Zong, Jun Sun, and Yang Yang
- Subjects
Molecular dynamics ,Phase transition ,Materials science ,Condensed matter physics ,Mechanics of Materials ,Rippling ,Mechanical Engineering ,Transition temperature ,Monolayer ,Ripple ,Phase (waves) ,Ferroics ,General Materials Science - Abstract
Ripples are a class of native structural defects widely existing in 2D materials. They originate from the out-of-plane flexibility of 2D materials introducing spatially evolving electronic structure and friction behavior. However, the effect of ripples on 2D ferroics has not been reported. Here a molecular dynamics study of the effect of ripples on the temperature-induced ferroic phase transition and stress-induced ferroic domain switching in ferroelastic-ferroelectric monolayer GeSe is presented. Ripples stabilize the short-range ferroic orders in the high-temperature phase with stronger ferroicity and longer lifetime, thereby increasing the transition temperature upon cooling. In addition, ripples significantly affect the domain switching upon loading, changing it from a highly correlated process into a ripple-driven localized one where ripples act as source of dynamical random stress. These results reveal the fundamental role of ripples on 2D ferroicity and provide theoretical guidance for ripple engineering of controlled phase transition and domain switching with potential applications in flexible 2D electronics.
- Published
- 2021
29. Effect of local lattice distortion on the core structure of edge dislocation in NbMoTaW multi-principal element alloys and the subsystems
- Author
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Duoduo Yang, Bing Chen, Suzhi Li, Xiangdong Ding, and Jun Sun
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Mechanics of Materials ,Mechanical Engineering ,General Materials Science ,Condensed Matter Physics - Published
- 2022
30. Perovskite‐Socketed Sub‐3 nm Copper for Enhanced CO 2 Electroreduction to C 2+
- Author
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Yuxi Li, Fuzhu Liu, Zitao Chen, Lei Shi, Zhenbao Zhang, Yue Gong, Yu Zhang, Xuezeng Tian, Xiaoyu Qiu, Xiangdong Ding, Xuedong Bai, Heqing Jiang, Yongfa Zhu, and Jiawei Zhu
- Subjects
Mechanics of Materials ,Mechanical Engineering ,General Materials Science - Published
- 2022
31. Plastic deformation behavior and microscopic mechanism of metastable Ti-10V-2Fe-3Al alloy single crystal pillars orientated to <011>β in submicron scales Part II: Phase transformation dependence of size effect and deformation mechanism
- Author
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Yan Pan, Xiangdong Ding, Lin Xiao, Qiaoyan Sun, and Jun Sun
- Subjects
010302 applied physics ,Materials science ,Condensed matter physics ,Mechanical Engineering ,Alloy ,02 engineering and technology ,engineering.material ,Plasticity ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Deformation mechanism ,Mechanics of Materials ,Diffusionless transformation ,Phase (matter) ,0103 physical sciences ,engineering ,General Materials Science ,Dislocation ,Deformation (engineering) ,0210 nano-technology ,Single crystal - Abstract
Double size effects are uncovered in metastable β Ti-10V-2Fe-3Al alloy single-crystal micropillars subjected to compress along β in the Part I of this paper. In this Part II, a series of samples at different deformation stages were systematically analyzed by transmission electron microscopy (TEM) to understand the deformation mechanism for double size effects. Two distinct phase transformations were observed to take place at different stages of plastic deformation. In the initial stage, dislocation interaction with ω precipitates and deformation-induced ω variants transformation from one to another are predominant plastic deformation mechanisms when the total strain is less than 10%. As a result, high density of ω precipitates contributes to the weak size effect and the continuous stable strain-hardening behavior in the metastable β Ti-10V-2Fe-3Al alloy. In comparison, the martensitic transformation from β to α″ is induced when the critical strain reaches to 10%. The strain-induced martensitic transformation becomes primary deformation modes, which result in higher strain-hardening exponent and stronger size effect, in the second deformation stage. These results provide a new perspective of designing micro-electromechanical materials with an excellent combination of the enhanced yield strength and stable plasticity.
