共查询到20条相似文献,搜索用时 15 毫秒
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Kunio Saegusa Wendell E. Rhine H. Kent Bowen 《Journal of the American Ceramic Society》1993,76(6):1495-1504
Lead barium titanate powder with 0.03–0.15 μm particle sizes was prepared from lead barium titanyl oxalate which was previously prepared by reacting high-purity ammonium titanyl oxalate with barium and lead acetate. The critical factor in preparing the barium titanyl oxalate was the reaction time. It was necessary to allow 2–4 h to synthesize the oxalate to get a single-phase barium titanate. The critical factors in preparing the lead titanyl oxalate were pH and the concentration of the solution. It was necessary to adjust the pH to around 0.5 and the concentration to <0.08 M . When lead barium titanyl oxalate is prepared, low pH, low concentration, and a long reaction time are necessary. 相似文献
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Preparation of Tetragonal Barium Titanate Thin Film on Titanium Metal Substrate by Hydrothermal Method 总被引:2,自引:0,他引:2
Koji Kajiyoshi Nobuo Ishizawa Masahiro Yoshimura 《Journal of the American Ceramic Society》1991,74(2):369-374
Tetragonal BaTiO3 thin films were prepared directly on Ti metal substrates in Ba(OH)2 solutions by a hydrothermal method at temperatures 400° to 800°C for 5 to 240 min. The film thickness estimated from weight gain of Ti plate was in the range from 0.5 to 2.5 μm, and it increased with increasing treatment temperature, treatment time, and Ba(OH)2 concentration. Rectangular crystals having {100} and {001} faces grew idiomorphically with approximate crystal size of 0.3 to 2.0 μm. The tetragonality of the BaTiO3 films became apparent when the average crystal size exceeded about 1 μm. Lattice parameters of the films were a = 3.994 Å, c = 4.035 Å, and c/a = 1.010. The films formed above 600°C had preferred orientation showing stronger XRD peaks of h 00 and 00 l than the other peaks. 相似文献
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Nanocrystalline tetragonal-BaTiO3 powder was prepared using a hydrothermal method, under moderate conditions, and with a high precursor concentration. Characterization via X-ray diffractometry and differential scanning calorimetry confirmed that the average particle size and tetragonal content of the prepared powder were 70 nm and 80%, respectively. The sintered sample made from the prepared powder had a room-temperature dielectric constant of 6900, which was high for BaTiO3 . 相似文献
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热水溶液中钛酸锶晶粒的结晶过程 总被引:6,自引:0,他引:6
研究了以TiCl4水解得到的H4TiO4胶体作为钛源,在热水溶液中制备SrTiO3晶粒的结晶过程,TEM和XRD结果表明,其结晶过程主要包括3个阶段,第1阶段主要是SrTiO3晶核的形成过程;第2阶段主要是SrTiO3晶粒的配向聚集生长过程;第3阶段主要是SrTiO3晶粒的溶解结晶过程,其中第1阶段的控制步骤为H4TiO4胶体的溶解,第2阶段中晶粒的配向聚集生长在短时间内即可完成,很快进入第3阶段小晶粒的溶解和大晶粒的重结晶过程,该阶段反应速度慢,需要较长时间才能得到结晶完好的晶粒,在热水溶液中以H4TiO4胶体作为钛源制备SrTiO3晶粒关键在于控制结晶过程的第1阶段和第2阶段。 相似文献
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通过正交实验法,对不同钡钛比、反应温度、保温时间进行了水热合成钛酸钡纳米粉体的实验研究,对所得粉体进行了DTA,XRD,TEM等分析表征,分析研究了不同水热反应条件对合成钛酸钡纳米粉体的影响。 相似文献
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Mingmei Wu Junbiao Long Guangguo Wang Aihong Huang Yuji Luo Shouhua Feng Ruren Xu 《Journal of the American Ceramic Society》1999,82(11):3254-3256
Tetragonal BaTiO3 powders were prepared hydrothermally, using Ba(OH)2 ·8H2 O and TiO2 (anatase), in the absence of anions such as chloride ions, at a temperature of 220°C for several days. Characterization via X-ray diffractometry, scanning electron microscopy, and differential scanning calorimetry confirmed that increasing the Ba:Ti molar ratios (from 1:1 to 4:1) and alkaline concentrations (from 1.0 M to 3.0 M ) promotes the formation of tetragonal BaTiO3 . 相似文献
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Tetragonal BaTiO3 powders were prepared hydrothermally at 240°C, in only 12 h, using BaCl2 ·2H2 O and TiCl4 , which are rather easy to manipulate. Characterization via X-ray diffractometry, scanning electron microscopy, Brunauer–Emmett–Teller analysis, and differential scanning calorimetry confirmed that increasing the NaOH excess concentration (from 0.5 M to 2.0 M ) and decreasing the initial TiCl4 concentration (from 0.625 M to 0.15 M ) promotes the formation of tetragonal BaTiO3 powders. After reaction, the powders were proved to be phase-pure BaTiO3 , with no impurities, such as Cl− and CO3 2− . 相似文献
