固相烧结SiC陶瓷的非线性电学行为研究

固相烧结SiC(SSiC)陶瓷大多数用于结构陶瓷材料, 用于电子和电阻元器件的研究很少。实验以添加不同C含量的致密SSiC陶瓷材料为研究对象, 研究了添加不同C含量SSiC陶瓷的伏安特性、电阻率与电流密度的变化关系及电阻率与温度的变化关系。研究结果表明: SSiC陶瓷表现出明显的非线性电学特性, 其电阻率随着电流的增大而降低; 对于添加3wt% C含量的SSiC陶瓷, 当电场强度超过15.8 V/mm时, 晶界势垒被击穿; 对于添加6wt% C含量的SSiC陶瓷, 当电场强度超过70.7 V/mm时, 晶界势垒被击穿, 它们的电阻率将为晶粒所控制, 电阻率较小; 同时在电场强度1 V/mm条件下, SSiC陶瓷电阻率随着温度的升高而降低, 表现出很好热敏特性, 从常温的10⁶ Ω·cm变化为400℃的5 Ω·cm左右。

Nonlinear Electrical Behavior of Solid State Sintered SiC Ceramics

The solid state sintered SiC (SSiC) ceramics are mainly used for structural materials, but they are rarely used for electronic devices and resistance components. In this work, the electrical properties of the SSiC ceramics with different carbon additives were investigated, including V-I characteristic, the relationship between current and resistance, as well as the relationship between temperature and resistance. These results show that the SSiC ceramics present obvious nonlinear electrical behavior and their resistance decreases with the current increase. When the electrical field intensity is over 15.8 V/mm for the SSiC ceramics with 3wt% carbon additives, as well as 70.7 V/mm for the SSiC ceramics with 6wt% carbon additives, the boundary barrier is breakdown and the resistance becomes very low, due to the resistance being only controlled by the grain size. The resistance of the SSiC ceramics decreases with the temperature increase at the electrical field intensity of 1 V/mm, indicating thermo-sensitive characteristic of SSiC ceramics of which the resistance is changed from 10⁶ Ω·cm at 25℃ to 5 Ω·cm at 400℃.