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1.
Guo DongYun Li MeiYa Liu Jun Yu BenFang Pei Ling Wang YunBo Yu Jun Yang Bin 《中国科学E辑(英文版)》2008,51(1):10-15
We have investigated the preparation and properties of Bi3.4Ce0.6Ti3O12 thin films. The Bi3.4Ce0.6Ti3O12 thin films were fabricated on the Pt/Ti/SiO2/Si substrates using sol-gel method. The structure and morphology of the films were characterized using X-ray diffraction
and atomic force microscopy. The thin films showed a perovskite phase and dense microstructure. The dielectric constant and
the dissipation factor of the Bi3.4Ce0.6Ti3O12 thin films were about 172 and 0.031 at 1 kHz, respectively. The 2P
r and 2E
c of the Bi3.4Ce0.6Ti3O12 thin films were 67.1 μC/cm2 and 299.7 kV/cm, respectively, under an applied field of 600 kV/cm. The Bi3.4Ce0.6Ti3O12 film did not show fatigue up to 4.46×109 switching cycles at a frequency of 1 MHz, and showed good insulating behavior according to the test of leakage current.
Supported by the Natural Science Foundation of Hubei Province (Grants No. 2004ABA082) 相似文献
2.
Bi3.25La0.75Ti3O12(BLT) thin films were prepared on Pt/Ti/SiO2/Si substrate by the sol-gel method. The effect of annealing on their structures and ferroelectric properties was investigated.
The XRD patterns indicate that the BLT films annealed at different temperatures are randomly orientated and the single perovskite
phase is obtained at 550°C. The remnant polarization increases and the coercive field decreases with the annealing temperature
increasing. The leakage current density of the BLT films annealed at 700°C is about 5.8×10−8 Al cm2 at the electric field of 250 kV/cm.
Funded by the National Natural Science Foundation of China (No. 90407023) 相似文献
3.
贺海燕 《武汉理工大学学报(材料科学英文版)》2009,24(3):359-362
Fatigue-free Bi3.2La0.8Ti3O12 ferroelectric thin films were successfully prepared on p-Si (100) substrates using metalorganic solution deposition process. The orientation and formation of 5-layers thin films
were studied under different processing conditions using XRD. Experimental results indicate that increase in annealing time
at 700 °C after preannealing for 10 min at 400 °C can remarkably increase (200)-orientation of the films derived from the
precursor solutions with two contents of citric acid. Meanwhile, high content of citric acid increases the film thickness
and is conducive to the a-orientation of the films with the preannealing, and low concentration of the solution is conducive to the c-orientation of
the films without the preannealing. 相似文献
4.
The Bi4Ti3O12 and Bi3.25La0.75Ti3O12 thin films were prepared on the Pt/Ti/SiO2/Si substrate using the sol-gel method. The effect of La doping on the microstructure and ferroelectric properties of Bi4Ti3O12 films were investigated. Both the Bi4Ti3O12 and Bi3.25La0.75Ti3O12 thin films exhibited typical bismuth layered perovskite structure. The 2Pr (remanent polarization) value of Bi3.25La0.75Ti3O12 thin films is 18.6 Μc/cm2, which is much larger than that of Bi4Ti3O12 thin films. And the Bi3.25La0.75Ti3O12 films show fatigue-free behavior, while the Bi4Ti3O12 thin films exhibit the fatigue problem. The mechanism of improvement of La doping was discussed. 相似文献
5.
