Anisotropic compression in the high pressure regime of pure and Cr-doped vanadium dioxide

TL;DR

This study investigates how pure and Cr-doped vanadium dioxide structurally respond to high pressure, revealing anisotropic lattice compression and phase transitions linked to charge delocalization.

Contribution

It provides new insights into the high-pressure structural behavior and phase transitions of Cr-doped VO₂, highlighting anisotropic compression and symmetry changes.

Findings

Monoclinic M1 symmetry persists up to 12 GPa.

Transition to Mx phase occurs above 12 GPa.

Anisotropic compression observed in the b-c plane.

Abstract

We present structural studies of V$_{1-x}$Cr$_x$O$_2$ (pure, 0.7% and 2.5% Cr doped) compounds at room temperature in a diamond anvil cell for pressures up to 20 GPa using synchrotron x-ray powder diffraction. All the samples studied show a persistence of the monoclinic $M_1$ symmetry between 4 and 12 GPa. Above 12 GPa, the monoclinic $M_1$ symmetry changes to isostructural $M_x$ phase (space group $P2_1/c$) with a significant anisotropy in lattice compression of the $b$-$c$ plane of the $M_{1}$ phase. This behavior can be reconciled invoking the pressure induced charge-delocalization.