High-pressure structural investigations on InPO4

High-pressure Raman scattering and angle dispersive x-ray diffraction investigations have been carried out on Indium phosphate (InPO4). Our experimental studies show that ambient Cmcm phase of InPO4 remains stable up to ~10 GPa. On the further increase of pressure to ~12 GPa, diffraction patterns show the signature of structural phase transformation. Rietveld refinements of diffraction patterns suggest that at high-pressure both the zircon (Space Group I41/amd) and scheelite (Space Group I41/a) type tetragonal phases are present along with the ambient orthorhombic Cmcm phase. In both the zircon and scheelite phases, the indium atoms become eight coordinated with respect to the oxygen atoms while phosphorous continues to be four coordinated.