Y_(2)O_(3)、Ga_(2)O_(3)和B_(2)O_(3)共掺杂对ZnO压敏电阻微观结构和电气性能的影响

Effect of Y_(2)O_(3),Ga_(2)O_(3)and B_(2)O_(3)Co-doping on Microstructure and Electrical Properties of ZnO Varistors

稀土元素的掺杂能显著提高ZnO压敏电阻的电压梯度(E1mA),但却会导致泄漏电流的增加,从而致使ZnO压敏电阻的老化稳定性降低。为了解决稀土元素掺杂导致泄漏电流增加的问题,研究了Y_(2)O_(3)、Ga_(2)O_(3)和B_(2)O_(3)共掺杂对ZnO压敏电阻微观结构和电气性能的影响。掺杂的Y_(2)O_(3)通过钉扎效应能够显著抑制ZnO晶粒的生长提高样品的E1mA。Ga_(2)O_(3)的掺杂则有助于提高晶界层的势垒高度(φb)、抑制泄漏电流密度(JL)的增加。而B_(2)O_(3)的掺杂则有助于改善样品的液相烧结,避免具有高电阻率Y尖晶石相聚集现象的发生,传输通道的阻断有利于降低样品的JL。此外,B_(2)O_(3)的掺杂能够促进ZnO晶粒与其他添加剂在晶界处的离子交换,使φb得到有效的提高,进一步降低其JL。通过Y_(2)O_(3)、Ga_(2)O_(3)和B_(2)O_(3)的共掺杂获得了综合性能相对优异的ZnO压敏电阻:其E1mA=466 V/mm,JL=0.41 A/cm^(2),非线性系数为95。高梯度、低泄漏ZnO压敏电阻的成功研发对于解决金属氧化物避雷器整体电位分布不均的问题具有重要的意义。

The doping of rare earth elements can significantly improve the voltage gradient(E1mA)of ZnO varistors,whereas it will lead to an increase in the leakage current,thereby reducing the aging stability of ZnO varistors.In order to solve the problem of increasing leakage current caused by doping rare earth elements,the influences of Y_(2)O_(3),Ga_(2)O_(3)and B_(2)O_(3)co-doping on the microstructure and electrical properties of ZnO varistors were studied in this paper.The doped Y_(2)O_(3)can significantly inhibit the growth of ZnO grains and increase the E1mA of the sample through the pinning effect.The doping of Ga_(2)O_(3)helps to increase the barrier height(φb)of the grain boundary layer and restrain the increase of leakage current density(JL).The doping of B_(2)O_(3)is helpful to improve the liquid phase sintering of the sample and avoid the occurrence of Y spinel phase aggregation with high resistivity,and the blocking of the transmission channel is beneficial to reduce the JL of the sample.In addition,the doping of B_(2)O_(3)can promote the ion exchange between ZnO grains and other additives at the grain boundary,so thatφb can be effectively improved and its JL can be further reduced.In this paper,ZnO varistors with relatively excellent comprehensive performance were obtained by co-doping Y_(2)O_(3),Ga_(2)O_(3)and B_(2)O_(3),of which the voltage gradient(E1mA)is 466 V/mm,the leakage current density(JL)is 0.41 A/cm^(2),and its nonlinear coefficient is 95.The successful development of high gradient and low leakage ZnO varistors is of great significance for solving the problem of uneven distribution of the overall potential of metal oxide arrester.