First-principles study of InVO4 under pressure: phase transitions from CrVO4- to AgMnO4-type structure

Abstract

First-principles calculations have been done to study the InVO4 compound under pressure. In this work, total energy calculations were performed in order to analyze the structural behavior of the experimentally known polymorphs of InVO4: monoclinic _-MnMoO4-type (I), orthorhombic CrVO4-type (III), and the monoclinic wolframite (V). Besides, in this paper we present our results about the stability of this compound beyond the pressures reached by experiments. We propose some new high pressure phases based in the study of 13 possible candidates. The quasiharmonic approximation has been used to calculate the sequence of phase transitions at 300 K: CrVO4-type, III (in parentheses the transition pressure) ! wolframite, V (4.4 GPa) ! raspite, VI (28.1 GPa) ! AgMnO4-type, VII (44 GPa). Equations of state and phonon frequencies as function of pressure have been calculated for the studied phases. In order to determine the stability of each phase we also report the phonon dispersion along the Brillouin zone and the phonon density of states for the most stable polymorphs. Finally, the electronic band structure for the low- and high-pressure phases for the studied polymorphs is presented as well as the pressure evolution of the band gap. Where a change from 3.06 eV at ambient pressure to 1.2 eV at 60 GPa is observed in InVO4, behaving the material as a narrow-gap semiconductor.