- Published
- 2019
32. Plastic deformation behavior and microscopic mechanism of metastable Ti-10V-2Fe-3Al alloy single crystal pillars orientated to <011>β in submicron scales Part I: Double size effects and martensitic transformation prediction
- Author
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Jun Sun, Qiaoyan Sun, Lin Xiao, Xiangdong Ding, and Yan Pan
- Subjects
010302 applied physics ,Materials science ,Condensed matter physics ,Mechanical Engineering ,Alloy ,02 engineering and technology ,Plasticity ,engineering.material ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Mechanics of Materials ,Metastability ,Martensite ,Diffusionless transformation ,Phase (matter) ,0103 physical sciences ,engineering ,General Materials Science ,Orthorhombic crystal system ,0210 nano-technology ,Single crystal - Abstract
The effects of ω precipitates and orthorhombic (α″) martensitic transformation on stress-strain behavior were studied in metastable β Ti-10V-2Fe-3Al alloy single-crystal in submicron scales. We successfully distinguished the size effects induced by ω precipitates and α″ phase transformation through compressing the metastable β Ti-10V-2Fe-3Al along the orientation of β, which is unfavorable for α″ phase transformation. Two individual exponential curves express well the relationship between the strengthening exponents, which were regressed using the flow stresses at different ranges of plastic strains of 0.2–13% and the pillar widths, and the corresponding plastic strain. It is worth noting that the strengthening exponent jumps from 0.256 to 0.293 at 8% plastic strain. Double size effects are uncovered in metastable β Ti-10V-2Fe-3Al alloy single-crystal micropillars. The first (ω precipitate-related) size effect has been predicted with the proposed models, and the second (martensitic transformation-induced) size effect is interpreted with the modified Liu's equation.
- Published
- 2019
33. Can experiment determine the stacking fault energy of metastable alloys?
- Author
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Xun Sun, Song Lu, Xianghai An, Levente Vitos, Wei Li, Chuanxin Liang, Tianlong Zhang, Ruiwen Xie, Hualei Zhang, Xiangdong Ding, and Yunzhi Wang
- Subjects
Work (thermodynamics) ,Materials science ,Twinning ,Alloy ,Thermodynamics ,FOS: Physical sciences ,Stacking fault energy ,02 engineering and technology ,Applied Physics (physics.app-ph) ,engineering.material ,010402 general chemistry ,01 natural sciences ,Metastable alloy ,Condensed Matter::Materials Science ,Annan materialteknik ,Stacking-fault energy ,Phase (matter) ,Metallurgy and Metallic Materials ,lcsh:TA401-492 ,General Materials Science ,Other Materials Engineering ,Astrophysics::Galaxy Astrophysics ,Condensed Matter - Materials Science ,Mechanical Engineering ,Materials Science (cond-mat.mtrl-sci) ,Physics - Applied Physics ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Deformation mechanism ,Mechanics of Materials ,Martensitic transformation ,engineering ,Partial dislocations ,Density functional theory ,lcsh:Materials of engineering and construction. Mechanics of materials ,Deformation (engineering) ,Metallurgi och metalliska material ,0210 nano-technology - Abstract
Stacking fault energy (SFE) plays an important role in deformation mechanisms and mechanical properties of face-centered cubic (fcc) metals and alloys. In many concentrated fcc alloys, the SFEs determined from density functional theory (DFT) calculations and experimental methods are found having opposite signs. Here, we show that the negative SFE by DFT reflects the thermodynamic instability of the fcc phase relative to the hexagonal close-packed one; while the experimentally determined SFEs are restricted to be positive by the models behind the indirect measurements. We argue that the common models underlying the experimental measurements of SFE fail in metastable alloys. In various concentrated solid solutions, we demonstrate that the SFEs obtained by DFT calculations correlate well with the primary deformation mechanisms observed experimentally, showing a better resolution than the experimentally measured SFEs. Furthermore, we believe that the negative SFE is important for understanding the abnormal behaviors of partial dislocations in metastable alloys under deformation. The present work advances the fundamental understanding of SFE and its relation to plastic deformations, and sheds light on future alloy design by physical metallurgy.
- Published
- 2021
34. Determining Multi‐Component Phase Diagrams with Desired Characteristics Using Active Learning
- Author
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Yumei Zhou, Dezhen Xue, Jun Sun, Xiangdong Ding, Turab Lookman, Yuan Tian, Yunfan Wang, and Ruihao Yuan
- Subjects
Triple point ,Computer science ,Active learning (machine learning) ,General Chemical Engineering ,Science ,Materials informatics ,General Physics and Astronomy ,Medicine (miscellaneous) ,shape memory alloys ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Biochemistry, Genetics and Molecular Biology (miscellaneous) ,materials informatics ,Component (UML) ,General Materials Science ,Phase diagram ,Bayesian optimization ,multi‐component phase diagrams ,Full Paper ,ferroelectrics ,General Engineering ,Experimental data ,Full Papers ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,machine learning ,Bayesian experimental design ,0210 nano-technology ,Algorithm - Abstract
Herein, we demonstrate how to predict and experimentally validate phase diagrams for multi‐component systems from a high‐dimensional virtual space of all possible phase diagrams involving several elements based on small existing experimental data. The experimental data for bulk phases for known systems represents a sampling from this space, and screening the space allows multi‐component phase diagrams with given design criteria to be built. This approach uses machine learning methods to predict phase diagrams and Bayesian experimental design to minimize experiments for refinement and validation, all within an active learning loop. The approach is proven by predicting and synthesizing the ferroelectric ceramic system (1‐ω)(Ba0.61Ca0.28Sr0.11TiO3)‐ω(BaTi0.888Zr0.0616Sn0.0028Hf0.0476O3) with a relatively high transition temperature and triple point, as well as the NiTi‐based pseudo‐binary phase diagram (1‐ω)(Ti0.309Ni0.485Hf0.20Zr0.006)‐ω(Ti0.309Ni0.485Hf0.07Zr0.068Nb0.068) designed for high transition temperature (ω ⩽ 1). Each phase diagram is validated and optimized through only three new experiments. The complexity of these compounds is beyond the reach of today's computational methods., A machine learning‐based approach is proposed to predict all possible phase diagrams of a given multi‐component system from a high‐dimensional virtual space. By quickly screening the space, a specific phase diagram with given design criteria can be constructed. Bayesian experimental design is then employed to refine the phase diagram with as few experiments as possible.
