Effects of process parameters on electrical properties of n-type Bi2Te3 prepared by mechanical alloying and spark plasma sintering

n-Type Bi2Te3 thermoelectric materials were prepared by spark plasma sintering (SPS) using mechanically alloyed powders. Seebeck coefficient and electrical conductivity of the resultant materials were measured, with emphasis on the effects of sintering process parameters on the electrical properties. The power factor was improved from 1.5 to 1.6mW/mK(2) when the SPS pressure was increased from 20 to 50 MPa at 623 K, and was further increased to 2.1 mW/mK(2) under 50 MPa by raising the SPS temperature from 623 to 673 K. The maximum power factor was obtained for the sample sintered under optimized SPS process parameters, in which the sintering temperature and the sintering pressure are 673 K and 50 MPa, respectively. (C) 2007 Elsevier B.V. All rights reserved.