ホットプレスと常圧焼成の組み合わせにより作製したBi2Te2.85Se0.15焼結体の微構造および熱電特性

n-type Bi2Te2.85Se0.15 sintered materials were prepared by hot pressing alone and combination of pressureless sintering and hot pressing, and the effect of pressureless sintering on the microstructures and thermoelectric properties of the sintered materials were studied. Samples hot pressing after pressureless sintering showed greater power factors in comparison with samples prepared by hot pressing alone and pressureless sintering after hot pressing. This is considered to be attributed to increased mobility caused by increased in grain size and anisotropic texture due to pressureless sintering. Thermal conductivity also showed a little higher value due to an increase in both carrier and lattice thermal conductivities. These thermoelectric properties did not exhibit a dependency on the pressureless sintering period. Consequently, the samples prepared by hot pressing after pressureless sintering showed the highest figure of merit of Z =2.89×10-3K-1 for a pressureless sintering period of 7.2 ks.