Theoretical Prediction of Negative Thermal Expansion in Cubic VF3

Designing and discovering negative thermal expansion materials is import in precisely controlled thermal expansion devices. In this work, the NTE of cubic metal fluoride VF3 with ReO3-Type was predicted by density functional theory within quasi-harmonic approximation. These results reveal that cubic VF3 displays negative thermal expansion behavior below 200 K, and the predicted minimum negative thermal expansion coefficient is approximately -6.4×10-6 K-1 at 80 K. The negative thermal expansion was mainly dominated by the prominently negative Grüneisen parameter situated at M(0.5,0.5,0) and R(0.5,0.5,0.5). The underlying mechanism was attributed to the anisotropic F atom vibration where the amplitude of transverse vibration perpendicular to V-F-V connection are much larger than that of vibration along the parallel V-F-V direction. This research provides a good understanding of relationship between NTE and crystal structure.

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