- Published
- 2021
35. Quasi‐Linear Superelasticity with Ultralow Modulus in Tensile Cyclic Deformed TiNi Strain Glass
- Author
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Shuangshuang Zhao, Qianglong Liang, Chuanxin Liang, Dong Wang, Yuanchao Ji, Yu Wang, Yufeng Zheng, Xiangdong Ding, Michale Mills, Xiaobing Ren, and Yunzhi Wang
- Subjects
General Materials Science ,Condensed Matter Physics - Published
- 2022
36. High‐Ranged ZT Value Promotes Thermoelectric Cooling and Power Generation in n‐Type PbTe
- Author
-
Yu Xiao, Haijun Wu, Haonan Shi, Liqing Xu, Yuke Zhu, Yongxin Qin, Guyang Peng, Yang Zhang, Zhen‐Hua Ge, Xiangdong Ding, and Li‐Dong Zhao
- Subjects
Renewable Energy, Sustainability and the Environment ,General Materials Science - Published
- 2022
37. Lead-free molecular ferroelectric [N,N-dimethylimidazole]3Bi2I9 with narrow bandgap
- Author
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Changxi Zheng, Jefferson Zhe Liu, Xiangdong Ding, Kai-Bin Chu, Jun-Ling Song, Lixue Zhang, Jun Sun, Weijie Yang, and Junkai Deng
- Subjects
Ferroelectrics ,Phase transition ,Materials science ,Band gap ,Bandgap ,02 engineering and technology ,Dielectric ,010402 general chemistry ,01 natural sciences ,Phase (matter) ,Organic-inorganic hybrid ,lcsh:TA401-492 ,General Materials Science ,Perovskite (structure) ,business.industry ,Mechanical Engineering ,Energy conversion efficiency ,021001 nanoscience & nanotechnology ,Ferroelectricity ,0104 chemical sciences ,Mechanics of Materials ,Phase transitions ,Optoelectronics ,Curie temperature ,lcsh:Materials of engineering and construction. Mechanics of materials ,0210 nano-technology ,business - Abstract
Lead-based organic-inorganic hybrid perovskite materials are widely applied in solar cells due to their excellent optoelectronic properties. These materials usually appear ferroelectricity with the built-in electric field, which can be used to improve the power conversion efficiency (PCE) of solar cells. However, the toxicity of lead has severely hampered their applications. Hence, it is of utmost significance to explore novel organic-inorganic hybrid perovskite materials with non-toxicity, ferroelectricity, and narrow bandgap at room temperature to enhance the PCE for broad practical applications. Herein, we reported a lead-free hybrid molecular ferroelectric material, i.e. (C5N2H9)3Bi2I9, with zero-dimensional perovskite-like structure. (C5N2H9)3Bi2I9 undergoes first-order ferroelectric phase transition with a Curie temperature of 327 K. Moreover, the dielectric constants of (C5N2H9)3Bi2I9 exhibit a step-like anomaly varied between the high-temperature paraelectric phase and the low-temperature ferroelectric phase. Furthermore, (C5N2H9)3Bi2I9 demonstrates a narrow bandgap of 2.1 eV. Hence, the as-reported novel member of the organic-inorganic hybrid family renders great promise for optoelectronic devices.
