Tb掺杂CaMnO_3氧化物材料热电输运性能的研究

Investigation on Thermoelectric Transport Properties of Tb Doped CaMnO_3 Oxide Material

采用溶胶-凝胶法结合陶瓷烧结工艺制备了Tb掺杂CaMnO_3基氧化物热电材料,系统研究了Tb掺杂材料物相组成、微观组织和和电输运性能。结果表明,Tb掺杂试样均为单一物相的CaMnO_3晶体材料。随着Tb掺杂量的增加,试样晶粒逐渐细化。所得CaMnO_3基材料内部晶粒互连,试样结构较为致密。所有Tb掺杂试样电阻率随温度升高而降低,呈明显的半导体传输特性,其中Tb掺杂量为0. 14的试样电阻率最低。Tb掺杂试样Seebeck系数绝对值随掺杂量的增加而降低,这是由于Tb掺杂引入的电子型载流子造成的。所有试样功率因子均随温度升高而逐渐增加,并且所有Tb掺杂试样的功率因子均大于未掺杂试样。其中Tb掺杂量为0. 08的块体试样功率因子在测试温度最高点973 K时达到最大值2. 0×10-4W·m-1·K-2,远高于未掺杂试样,通过稀土元素Tb掺杂可以优化CaMnO_3基过渡金属氧化物材料的电性能。

The Tb doped CaMnO 3 oxide thermoelectric materials are fabricated by the sol-gel and the ceramic sintering method.The phase composition,microstructure as well as the electrical properties are studied.The results show that the as prepared Tb doped samples are single phase crystalline materials.The grain size is decreased by increasing the Tb doping content.The grains inter-connected and the bulk materials are consolidated.The resistivity for all Tb doped samples is decreased by increasing temperature with semiconductor transport.The sample with Tb doping content of 0.14 show lowest resistivity.The absolute value of Seebeck coefficient is decreased by increasing the Tb doping content,this is caused by the induced electron carriers by Tb.The power factors for all samples are increased by increasing temperture,and the doped samples show enhanced power factor comparing with that of the un-doped counterpart.The sample with Tb doping content of 0.08 shows highest power factor of 2.0×10^-4 W·m^-1·K^-2 at 973 K,which is very much higher than that of the un-doped one.The electrical property of the titled oxide material can be optimized by rare earth Tb doping.