High pressure structural, electronic, and optical properties of polymorphic InVO4 phases

Abstract

In the present work, we report a detailed density functional theory calculation on polymorphic InVO 4 phases by means of projector augmented wave method. The computed first-order structural phase transformation from orthorhombic (Cmcm) to monoclinic (P2/c) structure is found to occur around 5.6 GPa along with a large volume collapse of 16.6%, which is consistent with previously reported experimental data. This transformation also leads to an increase in the coordination number of vanadium atom from 4 to 6. The computed equilibrium and high pressure structural properties of both InVO 4 phases, including unit cell parameters, equation of state, and bulk moduli, are in good agreement with the available experimental data. In addition, compressibility is found to be highly anisotropic and the b-axis being more compressible than the other for both the structures. Electronic band structures for both the phases were calculated, and the band gap for orthorhombic and monoclinic InVO 4 are found to be 4.02 and 1.67 eV, respectively, within the Tran-Blaha Modified Becke-Johnson potential as implemented in linearized augmented planewave method. We further examined the optical properties such as dielectric function, refractive index, and absorption spectra for both the structures. From the implications of these results, it can be proposed that the high pressure InVO 4 phase can be more useful than orthorhombic phase for photo catalytic applications.

High-pressure characterization of the optical and electronic properties of InVO4, InNbO4, and InTaO4

“…Previous [11,25,27] and present theoretical studies corroborate the conclusions extracted from the experimental results. Calculations support that InVO 4 is a direct band-gap material with the gap at the Y point of the BZ.…”

“…Calculations support that InVO 4 is a direct band-gap material with the gap at the Y point of the BZ. The calculated values [25,27] tend to overestimate E g (see Table 1). However, it should be noted here that the value of E g is very sensitive to the functionals selected for DFT calculations [25] and differences of up to 1 eV between measured and calculated band gaps are typical [25,46].…”

“…On the other hand, O 2p states dominate the upper part of the valence bands. However, in the literature, it can be seen that there are significant discrepancies in the reported E g values, which range from 1.8 to 4.8 eV, as well as about their band-gap nature, i.e., indirect or direct transition [11,[15][16][17][18][19][20][21][22][23][24][25][26]. In fact, in some studies, the absorption of light by defects has been mistakenly assigned to the fundamental band gap [11].…”

First-Principles Study of InVO4 under Pressure: Phase Transitions from CrVO4- to AgMnO4-Type Structure

“…To the best of our knowledge there are very few studies about the stability of InVO 4 under extreme conditions of temperature 24 and pressure. 25,29 The X-ray diffraction pattern of InVO 4 in the CrVO 4 -type structure was reported from ambient temperature to 1023 K. 24 No phase transition in this range of temperature was reported, only a smooth increase in the unit-cell parameters and a significantly higher conductivity above 723 K were observed.…”

“…, phase IV was never observed as a pure phase.On the other hand, first-principles calculations were used to study the phase transition from CrVO 4 -type structure to wolframite 29. Where a phase transition pressure of 5.6 GPa was reported.…”