共查询到15条相似文献,搜索用时 125 毫秒
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以熔盐法制备的片状SrBi2Nb2O9晶体为模板剂,采用模板晶粒生长技术和流延法制备了Sr-Bi2Nb2O9织构陶瓷,研究了模板含量对SrBi2Nb2O9织构陶瓷烧结行为、织构度、显微结构的影响。结果表明:模板含量为10wt%时,1200℃保温2h烧结可获得体积密度最大的SrBi2Nb2O9织构陶瓷,模板含量继续增加,体积密度降低;织构陶瓷的晶粒尺寸随模板含量的增加而逐渐增大,且晶粒取向性生长趋于明显,当模板含量为10wt%时,织构化SrBi2Nb2O9陶瓷的晶粒取向率f达到最大值,为0.81;织构化陶瓷的压电常数d33达到13pC/N,高于固相法制备的陶瓷的压电常数。 相似文献
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以熔盐法合成各向异性的片状单相SrBi2Nb2O9 (SBN) 陶瓷粉体作为模板,采用模板晶粒生长(TGG)技术成功得制备出织构化SrBi2Nb2O9 (SBN) 陶瓷.通过SEM和XRD分析了烧结制度及模板尺寸对SBN陶瓷晶粒取向率的影响.结果表明,晶粒取向率随着烧结温度、烧结时间、升温速率、模板尺寸的升高而升高.合理控制制备工艺可获得晶粒取向率为0.89的高度织构化SBN陶瓷.织构化SBN陶瓷的相对体积密度随着模板平均粒径的增加而降低.在高温阶段,片状SBN模板晶粒消耗周围的基体粉体沿着流延方向生长,从而最终得到晶粒高度定向的陶瓷. 相似文献
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钛酸铋钠基陶瓷的烧结机制 总被引:1,自引:0,他引:1
应用晶粒生长动力学唯象理论研究籽晶模板对0.94Na0.5Bi0.5TiO3-0.06BaTiO3无铅压电织构陶瓷烧结机制的影响规律,确定了晶粒生长动力学指数和激活能,探讨了籽晶含量对陶瓷晶粒生长的作用机理。实验结果表明:籽晶Bi2.5Na3.5Nb5O18含量小于或等于15wt%时,晶粒生长以界面反应和晶格扩散两种机制控制,籽晶含量大于或等于20wt%时,以界面反应机制为主;取向长条晶需要的激活能小而容易生长,且晶粒尺寸比等轴晶大。 相似文献
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材料微结构的织构化能充分发挥材料中晶体各向异性所表征的物理效应,改善材料的性能。评述了近年来织构化工艺在无铅压电陶瓷材料研究中的应用和进展状况,归纳和分析了热锻(HF)、模板晶粒生长(TGG)、反应模板晶粒生长(RTGG)和多层晶粒生长(MLGG)等技术间的差异、优缺点以及应用范围。重点讲述了TGG和RTGG技术在高对称性钙钛矿型NBT陶瓷中的应用及织构化过程中的晶粒生长机制,展望了今后的发展趋势。 相似文献
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Seth VK Schulze WA 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1989,36(1):41-49
The concept of grain-oriented fabrication in ceramics, which utilizes anisotropy either in morphology or some specific property of the particle, is reviewed. A fabrication method, which maximizes the grain orientation, is described for Bi(4)Ti(3)O(12 ). The process utilized plate-like morphology of Bi(4)Ti (3)O(12) particles and yielded a ceramic with an X-ray density of 95.4% and an unprecedented value of 100% for Lotgering's orientation factor in the direction of orientation. The dielectric and piezoelectric properties of this ceramic are described and compared to single crystal values. Complex impedance analysis of the ceramics was used to explain the dielectric relaxations at elevated temperatures. The use of grain-oriented fabrication as a practical technique for making polycrystalline ceramics with electrical properties close to those of single crystals (in the direction of orientation) is emphasized. The use of grain-oriented Bi(4)Ti(3)O(12) ceramics as a high-temperature piezoelectric transducer is suggested. 相似文献
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弛豫铁电单晶及织构陶瓷的研究进展 总被引:2,自引:0,他引:2
综述了近年来弛豫铁电单晶和织构陶瓷的制备及其介电、压电性能的研究进展。弛豫铁电单晶的制备方法主要有高温溶液法、布里奇曼法和固态再结晶法,尺寸可达40mm以上,(001)切片压电常数d33最大可达3000pC/N,k3达到0.93,但是成分不均匀仍是影响晶体压电性能的一个主要因素。织构陶瓷的制备方法主要为固态再结晶法(TGG法和RTGG法),其耗时短、成本低,压电性能可达到单晶的60%~80%,介电常数甚至可以超过部分单晶,是一个新的发展方向。 相似文献
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Deng Xiangyun Wang Xiaohui Li Dejun Li Longtu 《Frontiers of Materials Science in China》2007,1(3):319-321
Dense nanocrystalline BaTiO3 (BT) ceramics with 50 nm average grain size obtained by spark plasma sintering were investigated. The dielectric data showed
a ferropara phase transition with a maximum permittivity of 1,602 at 120°C and at 1 kHz. The polarization reversal characteristics
were measured, and the typical piezoelectric hysteresis loop was recorded. The asymmetry of permanent polarization and coercive
field in polarization-electric field curves were obtained and attributed to the existence of an internal electric field. The
present results provide experimental evidence, indicating that if a critical grain size exists for ferroelectricity, then
it is less than 50 nm for polycrystalline BT ceramics. 相似文献