Microwave-assisted synthesis of thermoelectric oxides and chalcogenides

Abstract

The combination of microwaves with other classical synthetic methods may be considered as a powerful tool for the preparation of metal oxides and metal chalcogenides. This approach allows the modification of the reaction kinetic significantly by shortening the processing time to minutes and it minimizes the energy consumption during the synthesis. In this work, potential thermoelectric compounds, which enable the direct conversion of temperature gradients into useful electric energy, have been produced by means of microwave-chemistry routes. Pure phases of SnS1-xSex (x = 0, 0.2, 1) have been synthesized in just 1 min by using microwave-hydrothermal synthesis. Moreover, Zn0.98M0.02O (M = Al, Ga) rods were formed by microwave-coprecipitation method in 5 min. Besides, 8 min of microwave-heating were enough for the combustion of Sr1-xLaxTiO3-δ (x = 0, 0.05, 0.1). In all cases, the utilization of microwave radiation produces high-quality phases. A comprehensive study of the structural, microstructural and thermoelectric properties of the microwave-synthesized materials is here performed by means of X-ray diffraction, SEM, HRTEM and temperature dependence measurements of Seebeck coefficient, electrical conductivity and thermal conductivity.