Phonon anharmonicity and equation of state parameters of orthovanadate Mg3(VO4)2: Raman Spectroscopy and X-ray diffraction investigation

Isothermal compression effect is investigated on structure and vibrational properties of orthovanadate Mg3(VO4)2 using Raman spectroscopy and X-ray powder diffraction up to pressures 20.2 and 25.7 GPa respectively. Isobaric temperature effect on the vibrational properties of Mg3(VO4)2 have also been investigated using Raman spectroscopy up to 1273 K. The present investigation indicates stable orthorhombic (Cmca) structure up to the highest pressure achieved and up to near its melting temperature. The high pressure structural behavior is similar to the isostructural compounds Zn3(VO4)2 and Ni3(VO4)2 unlike another isostructural compound Mn3(VO4)2 which is reported to show irreversible structural phase transformation. Experimental equation of state parameters are compared with those reported on the similar compounds and the obtained bulk modulus (141 GPa) of Mg3(VO4)2 matches very well with the empirically calculated value reported earlier. The anharmonicities estimated after combining both studies suggest dominant contribution of three phonon decay process.