共查询到20条相似文献,搜索用时 15 毫秒
1.
Ruitao Zhang Jie Fang Li Dwight Viehland 《Journal of the American Ceramic Society》2004,87(5):864-870
Structure–property relationships were investigated to reveal the generic influence of various substituents on ferroelectric BaTiO3 . Compositional modifications of ferroelectric BaTiO3 were systematically investigated for La3+ and Nb5+ substituents. A generic influence of charged point defects in breaking down the ferroelectric domains into polar clusters was demonstrated. In both types of modified BaTiO3 , relaxor ferroelectric behavior was induced for higher concentrations of substituents. 相似文献
2.
3.
4.
A. K. Bain T. J. Jackson Yiannis Koutsonas M. Cryan S. Yu M. Hill R. Varrazza J. Rorison M. J. Lancaster 《Ferroelectrics Letters Section》2007,34(5):149-154
Barium strontium titanate (Ba0.05Sr0.95TiO3) ferroelectric thin films have been prepared on single crystal [001] MgO substrates using the pulsed laser deposition method. The X-ray diffraction (XRD) analysis show the films were oriented with the [001] direction perpendicular to the plane of the substrate. The refractive index of Ba0.05Sr0.95TiO3 is determined from model fitting with the calculated data of the reflectivity of Ba0.05Sr0.95TiO3 in the wavelength 1450-1580 nm at the room temperature. The dispersion curve decreases gradually with increasing wavelength. The average value of the refractive index is found to be 1.985 in the wavelength 1450-1580 nm which is important for optoelectronic device applications. 相似文献
5.
W. R. BRATSCHUN 《Journal of the American Ceramic Society》1963,46(3):141-144
Hot-pressed barium zirconate-lead titanate ceramics have been examined to determine crystal-line symmetry and dielectric, ferroelectric, and piezoelectric properties. Barium zirconate additions to lead titanate form solid solutions with a decreasing tetragonal c/a axial ratio until at 60PbTiO3 –40BaZrO3 to 75PbTiO3 –25BaZrO3 the ceramics have coercive forces low enough to permit polarization. High-coercive-force piezo-electric ceramics are formed with kp up to 0.30 and d33 up to 110 × 10−12 coulombs per newton. 相似文献
6.
Richard J. Meyer Robert E. Newnham Ahmed Amin Bernard M. Kulwicki 《Journal of the American Ceramic Society》2003,86(6):934-938
This paper describes the performance of the cymbal flextensional transducer using Dy-doped barium strontium titanate (BST) as the driver material. BST was first characterized for its dielectric and loss behavior as a function of temperature and electrical bias field. With no electrical bias, the transition temperature was measured to be near 20°C and have a dielectric constant >20 000. The strain of a BST disk was then measured and compared with other ceramics. At room temperature the strain and average effective piezoelectric d 33 of this non-lead composition was slightly larger than Navy type I lead zirconate titanate (PZT-4) ceramic. The strain/field behavior was also measured as a function of temperature. Cymbal capped BST ceramic was found to have an amplified displacement of 28×, also very similar to type I ceramic. The stiffness of BST was found to be tunable by dc voltage and 2 to 3 times larger than that of PZT. This material has promise for applications in actuators and transducers with large generative force. 相似文献
7.
The aging phenomenon in tetragonal ferroelectric bairum titanate was investigated by optical microscopy and by electrical measurements. Transmission electron microscopy was used to observe in detail domain reactions which occurred during aging. Aging may be characterized as an exhaustion-type process because of the increase in the apparent activation energy with time. It is concluded that aging is the relief of the residual stresses of the ferroelectric transition by the thermally activated nucleation of 90° domains. 相似文献
8.
