【摘要】 研究了Na对新型(Co,Nb)掺杂SnO2压敏材料微观结构和电学性质的影响。当Na2CO3的含量从0增加到1.2mol%时,(Co,Nb)掺杂SnO2压敏电阻的击穿电压从275V/mm增到919V/mm。样品的微观结构分析发现,当Na2CO3的含量从0增加到1.2mol%时,SnO2的晶粒尺寸明显的变小。晶界势垒高度测量揭示,SnO2的晶粒尺寸的迅速减小是压敏电压急剧增高的原因。对Na含量增加引起SnO2晶粒减小的根源进行了解释。掺杂0.4mol%Na2CO3的SnO2压敏电阻非线性系数达28.4,击穿电压为755V/mm,掺杂1.2mol%Na2CO3的SnO2压敏电阻非线性系数为11.5,击穿电压高达919V/mm,它们在中高压保护领域会有很好的应用前景。本文并指出替代Sn的受主离子Na不应处于SnO2晶格中,而是处于间界上,从而进一步解释了压敏电压急剧增高的原因。更多还原

【Abstract】 The effect of Na on the microstructure and electrical properties of the novel （Co, Nb）-doped SnO₂ varistors was investigated. The breakdown voltage of the SnO₂ based varistors increased from 275V/mm to 919V/mm with increasing Na2CO₃ concentration from 0 to 1.2 mol%. Measurement of the barrier height at grain boundaries reveal that the significant decrease of the SnO₂ grain size with increasing Na₂CO₃ concentration from 0 to 1.2 mol% was the reason for raising the breakdown voltage. The origin for the deduction of SnO₂ grain size with increasing Na₂CO₃ concentration was explained. The varistors with quite high breakdown voltage and quite large nonlinear coefficient _α, 755V/mm and _α=28.4 for 0.4mol% Na₂CO₃-doped and 919V/mm and _α=11.5 for 1.2mol%, were obtained. Medium breakdown voltage and quite larger nonlinear coefficient a make the Na-doped SnO₂ varistors probably the excellent candidate used in the medium voltage protection system.更多还原