高温极化压电陶瓷的研究

The Investigation of Poling Piezoceramics at High Temperature

极化是压电陶瓷的一个重要工艺阶段;一般在有机硅油中的低温极化(T_p=120℃)条件下,大尺寸、较小绝缘电阻的高居里点硬性压电陶瓷难以达到饱和极化,且老化性能有时也不尽人意.本文提出了一种新的极化工艺—高温极化,即在极化温度高于居里温度下弱电场极化;该工艺方法简单,效果较好.对 Mn^(4+)掺杂改性的硬性压电陶瓷 PCM 进行实验,发现当极化温度 T_p=260℃(T_c=258℃)时,饱和极化场强 E_p 仅需要150V/mm.高温极化的主要机理是内偏置电场的建立和平衡问题.

Poling condition is a very important stage for preparing high quality piezoceramics.In general,if the sample with high thickness and low resistance be poled at low temperature (T_p=120℃),it will be difficult to get saturation polarization and good ageing behaviors. In this paper,we put forward a new poling technology—high temperature poling;that is, under poling temperature T_p larger than Curie temperature (T_c),and using.weak electric field to pole piezoceramics.This method is simple and effective.In the experiments we used hard- piezoceramics doped with Mn^(4+),we got the optimum condition,T_p=260℃ and E_p=150V/mm. The mechanism of high temperature poling is the foundation and balance of internal bias electric field.