Negative thermal expansion in hexagonal VF₃ predicted by first-principles calculation

Searching negative thermal expansion (NTE) materials is challenging. Herein, hexagonal VF 3 is predicted as a new NTE material for the first time. VF 3 displays NTE property in the temperature range from 0 to 380 K, and the minimum NTE coefficient( α ) is approximately −4.68 × 10 −6 K −1 at 120 K. The NTE mechanism was ascribed to the vibrations of F atom with larger atomic displacement parameters, which dominates the negative Grüneisen parameters. The difference of minimum NTE coefficient between VF 3 and TiF 3 might be caused by their different chemical bond strength between Ti–F and V–F. This research provides a deeper understanding between NTE and crystal structure.