27 results on '"Hongwei Chen"'
Search Results
2. Magnetic and critical behavior studies of Ni2+-doped perovskite manganese oxides
- Author
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Cheng Li, Xiang Jin, Huiqin Yun, Hongwei Chen, and Jianjun Zhao
- Subjects
Electrical and Electronic Engineering ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials - Published
- 2022
3. Magnetic and critical behavior studies of perovskite manganites La0.8-xEuxSr0.2MnO3(x = 0 and 0.05)
- Author
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Cheng Li, Hongwei Chen, Jianjun Zhao, Wenxing Wang, Yi Lu, Lin Zheng, Fengze Cao, and Xiang Jin
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010302 applied physics ,Materials science ,Analytical chemistry ,Coercivity ,Condensed Matter Physics ,01 natural sciences ,Magnetic susceptibility ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Paramagnetism ,Magnetization ,Ferromagnetism ,Remanence ,0103 physical sciences ,Magnetic refrigeration ,Curie temperature ,Electrical and Electronic Engineering - Abstract
Effects of Eu doping at the A site on the magnetic properties of the perovskite manganite La0.8-xEuxSr0.2MnO3(x = 0 and 0.05)polycrystalline samples were investigated in this paper. The polycrystalline La0.8-xEuxSr0.2MnO3 (x = 0,0.05)samples were synthesized using a traditional solid-phase reaction method. X-ray diffraction (XRD) analysis of the polycrystalline samples did not indicate any impurities, confirming that the samples are single phase. The magnetization vs. temperature curve (M-T), as well as the magnetization vs. magnetic field curves (M-H) of the two samples, show that both synthesized structures are paramagnetic in the high-temperature region, while near the Curie temperature (Tc), the material is ferromagnetic. The Tc of both samples, La0.8-xEuxSr0.2MnO3 with x = 0 and the Eu3+-doped sample with x = 0.05, increased to 283 K and 284 K, respectively. The hysteresis loops of the samples show insignificant coercive force and no remanence. The inverse magnetic susceptibility vs. temperature curves (χ−1-T, χ−1 = H/M) indicate that the Griffiths phase temperature remains unchanged, while the Curie temperature decreases. The trends confirm that $${Eu}^{3+}$$ doping changed the ferromagnetic coupling of the system. The average field model provides a good fit for the critical parameter response of both the parent and the doped synthesized material. At an applied field of 7 T, the change in magnetic entropy of the doped sample reaches its highest value at 4.19 J/kg·K, and the refrigeration efficiency is 445 J/kg. Our results show that the newly synthesized polycrystalline samples could be used as magnetic refrigeration materials.
- Published
- 2021
4. Effect of Zr:Sn ratio in the PBLZST ceramic thick films on the energy storage characteristics
- Author
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Chuanjie Zhou, Hongwei Chen, Jinyu Zhao, Jihua Zhang, Libin Gao, and Tianpeng Liang
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010302 applied physics ,Phase transition ,Materials science ,Field strength ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Energy storage ,Electronic, Optical and Magnetic Materials ,Crystal ,Tetragonal crystal system ,visual_art ,Phase (matter) ,0103 physical sciences ,visual_art.visual_art_medium ,Curie temperature ,Ceramic ,Electrical and Electronic Engineering ,Composite material - Abstract
Pb0.91Ba0.06La0.02(Zr0.95−xSnxTi0.05)O3 (PBLZST, x = 0.325, 0.35, 0.375, 0.4) thick films are prepared by solid-state reaction method and flow-casting method. Trace Ba2+ content is introduced to PLZST which is effective in narrowing the hysteresis loop, lowering the Curie temperature point, and improving the fatigue characteristics. Besides that, Zr:Sn ratios are adjusted to study its influence on the material’s energy storage characteristics. PBLZST ceramics with different Zr:Sn ratios are all in tetragonal perovskite structure. The increase of Sn4+ content promotes miniaturization of crystal grain and contributes to stability of antiferroelectric phase, together with enhances the phase transition field strength and breakdown field strength of PBLZST ceramics. The PBLZST ceramic has high energy storage efficiency, which is more than 80%. The maximum effective energy storage density of PBLZST ceramics at 1.94 J/cm3 is obtained when x = 0.35, and their energy storage efficiency is 81.9%, which confirms that they are the potential materials in the pulse energy storage components.
