Raman study of polycrystalline PbWO₄ under high pressure

Abstract

Raman spectroscopy is employed in the investigation of the structural stability of polycrystalline PbWO₄ under hydrostatic pressure up to 15 GPa. Drastic changes of the Raman spectra at 5.6 GPa manifest the onset of a new phase that coexists with the ambient pressure scheelite structure of PbWO₄ for pressure up to ∼9 GPa. The scheelite structure is locally restored upon pressure release but spectral features of the high-pressure phase are also observable at ambient pressure, while rapid release of pressure seems to favour the recovery of the high-pressure phase. The structure richness of the high-pressure Raman spectra is indicative of a rather complex phase where the coordination of the W cation is increasing becoming probably octahedral.

Keywords:

• Scheelites
• Stolzite
• Phase transitions
• High pressure
• Raman spectroscopy