Probing structural evolutions in GdVO4 under extreme thermodynamic conditions

Abstract

Externally applied Pressure and temperature parametres can influence the stability of any material and can also elucidate the stability range of material. The present manuscript reports pressure and temperature-induced structural phase progression/stability in GdVO4, a rare-earth vanadate synthesized using a solid-state reaction. The synthesized sample had a zircon crystalline structure and the expected phonon/vibrational modes. High-pressure XRD studies up to 27.1 GPa revealed a structural transition from ambient zircon to scheelite phase which was found to be initiated at about 0.4 GPa and completed at 12.2 GPa. The pressure induced changes in the lattice parameters as well as unit cell volumes were deduced and the third order Birch-Murngahan equation was used to fit the pressure-volume data. The bulk modulus of zircon and scheelite phases was found to be 85.1 GPa and 145.2 GPa respectively. The temperature-dependent Raman measurements reveal good structural phase stability of zircon structure in the temperature range of 80–440 K. All the phonon modes except one, showed phonon softening with an increase in temperature. Finally, the anharmonic contributions associated with temperature dependent shifts in a few of the Raman modes are calculated in terms of the anharmonic constants.