Highly efficient functional Ge_xPb_1-xTe based thermoelectric alloys

Methods for enhancement of the direct thermal to electrical energy conversion efficiency, upon development of advanced thermoelectric materials, are constantly investigated mainly for efficient implementation of thermoelectric devices in automotive vehicles, for converting the waste heat generated in such engines into useful electrical power and thereby reduction of the fuel consumption and CO₂ emission levels. It was recently shown that GeTe based compounds and specifically GeTe-PbTe rich alloys are efficient p-type thermoelectric compositions. In the current research, Bi₂Te₃ doping and PbTe alloying effects in Ge_xPb_1-xTe alloys, subjected to phase separation reactions, were investigated for identifying the phase separation potential for enhancement of the thermoelectric properties beyond a pure alloying effect. All of the investigated compositions exhibit maximal dimensionless figure of merit, ZT, values beyond 1, with the extraordinary value of 2.1 found for the 5% Bi₂Te₃ doped-Ge_0.87Pb_0.13Te composition, considered as among the highest ever reported.