Electron Emission from Barium Strontium Titanate Ceramics 总被引:1,自引:0,他引:1
Shutao Chen Xianlin Dong Shuxin Zheng Ziqiu Zhu Chuanxiang Tang 《Journal of the American Ceramic Society》2006,89(7):2118-2122
This paper focuses on understanding the influence of materials' properties on the ferroelectric electron emission. Ferroelectric ( x =1.0 and 0.8) and paraelectric ( x =0.67 and 0.5) compositions of barium strontium titanate (Ba x Sr(1− x ) TiO3 ) system were chosen for study based on their different ferroelectric and dielectric properties. Similar emission current waveforms were obtained from four compositions with negative triggering voltage applied to the rear electrode of the samples. It was difficult to explain the experimental results using the spontaneous polarization-switching model. The mechanism of electron emission from Ba x Sr(1− x ) TiO3 ceramics was ascertained to surface plasma emission. 相似文献
9.
10.
Viswanathan Kumar 《Journal of the American Ceramic Society》1999,82(10):2580-2584
Hydrolytic reactions of metal alkoxides offer a broad range of possibilities for their use in the preparation of ceramic powders. This paper reports a unique and novel process to prepare fine powders of BaTiO3 and SrTiO3 from stable precursor solutions by carefully controlling the pH and temperature. This simple route offers good control of stoichiometry and the powders are agglomerate-free with fine particles of size 0.06–0.1 µm and were well sintered at 1200° and 1350°C, respectively. The dielectric properties of the dense ceramics are also reported. The formation aspects of these perovskite phases are also discussed. 相似文献
11.
首次应用粉末-溶胶工艺合成出铌酸锶钡/钛酸锶钡复相陶瓷(SBN/SBT)。以Clausius(克劳修斯)-Mosotti(莫索缔)方程为基础,采用混合对数法则,通过实验得到的复合材料的晶格参数和铌酸锶钡、钛酸锶钡的理论极化率,建立了描述铌酸锶钡/钛酸锶钡复相陶瓷的介电常数预测模型,通过数学模型得到的预测数值与实验数值吻合。 相似文献
12.
13.
H. A. SAUER S. S. FLASCHEN D. C. HOESTEREY 《Journal of the American Ceramic Society》1959,42(8):363-366
A large piezoresistance response to hydrostatic pressure is reported for a series of ceramic compositions in the system barium strontium lanthanum titanate (Ba, Sr, La)TiO2 . This property appears to be closely associated with the Curie region (cubic-tetragonal phase transition) and the phenomenon of a positive temperature coefficient of resistance for these same compositions. The piezoresistance coefficient, similar to the temperature coefficient of resistance, is positive in the Curie region, and is found to range up to the order of 700 X 10 −12 sq. cm. per dyne. Consistent with the observed piezoresistance effect, a positive piezocapacitive effect, ranging up to the order of 700 x 10−12 sq. cm. per dyne, is observed in these compositions in the absence of the lanthanum impurity which produces semiconduction. It is suggested that these materials may be of interest in pressure-sensitive devices such as acoustic transducers and pressure-sensing elements and in techniques for measuring force and displacement. 相似文献
14.
Dependence of Crystallization Behavior on Particle Size in Barium Strontium Titanate Glass‐Ceramics 下载免费PDF全文
Jia Zhu Yong Zhang Xiaozhen Song Qian Zhang Dongliang Yang Yongzhou Chen 《Journal of the American Ceramic Society》2015,98(8):2340-2343
Differential thermal analysis studies on the crystallization kinetics and phase developments of barium strontium titanate glass‐ceramics have been performed for a series of glass particles with different particle sizes. The crystallization behavior was deduced to be influenced strongly by the particle size of the glass samples. These studies have revealed the initial formation at lower temperatures of metastable fresnoite Ba2TiSi2O8 (BTS) phase followed by its transformation at higher temperatures to feldspar BaAl2Si2O8 (BAS) and perovskite (Ba,Sr)TiO3 (BST) phases. The metastable BTS phase was proved to crystallize predominately by surface crystallization while the feldspar BAS phase showed significant evidence of internal crystallization. And for the perovskite BST phase, crystallization mechanism changes from surface to internal type at a critical particle size of 75 μm. In addition, activation energy and the Avrami parameter for crystallization have been determined for the three phases by the employment of glass samples with two typical particle sizes. 相似文献
15.
