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Phase Behavior of TmVO4 under Hydrostatic Compression: An Experimental and Theoretical Study
Enrico Bandiello1, Daniel Errandonea1, Javier González-Platas2
1Departamento de Física Aplicada-ICMUV, MALTA Consolider Team, Universidad de Valencia, Edificio de Investigación, C/Dr. Moliner 50, Burjassot, 46100 Valencia, Spain.
Inorganic Chemistry
|March 20, 2020
Summary
High pressure transforms thulium vanadate (TmVO4) from zircon to scheelite structure above 6 GPa. This structural change significantly impacts its electronic properties, including a large band gap collapse.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Crystallography
Background:
- Thulium vanadate (TmVO4) is a magnetoelastic material with a zircon-type structure.
- Understanding its behavior under high pressure is crucial for materials science applications.
Purpose of the Study:
- To structurally and optically characterize TmVO4 under high pressure.
- To investigate the phase transition and its effect on electronic and vibrational properties.
Main Methods:
- High-pressure powder and single-crystal X-ray diffraction.
- Density functional theory (DFT) calculations.
- Optical spectroscopy (band gap determination).
Main Results:
- TmVO4 undergoes an irreversible phase transition to a scheelite structure above 6 GPa.
- Anisotropic bulk moduli were determined for both phases.
- The band gap (3.7 eV) collapses by 1.15 eV during the phase transition.
- V 3d and O 2p states of the VO4 unit govern the band gap behavior.
- Soft modes indicate dynamic instability preceding the phase transition.
Conclusions:
- The structural phase transition in TmVO4 is driven by the compression of VO4 units.
- High pressure significantly alters the electronic and vibrational properties of TmVO4.
- DFT calculations accurately predict the experimental observations.
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