- Published
- 2020
38. Enhanced piezoelectricity in twinned ferroelastics with nanocavities
- Author
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Guangming Lu, Jun Sun, Suzhi Li, Xiangdong Ding, and Ekhard K. H. Salje
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Field (physics) ,Point reflection ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Piezoelectricity ,Condensed Matter::Materials Science ,Matrix (mathematics) ,Electric field ,0103 physical sciences ,Domain (ring theory) ,General Materials Science ,Multiferroics ,Deformation (engineering) ,010306 general physics ,0210 nano-technology - Abstract
Enhancing the electromechanical response by engineering domain boundaries in multiferroics has become a highly active research field in recent years. The starting point is the discovery that ferroelastic twin walls are polar inside a nonpolar matrix. The density of such twin walls is then greatly enhanced by forming complex twin patterns. Our computer simulations show that the interaction of nanocavities with differently charged configurations with twin boundaries generates strong piezoelectricity in ferroelastic (nonferroelectric) crystals. Cavity-induced domain patterns statistically break the inversion symmetry of a sample even when the cavities themselves obey inversion symmetry with relatively weak emerging piezoelectricity $(d\ensuremath{\sim}{10}^{\ensuremath{-}3}\phantom{\rule{0.16em}{0ex}}\mathrm{pm}/\mathrm{V})$ . Stronger piezoelectricity occurs in noncentrosymmetric charged cavity arrangements with a coefficient of $d\ensuremath{\sim}{10}^{\ensuremath{-}1}\mathrm{pm}/\mathrm{V}$. Structurally, the electric field polarizes and shifts the nanocavities by the displacement of trapped surface charges. The related strain fields interact with the ferroelastic domains, which act as soft bridges between the nanocavities. This leads to a significant deformation of the entire sample and hence to enhanced piezoelectricity. Our simulation results point to new directions for designing and enhancing electromechanical nanodevices based on ferroelastic templates even when the bulk material is structurally centrosymmetric.
- Published
- 2020
39. Generalized Stacking Fault Energy of Al-Doped CrMnFeCoNi High-Entropy Alloy
- Author
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Xun Sun, Hualei Zhang, Yunzhi Wang, Wei Li, Xiangdong Ding, and Levente Vitos
- Subjects
Materials science ,General Chemical Engineering ,Alloy ,Thermodynamics ,02 engineering and technology ,engineering.material ,Fault (power engineering) ,01 natural sciences ,lcsh:Chemistry ,symbols.namesake ,Condensed Matter::Materials Science ,interfacial energy ,Stacking-fault energy ,0103 physical sciences ,Metallurgy and Metallic Materials ,General Materials Science ,high-entropy alloys ,010302 applied physics ,High entropy alloys ,Communication ,first-principles ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Surface energy ,Gibbs free energy ,lcsh:QD1-999 ,symbols ,engineering ,generalized stacking fault energy ,Metallurgi och metalliska material ,0210 nano-technology ,Crystal twinning ,Den kondenserade materiens fysik ,Stacking fault - Abstract
Using first-principles methods, we investigate the effect of Al on the generalized stacking fault energy of face-centered cubic (fcc) CrMnFeCoNi high-entropy alloy as a function of temperature. Upon Al addition or temperature increase, the intrinsic and extrinsic stacking fault energies increase, whereas the unstable stacking fault and unstable twinning fault energies decrease monotonously. The thermodynamic expression for the intrinsic stacking fault energy in combination with the theoretical Gibbs energy difference between the hexagonal close packed (hcp) and fcc lattices allows one to determine the so-called hcp-fcc interfacial energy. The results show that the interfacial energy is small and only weakly dependent on temperature and Al content. Two parameters are adopted to measure the nano-twinning ability of the present high-entropy alloys (HEAs). Both measures indicate that the twinability decreases with increasing temperature or Al content. The present study provides systematic theoretical plasticity parameters for modeling and designing high entropy alloys with specific mechanical properties.
- Published
- 2020
40. Periodic Wrinkle‐Patterned Single‐Crystalline Ferroelectric Oxide Membranes with Enhanced Piezoelectricity
- Author
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Wanbo Qu, Zuo-Guang Ye, Zhongqiang Hu, Yuqing Zhou, Guohua Dong, Xiangdong Ding, Ziyao Zhou, Stephen J. Pennycook, Tao Li, Wei Ren, Bin Peng, Tianxiang Nan, Zhuangde Jiang, Ming Liu, Suzhi Li, Zhenlin Luo, Yuxin Cheng, Zhiguang Wang, Xiaohua Wang, Haijun Wu, Haixia Liu, Tai Min, Ju Li, Jun Sun, and Yifan Zhao
- Subjects
Materials science ,Crazing ,Mechanical Engineering ,Flexoelectricity ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Ferroelectricity ,Piezoelectricity ,0104 chemical sciences ,Stress (mechanics) ,Membrane ,Mechanics of Materials ,General Materials Science ,Composite material ,Deformation (engineering) ,0210 nano-technology ,Ductility - Abstract
© 2020 Wiley-VCH GmbH Self-assembled membranes with periodic wrinkled patterns are the critical building blocks of various flexible electronics, where the wrinkles are usually designed and fabricated to provide distinct functionalities. These membranes are typically metallic and organic materials with good ductility that are tolerant of complex deformation. However, the preparation of oxide membranes, especially those with intricate wrinkle patterns, is challenging due to their inherently strong covalent or ionic bonding, which usually leads to material crazing and brittle fracture. Here, wrinkle-patterned BaTiO3 (BTO)/poly(dimethylsiloxane) membranes with finely controlled parallel, zigzag, and mosaic patterns are prepared. The BTO layers show excellent flexibility and can form well-ordered and periodic wrinkles under compressive in-plane stress. Enhanced piezoelectricity is observed at the sites of peaks and valleys of the wrinkles where the largest strain gradient is generated. Atomistic simulations further reveal that the excellent elasticity and the correlated coupling between polarization and strain/strain gradient are strongly associated with ferroelectric domain switching and continuous dipole rotation. The out-of-plane polarization is primarily generated at compressive regions, while the in-plane polarization dominates at the tensile regions. The wrinkled ferroelectric oxides with differently strained regions and correlated polarization distributions would pave a way toward novel flexible electronics.
