Bi掺杂对Ca3-xBixCo4O9氧化物微观结构和热电性能的影响

采用固态反应法制备Ca3-xBixCo4O9 (0.0≤x≤0.45)样品,并研究了Bi掺杂对样品的微观结构和热电性能的影响.XRD与SEM结果显示,在含Bi样品中形成了c轴取向的结构,x=0.3和x=0.45样品具有大的晶粒取向度和晶粒尺寸,这就导致了这两个样品具有较高的电导率.由于Bi3+替代Ca2+降低了载流子浓度,样品的塞贝克系数随Bi含量的增加而增加.在1000 K,x=0.3样品的功率因子可达2.77×10-4 W/m·K2,这一数值与利用热压法制备的Ca3Co4O9样品的功率因子相当.

Effect of Bi Doping on the Microstructure and Thermoelectric Properties of Ca_(3-x)Bi_xCo_4O_9 Oxides

Ca3-xBixCo4O9(0.0≤x≤0.45) samples were prepared by conventional solid-state reaction method and the effect of Bi doping on the microstructure and thermoelectric properties was investigated. XRD and SEM investigations revealed that c-axis-oriented structure could be formed in the Bi-containing samples.x=0.3 and 0.45 samples had larger degree of orientation and grain size, which resulted in larger conductivity in these samples. Since the substitution of Bi3+ for Ca2+ decreased the hole concentration, Seebeck coefficients of the samples increased with the increase of Bi content. The power factor of x=0.3 sample could reach 2.77×10-4 W/m·K2 at 1000 K, which was equal to that of Ca3Co4O9 sample prepared by the hot-pressing method.