Guo DongYun Li MeiYa Liu Jun Pei Ling Yu BenFang Zhao XingZhong Yang Bin Wang YunBo Yu Jun 《中国科学E辑(英文版)》2007,50(4):472-477
The Bi4Zr0.5Ti2.5O12 (BZT) thin films were fabricated on the LaNiO3 bottom electrode using sol-gel method. The structure and morphology of the films were characterized using X-ray diffraction, AFM and SEM. The results show that the films have a perovskite phase and dense microstructure. The 2Pr and 2Vc of the Pt/BZT/LaNiO3 capacitor are 28.2 μC/cm2 and 14.7 V respectively at an applied voltage of 25 V. After the switching of 1×1010 cycles, the Pr value decreases to 87% of its pre-fatigue values. The dielectric constant (ε) and the dissipation factor (tanδ) of the BZT thin films are about 204 and 0.029 at 1 kHz, respectively. The films show good insulating behavior according to the test of leakage current. The clockwise C-V hysteresis curve observed shows that the Pt/BZT/LaNiO3 structure has a memory effect because of the BZT film's ferroelectric polarization. 相似文献
6.
Ferroelectric properties of Bi_(3.25)La_(0.75)Ti_(3)O_(12) thin films prepared by sol-gel method 总被引:1,自引:1,他引:1
GUO DongYun LI MeiYa PEI Ling YU BenFang WU GengZhu ZHAO XingZhong WANG YunBo YU Jun 《中国科学E辑(英文版)》2007,50(1)
The Bi3.25La0.75Ti3O12 thin films were fabricated on the Pt/Ti/SiO2/Si substrates using sol-gel method. The structure and morphology of the films were characterized us-ing X-ray diffraction and atomic force microscopy. The thin films showed a perov- skite phase and dense microstructure. The 2Pr and 2Vc of the Bi3.25La0.75Ti3O12 thin films annealed at 700℃ were 18.6 μC/cm2 and 4.1 V, respectively, under an applied voltage 10 V. After the switching of 1×1010 cycles, the Pr value decreased to 90% of its pre-fatigue values. The films showed good insulating behavior according to the test of leakage current. The dielectric constant and the dissipation factor of the Bi3.25La0.75Ti3O12 thin films were about 176 and 0.046 at 1 kHz, respectively. 相似文献
7.
Sol-gel derived bismuth cerium titanate (BCT) thin films with different Bi contents in precursor solutions were deposited
on the Pt/Ti/SiO2/Si substrates. The effect of Bi content in the precursor solutions on the microstructure and ferroelectric properties of
the films was investigated. It is found that with Bi content increasing from 90% to 110% of the nominal value in the precursor
solutions, the dissipation factor and leakage current density of the BCT films obtained decrease, while the grain sizes, dielectric
constant and remanent polarizations (2Pr) increase, and concurrently, a Bi-deficient phase of Bi2Ti2O7 gradually disappears. The film prepared from solution with 110% of the nominal Bi content exhibits pure Bi-layered Aurivillius
polycrystalline phase, and the 2Pr value and coercive field value are 67.1 μC/cm2 and 299.7 kV/cm, respectively. Their dielectric constant and the dissipation factor are about 172 and 0.033 at 1 kHz, respectively.
Moreover, this film shows no polarization fatigue after 4.46×109 switching cycles.
Supported by the Hubei Province Natural Science Foundation (Grant No. 2007ABA309) 相似文献
8.
We have prepared the Ho-substituted bismuth titanate (Bi3.4Ho0.6Ti3O12, BHT) thin films on Pt/Ti/SiO2/Si substrates using sol-gel method. The crystal structure and morphology of the films were characterized using X-ray diffraction
and atomic force microscopy. The BHT film shows a single phase of Bi-layered Aurivillius structure and dense microstructure.
The 2Pr and 2Ec of the 600-nm-thick BHT film were 38.4 μC/cm2 and 376.1 kV/cm, respectively at applied electric field 500 kV/cm. The dielectric constant and dielectric loss are about
310 and 0.015 at a frequency of 1 MHz, respectively. The Pr value decreased to 93% of its pre-fatigue values after 4.46×109 switching cycles at 1 MHz frenquency, and the BHT film shows good insulating behavior according to the test of leakage current.
Supported by the Hubei Province Natural Science Foundation (Grant No. 2007ABA309) 相似文献
9.
