Theoretical Study on the Structures and Electronic Properties of Tungsten Fluorides at High Pressures

Abstract

AbstractTransition metal fluorides are a series of strong oxidizing agents. Tungsten (W) fluorides, particularly WF6, have shown broad applications such as luminescence and fluorinating agent. However, other stoichiometries of W fluorides have rarely been studied. It is well‐known that pressure can induce structural phase transition, stabilize new compounds, and produce novel properties. In this work, the high‐pressure phases of W−F were searched systematically at the pressure range of 0–200 GPa through first‐principles swarm‐intelligence structural search calculations. A new stoichiometry of WF4 has been predicted to be stable under high pressures. On the other hand, two new high‐pressure phases of WF6 with the symmetries of /m and ‐1 were found with decahedral structural units. The electronic properties of the W−F compounds were then investigated. The predicted stable WF6 high‐pressure phases maintain semiconducting features, since the W atom provides all its valence electrons to fluorine. We evaluated the oxidizing ability of WF6 by calculating its electron affinity potential. The high pressure /m WF6 molecular phase shows higher oxidation capacity than the ambient phase. The built pressure‐composition phase diagram and the theoretical results of W−F system provide some useful information for experimental synthesis.