G. GOODMAN 《Journal of the American Ceramic Society》1960,43(2):105-113
An unusual type of ferroelectric behavior has been observed in barium zirconium metaniobate, BaNb1.5 Zr0.25 O5.25 . The orthorhombic, pseudotetragonal single crystal displays dielectric hysteresis only in its c direction, with normal dielectric properties in the a-b plane. No evidence of a fist- or second-order ferroelectric-paraelectric transition has been observed up to 1400°C. The crystal melts incongruently at about 1525°C. A maximum in the dielectric constant occurs at 80°C. when measured at 103 c.p.s. but is not accompanied by any effect in the spontaneous polarization. The temperature of this k' maximum has the frequency dependence of a dielectric relaxation process with an average activation energy of 0.2 e.v. These properties are consistent with the idea of a higher than second-order ferroelectric-paraelectric transition in this material. The dielectric behavior is explicable in terms of 180°"dipole aggregates" having a wide range of activation energies of reversal. There are suggestions in the technical literature of similar behavior in other materials. 相似文献
16.
17.
18.
Phase equilibria in the system BaTiO3 –SrTiO3 (with 0 to 7 mol% SrTiO3 ) were studied at temperatures above 1600°C in air. Quenching experiments were performed using high-purity starting materials, and run products were examined by X-ray diffraction and differential scanning calorimetry to determine phase composition and Sr concentration. Melting involves a binary loop intersected by the invariant reaction hexagonal (Ba, Sr)TiO3 ( ss ) ⇌ cubic (Ba, Sr)TiO3 ( ss ) + liquid. In contrast with earlier work, these results indicate that there is no depression of the melting point with Sr addition and no congruent melting point in this compositional range. 相似文献
19.
Maria C. Gust Leslie A. Momoda Neal D. Evans Martha L. Mecartney 《Journal of the American Ceramic Society》2001,84(5):1087-1092
Microstructural development of thin-film barium strontium titanate (Ba x Sr1– x TiO3 ) as a function of strontium concentration and thermal treatment were studied, using transmission electron microscopy (TEM) and X-ray diffractometry (XRD). Thin films, ∼250 nm thick, were spin-coated onto Pt/Ti/SiO2 /Si substrates, using methoxypropoxide alkoxide precursors, and crystallized by heat-treating at 700°C. All films had the cubic perovskite structure, and their lattice parameters varied linearly with strontium content. Films with higher strontium concentrations had a larger average grain size. In situ TEM heating experiments, combined with differential thermal analysis/thermogravimetric analysis results, suggest that the gel films crystallize as an intermediate carbonate phase, Ba x Sr1– x TiO2 CO3 (with a solid solution range from x = 1 to x = 0). Before decomposition at 600°C, this carbonate phase inhibits the formation of the desired perovskite phase. 相似文献
20.
Direct-Current Field Dependence of Dielectric Properties in Alumina-Doped Barium Strontium Titanate 总被引:7,自引:0,他引:7
Long Wu Yih-Chien Chen Cheng-Liang Huang Yi-Ping Chou Yuan-Tu Tsai 《Journal of the American Ceramic Society》2000,83(7):1713-1719
The dielectric properties of (Ba0.6 Sr0.4 )TiO3 and Al2 O3 -doped (Ba0.6 Sr0.4 )TiO3 have been characterized. The grain size of the specimen is maximum for (Ba0.6 Sr0.4 )TiO3 that has been doped with 1 wt% Al2 O3 . The density and the real part of the relative dielectric constant each decrease as the Al2 O3 content increases. The loss factor is minimum for (Ba0.6 Sr0.4 )TiO3 that has been doped with 2 wt% Al2 O3 . The dielectric constant of the specimens decreases as the applied dc field increases. The influence of the dc field on the loss factor is much less than that on the dielectric constant. The tunability is ∼24% for (Ba0.6 Sr0.4 )TiO3 that has been doped with 1 wt% Al2 O3 . 相似文献