A systematic first‐principles study of the tungsten trioxide polymorphs

E-ISSN： 1521-3951|370-1972|10|2290-2295

ISSN： 0370-1972

Source： PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Vol.370-1972, Iss.10, 2015-10, pp. : 2290-2295

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

AbstractTungsten trioxide (WO3) is a compound that has a high degree of polymorphism, but a detailed phase diagram of this material is not available in the literature and a systematic ab‐initio study including all its crystallographic phases does not exist. In this work, we have performed a first‐principles density functional theory study of all WO3 crystalline phases within the generalized gradient and hybrid approximations of the exchange–correlation functional. We have calculated the equations of state, the isothermal bulk moduli, the Γ‐centered vibrational frequencies, and the phase diagram using the Debye–Einstein model. The calculated phase diagram shows only the γ→ϵ crystallographic phase transition at high pressure and low temperature, being the γ‐phase the stable polymorph at room temperature and ambient pressure, and the ϵ‐phase stable at low temperatures and high pressures. In addition, the band structures were calculated observing a variation of the energy gap between 1.76 up to 2.79 eV with a similar topology of the top valence and bottom conduction bands across all the polymorphs.