QingQuan Tian XiuFeng Wang ChengLong Yu HongTao Jiang ZhengGuang Zhang Yan Wang SheBao Lin 《中国科学E辑(英文版)》2009,52(8):2295-2301
Highly ordered Bi4Si3O12 micro-crystals were prepared at normal atmosphere. Phase identification of the prepared crystals was accomplished by X-ray
diffractometer (XRD). Domain structure and defects were characterized by environmental scanning electron microscopy (ESEM).
XRD shows that the obtained micro-crystals are of eulytite structure with chemical formulation of Bi4Si3O12. A highly ordered growth pattern is confirmed due to the faster growth of the {124} faces than that of the {204} faces by
ESEM. The growing process of the domain structure is of pollen parent and filial generation pattern. The filial generations
of Bi4Si3O12 crystals are generated from the pollen parent. Cracks generate from the defect areas and propagate along the {124} faces
due to their lower binding energy under a proper temperature gradient, contributing to the total transcrystalline fracture.
It is confirmed that the generation and development of the voids in the crystal grains can be developed when unmatched dimensions
of the two opposite faces are formed. And the development of the voids is dependent on the dimensions and orientations of
the two opposite faces.
Supported by the Innovation Research Team Funds of Shaanxi University of Science & Technology (Grant No. SUST-A04) 相似文献
10.
MeiYa Li Ling Pei Jun Liu BenFang Yu DongYun Guo XiaoHua Sun XingZhong Zhao 《中国科学E辑(英文版)》2008,51(11):1843-1849
Ferroelectric Bi3.25La0.75Ti3O12 (BLT) and Bi3.15Nd0.85Ti3O12 (BNT) thin films were fabricated on Pt/TiO2/SiO2/Si (100) substrates by a modified sol-gel technique. X-ray diffraction indicated that these films were of single phase with
random polycrystalline orientations. The surface morphologies of the films were observed by scanning electron microscope,
showing uniform, dense films with grain size of 50–100 nm. Well-saturated hysteresis loops of the films were obtained in metal-ferroelectric-metal
type capacitors with Cu top electrodes at an applied voltage of 400 kV/cm, giving the remanent polarization (2P
r) and coercive field (2E
c) values of the films of 25.1 μC/cm2 and 203 kV/cm for BLT, and 44.2 μC/cm2 and 296 kV/cm for BNT, respectively. Moreover, these capacitors did not show fatigue behaviors after up to 1.75×1010 switching cycles at the test frequency of 1 MHz, suggesting a fatigue-free character. The influences of the La3+ and Nd3+ doping on the properties of the films were comparatively discussed.
Supported by the National Key Basic Research and Development Program of China (Grant No. 2006CB932305) and the Natural Science
Foundation of Hubei Province, China (Grant No. 2004ABA082) 相似文献
11.
The transparent anatse TiO2 nanometer thin films were prepared by the sol-gel method on soda-line glass,X-ray diffraction,thermal analysis and UV-visible spectrophotometer were used to analyze the formation of the phases,Only increasing the heat-treatment time,the average graing size has no obvious change,The mechanism of grain growth in TiO2 thin film is probably as follows:the grain of coating will become grain core later;TiO2 sol constantly deposited on the surface of TiO2 grain and formed membrance with increasing of coating cylce time ;TiO2 grain in the film grow steadily. 相似文献
12.
SUHao WUShun-hua YANHai-yang 《武汉理工大学学报(材料科学英文版)》2004,19(4):62-64
The dielectric ceramics with a main crystal phase of MGTiO3 and additional crystal phase of CaTiO3 were prepared by the conventional electronic ceramics technology .the strucures of MgTiO3 are ilmenitetype,and belong to hexagonal syngony.the ratio of MgTiO3 to Ca TiO3 doping on the dielectric properties of MGTiO3-CaTiO3(MCT)ceranics were inrestigated.the addition of B2O3 decreases the sintering temperatnre and results in rapid desification without obrious negative effect on the Q values of the system(Q=1/tan ).B2O3 exists as liquid phase in the sintering process,promoting the reactions as a singering agent. 相似文献
13.
