FEATURES IN MICROSTRUCTURE AND THERMOELECTRIC PROPERTIES OF TWO-PHASED CERAMIC MATERIAL BASED ON HIGH-ENTROPY Bi–Sb–Te–Se–S SYSTEMS

Abstract

The aim of present work is to prepare by using the method of reactive spark plasma sintering, a ceramic material based on the high-entropy Bi–Sb-Te–Se–S system, the nominal composition of which corresponds to the BiSbTeSeS compound (all the atoms are taken in an equiatomic ratio), and to analyze the features in the microstructure and thermoelectric properties of this material. During reactive spark plasma sintering of starting Bi, Sb, Se, Te, and S powders, hexagonal and orthorhombic phases are formed in the bulk material. The hexagonal phase, which corresponds to the high-entropy compound Bi1.5Sb0.5Te1.25Se1.25S0.5, forms a continuous connected “net”. The orthorhombic phase, which corresponds to the wide-gap Sb3S2 semiconductor, fills the hollows in the net isolated from each other. The thermoelectric properties of the material being developed, which are mailnly due to the properties of the high-entropy phase, are promising enough (the maximum value of the thermoelectric figure of merit reaches ~ 0.18). Therefore, this material should be considered as a new prospect high-entropy thermoelectric.