钙钛矿氧化物KNb_(0.85)Ti_(0.15)O_(2.925)的离子导电性

Ionic Conduction of the Perovskite-type Oxide KNb_(0.85)Ti_(0.15)O_(2.925)

采用高温高压法首次制备出钙钛矿型KNb0.85Ti0.15O2.925固体电解质,使用XRD、TG-DTA及交流复阻抗谱对样品的结构和离子导电性进行了表征。XRD结果表明,高压能加快固态反应过程,降低合成温度。合成的KNb0.85Ti0.15O2.925固熔体几乎为纯的四方钙钛矿结构.阻抗谱结果表明KNb0.85Ti0.15O2.925固熔体具有离子导电特征,通过拟合阻抗谱数据获得了电导率与温度的关系。在测量温度范围内,电导率可以拟合成两条直线,低温活化能小于高温活化能,800℃时氧离子电导率为5.6×10-3S·cm-1。

KNb0.85Ti0.15O2.925 solid electrolytewassynthesized byhigh temperature and high pressure method for the first time. The structural characteristics and ionic conductionof KNb0.85Ti0.15O2.925 solid solutions were investigated by XRD,TG-DTA and impedance spectroscopy measurements. XRD results showed that the KNb0.85Ti0.15O2.925solid solution was crystallized in tetragonal perovskitetype structure. High pressure can promote the process of solid state reactions and decrease the synthesizing temperature.The ionic conduction of KNb0.85Ti0.15O2.925 was measured by impedance spectroscopy .The ionic conductivity of KNb0.85Ti0.15O2.925 solid solution at 800 ℃ is 5.6×10-3S·cm-1.By imitatingthe impedance spectroscopy data, the temperature dependence of bulk conductivitywas obtained. A marked curvature at T =630 ℃has been observed in the Arrhenius plot of the bulk conductivity against temperature.The activation energy below 630 ℃is lower than that above 630 ℃,and the reason has been discussed.