Effect of Heat Treatment on the Thermoelectric and Mechanical Properties of an n-Type Bi₂Te_2.5Se_0.5 Solid Solution Prepared via Extrusion

In this paper, we compare mechanical and thermoelectric parameters of Bi₂Te_2.5Se_0.5 alloy prepared via zone recrystallization and extrusion. We have studied the effect of heat treatment on the ultimate strength and thermoelectric figure of merit of an n-type solid solution prepared via extrusion. Its thermoelectric parameters—Seebeck coefficient, electrical conductivity, and thermal conductivity—have been measured at room temperature and in the range 300–430 K, and its thermoelectric figure of merit ZT has been evaluated. The highest 350-K ZT value of the materials prepared via zone recrystallization is 1.0 ± 0.1, whereas the highest ZT value of the materials prepared via extrusion is 0.90 ± 0.1. Heat treatment in a vacuum thermostat at a temperature of 573 K for 24 h increased the highest ZT value of the materials prepared via extrusion to 0.96 ± 0.1 and their ultimate strength to 165 MPa.