Crystal growth of ternary and quaternary alkali metal bismuth chalcogenides using Bridgman technique

Abstract

Our exploratory research in new thermoelectric materials has identified the ternary and quaternary bismuth chalcogenides β-K2Bi8Se13, K2.5Bi8.5Se14 and K1+xPb4-2xBi7+xSe15, to have promising properties for thermoelectric applications. These materials have needlelike morphology so they are highly anisotropic in their electrical and thermal properties. In order to achieve long and well-oriented needles for which, consequently, the best thermoelectric performance is expected, we developed a modified Bridgman technique for their bulk crystal growth. The preliminary results of our crystal growth experiments as well as electrical conductivity, Seebeck coefficient and thermal conductivity for the compounds obtained from this technique are presented.