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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
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以钛酸丁酯、硝酸钡和醋酸锌为原料,采用微波水热法制备了掺锌的BaTiO3微粉。利用XRD和SEM对产物进行了表征。研究表明,掺杂后锌固溶到了钛酸钡的晶格中并取代钡位或钛位。微波水热合成锌掺杂钛酸钡微粉温度更低,同时反应速率明显提高。 相似文献
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Nanosized Barium Titanate Powder by Mechanical Activation 总被引:3,自引:0,他引:3
Mechanical activation, without any additional heat treatment, is used to trigger the formation of a perovskite BaTiO3 phase in an oxide matrix that consists of BaO and TiO2 in a nitrogen atmosphere. The resulting BaTiO3 powder exhibits a well-established nanocrystalline structure, as indicated by phase analysis using X-ray diffractometry. A crystallite size of ∼14 nm is calculated, based on the half-width of the BaTiO3 (110) peak, using the Scherrer equation, and an average particle size of 20–30 nm is observed using transmission electron microscopy for the activation-derived BaTiO3 powder. 相似文献
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Preparation of Highly Dispersed Ultrafine Barium Titanate Powder by Using Microbial-Derived Surfactant 总被引:1,自引:0,他引:1
Hidehiro Kamiya Kenjiro Gomi Yuichi Iida Kenji Tanaka Takashi Yoshiyasu Toshihito Kakiuchi 《Journal of the American Ceramic Society》2003,86(12):2011-2018
To uniformly disperse ultrafine BaTiO3 particles with a stoichiometric composition and several tens of nanometers in diameter to primary particles during the sol–gel synthesis process, a new aqueous surfactant with a high hydrophilic group density and special cis-structure was prepared from a microbial product and added to solution before the sol–gel synthesis reaction. Because of the rapid formation of large and porous aggregates which were 30–50 μm in diameter in suspension without addition of this unique structural surfactant, the prepared ultrafine BaTiO3 particles caused rapid sedimentation in suspension. The addition of the surfactant in the range of 7.1 wt% for the synthesized BaTiO3 particles made it possible to decrease the size of the aggregates in suspension as well as the sedimentation velocity while maintaining the stoichiometric composition. The optimum additive content to obtain the minimum aggregate size of about 100–200 nm in diameter and the highest dispersion stability in suspension while maintaining the stoichiometric composition of prepared ultrafine BaTiO3 particles without other phases was determined at about 7.1 wt%. Because the excess addition of this surfactant at more than 8.5 wt% inhibited the uniform synthesis of BaTiO3 particles, an amorphous phase with a highly specific surface area and a BaCO3 phase formed in the synthesized particles. 相似文献
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钡钛醋酸盐凝胶制备BaTiO3粉体 总被引:2,自引:1,他引:2
本文报道了用sol-gel法制备钡醋酸盐凝胶,并分别作高灼烧和水热处理制备BaTiO3粉体。通过对产物的表征,比较了这两种处理过程,进而对水热条件下陶瓷粉体的形成机理作了探讨。由于水热条件,凝胶在反应介质中溶解,进而结晶形成晶粒,因此所形成的BaTiO3晶粒线度小;线度分布范围窄。晶粒形貌完整,明显优于高温灼烧处理后得到的粉体。 相似文献
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The dielectric aging phenomenon was observed in tetragonal polycrystalline solid solutions of calcium titanate in barium titanate between 30° and 90°C, and the 90° ferroelectric domain microstructures were analyzed using replica electron microscopy and statistical procedures. The results show a correlation between aging rate and 90° domains that may be satisfactorily interpreted in terms of the internal residual stress relaxation theory of aging. 相似文献
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The high-temperature hexagonal (h) phase has been found to retain metastability at room temperature and co-exist with the room-temperature tetragonal (t) phase in hot-pressed BaTiO3 ceramics. The crystallographic orientation relationships between two polytypes have been analyzed by TEM and selected-area diffraction patterns (SADPs). The relationships are illustrated using transformation matrices for both the forward h→t phase transformation ( M f ) and the backward t→h phase transformation ( M b ) based on two independent microstructures containing h-particle in t-matrix and t-particle in h-matrix, respectively. Self-consistent transformation matrices are derived from the coincident reflections in corresponding SADPs. The forward and backward matrices are inverse matrix to each other. 相似文献