- Published
- 2021
5. Effects of Bi2O3, Sm2O3 content on the structure, dielectric properties and dielectric tunability of BaTiO3 ceramics
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Jinyu Zhao, Hongwei Chen, Libin Gao, Lei Chen, Jihua Zhang, Meng Wei, and Xiangxiang Dong
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010302 applied physics ,Materials science ,Doping ,Sintering ,Dielectric ,Condensed Matter Physics ,01 natural sciences ,Ferroelectricity ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Electric field ,visual_art ,0103 physical sciences ,visual_art.visual_art_medium ,Curie temperature ,Dielectric loss ,Ceramic ,Electrical and Electronic Engineering ,Composite material - Abstract
(1 − x)BaTiO3–x (Bi2O3, Sm2O3) (BT–BS, x = 0.1, 0.15, 0.2, 0.25, 0.3) ceramics were prepared by traditional solid phase sintering method. The effects of structure, temperature and frequency on dielectric tunability, ferroelectric relaxation characteristics and dielectric loss were analyzed. Phase analysis by XRD showed that the main crystal phase was BaTiO3 perovskite structure, in addition to the second phase of Bi7.68Ti0.32O12.16 was also generated. The surface morphology was analyzed by SEM, it was found that the generation of second phase and the porosity decreased with the increase of BS content. At the same time, the increase of Sm3+ promoted the growth of crystal particles. The dielectric constant-temperature curve gradually became flat, which indicated that the relaxation characteristics of the ferroelectric ceramic gradually appear. The Curie temperature point gradually decreased with the doping of the BS. The relationship between dielectric loss and temperature showed that the dielectric loss increased when the temperature over 150 °C. This is mainly related to relaxation polarization at high temperature. Under the action of DC applied electric field and room temperature, dielectric loss and dielectric constant decreased with the increase of BS content. Meanwhile, dielectric tunability was improved when composite phase appeared. The maximum dielectric tunability (E = 50 kV/cm, 10 kHz) was 58.4% at x = 0.25.
- Published
- 2019
6. Energy-storage properties of Sr-doped PLZST bulk ceramics and thick films
- Author
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Xingyu Qi, Jihua Zhang, Jinyu Zhao, Meng Wei, Bowen Deng, Libin Gao, and Hongwei Chen
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010302 applied physics ,Phase transition ,Materials science ,Doping ,Dielectric ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Phase (matter) ,visual_art ,Electric field ,0103 physical sciences ,visual_art.visual_art_medium ,Orthorhombic crystal system ,Ceramic ,Electrical and Electronic Engineering ,Composite material ,Perovskite (structure) - Abstract
The dielectric and energy-storage properties of (Pb0.97−xSrxLa0.02)(Zr0.675Sn0.285Ti0.04)O3 (x = 0, 0.005, 0.01, 0.015) bulk ceramics and thick films were investigated. All samples are orthorhombic perovskite antiferroelectric phase and have dielectric temperature relaxation property. Sr-dopant can improve the stability of the antiferroelectric phase and increase the phase transition field, but cause a decrease in dielectric constant. Thick films have a higher maximum tolerable external electric field strength than bulk ceramics. Compared with undoped thick film, the forward phase transition field and the backward phase transition field of the 1.5% doped thick film increased by 32% and 27%, respectively. The maximum polarization of the 1.5% doped thick film is decreased by 17%. The largest recoverable energy-storage density was obtained in thick film with 1% Sr doping. The largest recoverable energy-storage density is 2.77 J/cm3, which is 9.4% higher than the undoped thick film ceramic and 477% higher than the bulk ceramic with 1% Sr doping. The high energy storage density indicates that the obtained thick film is promising for pulsed power capacitors.
- Published
- 2019
7. Enhanced dielectric properties of barium strontium titanate thin films by doping modification
- Author
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Jihua Zhang, Kexin Liang, Shixian Huang, Libin Gao, Hongwei Chen, and Zhipu Guan
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010302 applied physics ,Alkaline earth metal ,Materials science ,business.industry ,Doping ,chemistry.chemical_element ,Barium ,Dielectric ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,chemistry ,0103 physical sciences ,Optoelectronics ,Dielectric loss ,Electrical and Electronic Engineering ,Thin film ,business ,Microwave - Abstract
Barium strontium titanate (BaxSr1–xTiO3, BST) thin films have large dielectric constant, low dielectric loss, especially the high dielectric tunability, which make them prospective candidates for microwave tunable applications. Resent developments in BST thin films by doping modification are reviewed. The A-site doping, B-site doping, and both sites codoping modifications are summarized and analyzed, respectively. The comparison of dielectric properties and microstructure of the BST thin films with different sites doping modifications is critically analyzed. The single A-site or B-site doping modification cannot obtain the BST thin films with balanced enhancement of the dielectric properties. However, the different elements codoping in both A-site and B-site of BST thin films is demonstrated to be an effective method to achieve balanced dielectric property optimization.
