Transport properties of quaternary Ag-Bi-Sb-Te alloys prepared by pressureless sintering

Quaternary Ag-Bi-Sb-Te alloys with the general formula of AgxBi0.5Sb1.5-xTe3 (x=0 similar to 0.4) were prepared by pressureless sintering (ternary Bi0.5Sb1.5Te3 alloy is used for comparison), and their transport properties involving Seebeck coefficients (alpha) and electrical conductivities (sigma) were evaluated. Measurements revealed that the quaternary AgxBi0.5Sb1.5-xTe3 (x=0.05 similar to 0.4) alloys exhibit large sigma values than ternary alloy Bi0.5Sb1.5Te3 in the whole temperature range. The maximum power factor of 1.3 x 10(-3) (W.K-2 m(-1)), calculated from alpha and sigma values, was obtained for the AgxBi0.5Sb1.5-xTe3 materials (x = 0.05,0.1), being approximately twice as large as and 2.5 times those of ternary Bi0.5Sb1.5Te3 alloy at room temperature and the temperature at which the maximum power factor is achieved respectively. High performance and great potentiality of the quaternary AgxBi0.5Sb1.5-xTe3 (x = 0.05,0.1) thermoelectric alloys can therefore be expected. (C) 2005 Elsevier B.V. All rights reserved.