Impact of melt solidification rate on structural and thermoelectric properties of n-type Bi2Te3 alloy

Alloys based on bismuth telluride (Bi2Te3) form an important class of thermoelectric materials used in Peltier cooling devices and thermoelectric generators. In this work, polycrystalline n-type Bi2Te3 alloy was prepared by a melt-quenching process using different quenching mediums: alkaline ice water, ice water, normal water, liquid nitrogen, and air-cooling. The relation between melt solidification rate and structural and thermoelectric transport properties of Bi2Te3 alloy were studied. The pure phase of Bi2Te3 is confirmed by structural characterizations: XRD and Raman. This study showed that the melt solidification rate has a consequential role in modulating the microstructure and thermoelectric transport properties. The moderate cooling rate of melt solidification showed the highest zT of ~ 0.06 at 423 K due to higher defect density. This study attempts to explain the different zT values observed for different quenching mediums.