- Published
- 2019
8. Two-step sintering for improving the energy storage properties of 0.8BaTiO3–0.2BiYO3 ceramics
- Author
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Meng Wei, Peng Zhang, Jihua Zhang, Hongwei Chen, and Kaituo Wu
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010302 applied physics ,Materials science ,Sintering ,02 engineering and technology ,Dielectric ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Grain size ,Energy storage ,Electronic, Optical and Magnetic Materials ,visual_art ,Scientific method ,0103 physical sciences ,visual_art.visual_art_medium ,Relative density ,Ceramic ,Electrical and Electronic Engineering ,Composite material ,0210 nano-technology ,Efficient energy use - Abstract
In this paper, 0.8BaTiO3–0.2BiYO3 was prepared by traditional process. The samples were sintered with tradition method and two-step sintering method, respectively. The effects of different sintering conditions on grain size, density and dielectric properties were investigated. When the samples heated to 1100 °C, cooled to 1000 °C and held for 20 h, the relative density and the recoverable energy density of the samples reached the maximum (0.379 J/cm3 with energy efficiency of 72.8%).
- Published
- 2017
9. Enhanced energy storage density performance in (Pb0.97La0.02)(Zr0.5Sn0.44Ti0.06)–BiYO3 anti-ferroelectric composite ceramics
- Author
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Meng Wei, Chuanren Yang, Jihua Zhang, Jiapeng Huang, Hao Yu, and Hongwei Chen
- Subjects
010302 applied physics ,Materials science ,Doping ,Composite number ,Analytical chemistry ,Nanotechnology ,02 engineering and technology ,Dielectric ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,Ferroelectricity ,Atomic and Molecular Physics, and Optics ,Energy storage ,Electronic, Optical and Magnetic Materials ,Ion ,visual_art ,0103 physical sciences ,visual_art.visual_art_medium ,Ceramic ,Electrical and Electronic Engineering ,0210 nano-technology - Abstract
(1 − x)(Pb0.97La0.02)(Zr0.5Sn0.44Ti0.06)–xBiYO3 ((1 − x)PLZST–xBYO), with x = 0.0–0.5, have been fabricated by the conventional solid-state reaction process. The phase evolution, microstructure, dielectric and energy storage properties have been investigated in detail. According to the XRD study, a secondary phase was found at room-temperature. The secondary phase was gradually increased with increasing x. The microstructure further revealed that the BYO doping leads to an increase in secondary phase. The EDS analysis revealed that Bi ions and Y ions are mainly substituted for A-site in the perovskite structure. As a result, the maximum value of energy storage density is 0.8 J/cm3, which is 2.66 times as high as that of pure PLZST ceramics.
- Published
- 2016
10. Effect of multiple times pre-sintering on the dielectric properties of TiO2/glass composite
- Author
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Jihua Zhang, Hongwei Chen, Hetuo Chen, Jianfeng Liu, Meng Wei, and Chuanren Yang
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010302 applied physics ,Materials science ,Composite number ,Sintering ,02 engineering and technology ,Dielectric ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Grain size ,Electronic, Optical and Magnetic Materials ,law.invention ,Capacitor ,law ,0103 physical sciences ,Electrical and Electronic Engineering ,Composite material ,0210 nano-technology ,Ceramic capacitor ,Porosity ,Ball mill - Abstract
NanoTiO2/glass composite was potential in pulse power capacitors applications. The glass addition could deduce the porosity, suppress the grain size and improve the BDS of the composite, simultaneously. In this study, the composite was densified successfully by the method of repeating the pre-sintering and ball milling procedure multiple times, which could improve the density and the breakdown strength (BDS) of the composite significantly. When the ratio of TiO2 with 15 % glass addition and the number of pre-sintering times was 4, the energy density achieved the highest energy density 1.41 J/cm3. The method was very simple and inexpensive to compatible with multilayer ceramic capacitor, comparing to sol–gel method and other methods.
