氧化钐掺杂对氧化锌压敏陶瓷电学特性的影响

以氧化锌、氧化镨、氧化亚钴、氧化铬和氧化钐作为原料,经配料、球磨、造粒、压片和烧结等工序制得压敏电阻片,采用电流-电压特性测试、X射线衍射和扫描电子显微镜分别获得陶瓷的电性能参数,材料成分和微观结构图.实验结果表明:随着氧化钐含量的增加,氧化锌压敏陶瓷的非线性和压敏电压呈现先增大后降低的趋势.当氧化钐摩尔百分比低于0.3时,非线性系数和压敏电压随氧化钐含量的增加而增大.而氧化钐摩尔分数为0.3%时,压敏陶瓷具有最佳非线性电学特性,非线性系数为35,压敏电压为435伏/毫米;继续增加氧化钐至摩尔分数为0.5%时,非线性系数和压敏电压将会降低.氧化钐绝大多数聚集在晶界层,抑制晶粒生长,从而提高了压敏陶瓷的压敏电压.而极少数氧化钐与氧化锌发生置换反应,降低了氧化锌颗粒的电阻,从而提高了非线性.因此氧化锌压敏陶瓷因掺杂氧化钐提高了电性能而有望应用在高压领域.

Effect of samarium oxide doping on electrical properties of zinc oxide varistor ceramics

Zinc oxide, praseodymium oxide, cobaltous oxide, chromium oxide and samarium oxide were used as raw material, and zinc oxide varistor ceramics were prepared through the process of ingredient, milling, granulating, pressing and sintering. Microstructures, electrical parameters and material composition were examined by scanning electron microscopy （SEM）, X-ray diffractometry （XRD） and I-V characteristics test respectively. The results show that the nonlinear coefficient and breakdown voltage increases at first and then deceases with samarium oxide added, when the doping level of samarium oxide is no more than 0. 3 mol%, nonlinear coefficient and breakdown voltage of varistor ceramics increase; the varistor ceramics exhibit the optimum nonlinear electrical characteristics at the content 0. 3 mol% of samarium oxide： the nonlinear coefficient of is 35, breakdown voltage is 435 V/mm; with the doping level of samarium oxide is more than 0.5 mol%, the nonlinear coefficient and breakdown voltage decreases. Most of samarium oxide are isolated to grain boundaries to inhibit grain growth and improve the varistor voltage. The nonlinear coefficient is enhanced after solid solution reaction occurres between a handful of samarium oxide and zinc oxide which reduces the resistance of zinc oxide particles. Therefore, zinc oxide varistor ceramics is hopeful to be applied in the field of high- voltage because its electricity property is enhanced by samarium oxide-doped.