Plasticity of Bi<sub>2</sub>Te<sub>3</sub>-family thermoelectric crystals.

Li, Ze; Deng, Tingting; Qiu, Pengfei; Ming, Chen; Gao, Zhiqiang; Chen, Lidong; Shi, Xun · Nat Commun · 2025

basic_science · Level V

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Abstract

The exceptional plasticity discovered most recently in defective Bi<sub>2</sub>Te<sub>3</sub> bulk crystal inspires the great interest on investigating the plasticity of other Bi<sub>2</sub>Te<sub>3</sub>-family bulk crystals. In this work, Bi<sub>2</sub>Se<sub>3</sub>, Sb<sub>2</sub>Te<sub>3</sub>, and their solid solutions with Bi<sub>2</sub>Te<sub>3</sub> are grown by the temperature gradient method to comprehensively clarify the relationship among chemical composition, native defect, microstructure, and plasticity of Bi<sub>2</sub>Te<sub>3</sub>-family compounds. Compared with Bi<sub>2</sub>Te<sub>3</sub> bulk crystal, Bi<sub>2</sub>Se<sub>3</sub> and Sb<sub>2</sub>Te<sub>3</sub> bulk crystals exhibit poorer plasticity at room temperature. The origin is attributed to the lack of substantial antisite defects in Bi<sub>2</sub>Se<sub>3</sub> and Sb<sub>2</sub>Te<sub>3</sub> alike that in Bi<sub>2</sub>Te<sub>3</sub>, which impedes the formation of the high-density, diverse microstructures. Alloying either Se or Sb in Bi<sub>2</sub>Te<sub>3</sub> modifies the native defects and microstructures and thus changes plasticity and thermoelectric performance. Finally, the composition range for the Bi<sub>2</sub>(Te,Se)<sub>3</sub> and (Bi,Sb)<sub>2</sub>Te<sub>3</sub> bulk crystals that simultaneously possess exceptional plasticity (maximum bending strain >10%) and thermoelectric performance is determined.