(La，Nb)共掺杂TiO2压敏陶瓷中第二相的研究  

Studies of Secondary Phases in(La,Nb)-Codoped TiO_2 Varistors Ceramics

作　　者：严继康[1] 甘国友[1] 陈海芳[1] 张小文[2] 孙加林 

机构地区：[1]昆明理工大学材料与冶金工程学院,云南昆明650093 [2]昆明物理研究所,云南昆明650223 [3]云南省科学技术协会,云南昆明650021

出　　处：《压电与声光》2008年第1期67-70,共4页Piezoelectrics & Acoustooptics

基　　金：云南省科技攻关基金资助项目(2002GG09);昆明理工大学科研基金资助项目(2007-15)

摘　　要：研究了(La,Nb)掺杂TiO2压敏陶瓷中第二相的转变及其对压敏性能的影响。采用实验方法研究了La2O3和Nb2O5的掺杂量及烧结温度对TiO2压敏陶瓷的压敏电压和非线性系数的影响。采用SEM、EPMA和XRD测试了TiO2陶瓷的显微结构、化学组成和物相。研究结果表明,(La,Nb)掺杂TiO2压敏陶瓷中存在第二相,随着烧结温度的增加,第二相会从LaNbO4向LaNbTiO6转变。根据La2O3-TiO2、La2O3-Nb2O5和Nb2O5-TiO2的二元相图,绘出了La2O3-Nb2O5-TiO2三元相图,在三元相图基础上初步估算了在不同烧结温度TiO2压敏陶瓷中第二相的相对含量。第二相LaNbTiO6的析出,导致钛空位(V″Ti″)浓度增大,而使压敏电压和非线性系数增加。Transition of secondary phase in TiO2 varistor ceramics doped with Nb2O5 and La2O3 and effects of secondary phase on properties of samples was investigated. The effects of different dopants and sintering temperature on varistor voltage V1mA and nonlinear coefficient a were discussed by experimental method. SEM, XRD, XPS and EDAX were carried out to measured the microstructure, chemical composition and crystal phase of TiO2 ceramics. The results show that there exist secondary phases in （La,Nb） doped TiO2 varistors ceramics. With sintering temperature increasing, secondary phases will transit from LaNbO4 to LaNbTiO6. Ternary phase diagram of La2O3-Nb2O5-TiO2 was plotted based on binary phase diagram of La2 O3-Nb2O5 , Nb2O5-TiO2 and La2 O3-TiO2. According to the ternary phase diagram, the relative content of secondary phases in TiO2 ceramics sintered at different temperature were estimated. It is suggested that segregations of secondary phases cause an increasing concentration of titanium vacancy VTi″″, which result in a higher V1 mA and α.

关 键 词：TIO2 压敏陶瓷 第二相 LaNbO4 LaNbTiO6 

分 类 号：TQ174[化学工程—陶瓷工业]