- Published
- 2016
11. Microstructure and electrical properties of TiO2–CaO–MgO–Al2O3–SiO2 glass-ceramic with sol–gel method
- Author
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Meng Wei, Jiapeng Huang, Jihua Zhang, Chuanren Yang, and Hongwei Chen
- Subjects
010302 applied physics ,Materials science ,Glass-ceramic ,Sintering ,chemistry.chemical_element ,02 engineering and technology ,Dielectric ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Titanate ,Electronic, Optical and Magnetic Materials ,law.invention ,chemistry ,law ,0103 physical sciences ,Breakdown voltage ,Electrical and Electronic Engineering ,Composite material ,0210 nano-technology ,Sol-gel ,Titanium - Abstract
In this paper, the composites of the TiO2–CaO–MgO–Al2O3–SiO2 glass-ceramic were successfully produced by the method of Sol–Gel from tetrabutyl titanate as the titanium (Ti) source, which were sintering at 1300 °C for 2 h. The dielectric properties of the composites were studied. The highest energy density reached 1.05 J/cm3 with low loss (
- Published
- 2016
12. Dielectric properties of manganese-doped TiO2 with different alkali-free glass contents for energy storage application
- Author
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Meng Wei, Jihua Zhang, Hongwei Chen, Chuanren Yang, Jianfeng Liu, and Zongying Yao
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010302 applied physics ,Materials science ,Doping ,chemistry.chemical_element ,02 engineering and technology ,Dielectric ,Manganese ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Grain size ,Electronic, Optical and Magnetic Materials ,Hysteresis ,chemistry ,visual_art ,0103 physical sciences ,visual_art.visual_art_medium ,Dielectric loss ,Ceramic ,Electrical and Electronic Engineering ,Composite material ,0210 nano-technology - Abstract
The dielectric properties and microstructures of 0.05 mol% manganese (Mn)-doped TiO2 with different alkali-free glass (BaO–B2O3–Al2O3–SiO2) contents were investigated. The alkali-free glass which coated Mn-doped TiO2 ceramic powders was prepared by sol–gel method, all samples were sintered at 1100 °C for 6 h. Microstructure observation indicated that the grain size greatly reduced and microstructure uniformity was improved by adding 15 wt% alkali-free glass. The alkali-free glass did not only decrease the dielectric loss (
- Published
- 2016
13. Property optimization of nano TiO2-based composite glass ceramics for energy-storage applications
- Author
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Jianfeng Liu, Chuanren Yang, Meng Wei, Hongwei Chen, Jihua Zhang, and Jiapeng Huang
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010302 applied physics ,Permittivity ,Materials science ,Nanocomposite ,Composite number ,02 engineering and technology ,Dielectric ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Energy storage ,Electronic, Optical and Magnetic Materials ,Rutile ,visual_art ,0103 physical sciences ,visual_art.visual_art_medium ,Breakdown voltage ,Ceramic ,Electrical and Electronic Engineering ,Composite material ,0210 nano-technology - Abstract
In this search, the nanocomposite of the rutile nano TiO2 and alkali-free glass (CaO–MgO–Al2O3–SiO2) were successfully produced by the method of sol–gel, which were sintered at 1200 °C for 2 h. The dielectric properties of the composites were studied. The permittivity of the composite with 15 % alkali-free glass addition is 114, while the breakdown voltage is 52.2 kV/mm and the energy density reaches 1.08 J/cm3 with low loss (
- Published
- 2016
14. Glass/ZnO nanocomposites with high dielectric constant and low loss
- Author
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Jianfeng Liu, Jihua Zhang, Chuanren Yang, Meng Wei, and Hongwei Chen
- Subjects
Materials science ,02 engineering and technology ,Dielectric ,engineering.material ,010402 general chemistry ,01 natural sciences ,law.invention ,Coating ,law ,Nano ,Electrical and Electronic Engineering ,Composite material ,Ceramic capacitor ,High-κ dielectric ,Nanocomposite ,business.industry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Capacitor ,Semiconductor ,engineering ,0210 nano-technology ,business - Abstract
Glass/semiconductor nanocomposites have a high dielectric constant and voltage resistant, which has potential as dielectric material for multilayer ceramic capacitor and low frequency capacitor. This article reported a glass/semiconductor nanocomposite of coating ZnO nano powders by a kind of PbO–B2O3 glass by spray-drying method. We used lead acetate [(CH3COO)2Pb·3H2O] and boric acid (H3BO3) which were water-solubility for raw materials. The size of semiconductor powders were between 200 and 300 nm. This method could make the ZnO coating by glass insulated. In addition, ZnO coated by 40 wt% glass can obtain a high dielectric constant of 150 and the loss below 2 %. This method was very simple and easy to control. Semiconductor-glass was another way to obtain high dielectric constant and low loss.
