Response to Long-Time Exposure at High Temperature of Thermoelectric Modules of Bi–Te Prepared by Mechanical Alloying

Abstract

Thermoelectric modules assembled with nickel or copper electrodes and bismuth telluride system semiconductors prepared by mechanical alloying were evaluated for long exposure time dependence.
Modules exposed at temperatures of 400 and 473 K from 1 to 1000 h in air were measured for thermoelectric motive forces and internal resistances. The properties of nickel and copper electrode modules did not change up to 400 K. However, the internal resistance increased with increasing exposure time at 473 K. This was because the tin element in the soldering material was diffused in the bismuth telluride system semiconductors, making many voids in the junction layer. Furthermore, these results showed that the maximum output could be effectively evaluated using the Larson-Miller parameter (C=15.2).