钇掺杂对ZnO电阻片微观结构和电性能的影响

研究了在ZnO-Bi2O3-Sb2O3系ZnO电阻片中添加少量硼酸和掺杂0.2%～0.8%(摩尔分数)的氧化钇(Y2O3),其显微结构和电性能的变化情况。结果表明,随Y2O3掺杂量的增加,ZnO压敏电阻片的电位梯度从210V/mm提高到422.5V/mm;当掺杂量为0.6%(摩尔分数)时,电性能达到最佳,即残压比最小,为1.12;漏电流最小,为353.0μA。掺杂Y2O3使ZnO晶粒周围除了形成Zn7Sb2O12尖晶石外,还形成了具有细微颗粒的含钇相(Zn-Sb-Y-O)和含铋相(Bi-Sb-O),尖晶石相、含钇相和含铋相的同时存在更加有效地抑制了ZnO晶粒的长大。添加硼酸和增加含钇相在很大程度上改善了ZnO电阻片的电性能。

Microstructural and Electrical Characteristics of ZnO-Bi2O3-Sb2O3 Based Varistor Ceramics Doped with Y2O3

The microstructural and electrical characteristics of ZnO-Bi2O3-Sb2O3 based varistor ceramics doped with a small quantity of boric acid and various amount of Y2O3 in the range from 0.2% to 0.8%(mole fraction) have been investigated.As the amount of Y2O3 increased,the threshold voltage of the ceramics increased from 210 V/mm to 422.5 V/mm.When the amount of Y2O3 increased to 0.6 %,the ZnO varistor achieved the optimum electrical characteristics.i.e.,the minium voltage ratio 1.12 and the minium leakage current 353.0 μA.Besides Zn7Sb2O12 spinel formation around ZnO grains,the addition of Y2O3 results in the formation of a fine-grained Zn-Sb-Y-O phase(Y2O3-contained phase)and Bi-Sb-O phase(Bi-contained phase)located at the grain boundaries of the ZnO grains.The spinel phase,Y2O3-contained phase and Bi-contained phase exist together in the ZnO varistor inhibiting the grain growth efficiently.The improvement of microstructural and electrical characteristics of ZnO varistor is mainly contributed by the addition of boric acid and the increase of Y2O3-contained phase at the grain boundary.