- Published
- 2020
41. Electrically driven ferroelastic domain walls, domain wall interactions, and moving needle domains
- Author
-
Jun Sun, Guangming Lu, Xiangdong Ding, Ekhard K. H. Salje, and Suzhi Li
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Physics::Fluid Dynamics ,Lattice (module) ,Molecular dynamics ,Dipole ,Domain wall (magnetism) ,Electric field ,0103 physical sciences ,Domain (ring theory) ,Perpendicular ,Periodic boundary conditions ,General Materials Science ,010306 general physics ,0210 nano-technology - Abstract
Ferroelastic domains generate polarity near domain walls via the flexoelectric effect. Applied electric fields change the wall dipoles and generate additional dipoles in the bulk. Molecular dynamics simulations show that the thickness of domain walls changes when an electric field is applied to the sample. Fields parallel to the walls lead to expansion of the wall thickness while fields perpendicular to the wall lead to shrinking of the wall thickness. The interactions between polar domain walls expand over more than 45 unit cells, the resulting forces change the wall-wall distances if pinning effects are small. The interaction increases nonlinearly with decreasing wall-wall distances favoring equal wall distances as the consequence of energy minimization under the constraints of a constant number of domain walls. Even for small groups of three walls the sequence of walls is locally periodic: assemblies of three parallel domain walls arrange themselves so that the intermediate domain wall is located exactly in the middle between the two outer walls. The driving force is appreciable if the distance between the outer domain walls is below approximately 30 lattice units. Pairs of domain walls often form needle domains where the shaft of the needle is ca. 3 lattice units wide. The movement of needle domains under applied electric field was simulated. The advancement and retraction of needles is larger in finite samples with charge-free surfaces than under periodic boundary conditions in the bulk. The needle tip moves even more freely when the sample surface is charged.
- Published
- 2019
42. Accelerated Search for BaTiO3‐Based Ceramics with Large Energy Storage at Low Fields Using Machine Learning and Experimental Design
- Author
-
Deqing Xue, Ruihao Yuan, Jun Sun, Yumei Zhou, Yuan Tian, Dezhen Xue, Xiangdong Ding, and Turab Lookman
- Subjects
General Chemical Engineering ,Crossover ,General Physics and Astronomy ,Medicine (miscellaneous) ,02 engineering and technology ,Dielectric ,ceramics ,010402 general chemistry ,Machine learning ,computer.software_genre ,01 natural sciences ,Biochemistry, Genetics and Molecular Biology (miscellaneous) ,Energy storage ,Combinatorial search ,General Materials Science ,lcsh:Science ,Phase diagram ,Bayesian optimization ,business.industry ,energy storage ,General Engineering ,Feedback loop ,021001 nanoscience & nanotechnology ,Ferroelectricity ,0104 chemical sciences ,machine learning ,optimal experimental design ,lcsh:Q ,Artificial intelligence ,0210 nano-technology ,business ,computer - Abstract
The problem that is considered is that of maximizing the energy storage density of Pb‐free BaTiO3‐based dielectrics at low electric fields. It is demonstrated that how varying the size of the combinatorial search space influences the efficiency of material discovery by comparing the performance of two machine learning based approaches where different levels of physical insights are involved. It is started with physics intuition to provide guiding principles to find better performers lying in the crossover region in the composition–temperature phase diagram between the ferroelectric phase and relaxor ferroelectric phase. Such an approach is limiting for multidopant solid solutions and motivates the use of two data‐driven machine learning and design strategies with a feedback loop to experiments. Strategy I considers learning and property prediction on all the compounds, and strategy II learns to preselect compounds in the crossover region on which prediction is carried out. By performing only two active learning loops via strategy II, the compound (Ba0.86Ca0.14)(Ti0.79Zr0.11Hf0.10)O3 is synthesized with the largest energy storage density ≈73 mJ cm−3 at a field of 20 kV cm−1, and an insight into the relative performance of the strategies using varying levels of knowledge is provided.
