掺Fe_2O_3的ZnO压敏性能

The Varistor Effect Study of Fe_2O_3-doped ZnO

在一定成型压力和烧结温度下掺杂浓度对掺Fe2O3的ZnO陶瓷的致密度和压敏性能的影响研究。得到以下结果:(1)在1 000℃,ZnO与Fe2O3固相反应生成ZnFe2O4,在1 200℃ZnO陶瓷完全致密化;(2)在优化工艺参数后,研究了在ZnO中掺杂不同浓度的Fe2O3的电阻率,只有在一定电阻率范围内才具有压敏效应。随Fe2O3掺杂含量升高,电阻率在0.1%at达到极大值,而后降低,在2%at以后电阻率急剧升高,压敏效应增大,在4%at时阈值电压为92伏,非线性最好。过高的掺杂浓度(>5%at)导致绝缘相厚度过大而没有压敏效应;(3)Fe2O3掺4%at后,烧结温度超过1 200℃时,由于ZnFe2O4相分解产生载流子浓度增大使电阻率下降。

The influence of dopant concentration of Fe2O3 on ZnO ceramic density and varistor effect was investigated under a certain pressure and sintering temperature. The results indicate that ： （ 1 ） ZnO reacts with Fe2O3 to form ZnFe2O4 phase when sintering temperature is over 1 000 ℃ and densification is finished above 1 200 ℃. （2） At optimized process parameters, the resistivity of different doped concentration was studied as varistor effect happened in a certain range of resistivity. With the increase of the concentration of Fe2 03 , the resistivity firstly increases and rea- ches the peak at 0. 1% at dopant, then decreases. When the doped concentration increases from 2% at to 4% at,resistivity and varistor effect increase dramatically. At 4% at, the valve voltage is 92 V and nonlinearity effect,improves. When the dopant concentration is more than 5% at, varistor effect disappears because of insulator phase; （3） At the concentration of 4% at Fe203 ,with the increase of sintering temperature ,ZnO and ZnFe2Q phases discompose and carriers concentration increases ,which leads to the resistivity decreasing.