Highly crystalline orthorhombic Bi2WO6 powders were hydrothermally synthesized from aqueous solutions of Na2WO4 · 2H2O and Bi (NO3)3 · 5H2O over a wide range of pH. The effect of pH on morphologies, sizes and properties of the Bi2WO6 crystals was investigated. The band gaps of the as-prepared Bi2WO6 were determined from the onset of the absorption edge of UV-vis diffuse reflectance spectra. The methyl orange photodegradation
was employed as a probe reaction to test the photocatalytic activity of the as-prepared samples under visible light irradiation.
The photocatalytic activities of methyl orange degradation under visible light irradiation are strongly dependent on the pH
used in the synthesis. The highest efficiency is observed at pH=7.
Funded by the PCSIRT, the National Natural Science Foundation of China (Nos. 50532030 and 50625206) and the Zhejiang Provincial
Natural Science Foundation of China (No. Z4080021) 相似文献
14.
Cu2ZnSnS4 (CZTS) thin films were successfully fabricated on glass substrates by sulfurizing Cu-Sn-Zn multilayer precursors, which were
deposited by ion beam sputtering and RF magnetron sputtering, respectively. The structural, electrical and optical properties
of the prepared films under various processing conditions were investigated in detail. Results showed that the as-deposited
CZTS thin films with the precursors by both ion beam sputtering and RF magnetron sputtering have a composition near stoichiometric.
The crystallization of the samples, however, has a strong dependence on the atomic percent of constituents of the prepared
CZTS films. A single phase stannite-type structure CZTS with a large absorption coefficient of 104/cm in the visible range could be obtained after sulfurization at 520°C for 2 h. The samples relative to the RF magnetron
sputtering showed a low resistivity of 0.073 Ωcm and band gap energy of about 1.53 eV. The samples relative to the ion beam
sputtering exhibited a resistivity of 0.36 Ωcm and the band gap energy is about 1.51 eV.
Supported by the National Natural Science Foundation of China (Grant No. 10574106), the Planned Science and Technology Project
of Guangdong Province (Grant No.2003C05005) and the Natural Science Fund of Zhanjiang Normal University (Grant No.200801) 相似文献
15.
金属有机物热分解法制备Bi4Ti3O12薄膜的工艺研究 总被引:2,自引:1,他引:1
由硝酸铋和钛酸丁酯原料出发,采用金属有机物热分解法(MOD)制备了铁电钛酸铋薄膜;对先体溶液进行了红外光谱和差热分析,研究了旋转甩胶工艺和烧结温度与膜厚的关系,由X射线衍射和扫描电子显微镜分析了薄膜的物相和断面形貌,得到:在450 ̄650℃较低烧结温度下即可合成钛酸铋致密多晶薄膜。薄膜厚度随烧结温度增高而减小,在500 ̄650℃范围内基本呈线性,温度每增高50℃膜厚减小约5%。 相似文献
16.
GUO DongYun LI MeiYa LIU Jun PEI Ling YU BenFang ZHAO XingZhong YANG Bin WANG YunBo & YU Jun Department of Physics Wuhan University Wuhan China Department of Electronic Science Technology Huazhong University of Science Technology Wuhan China 《中国科学E辑(英文版)》2007,50(4)
The Bi4Zr0.5Ti2.5O12 (BZT) thin films were fabricated on the LaNiO3 bottom electrode using sol-gel method. The structure and morphology of the films were character-ized using X-ray diffraction, AFM and SEM. The results show that the films have a perovskite phase and dense microstructure. The 2Pr and 2Vc of the Pt/BZT/LaNiO3 capacitor are 28.2 μC/cm2 and 14.7 V respectively at an applied voltage of 25 V. After the switching of 1×1010 cycles, the Pr value decreases to 87% of its pre-fatigue val-ues. The dielectric constant (ε) and the dissipation factor (tanδ) of the BZT thin films are about 204 and 0.029 at 1 kHz, respectively. The films show good insulating behavior according to the test of leakage current. The clockwise C-V hysteresis curve observed shows that the Pt/BZT/LaNiO3 structure has a memory effect be-cause of the BZT film’s ferroelectric polarization. 相似文献
17.