- Published
- 2015
15. X-ray diffraction analyses of RF sputtered Ba0.6Sr0.4TiO3 thin films grown on Pt/Ti/LaAlO3 (100) substrates
- Author
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Hong Ji, Yu Tan, Li Zeng, Lang Liu, Linling Chen, Chuanren Yang, Jihua Zhang, and Hongwei Chen
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Diffraction ,Materials science ,Analytical chemistry ,Substrate (electronics) ,Pole figure ,Sputter deposition ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Crystallography ,X-ray crystallography ,Ferroelectric thin films ,Crystallite ,Electrical and Electronic Engineering ,Thin film - Abstract
Ba0.6Sr0.4TiO3 ferroelectric thin films were deposited on Pt/Ti/LaAlO3 (100) substrates by RF magnetron sputtering system. This paper focused on X-ray diffraction (XRD) analyses of Ba0.6Sr0.4TiO3 thin films on single-crystal LaAlO3 (LAO) substrates by three aspects research. Triple-axis XRD was utilized to investigate the mosaic defects of single-crystal LAO substrate. Both the out-of-plane grazing incidence mapping and ω-scan techniques were applied to research the crystallographic oriented growth of polycrystalline Ba0.6Sr0.4TiO3 thin films. X-ray Φ-scans and pole figures were used to assess the orientation relationship between the film and substrate.
- Published
- 2014
16. Effects of RF magnetron sputtering power density on NTC characteristics of Mn–Co–Ni thin films
- Author
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Feizhi Lou, Guanhuan Lei, Li Zeng, Chuanren Yang, Qiang Zhao, Hongwei Chen, Jihua Zhang, Shanxue Zheng, and Linling Chen
- Subjects
Materials science ,Atomic force microscopy ,Analytical chemistry ,Oxide ,Crystal structure ,Sputter deposition ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,chemistry ,Sputtering ,Electrical and Electronic Engineering ,Thin film ,Temperature coefficient ,Power density - Abstract
Thin film NTCR (negative temperature coefficient resistance), based on Mn–Co–Ni oxide, was prepared by reactive RF magnetron sputtering with various sputtering power density (0.95–3.82 W/cm2). The crystalline structure and surface morphology of the NTC thin film were analyzed by XRD and AFM. The NTC characteristics, as a function of sputtering power density, were investigated. The values of B, α 25 and R 25 were in the range of 3,740–3,847 K, −4.328 to −4.207 %/K and 8.7–2,082.5 KΩ, respectively. With the increasing power density, the standard resistance (R 25 ) decreased and the consistency of R25 increased. Thin film NTCR with stable B value (3,740 K), low R 25 (104 Ω) and excellent consistency could be fabricated in mass production with about 3.82 W/cm2 sputtering power density.
- Published
- 2012
17. Two critical grain sizes of Ba0.6Sr0.4TiO3 thin films
- Author
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Zhihong Wang, Li Zhao, Hong Ji, Hongwei Chen, Jihua Zhang, Chuanren Yang, Wenjian Leng, and Jiaxuan Liao
- Subjects
Materials science ,Sputter deposition ,Condensed Matter Physics ,Ferroelectricity ,Atomic and Molecular Physics, and Optics ,Grain size ,Electronic, Optical and Magnetic Materials ,Amorphous solid ,chemistry.chemical_compound ,Crystallography ,chemistry ,Transmission electron microscopy ,Barium titanate ,Electrical and Electronic Engineering ,Thin film ,Composite material ,High-resolution transmission electron microscopy - Abstract
Ba0.6Sr0.4TiO3 (short for BST) thin films were prepared by RF magnetron sputtering. By adjusting annealing conditions, the BST thin films with different grain sizes were obtained. The microstructures of BST thin films were studied by X-ray diffraction (XRD), atomic force microscopy (AFM), and high-resolution transmission electron microscopy (HRTEM). It is found that there are two critical sizes in BST thin films in relation to grain sizes. The crystalline critical size from amorphous to crystalline is about 10 nm. The ferroelectric critical size from cubic (paraelectric) to tetragonal (ferroelectric) is about 20 nm.
