铌对(Y,Nb)掺杂的二氧化钛压敏-电容性能的影响

研究了铌对(Y,Nb)掺杂的二氧化钛压敏-电容性能的影响.研究中发现掺入0.10mol%Nb2O5的样品显示出最低的视在电场(EB=8.8V/mm)、最高的非线性常数(α=7.0)以及最高的相对介电常数(εr=7.6×104),与样品的晶界缺陷势垒特性、电容和电阻的频谱特性相一致.样品的性能变化可用Nb5+对Ti4+的掺杂取代和该取代存在的饱和值来解释.

Nonlinear Electrical Properties of TiO2

The nonlinear electrical properties of TiO₂·Y₂O₃·Nb₂O₅ ceramics were investigated as a new varistor material. An optimal doping composition of 99.75%TiO₂·0.60%Y₂O₃·0.10%Nb₂O ₅was obtained with low breakdown electrical field of 8.8V/mm, high nonlinear constant of 7.0 and ultrahigh relative dielectric constant of 7.6×10⁴, being consistent with the highest and narrowest grain boundary barriers of the ceramic. The frequency dependence of the capacitance and the resistivity shows that the samples doped with 0.10%mol Nb₂O₅ exhibit the highest capacitance and resistivity at low frequencies and comparatively low in comparison with other samples at high frequencies. In view of these electrical characteristics; the ceramic of 99.75%TiO₂·0.60%Y₂O₃·0.10%Nb₂O₅ is a viable candidate for capacitor-varistor functional devices. The characteristics of the ceramics can be explained by the effect and the maximum of the substitution of Ti⁴⁺ with Nb⁵⁺. In order to illustrate the grain boundary barriers formation in TiO₂·Y₂O₃·Nb₂O₅ varistors, a grain-boundary defect barrier model was also introduced.