热压法制备Bi_2Te_3基热电材料的组织与性能

Microstructures and properties of Bi_2Te_3-based thermoelectric materials prepared by hot pressing

采用真空单轴热压(HUP)方法制备了Bi_2Te_3基热电材料。结果表明,HUP试样的密度在原始区熔材料的97％以上。所有HUP试样的剪切强度都在21MPa以上,与区熔Bi_2Te_3基材料(001)解理面的强度相比,提高4倍左右。电学性能测试发现,HUP试样的电学性能低于区熔试样,其原因被认为主要是由于在材料粉碎和热压过程中,有效载流子浓度发生了变化。实验发现,相对于区熔试样,p型HUP试样的最佳工作温度向低温方向偏移,而n型HUP试样的最佳工作温度向高温方向移动。

Bi_2Te_3 - based thermoelectric materials have been prepared by hot uniaxial pressing (HUP) from the commercial zone - melted (ZM) ingots. A relative density above 97% of the density of pristine ZM blocks has been obtained for all HUP samples. A shear strength over 21MPa has been measured for all HUP samples, which is about four times higher than that of a ZM Bi_2Te_3 - based alloy along the (001) cleavage plane. It was found that the electric properties of the HUP samples are lower than those of the corresponding ZM samples, which is considered being originated from the change of the effective carrier density during the HUP process. It was also found that the temperature with the best properties decreases for the p - type samples while increases for the n - type samples.