(Cu,Mg,Nb)掺杂的SnO_2压敏材料的性质

Properties of (Cu,Mg,Nb) Doped SnO_2 Varistor Ceramics

研究了 Cu O对 Sn O2 · Mg O· Nb2 O5压敏材料的密度、非线性特性、介电常数的影响。实验发现 ,适当掺杂 Cu O不仅能增大 Sn O2 · Mg O· Nb2 O5材料的致密度 ,而且能提高非线性系数 ,减小漏电流。掺 2 % Cu O(摩尔比 )时 ,Sn O2 · Mg O· Nb2 O5材料的致密度达到理论值的 93% ,非线性系数 α高达 9.5 ,压敏电压 V1 m A高于4 2 3V/ mm。在 2 0～ 2 0 0°C温度范围和 0 .1～ 10 0 0 k Hz频率范围 ,Sn O2 · Cu O· Mg O· Nb2 O5的介电常数变化很小 ,应用晶界缺陷势垒模型 ,对 Sn O2 · Cu O· Mg O· Nb2 O5材料压敏特性进行了解释。

Investigations have carried out concerning the influence of the addition of CuO on the density,nonlinear electrical characteristics and dielectric constants of SnO 2·MgO·Nb 2O 5 varistor system.Proper addition of CuO can not only improve the density,but also enhance the nonlinear coefficient and reduce the current leakage of SnO 2·MgO·Nb 2O 5 varistors.It is found that an addition of 2.0% CuO makes 96.9% SnO 2+1.0% MgO+0 1% Nb 2O 5+2% CuO varistor possesses the 93% relative density to theortical density,the highest nonlinear coefficient (α=9.5),the varistor voltage 423 V/mm at 1 mA.It is also found from the dielectric temperature spectrum of SnO 2·CuO·MgO·Nb 2O 5 varistors that variations of the dielectric constants are very small among 20～200 °C and 0 1～1 000 kHz.In order to illustrate the nonlinear electrical behaviour of the SnO 2·CuO·MgO·Nb 2O 5 varistors,a grain defect barrier model was introduced.