Prediction of New Structure, Phase Transition, Mechanical, and Thermodynamic Properties of Nb3Si

Although Nb‐based silicides are promising high temperature materials, the high temperature application of Nb‐based silicides is markedly influenced by Nb 3 Si phase. However, the structure and relevant properties of Nb 3 Si are not completely clear. To solve these problems, in this paper, we systematically investigate the structure, elastic properties, brittle or ductile behavior, and thermodynamic properties of Nb 3 Si based on the first‐principle calculations. Additionally, phase transition of Nb 3 Si under high pressure is studied in detail. The calculated results show that two new Nb 3 Si phases: Br 3 Sm‐type (space group: Cmcm, No.63) and Sc 3 In‐type (space group: P63/mmc, No.194) are predicted. Although Nb 3 Si with Ta 3 Si‐type is the most stable structure, pressure leads to phase transition from Ta 3 Si‐type structure to V 3 Si‐type structure at ≈60 GPa. We further demonstrate that Nb 3 Si is a ductile material. Importantly, we find that the heat capacity of Nb 3 Si with tetragonal structure is about 190 J (mol K) −1 , which is two times larger than that of other structures.