Sol-Gel法制备ZnO压敏陶瓷及其电性

Preparation of Rare Earth Oxide Doped ZnO Varistor and its Electrical Properties

采用溶胶－凝胶（ｓｏｌ－ｇｅｌ）工艺制备ＺｎＯ电压敏陶瓷粉体．探讨其制备的最佳工艺条件：以 Ｚｎ（ＮＯ３）２与 ＮａＯＨ为反应前驱物制取胶体， Ｚｎ２＋浓度控制在 ０．５ｍｏｌ·Ｌ－１以上， ｐＨ值７．５左右，预烧温度３００℃，陶瓷烧结温度１２００℃；制得的压敏电阻的非线性系数α＝２８；研究了稀土Ｌａ２Ｏ３掺杂对该陶瓷电性的影响：低浓度掺杂时，可提高压敏电压，高浓度掺杂时；不呈现压敏特性；对粉体进行了Ｘ射线衍射和透射电镜分析，预烧后得到五元掺杂的ＺｎＯ粉体粒形呈球状，属六方晶系，粒径分布窄，约为４０～８０ｎｍ．

A new process of preparing non--linear ZnO varistor ceramics was reported. The optimum processing conditions were determined as follows: Zn(NO3)2 and NaOH as the raw material, the concentration of Zn2+ to be above 0.5mol·L-l ， pH value of 7.5, calcining temperature of 300℃, sintering temperature of 1200℃; the varistors with non-linear coefficient of 28 were obtained. The effect of rare earth element La2O3 on the electrical properties of the ceramics was discussed to be ： doping at low concentration is helpful to enhance its breakdown voltage, at high.concentration its voltage sensitive properties will disappear. The powder was characterized by XRD and TEM, showing the five--additive powder to be spherical and with a diameter about 40-80 nm.