Synthesis, structure, elastic properties, lattice dynamics and thermodynamics of YVO4 polymorphs from experiments and density functional theory calculation

Pure zircon and scheelite YVO4 were prepared by solid state reaction and high-pressure route, respectively. Calculated structural parameters, bulk modulus and elastic constants show good agreement with experimental results. Calculated phonon dispersions show that zircon and scheelite YVO4 are dynamically stable. Raman frequencies were determined and assigned to different modes according to the calculated results. After phase transition from zircon to scheelite, V-O bond length becomes longer and shows more ionic characteristic, which leads to smaller discrepancy of V atoms' Born effective charge from their nominal charge and the shift downward of the internal modes frequencies. Thermodynamic properties of YVO4 polymorphs were accurately predicted by quasi-harmonic approach.