Structure and Thermoelectric Properties of Te-Ag-Ge-Sb (TAGS) Materials Obtained by Reduction of Melted Oxide Substrates

Abstract

Ge0.77Ag0.1Sb0.13Te1 alloy was fabricated by a novel two-step route. Firstly, oxide reagents were melted at high temperature and quenched into pellets. The pellets were milled to powder and then reduced in hydrogen at various temperatures for various periods of time. Energy-dispersive x-ray analysis indicated the possibility of successful fabrication of stoichiometric thermoelectric materials from the Te-Ag-Ge-Sb system. The electrical conductivity and Seebeck coefficient have been determined over the temperature range from 20°C to 340°C in argon atmosphere. It was also shown that, for most of the fabricated samples, the crystallite size as well as electrical parameters such as the electrical conductivity, Seebeck coefficient, and figure of merit (ZT) increased with increasing reduction time. The highest value of ZT (∼1.0 at 340°C) was obtained for samples reduced in hydrogen atmosphere at 400°C for 20 h and 40 h.