- Published
- 2019
43. Damping and transformation behaviors of Ti 50 (Pd 50−x Cr x ) shape memory alloys with x ranging from 4.0 to 5.0
- Author
-
Deqing Xue, Dezhen Xue, Yumei Zhou, Jun Sun, G.-J. Zhang, Xiangdong Ding, and Ruihao Yuan
- Subjects
010302 applied physics ,Materials science ,Condensed matter physics ,Crossover ,Relaxation (NMR) ,General Physics and Astronomy ,Ranging ,02 engineering and technology ,Shape-memory alloy ,021001 nanoscience & nanotechnology ,01 natural sciences ,Damping capacity ,Transformation (function) ,Diffusionless transformation ,0103 physical sciences ,General Materials Science ,0210 nano-technology - Abstract
The damping and transformation behaviors of Ti50(Pd50−xCrx) shape memory alloys with x ranging from 4.0 to 5.0 are systematically investigated. The damping capacity (Q−1) at the martensitic transformation is found to be inversely proportional to the square root of frequency, i.e., Q−1∝ω−0.5. A relaxation peak or shoulder is observed slightly below the martensitic transformation damping peak for compositions within the compositional crossover region (4.5 ⩽ x ⩽ 4.8). Furthermore, the damping capacity at the martensitic transformation is smaller within the compositional crossover region (4.5 ⩽ x ⩽ 4.8), compared with that of compositions at both sides ( x = 4.0 and x = 5.0 ). These observations can be ascribed to the hysteretic motion of interfaces between different phases near the compositional crossover region.
- Published
- 2018
44. Detwinning through migration of twin boundaries in nanotwinned Cu films under in situ ion irradiation
- Author
-
Peipei Wang, Zaoming Wu, Marquis A. Kirk, Yanxiang Liang, Xiangdong Ding, Kaiyuan Yu, Xingjun Wang, J.L. Du, Meimei Li, and Engang Fu
- Subjects
In situ ,detwinning ,Materials science ,102 Porous / Nanoporous / Nanostructured materials ,lcsh:Biotechnology ,106 Metallic materials ,Dose dependence ,02 engineering and technology ,01 natural sciences ,Article ,Ion ,Stress (mechanics) ,10 Engineering and Structural materials ,lcsh:TP248.13-248.65 ,0103 physical sciences ,lcsh:TA401-492 ,General Materials Science ,Irradiation ,010302 applied physics ,Condensed matter physics ,ion irradiation ,021001 nanoscience & nanotechnology ,nanotwins ,lcsh:Materials of engineering and construction. Mechanics of materials ,Engineering and Structural materials ,Deformation (engineering) ,0210 nano-technology - Abstract
The mechanism of radiation-induced detwinning is different from that of deformation detwinning as the former is dominated by supersaturated radiation-induced defects while the latter is usually triggered by global stress. In situ Kr ion irradiation was performed to study the detwinning mechanism of nanotwinned Cu films with various twin thicknesses. Two types of incoherent twin boundaries (ITBs), so-called fixed ITBs and free ITBs, are characterized based on their structural features, and the difference in their migration behavior is investigated. It is observed that detwinning during radiation is attributed to the frequent migration of free ITBs, while the migration of fixed ITBs is absent. Statistics shows that the migration distance of free ITBs is thickness and dose dependent. Potential migration mechanisms are discussed.
- Published
- 2018
45. Improving radiation-tolerance of bcc multi-principal element alloys by tailoring compositional heterogeneities
- Author
-
Hongxiang Zong, Long Zhao, Xiangdong Ding, Hongjiang Li, and Yang Yang
- Subjects
Nuclear and High Energy Physics ,Range (particle radiation) ,Materials science ,Yield (engineering) ,Binding energy ,Binary number ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,010305 fluids & plasmas ,Molecular dynamics ,Nuclear Energy and Engineering ,Chemical physics ,Cascade ,0103 physical sciences ,General Materials Science ,0210 nano-technology ,Ternary operation ,Radiation resistance - Abstract
Molecular dynamic simulations were performed to investigate the displacement cascade process in refractory bcc complex concentrated alloys, including equi-atomic binary, ternary, and quaternary systems made of the elements Mo, Nb, Ta and W. Our simulation results show that more principal elements do not necessarily mean better radiation resistance. Instead, bcc binary MoNb and NbW CCAs, which have low binding energy of interstitial clusters, can also yield good resistance to the generation of radiation-induced defect clusters. At same time, MoNb also have low self-interstitial formation energy range, so there are more Frenkel Pairs than other bcc binary like MoTa and MoW although number of interstitials in clusters of MoNb is least. More importantly, we find the binding energy of interstitial clusters is highly tunable by changing elements combination and tailoring compositional heterogeneities (such as short-range ordering). Such strategies may pave the way for new design concepts of radiation-tolerant alloys.