- Published
- 2009
18. Effects of oxygen to argon ratio on Ba(Zr0.2Ti0.8)O3 thin films prepared by RF magnetron sputtering
- Author
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Jihua Zhang, Chuanren Yang, Hongwei Chen, An Yu, Bo Wang, and Ruiting Zhang
- Subjects
Materials science ,Argon ,Analytical chemistry ,chemistry.chemical_element ,Dielectric ,Sputter deposition ,Condensed Matter Physics ,Ferroelectricity ,Atomic and Molecular Physics, and Optics ,Grain size ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,chemistry ,Lanthanum aluminate ,Dissipation factor ,Electrical and Electronic Engineering ,Thin film - Abstract
Ba(Zr0.2Ti0.8)O3 (BZT) thin films were deposited on Pt/Ti/LaAlO3 (001) substrates by radio-frequency magnetron sputtering at different O2/Ar mixing ratios. As the O2/Ar ratio increased (1/4–4), the preferred orientation evolved from (00l) to (111). The grain size and the surface roughness increased, and the ferroelectric properties improved with increasing O2/Ar ratio. The BZT thin films deposited under oxygen-rich atmosphere (O2/Ar = 4) had larger dielectric constant (443) and tunability (44%), while the BZT films deposited under argon-rich atmosphere (O2/Ar = 1/4) had a lower loss tangent (0.016).
- Published
- 2008
19. Microstructure and dielectric properties of BaZr x Ti1−x O3 ceramics
- Author
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Hongwei Chen, Jun Shi, Jihua Zhang, Chuanren Yang, Wenjian Leng, and Chunlin Fu
- Subjects
Permittivity ,Zirconium ,Materials science ,Analytical chemistry ,chemistry.chemical_element ,Crystal structure ,Dielectric ,Coercivity ,Condensed Matter Physics ,Microstructure ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Tetragonal crystal system ,Lattice constant ,Nuclear magnetic resonance ,chemistry ,Electrical and Electronic Engineering - Abstract
The crystalline structure and dielectric properties of BaZr x Ti1−x O3 ceramics with x = 0.05, 0.10, 0.15, and 0.20 were investigated. As zirconium increased, the a-axis lattice constant gradually increased, however, the c-axis lattice constant and c/a ratio gradually decreased. When x = 0.20, the crystal structures of the BZT ceramics are very close to cubic, different from the tetragonal structure when x
- Published
- 2007
20. Linear and nonlinear optical properties of RF sputtered (Pb,La)(Zr,Ti)O3 ferroelectric thin films
- Author
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J. L. Tang, Wenjian Leng, Chuanren Yang, Hongwei Chen, Jihua Zhang, Hong Ji, and Lifeng Gao
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Materials science ,business.industry ,Band gap ,Sputter deposition ,Condensed Matter Physics ,Optical switch ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Pulsed laser deposition ,Optics ,Transmittance ,Optoelectronics ,Z-scan technique ,Electrical and Electronic Engineering ,Thin film ,business ,Refractive index - Abstract
Linear and nonlinear optical properties of (Pb,La)(Zr,Ti)O-3 (PLZT) ferroelectric thin films were presented in this paper. The PLZT ferroelectric thin films have been in situ grown on quartz substrates by radio-frequency (RF) magnetron sputtering at 650 degrees C. Their crystalline structure and surface morphologies were examined by X-ray diffraction and atomic force microscopy, respectively. It can be found that the PLZT thin films exhibit well-crystallized perovskite structure and good surface morphology. The fundamental optical constants (the band gap energy, linear refractive index, and linear absorption coefficient) were obtained through the optical transmittance measurements. A Z-scan technique was used to investigate the optical nonlinearity of the PLZT thin films on quartz substrates. The films display the strong third-order nonlinear optical effect. A large and negative nonlinear refractive index n(2) is determined to be 1.21 x 10(-6) esu for the PLZT thin films. All results show that the PLZT ferroelectric thin films have potential applications in optical limiting, switching, and modulated-type optical devices.
