Growth and physical properties of Sb2Te3 and related thermoelectric materials

Abstract

Research on crystal growth and characterization is inevitable to meet the requirements of the technological world, as there is a great demand for good quality samples free from flaws for application in newlinevarious fields which cannot be met by natural resources. The synthesis of newlinebulk crystals of Sb2Te3 compounds has intrigued the attention of the researchers in the present work, due to their diverse properties which provide boundless scope to develop innovative approaches towards the newlinedevelopment of devices with improved thermoelectric (TE) efficiency. The green technology of conversion of waste heat to electric current by the TE phenomena offers a noise-free alternative with low mechanical newlineand conduction losses for small scale refrigeration and power generation modules. Though, thermoelectric devices offer better reliability and durability, one of the major challenges is to develop a material system newlinewith high figure of merit (ZT) in the variable temperature ranges. From the research reports it is evident that, generally for scientific studies, conventional melt methods were used to grow bulk Sb2Te3 crystals, where nonstoichiometry, polycrystallinity and multi-phase formation raise problems. Furthermore, large fluctuations in TE properties have been exhibited by single crystals synthesized from the melt, which preclude their uses in devices. The ability to control as well as engineer various newlineproperties of Sb2Te3 depends on the choice of growth method, experimental tools and processes. Even though substantial work has been published on the studies of cleaved samples of crystals grown from the melt, the growth mechanism and TE investigations on vapor deposited platelet structures of Sb2Te3-xSx and Sb2-xInxTe3 have not been investigated so far. With the prime focus on vapor deposition as an alternative to melt methods to produce defect free, good quality stoichiometric and mechanically stable crystals with improved ZT, the research was aimed at growth and characterization of Sb2Te3 and related newlinethermoelectric materials.