Evidence for a monoclinic metallic phase in high-pressure VO ₂

Abstract

The pressure dependencies at room temperature of Raman and infrared (IR) data on VO ₂ are presented up to 19 and 15 GPa, respectively, together with preliminary X-ray diffraction (XRD) data collected up to 42 GPa. Both Raman and XRD indicate the persistence of a monoclinic lattice up the highest pressures. Observed modifications in the pressure dependence of Raman phonon frequencies, IR spectral weight, and unit cell volume at ∼10 GPa allow us to identify two regimes at low and high pressure and to conjecture a transition to a new unknown monoclinic phase where applying pressure activates a metallization mechanism.

Keywords:

• high pressure
• raman
• infrared
• X-ray diffraction
• metal insulator transition

Acknowledgement

We kindly acknowledge L. Dubrovinsky and his staff at Bayerisches Geoinstitut for HP XRD measurements.