- Published
- 2006
21. Effect of annealing on leakage current characteristics of Pt/Ba0.6Sr0.4TiO3/Pt thin-film capacitors
- Author
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Fu Chunlin, Chuanren Yang, Hongwei Chen, Fusheng Pan, and Wei Cai
- Subjects
Materials science ,business.industry ,Annealing (metallurgy) ,Schottky barrier ,chemistry.chemical_element ,Atmospheric temperature range ,Condensed Matter Physics ,Ferroelectricity ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Capacitor ,Depletion region ,chemistry ,law ,Optoelectronics ,Electrical and Electronic Engineering ,Thin film ,business ,Platinum - Abstract
The effect of annealing on leakage current characteristics of Pt/Ba0.6Sr0.4TiO3/Pt ferroelectric thin-film capacitors was investigated at the temperature range from 273 K to 393 K. The results show that the depletion layer width of the as-deposited BST film is about 3–5 times greater than that of the annealed film. For as-deposited samples, the Schottky barrier height increases with increasing temperature and voltage. However, for annealed samples, the Schottky barrier height linearly decreases with increasing voltage and is almost independent upon temperature.
- Published
- 2006
22. The ferroelectric and optical properties of (Pb0.92La0.08)(Zr0.65Ti0.35)O3 thin films deposited by radio-frequency magnetron sputtering
- Author
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Jihua Zhang, J. L. Tang, Hong Ji, Chuanren Yang, Hongwei Chen, and Wenjian Leng
- Subjects
Fused quartz ,Materials science ,Silicon ,Band gap ,business.industry ,chemistry.chemical_element ,Dielectric ,Sputter deposition ,Coercivity ,Condensed Matter Physics ,Ferroelectricity ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Optics ,chemistry ,law ,Optoelectronics ,Electrical and Electronic Engineering ,Thin film ,business - Abstract
Ferroelectric (Pb0.92La0.08)(Zr0.65Ti0.35)O3 (PLZT) films have been prepared on Pt/Ti/SiO2/Si and fused quartz substrates using radio-frequency (rf) magnetron sputtering at a deposition temperature of 650°C. X-ray diffraction analysis shows that the PLZT thin films on platinized silicon are polycrystalline with (100)-preferential orientation. A Al/PLZT/Pt capacitor has been fabricated and it shows that the films have excellent ferroelectric character, with saturation polarization (P s), remanent polarization (P r) and coercive field (E c) of 32.8μC/cm2, 24.3μC/cm2 and 142 kV/cm, respectively. The PLZT thin films exhibit good insulating property and the leakage current density of the films on platinized silicon is only about 0.86 × 10−7 A/cm2 at 200 kV/cm. By the optical transmission spectra measurements, the energy gap (E g) of the PLZT films on fused quartz is found to be about 3.54 eV. The optical constants (n and k) of the films in the wavelength range of 250–900 nm are obtained by a Filmetrics F20 reflectance spectrometer.
- Published
- 2006
23. Two critical grain sizes of Ba0.6Sr0.4TiO3 thin films.
- Author
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Hongwei Chen, Chuanren Yang, Jihua Zhang, Wenjian Leng, Hong Ji, Zhihong Wang, Jiaxuan Liao, and Li Zhao
- Subjects
THIN films ,MAGNETRON sputtering ,TRANSMISSION electron microscopy ,X-ray diffraction ,ATOMIC force microscopy - Abstract
Ba
0.6 Sr0.4 TiO3 (short for BST) thin films were prepared by RF magnetron sputtering. By adjusting annealing conditions, the BST thin films with different grain sizes were obtained. The microstructures of BST thin films were studied by X-ray diffraction (XRD), atomic force microscopy (AFM), and high-resolution transmission electron microscopy (HRTEM). It is found that there are two critical sizes in BST thin films in relation to grain sizes. The crystalline critical size from amorphous to crystalline is about 10 nm. The ferroelectric critical size from cubic (paraelectric) to tetragonal (ferroelectric) is about 20 nm. [ABSTRACT FROM AUTHOR]- Published
- 2010
- Full Text
- View/download PDF
24. Microstructure and dielectric properties of BaZr x Ti1− x O3 ceramics.
- Author
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Hongwei Chen, Chuanren Yang, Chunlin Fu, Jun Shi, Jihua Zhang, and Wenjian Leng
- Subjects
MICROSTRUCTURE ,DIELECTRICS ,CONSTITUTION of matter ,ELECTRONIC ceramics ,POLARIZATION (Electricity) ,ZIRCONIUM ,ELECTRIC fields ,CRYSTALS ,TEMPERATURE - Abstract
The crystalline structure and dielectric properties of BaZr
x Ti1− x O3 ceramics with x = 0.05, 0.10, 0.15, and 0.20 were investigated. As zirconium increased, the a-axis lattice constant gradually increased, however, the c-axis lattice constant and c/a ratio gradually decreased. When x = 0.20, the crystal structures of the BZT ceramics are very close to cubic, different from the tetragonal structure when x < 0.20. The temperature dependence of the dielectric constant was studied and an enhanced diffuse phase transition behavior is found to be caused by the increased Zr content. The decreases of coercive electric field and remanent polarization were the result of increase of Zr/Ti ratio in BaZrx Ti1− x O3 . [ABSTRACT FROM AUTHOR]- Published
