Microstructure evolution and thermoelectric behaviour of directionally solidified Bi2Te3 based multiphase thermoelectric

Thermoelectric materials are vital for sustainable energy applications, yet improving their efficiency remains a significant challenge. This study investigates the influence of unidirectional solidification on the Bi2Te3-Cu3Te2 eutectic alloy to enhance thermoelectric performance through microstructural control. Alloys of the same composition of Bi, Cu, and Te were processed using a Bridgman-type furnace under varying solidification velocities, with the resulting phases characterized as rhombohedral (Bi2Te3) and tetragonal (Cu3Te2). A distinctive eutectic columnar structure was formed at higher solidification rates, optimizing the balance between electrical and thermal transport. Alloy Solidified at 20 mu m/s, exhibited a peak figure of merit (zT) of 0.93 at 442 K due to improved power factor and reduced thermal conductivity. This work highlights unidirectional solidification as an effective approach to advancing thermoelectric material design.