掺钙铬酸镧-氧化物复合材料的导电性能研究

Conductivity of Ca-doped LaCrO_(3)-Oxide Composite

基于通用有效介质方程,建立掺钙铬酸镧-氧化物复合材料的电导率模型,研究服役温度、掺钙量、环境气氛和氧化物类型对电导率的影响。结果表明,掺钙LaCrO_(3)-ZrO_(2)中ZrO_(2)的临界体积分数为10%,临界指数为1.71;掺钙LaCrO_(3)-Al_(2)O_(3)中Al_(2)O_(3)的临界体积分数为15%,临界指数为1.74。当氧化物体积分数小于临界体积分数时,复合材料电导率随温度升高而逐渐减小;当氧化物体积分数远大于临界体积分数时,复合材料电导率随温度升高而急剧增大。复合材料电导率随掺钙量增加而逐渐提高,较低温度下氢气气氛中复合材料电导率明显低于在空气气氛中的电导率。掺钙铬酸镧中分别添加ZrO_(2)和Al_(2)O_(3)对导电性能的影响相差不大。

A conductivity calculation model for the Ca-doped LaCrO_(3)-oxide composite was established based on a general effective medium equation,and used to investigate the effects of service temperature,Ca-doped content,atmosphere and oxide type on the conductivity of composite.The results show that the critical volume fraction(that is percolation threshold)of the ZrO_(2) for the conductivity of Ca-doped LaCrO_(3)-ZrO_(2) composite is 10%and the critical exponent is 1.71;while the percolation threshold of the Al_(2)O_(3) for the conductivity of Ca-doped LaCrO_(3)-Al_(2)O_(3) composite is 15%and the critical exponent is 1.74.When the volume fraction of the oxides is less than the critical volume fraction,the conductivity of the composite gradually decreases with the increase of temperature;when the volume fraction of oxides is much greater than the critical volume fraction,the conductivity increases sharply with the increase of temperature.The conductivity of composite increases gradually with the increasing of the Ca doping amount,and the conductivity of the composite in H2 atmosphere at a lower temperature is significantly lower than that in air atmosphere.It is shown that the doping of ZrO_(2) or Al_(2)O_(3) has brought little effect to the conductivity of the composite.