Nb掺杂TiO_2压敏陶瓷的施主掺杂固溶度

Solid Solubility of Donor Dopant in Nb-doped TiO_2 Varistor Ceramics

研究了不同烧结温度TiO2压敏陶瓷的显微结构、施主掺杂固溶度和电学性能。采用SEM和EDS测试了其显微结构和晶粒化学组成。随烧结温度增加,TiO2晶粒迅速长大,显微结构均匀致密,但过高的烧结温度将导致较多气孔。1350℃为比较合适的烧结温度,其晶粒大小为15μm左右。在施主掺杂浓度一定的条件下,施主掺杂离子Nb5+在TiO2晶粒中的固溶度、晶粒电子浓度和电导率随烧结温度上升而增加,晶粒电阻率随烧结温度上升而下降。以能谱中O为参考确定TiO2晶格数量计算得到的固溶度及其电学性能更符合实验测试结果。

Microstructure,donor doping solid solubility and electrical properties of TiO_2 varistor ceramics sintered at different temperatures were investigated.Microstructures and grain compositions of samples were studied by scanning electron microscopy（SEM） and X-ray energy-dispersive spectroscopy（EDS）.With increasing sintering temperature,TiO_2 grains grow quickly and a compact and homogeneous microstructure was obtained.The TiO_2 ceramic sample sintered at an over high temperature contained some pores.For TiO_2 varistor ceramics,1350℃ is the reasonable sintering temperature and the grain size of the TiO_2 sample is about 15 μm.For a constant concentration of donor doping,solid solubility of donor Nb^（5＋） in TiO_2 grains,electron concentration and electrical conduction of TiO_2 grains increase but resistivity decrease with increasing sintering temperature.The number of TiO_2 lattices in TiO_2 ceramics is determined by O mol ratio in EDS analysis,and that solid solubility and electrical properties,which were calculated from the number of TiO_2 lattices,Nb and Ti mol ratio in EDS, coincide better with experimental results.