氧化热处理SrTiO_3压敏电阻的电容弥散频率

Capacitance Dispersion Frequency of SrTiO_3 Varistor Based on Oxidation Heat Treatment

经测量氧化热处理后SrTiO3压敏电阻的电容频率和复阻抗,结果表明:升高热处理温度提高压敏电压时,电容弥散频率显著降低,晶粒电阻明显增大。由电容频谱曲线的主要特征判断,界面驰豫极化机制主导这一电容弥散区。界面驰豫方程确定的特征驰豫时间和电容弥散频率计算式,与晶粒和晶界的电物理参数相关,弥散频率的计算值与实验结果定性相符。热处理温度升高使氧过度向晶粒体内扩散,导致晶粒电阻明显增大,是弥散频率降低的主要原因。

Measured and analyzed were the capacitance frequency spectrum and the complex impedance of SrTiO3 varistor based on oxidation heat treatment. Obtained results show that the increase of heat treatment temperature for promoting varistor voltage will bring the capacitance dispersion frequency down notably, and the grain resistance increases obviously. The main features of capacitance frequency curve recognize that the capacitance dispersion region results from the mechanism of interface relaxation polarization. The formulas from an interface relaxation equation for the calculation of specific relaxation time and capacitance dispersion frequency are related to the electrophysics parameters of the grain and grain boundary. The calculations of dispersion frequency are coinciding with the measure values qualitatively. Analysis indicates that grain resistance increase obviously with the increase of heat treatment temperature due to oxygen diffusing into the grain excessively It is a predominant reason on the decrease of dispersion frequency.