Mn离子的价态变化与ZnO压敏陶瓷的V-I非线性

Mn ION VALENCE CHANGE AND ZnO VARISTOR CERAMICS V-I NONLINEAR CHARACTER

制备了含Ｍｎ和不含Ｍｎ的ＺｎＯ压敏陶瓷样品，其Ｖ－Ｉ非线性α系数分别为５２．３０及１０．４０，采用电子自旋共振谱（ＥＳＲ）研究了含Ｍｎ的样品中ＭｎＯ２的作用，结果表明，Ｍｎ离子是一种受主杂质，其价态由烧结前的Ｍｎ＾４＋变为烧结后的Ｍｎ＾２＋。Ｍｎ离子价态变化发生在烧结过程中９５０℃这一特定温度，差热分析（ＤＴＡ）结果也显示，ＭｎＯ２在９５１℃存在一相变吸收峰。样品的Ｍｎ＾２＋特征ＥＳＲ信号愈强。

The V-I nonlinear parameters a of ZnO varistor ceramic samples with Mn and Mn- free were 52.30 and 10.40, respectively. Function of MnO_2 in ZnO ceramic materials was investigated by Electron Spin Resonance (ESR), results showed that the valence of Mn ion as an acceptor impurity had changed from Mn4+ before sintering to Mn2+ after sintering. It was found that the valence of Mn ion changed in a specific temperature range during the sintering process. The result of Different Thermal Analysis (DTA) also showed that MnO_2 has a phase transformation absorb peak at 951℃. The higher character ESR signal of Mn2+ in a sample is, the bigger its nonlinear parameter α is.