High-pressure characterization of multifunctional CrVO₄

The structural stability and physical properties of CrVO₄under compression were studied by x-ray diffraction, Raman spectroscopy, optical absorption, resistivity measurements, andab initiocalculations up to 10 GPa. High-pressure x-ray diffraction and Raman measurements show that CrVO₄undergoes a phase transition from the ambient pressure orthorhombic CrVO₄-type structure (Cmcm space group, phase III) to the high-pressure monoclinic CrVO₄-V phase, which is proposed to be isomorphic to the wolframite structure. Such a phase transition (CrVO₄-type → wolframite), driven by pressure, also was previously observed in indium vanadate. The crystal structure of both phases and the pressure dependence in unit-cell parameters, Raman-active modes, resistivity, and electronic band gap, are reported. Vanadium atoms are sixth-fold coordinated in the wolframite phase, which is related to the collapse in the volume at the phase transition. Besides, we also observed drastic changes in the phonon spectrum, a drop of the band-gap, and a sharp decrease of resistivity. All the observed phenomena are explained with the help of first-principles calculations.