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铌酸钾钠基无铅压电陶瓷制备及其织构化技术
Synthesis of Sodium Potassium Niobate Based Lead-Free Piezoelectric Ceramics and Their Textured Processing
【作者】 钟亮；
【作者基本信息】 哈尔滨工业大学 ， 材料加工， 2008， 硕士
【摘要】 本文介绍了当前铌酸钾钠基无铅压电陶瓷的发展现状,并从两个方面对(K0.44Na0.52Li0.04)(Nb0.84Ta0.10Sb0.06)O3陶瓷进行了研究:(1)采用熔盐法(MSS)工艺合成了(K0.44Na0.52Li0.04)(Nb0.84Ta0.10Sb0.06)O3粉体,讨论了熔盐类型、合成温度以及保温时间对粉体制备的影响,并与传统固相法(CMO)工艺进行了比较,结果表明,熔盐法工艺可以降低反应温度,缩短反应时间,且合成的钙钛矿结构粉体颗粒细小,无团聚,在(001)晶面有明显的取向。将固相法与熔盐法合成的粉体在1100℃~1200℃保温2h~8h烧结,结果表明,熔盐法所得陶瓷密度均高于同温度下的固相法陶瓷,且均在1150℃密度达到最大值;温度高于1150℃时,无论哪种方法,随着温度升高,陶瓷中碱金属元素挥发量都增大,但熔盐法所得陶瓷碱金属元素挥发量和挥发速度相对较小,而K的挥发速度大致为Na的两倍。熔盐法所得陶瓷压电常数及机电耦合系数均高于固相法所得陶瓷。(2)采用两步熔盐法,首先制备了四方相层状结构BiNN5前驱体,然后利用拓扑化学反应的方法将四方相层状结构的BiNN5前驱体转化为立方相钙钛矿结构的NaNbO3片状晶体,并以此NaNbO3片状晶体作为模板,应用TGG(模板晶粒生长法)和RTGG(反应模板晶粒生长法)技术,采用流延成型工艺无压固相烧结了(K0.44Na0.52Li0.04)(Nb0.84Ta0.10Sb0.06)O3织构陶瓷。结果表明,TGG工艺可以得到致密度较高的陶瓷,但RTGG工艺所得陶瓷织构度较高。
【Abstract】 The lead-free piezoelectric ceramics (K0.44Na0.52Li0.04)(Nb0.84Ta0.10Sb0.06)O3 have been studied from two aspects. Firstly, powders were synthesized by molten salt synthesis(MSS), we investigated the type of molten salt,temperature and soaking time on the impact of powder preparation,which was compared with the conventional mixed oxide method (CMO). The results show that the MSS process can acquire small perovskite structure powders with (001) grain orientation and without agglomeration at lower temperature in less time. Then the powders prepared by the CMO and MSS processes were sintered at 1100℃~1200℃for 2h~8h, indicating that the density of MSS ceramics is higher than the CMO ceramics and is the highest at 1150℃With increasing temperature, the quantity of volatile elements K and Na in both of CMO ceramics and MSS ceramics decreases, but the rate of evaportion speed in MSS ceramics is relatively small compared with the CMO ceramic, and the rate of K evaportion speed is twice the rate of Na.Secondly, through the two-step MSS process, the tetragonal layered structure BiNN5 precursor was prepared by the molten salt synthsis method, and then they were transformed into cubic perovskite structured NaNbO3 plate-like particles through the topochemical method; the textured (K0.44Na0.52Li0.04)(Nb0.84Ta0.10Sb0.06)O3 ceramics were sintered by the tape cast technology with the TGG (templated grain growth) and RTGG (reactive-templated grain growth) processes, using these NaNbO3 plate-like particles. The results show that the TGG process can obtain ceramics with high density and the RTGG process can obtain ceramics with high texture.
【Key words】 perovskite structure； niobate； texture； molten salt synthesis；