- 2008
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- View/download PDF
25. Linear and nonlinear optical properties of RF sputtered (Pb,La)(Zr,Ti)O3 ferroelectric thin films.
- Author
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Wenjian Leng, Chuanren Yang, Hong Ji, Jihua Zhang, Jinlong Tang, Hongwei Chen, and Lifeng Gao
- Subjects
FERROELECTRIC thin films ,RADIO frequency ,OPTICAL properties ,SPUTTERING (Physics) ,OPTICAL diffraction ,ATOMIC force microscopy - Abstract
Linear and nonlinear optical properties of (Pb,La)(Zr,Ti)O
3 (PLZT) ferroelectric thin films were presented in this paper. The PLZT ferroelectric thin films have been in situ grown on quartz substrates by radio-frequency (RF) magnetron sputtering at 650 °C. Their crystalline structure and surface morphologies were examined by X-ray diffraction and atomic force microscopy, respectively. It can be found that the PLZT thin films exhibit well-crystallized perovskite structure and good surface morphology. The fundamental optical constants (the band gap energy, linear refractive index, and linear absorption coefficient) were obtained through the optical transmittance measurements. A Z-scan technique was used to investigate the optical nonlinearity of the PLZT thin films on quartz substrates. The films display the strong third-order nonlinear optical effect. A large and negative nonlinear refractive index n2 is determined to be 1.21 × 10−6 esu for the PLZT thin films. All results show that the PLZT ferroelectric thin films have potential applications in optical limiting, switching, and modulated-type optical devices. [ABSTRACT FROM AUTHOR]- Published
- 2007
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26. Effect of annealing on leakage current characteristics of Pt/Ba0.6Sr0.4TiO3/Pt thin-film capacitors.
- Author
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Fusheng Pan, Hongwei Chen, Wei Cai, and Chuanren Yang
- Subjects
PLATINUM ,THIN films ,CAPACITORS ,DIELECTRIC devices - Abstract
Abstract?? The effect of annealing on leakage current characteristics of Pt/Ba
0.6 Sr0.4 TiO3 /Pt ferroelectric thin-film capacitors was investigated at the temperature range from 273?K to 393?K. The results show that the depletion layer width of the as-deposited BST film is about 3?5 times greater than that of the annealed film. For as-deposited samples, the Schottky barrier height increases with increasing temperature and voltage. However, for annealed samples, the Schottky barrier height linearly decreases with increasing voltage and is almost independent upon temperature. [ABSTRACT FROM AUTHOR]- Published
- 2007
27. The ferroelectric and optical properties of (Pb0.92La0.08)(Zr0.65Ti0.35)O3 thin films deposited by radio-frequency magnetron sputtering.
- Author
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Wenjian Leng, Chuanren Yang, Hong Ji, Jihua Zhang, Jinlong Tang, and Hongwei Chen
- Abstract
Abstract Ferroelectric (Pb
0.92 La0.08 )(Zr0.65 Ti0.35 )O3 (PLZT) films have been prepared on Pt/Ti/SiO2 /Si and fused quartz substrates using radio-frequency (rf) magnetron sputtering at a deposition temperature of 650°C. X-ray diffraction analysis shows that the PLZT thin films on platinized silicon are polycrystalline with (100)-preferential orientation. A Al/PLZT/Pt capacitor has been fabricated and it shows that the films have excellent ferroelectric character, with saturation polarization (Ps ), remanent polarization (Pr ) and coercive field (Ec ) of 32.8?C/cm2 , 24.3?C/cm2 and 142 kV/cm, respectively. The PLZT thin films exhibit good insulating property and the leakage current density of the films on platinized silicon is only about 0.86 × 10?7 A/cm2 at 200 kV/cm. By the optical transmission spectra measurements, the energy gap (Eg ) of the PLZT films on fused quartz is found to be about 3.54 eV. The optical constants (n and k) of the films in the wavelength range of 250–900 nm are obtained by a Filmetrics F20 reflectance spectrometer. [ABSTRACT FROM AUTHOR]- Published
- 2006
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