钙钛矿型氧离子导体KNb_(1-x)Mg_xO_(3-δ)的制备和表征  

Preparation and characterization of a new perovskite-type oxide ion conductor KNb_(1-x)Mg_xO_(3-δ)

作　　者：向军[1] 李莉萍[2] 苏文辉[2] 

机构地区：[1]华东船舶工业学院数理系,镇江212003 [2]吉林大学物理系,长春130023

出　　处：《物理学报》2003年第6期1474-1478,共5页Acta Physica Sinica

基　　金：江苏省高校自然科学研究计划项目 (批准号 :0 1KJD14 0 0 0 1)资助的课题~~

摘　　要：在高温高压 ( 4 0GPa ,870℃ )下合成了具有正交钙钛矿结构的KNb1 -xMgxO3-δ(x =0 0— 0 3 )系列固体电解质 ,并系统地研究了Mg掺杂对其结构相变和导电性的影响 .变温拉曼谱和DTA测量结果表明 ,随着温度的升高 ,KNb1 -xMgxO3-δ发生了结构相变 ,由铁电正交、四方相转变为顺电立方相 .由于Mg掺杂削弱了B位离子对自发极化的贡献以及A位离子与BO6 八面体间的耦合作用导致了居里温度下降 .其中KNb0 85Mg0 1 5O2 775的居里点大约下降 40℃ ,为 3 92℃ .阻抗谱测量表明 ,所有样品都具有离子导电特征 ,但晶界效应较强 ,电导主要由晶界决定 .通过掺杂 ,提高了样品的电导率 ,其中KNb0 9Mg0 1 O2 85的氧离子电导率最高 ,70 0℃时达到 1.2× 10 - 3S cm .A series of solid electrolytes KNb 1-xMg xO 3-δ(x=0.0—0.3) with an orthorhombic perovskite structure was synthesized under high temperature and high pressure(4.0GPa,870℃). The effect of Mg-doping on the structure transformation and electrical properties was systematically studied in this paper. The Raman spectra at different temperatures and differential thermal analysis results indicate that the structure of the samples transforms from ferroelectric orthorhombic to tetragonal phase, and finally to paraelectric cubic phase with increasing temperature. Weakening of the coupling effect of A-site cation on BO 6 octahedra and the B-site cation contribution to spontaneous polarization, as a result of the Mg 2+ doping in KNbO 3, leads to the decrease of Curie temperature.The Curie point of KNb 0.85Mg 0.15O 2.775,decreasing by about 40℃ in comparison with KNbO 3,is 392℃.Impedance spectroscopic data show that the conductivity of the samples is ionic, the grain-boundary effect is very significant, and the conductivity of the samples is determined mainly by the grain-boundary. Mg-doping increases the oxygen ion conductivity of the samples. KNb 0.9Mg 0.1O 2.85 has the highest conductivity of 1.2×10 -3S/cm at 700℃ in all of the samples,which makes it a kind of promising oxygen ionic conduction materials.

关 键 词：钙钛矿型氧离子导体 KNb1-xMgxO3-δ 高温高压 铁电相变 导电性 氧离子电解质 

分 类 号：TM911[电气工程—电力电子与电力传动]