The Characteristics of the Bismuth Telluride Based Materials Via Gas Phase Reaction Method

Abstract

Bismuth telluride based alloys powders are well known as thermoelectric materials near room temperature in 200~450K. Thermoelectric effect is direct conversion between thermal and electrical energy. Thermoelectric generator has several advantages such as eco-friendly (reusing the waste heat), reliable source of energy, simple maintenance, no-noise, long life time etc. But the low convert energy efficiency and high unit cost of production is still problem to solve. Energy conversion efficiency is involved with figure of merit ZT (ZT=σS2T/κ) where σ is the electrical conductivity, S is the Seebeck coefficient, T is the absolute temperature, κ is the total thermal conductivity. To enhance the energy conversion efficiency of thermoelectric materials, stoichiometrically dispersed powders within fine sized one particle has an advantage because of its composition uniformity. Spray pyrolysis is well known process as gas phase reaction method. The effects of the morphological, electrical and thermal properties of thermoelectric materials prepared by spray pyrolysis were investigated in this study. The phase of powders and bulk were analyzed by X-ray diffraction (XRD). The microstructures of powders and bulk were characterized by field emission scanning electron microscopy (FESEM). The thermoelectric properties of bismuth telluride based materials were analyzed using ZEM-3 (Ulvac-Rico) and thermal conductivity were calculated by the thermal diffusivity measured by the laser flash method (LFA457, Netzsch).