The surface organic modification of Fe3O4 nanoparticles with silane coupling reagent KH570 was studied. The modified and unmodified nanoparticles were characterized by FT-IR, XPS and TEM. The spectra of FT-IR and XPS revealed that KH570 was coated onto the surface of Fe3O4 nanoparticles to get Fe-O- Si bond and an organic coating layer also was formed. Fe3O4 nanoparticles were spheres partly with mean size of 18,8 nm studied by TEM, which was consistent with the result 17.9 nm calculated by Scherrer's equation. KH570 was adsorbed on surface and formed chemistry bond to be steric hindrance repulsion which prevented nanoparticles from reuniting. Then glycol-based Fe3O4 magnetic liquids dispersed stably was gained. 相似文献
18.
Magnetite Fe3O4 walnut spherical particles and octahedral microcrystals were successfully synthesized from K4 [Fe (CN)6], K3 [Fe (CN)6] and NaOH reagents via a simple hydrothermal process. And the uniform morphology of octahedral microcrystals was obtained
in the presence of ethylene glycol. The morphology and structure of products were characterized by powder X-ray diffraction,
scanning electron microscopy and transmission electron microscopy. The results showed that the Fe3O4 walnut spherical particles and octahedral microcrystals were single crystals with the face-center cubic structure and with
size distributions from 2.2 to 8.6 μm and 1.6 to 12.5 μm, respectively. Their magnetic properties were detected by a vibrating
sample magnetometer at room temperature. The walnut spherical particles exhibited a ferromagnetic behavior with the coercive
force (Hc), saturation magnetization (Ms) and remanent magnetization (Mr) being 150.57 Oe, 97.634 and 12.05 emu/g, respectively.
For the octahedral microcrystals they were 75.28 Oe, 101.90 and 6.69 emu/g, respectively. Different sizes of walnut spherical
particles were controlled synthesized through adjusting the NaOH concentration. It was found that ethylene glycol molecules
have a significant effect on the formation of Fe3O4 octahedra. A possible mechanism was also proposed to account for the growth of these Fe3O4 products.
Supported by Fund of weinan Teachers University (Grant No. 08YKZ008), the National Natural Science Foundation of China (Grant
No. 20573072) and Doctoral Fund of Ministry of Education of China (Grant No. 20060718010) 相似文献
19.
ZHOUXi-ya 《武汉理工大学学报(材料科学英文版)》2004,19(3):45-47
The composition, microstructures and properties of SiC/Al2O3/Al-Si composites formed by reactive penetration of the molten aluminum into the preforms of SiO2 and SiC were investigated. The composition of the composites was measured by X-ray diffraction ( XRD ). The microstructures of the composites were also measured by scanning electron microscopy (SEM) and optical microscopy. In addition, the factors affecting the properties of the composites were discussed. The experiments show that the mechanical properties of the composites depend on their relative densities and the sizes of the fillers“ SiC gains“. The denser the SiC/Al2O3/Al-Si composites, the higher their bending strength. As the filler “SiC gains“ become fine, the bending strength of the composites increases. 相似文献
20.
The influence of Mo on the microstructure, bending strength and HV of Ti/Al2O3 composite was studied, and the influence mechanism was analyzed. The results indicate that after the addition of Mo, the
composite organization is finer and phases distribution is better-proportioned which make the microstructure denser, the bending
strength and HV of composite are also increased to a degree. But the bending strength increases first then decreases with
the increasing of Mo content, so the appropriate Mo content for the Ti/Al2O3 composite is to be further confirmed.
WANG Zhi: Born in 1962
Funded by Natural Science Foundation of China (No. 50232020) and Natural Science Foundation of Shandong Province (No. 2002F21) 相似文献