High pressure XRD and Raman investigations on GdTaO₄

Gadolinium tantalate, GdTaO₄, belongs to the large family of REBO₄ (RE: trivalent rare earth cation; B: is pentavalent cation) compounds. These compounds are technologically important ranging their application as luminescence materials to laser host matrix. In this work we present the synthesis and high pressure structural and vibrational behaviour of GdTaO₄. The compound was synthesized in single phase by solid state reaction method and ambient structure was characterized by powder XRD and Raman spectroscopic techniques. All the observed Raman modes for fergusonite structure match with theoretically predicted values. Under pressure, X-ray diffraction studies show that the monoclinic phase of GdTaO₄ remains structurally stable up to 12 GPa. However, with pressure, some of the optical modes lose intensity in Raman scattering studies indicting change in electronic structure of the compound