Effect of cooling rate on the thermoelectric and mechanical performance of Bi0.5Sb1.5Te3 prepared under a high magnetic field

•The microstructure of p-type Bi0.5Sb1.5Te3 was tuned successfully by regulating the cooling rate.•Coherent BST/Te and Te/BSTⅡ interfaces were observed.•An enhanced ZT of 1.23 at 323 K with a maximal flexural strength 23.2 MPa is obtained.

Given the thermoelectric and mechanical performance of a given material is closely related to its microstructure, in this paper, the microstructure of p-type Bi0.5Sb1.5Te3, fabricated by a high magnetic field assisted melting-solidification (HMAMS) process, is successfully tuned by regulating the cooling rate during the solidification process, and a systematic investigation has been carried out to the effect of the cooling rate on the crystal orientation, microstructure, thermoelectric and mechanical performance of the obtained materials. By this approach, the thermal conductivity is sharply reduced due to the intensive phonon scattering by the massive BST/Te and Te/BSTⅡ interfaces, while the power factor is less affected, and the flexural strength is enhanced owing to the narrowing of eutectic strip and spacing. Eventually, a highest ZT of 1.23 at 323 K with a maximal flexural strength 23.2 MPa has been obtained in the sample prepared under a 6 T magnetic field at a cooling rate of 16 K/min.

Graphical abstractIn this paper, a systematic investigation is carried out to the effect of cooling rate on the microstructure, thermoelectric and mechanical performance of p-type Bi0.5Sb1.5Te3. By this approach, the thermal conductivity is sharply reduced due to the formation of coherent BST/Te and Te/BSTⅡ interfaces, while the electrical properties are less affected. Consequently, a highest ZT of 1.23 at 323 K with a maximal flexural strength 23.2 MPa is obtained in the sample prepared under a 6 T magnetic field at a cooling rate of 16 K/min.Figure optionsDownload full-size imageDownload as PowerPoint slide