稀土氧化物Pr2O3掺杂对高压ZnO压敏电阻性能的影响

采用低温固相化学反应法制备了Pr₂O₃掺杂的ZnO纳米复合粉体, 并用此粉体在不同烧结温度下制备了高压ZnO压敏电阻。采用X射线衍射、 比表面测试、 透射电镜、 扫描电镜等手段对制备的ZnO纳米复合粉体及高压ZnO压敏电阻进行了表征, 并与未掺杂ZnO压敏电阻进行了对比研究, 探讨了稀土氧化物Pr₂O₃掺杂对高压ZnO压敏电阻电性能的影响机制。结果表明: 较低的烧结温度(1030～1130 ℃)时, 掺杂的稀土氧化物Pr₂O₃偏析于ZnO晶界中, 有活化晶界、 促使晶粒生长的作用; 同时, Pr₂O₃掺杂导致1080 ℃烧结的ZnO压敏陶瓷体中晶体相互交织形成晶界织构, 比未掺杂的更均匀和致密, 这有助于高压ZnO压敏电阻晶界性能的改善, 从而提高其综合电性能。当烧结温度为1080 ℃时, Pr₂O₃掺杂的高压ZnO压敏电阻的综合电性能最佳: 电位梯度为864.39 V/mm, 非线性系数为28.75, 漏电流为35 μA。

Effects of Pr2O3 doping on the electric properities of the high-voltage ZnO varistor

Nanoscale ZnO composite powders doped with the rare earth Pr₂O₃ were synthesized by solid-state reaction at low temperature. The high-voltage ZnO varistors were prepared through the sintering of the above-mentioned powders at different temperature. The powders and high-voltage ZnO varistors were characterized by XRD, specific surface analysis, scanning electron microscope, TEM and so on. As a comparison, the ZnO varistors indoped by Pr₂O₃ were studied, and the mechanism of Pr₂O₃ doping was discussed in detail. The results show that the doped Pr₂O₃ tends to segregate at grain boundaries of ZnO varistors, and can activate the ZnO grain boundaries and promote the growth of crystal at low sintering temperature (1030-1130 ℃). Furthermore, the Pr₂O₃ doping leads to the formation of texture among the grain boundaries of ZnO varistors prepared at 1080 ℃, and make the doped-Pr₂O ZnO varistors more uniform and solid than that of the undoped-Pr₂O₃ ZnO varistors, which are helpful to the improvement of the grain boundaries of ZnO varistors, and enhancement of the electronic properties of ZnO varistors.The high-voltage ZnO varistor of doped Pr₂O₃ with the best electronic properties was prepared at 1080 ℃, which has a potential gradient of 864.39 V/mm, a nonlinear coefficient of 28.75 and a leakage current of 35 μA.