- Published
- 2021
46. Emergence of bulk photovoltaic effect in anion-ordered perovskite sulfur diiodide MASbSI2 with spontaneous out-of-plane ferroelectricity
- Author
-
Min Zhao, Hua Wang, Gaoyang Gou, Xiangdong Ding, and Jun Sun
- Subjects
Photocurrent ,Valence (chemistry) ,Materials science ,Physics and Astronomy (miscellaneous) ,Band gap ,02 engineering and technology ,Electronic structure ,Anomalous photovoltaic effect ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Ferroelectricity ,0104 chemical sciences ,Polarization density ,Chemical physics ,General Materials Science ,0210 nano-technology ,Energy (miscellaneous) ,Perovskite (structure) - Abstract
Organic-inorganic halide perovskites composed of three-dimensional (3D) corner-sharing octahedral framework, represented by methylammonium lead iodide MAPbI3, have attracted extensive research interests owing to their superior photovoltaic (PV) performance. On the other hand, taking advantage of spontaneous ferroelectricity and the associated bulk photovoltaic effect (BPVE), ferroelectric (FE)-PV materials are able to generate zero-bias photocurrent and above band gap photovoltage, offering the great promise for improved power conversion efficiency. However, FE nature of perovskite MAPbI3 remains controversial. Alternatively, heteroanionic perovskite where the multiple anions of distinct sizes and valence states are in ordered arrangement, can create polar crystal structures with permanent electric polarization. In current work, we choose the experimentally reported perovskite methylammonium antimony sulfur diiodide MASbSI2 as a prototypical example, and demonstrate trans S/I anion order and the stable out-of-plane ferroelectricity nearly independent of molecular dipoles from organic MA cations can be obtained in such a 3D organic-inorganic heteroanionic perovskite by first-principles calculations. The cooperative interplay of MA orientation, octahedral rotation, cation polar displacement and S/I anion arrangement that govern the origin and magnitude of ferroelectricity within MASbSI2 have been thoroughly explored and well rationalized by our comprehensive first-principles calculations and electrostatic bond strength sum analysis. Especially, based on our electronic structure and nonlinear photo-current responses simulations, FE perovskite MASbSI2 with combination of stable out-of-plane ferroelectricity up to 17.9 μC/cm2, tunable semiconducting band gap, static Rashba effect and polarization controllable strong photocurrent responses within the visible light range, is demonstrated to be a long-sought 3D FE organic-inorganic perovskite material for efficient light-current conversion through BPVE.
- Published
- 2021
47. Enhancement of the corrosion resistance of Molybdenum by La2O3 dispersion
- Author
-
Tianshu Li, Pengming Cheng, Zeng Yi, Can Chen, Xiangdong Ding, Hejie Yang, Wande Cairang, Dezhen Xue, Sun Yuanjun, and Jun Sun
- Subjects
Materials science ,020209 energy ,General Chemical Engineering ,Doping ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Microstructure ,Corrosion ,Chemical engineering ,chemistry ,Molybdenum ,0202 electrical engineering, electronic engineering, information engineering ,General Materials Science ,Grain boundary ,0210 nano-technology ,Dispersion (chemistry) ,Polarization (electrochemistry) ,Current density - Abstract
The corrosion behavior of pure Molybdenum (Mo) and Mo doped with 0.3 wt.% La2O3 was investigated in aerated 3.5 wt.% NaCl at 25 °C. Compared with the pure Mo, the doped Mo exhibits significantly increased corrosion resistance, with a smaller current density during anodic polarization and a 2∼3 times larger charge transfer resistance. Such an enhancement originates from the refinement of grains and purification of the grain boundary due to the addition of La2O3, which facilitates the formation of a compact and protective oxide film. Our results provide a recipe to improve the corrosion resistance of Mo alloys.
- Published
- 2021
48. Domain-knowledge-oriented data pre-processing and machine learning of corrosion-resistant γ-U alloys with a small database
- Author
-
Pengcheng Zhang, Xiangdong Ding, Chuang Dong, Zhen Li, Junhao Yuan, and Qing Wang
- Subjects
Optimization problem ,General Computer Science ,General Physics and Astronomy ,02 engineering and technology ,010402 general chemistry ,Machine learning ,computer.software_genre ,01 natural sciences ,Genetic algorithm ,Cluster (physics) ,General Materials Science ,Equivalence (measure theory) ,Mathematics ,Database ,business.industry ,Quinary ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Weighting ,Computational Mathematics ,Mechanics of Materials ,Domain knowledge ,Artificial intelligence ,Data pre-processing ,0210 nano-technology ,business ,computer - Abstract
The present work proposed a characteristic-parameter-embedded machine learning (ML) model to predict and design body-centered-cubic (BCC) γ-U alloys with high corrosion-resistant lifetime in 343 °C boiling water in U-Mo-Nb-Ti-Zr systems. The characteristic parameters of cluster formula approach and Mo equivalence (Moeq) were implemented into the ML for a more accurate prediction, in which the former reflects the interactions among elements and determines their added amounts and the latter represents the BCC-γ structural stability. The data samples in the current small-sample database of U alloys were first pre-processed with the guide of domain knowledge before ML, involving data screening and data weighting. Both auxiliary gradient-boosting regression tree (XGBR) and genetic algorithm (GA) methods were adopted to deal with the optimization problem during ML. The optimal compositions predicted by the ML with a screened & weighted database in existing alloy systems are well consistent with the experimental results. Especially, a new quinary U-7.17Mo-0.96Nb-0.31Ti-0.28Zr (wt. %) alloy with a maximum corrosion-resistant lifetime of D = 190.4 days is achieved. Without the constraint of cluster formula to compositions, 158 alloys would be obtained by the ML when setting D ≥ 182 days, resulting in a complexity of experimental verification. This cluster-formula-embedded ML modelwith a domain-knowledge-oriented data pre-processing can optimize alloy compositions with desired properties in multi-component systems efficiently and precisely.
