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/mK(2), measured at 423 K, before hot-forging to 3.1 mW/mK(2) 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. (C) 2007 Elsevier Masson SAS. All rights reserved.