Texture Development and Grain Alignment of Hot‐Pressed Tetradymite Bi0.48Sb1.52Te3 via Powder Molding

Bi2Te3‐based materials possess excellent thermoelectric (TE) properties near room temperature. The microstructure's orientations of these materials have a great influence on their properties owing to the lamellar structure. Herein, a process for the preparation of bismuth telluride, named hot‐pressing texture (HPT) where the hot‐pressed (HP) samples are preformed by powder molding, leads to the fine alignment of grains. The orientation factor of the HPT sample is improved by 20%, compared with that of the HP sample. After further carrier concentration optimization, the improved ZT of 1.1 at 350 K is achieved, with an average ZT of 0.9 between 300 and 500 K. Herein, it is shown that the proposed preparation process is an effective strategy for the fabrication of layered materials. Herein, the introduced powder‐molding process before hot‐pressing improves the texture of polycrystalline Bi2Te3 by 20%. First, it is reported that Na is an effective dopant for optimizing carrier concentration. Finally, in Bi0.48Sb1.47Na0.05 Te3, a maximum ZT reaches 1.1 at 350 K.