复合掺杂BZT粉体的水解沉淀合成与介电性能研究

Synthesis and Dielectric Properties of Complex Doped BZT Ceramics through Hydrolysis-precipitation

采用水解沉淀合成法制备分散均匀的超细掺杂锆钛酸钡材料,研究了还原气氛烧成下,向锆钛酸钡基陶瓷材料中同时引入Nb^5+和Ca^2+对材料结构和介电性能的影响。结果表明,采用水解沉淀法,通过控制NaOH浓度可制备出分散均匀、相结构单一的锆钛酸钡基陶瓷粉体。还原气氛烧成的试样主晶相以四方钙钛矿结构为主,Ca^2+的存在促进了材料中少量六方相BaTiO_(3-x)的形成,消耗了材料内部氧空位,使材料经还原烧成仍保持高阻值。Nb^5+取代Ti^(4+)作为施主掺杂与Ca^2+共同作用,在样品中形成少量液相,Ca^2+在样品中引入量按样品3 mol%计,Nb^5+引入量按0 mol%、0.1 mol%、0.2 mol%、0.4 mol%依次增加,样品相对密度和收缩率依次提高,有效地抑制了晶粒长大,样品的介电损耗依次降低。Nb^5+掺杂锆钛酸钡陶瓷材料介温曲线更平缓,适合做温度稳定型电容器介质材料。

Ultra-fine well dispersed doped barium zirconium titanate powder was synthesized by means of hydrolysis-precipitation method in this work.The effect of Nb^5+and Ca^2+on structure and dielectric properties of the barium titanate ceramics sintered in reducing atmosphere was studied.It is found that crystal phase of the doped sample has a tetragonal phase.The presence of Ca^2+accelerates the formation of a small quantity of hexagonal BaTiO3-x after sintered in the reducing atmosphere,which depleted oxygen vacancies in the sample and made it to have a high resistance after sintering.The donor doping of Nb^5+for Ti4+and Ca^2+work together to form a small amount of liquid phase in the sample during sintering at high temperatures.At the fixed Ca^2+concentration of 3 mol%,the contents of Nb^5+were 0,0.1,0.2,0.4 mol%.With increasing content of Nb^5+,the relative density was increased and the grain growth was promoted,which in turn resulted in a decrease in dielectric loss.The ε-t curves of the Nb5+doped samples are more flat,making them suitable for temperature stable type capacitor applications.