Enhanced thermoelectric and mechanical properties in textured n-type Bi2Te3 prepared by spark plasma sintering

n-Type Bi2Te3 thermoelectric materials were prepared by spark plasma sintering (SPS) using mechanically alloyed powders, and fine-grained Bi2Te3 bulks with preferred grain orientation have been fabricated by SPS as a hot-forging process. The effects of orientation degree and hot-forging temperature on thermoelectric properties were investigated. The electrical resistivity was reduced by increasing orientation degree, the Seebeck coefficient was increased by raising hot-forging temperature, and consequently the power factor was significantly increased from 2.1 mW/mK2, measured at 423 K, before hot-forging to 3.1 mW/mK2 after hot-forging at 733 K. The maximum ZT value after hot-forging at 733 K reached 1.18 measured at 423 K. This value was 20% higher than that before hot-forging, although the corresponding thermal conductivity was a little increased after hot-forging. The bending strength was greatly enhanced from 62 MPa to 120 MPa after the hot-forging.

n-Type Bi2Te3 thermoelectric materials were prepared by spark plasma sintering (SPS) using mechanically alloyed powders, and fine-grained Bi2Te3 bulks with preferred grain orientation have been fabricated by SPS as a hot-forging process. The orientation degree of the (0 0 l) c-planes was increased from 0.12 for the sample before hot-forging to 0.45 and 0.67 for the samples hot-forged at 673 K and 733 K, respectively. The effects of orientation degree and hot-forging temperature on the thermoelectric and mechanical properties were investigated.Figure optionsDownload as PowerPoint slide