Cr_(2)O_(3)掺杂量对SnO_(2)压敏电阻微观结构和电气性能的影响

Effect of Cr_(2)O_(3) Doping Amount on Microstructure and Electrical Properties of SnO_(2) Varistor

以SnO_(2)粉、CuO粉、Nb_(2)O_(5)粉、Cr_(2)O_(3)粉为原料,采用粉末冶金技术烧结制备(98.95-x)SnO_(2)-1CuO-0.05Nb_(2)O_(5-x)Cr_(2)O_(3)(x=0,0.01,0.02,0.03,0.05,物质的量分数/%)压敏电阻,研究了Cr_(2)O_(3)掺杂量对该压敏电阻微观结构和电气性能的影响。结果表明:随着Cr_(2)O_(3)掺杂量的增加,烧结试样的相对密度、收缩率、平均晶粒尺寸均先增大后减小,当Cr_(2)O_(3)物质的量分数为0.02%时相对密度和收缩率最高,Cr_(2)O_(3)物质的量分数为0.01%时晶粒尺寸最大,粒径分布最均匀;随着Cr_(2)O_(3)掺杂量增加,SnO_(2)压敏电阻的电压梯度增大,泄漏电流密度先减小后增大,非线性系数则先增大后减小,当Cr_(2)O_(3)物质的量分数为0.02%时,压敏电阻的泄漏电流密度最小,非线性系数最大,电压梯度较高,综合电气性能最好。

With SnO_(2) powder,CuO powder,Nb_(2)O_(5) powder and Cr_(2)O_(3) powder as raw materials,(98.95-x)SnO_(2)-1CuO-0.05Nb_(2)O_(5)-xCr_(2)O_(3)(x=0,0.01,0.02,0.03,0.05,mole fraction/%)varistor was prepared by powder metallurgy technique.The effect of Cr_(2)O_(3) doping amount on the microstructure and electrical properties of the varistor was studied.The results show that with the increase of Cr_(2)O_(3) doping amount,the relative density,shrinkage rate and average grain size of sintering samples first increased and then decreased.When the Cr_(2)O_(3) mole fraction was 0.02%,the relative density and shrinkage rate of sintering sample were both the highest.When the Cr_(2)O_(3) mole fraction was 0.01%,the grain size was the largest and the particle size distribution was the most uniform.With the increase of Cr_(2)O_(3) doping amount,the voltage gradient of SnO_(2) varistor increased,the leakage current density decreased first and then increased,and the nonlinear coefficient increased first and then decreased.When the mole fraction of Cr_(2)O_(3) was 0.02%,the leakage current density was the smallest,the nonlinear coefficient was the largest,and the voltage gradient was high,indicating the best comprehensive electrical performance.