- Published
- 2021
49. Ferroelectric switching and scale invariant avalanches in BaTiO3
- Author
-
Xiangdong Ding, Dezhen Xue, Karin A. Dahmen, James F. Scott, and Ekhard K. H. Salje
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,02 engineering and technology ,Scale invariance ,021001 nanoscience & nanotechnology ,01 natural sciences ,Power law ,Amplitude ,Mean field theory ,0103 physical sciences ,Exponent ,General Materials Science ,010306 general physics ,0210 nano-technology ,Scaling ,Energy (signal processing) ,Noise (radio) - Abstract
Ferroelectric-field switching in $\mathrm{BaTi}{\mathrm{O}}_{3}$ generates ``Barkhausen noise'' when domain walls are displaced. We show by acoustic emission spectroscopy that electric-field switching of ${90}^{\ensuremath{\circ}}$ boundaries generates large strain fields, which emit acoustic phonons during ferroelectric hysteresis measurements. We use highly sensitive receivers (microphones) to measure the time sequences of noise in close analogy to noise patterns in ferroelastic and magnetic materials. Domain-wall interactions and jamming generate the ``crackling noise'' that follows scale invariant avalanche dynamics: the avalanche energy and amplitude probability distribution functions follow power laws with exponents $\ensuremath{\varepsilon}=1.65$ (energy) and \ensuremath{\tau}\ensuremath{'} = 2.25 (amplitudes). Aftershocks are very common and follow Omori law with probability $\ensuremath{\sim}{t}^{\ensuremath{-}p}$ where $t$ is the time elapsed after the main shock and $p$ is the Omori exponent $p\ensuremath{\sim}1$. The interevent times follow a double power-law distribution with exponents 0.9 for small times and 2.2 for the larger times. The scaling behavior is consistent with predictions of mean field theory.
- Published
- 2019
50. Effect of Ti/Ni and Hf/Zr ratio on the martensitic transformation behavior and shape memory effect of TiNiHfZr alloys
- Author
-
Xiangdong Ding, Dezhen Xue, Yangyang Xu, Jianbo Pang, Jin Tian, Jun Sun, and Yumei Zhou
- Subjects
010302 applied physics ,Materials science ,Mechanical Engineering ,Alloy ,Thermodynamics ,02 engineering and technology ,Shape-memory alloy ,engineering.material ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Brittleness ,Mechanics of Materials ,Diffusionless transformation ,0103 physical sciences ,Volume fraction ,engineering ,General Materials Science ,0210 nano-technology - Abstract
The functional properties of shape memory alloys are strongly sensitive to the composition of alloys. In this study, the effect of Ti/Ni ratio and Hf/Zr ratio on the martensitic transformation behavior, shape memory effect and microscopic structures of two different quaternary TiNiHfZr alloys (TixHf15Zr5Ni80-x and Ti31.5HfyZr20-yNi48.5) have been investigated systematically. It is found that increasing Ti/Ni ratio of TixHf15Zr5Ni80-x alloys dramatically increases the martensitic transformation temperature and a maximum value (5%) of the recovered strain during shape recovery on heating is obtained for the alloy with x = 30. On the contrary, changing Hf/Zr ratio of Ti31.5HfyZr20-yNi48.5 alloys does not result in big change of martensitic transformation temperature or recovered strain. The evolution of macroscopic properties of TixHf15Zr5Ni80-x alloys with x can be understood by considering the balanced effect between the Ni content change of the matrix, and the volume fraction of Ti2Ni-like precipitates, which are often brittle and not desired for SMAs. Our results suggest that the TixHf15Zr5Ni80-x (x > 30.5 at. %) alloys are promising shape memory alloys for high temperature applications above 250 °C.
- Published
- 2021
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