Pressure induced phase transformation in U2O(PO4)2

The high pressure behavior of U2O(PO4)2 has been investigated with the help of Raman scattering and X-ray diffraction measurements up to ∼14 and 6.5 GPa, respectively. The observed changes in the Raman spectra as well as the X-ray diffraction patterns suggest that U2O(PO4)2 undergoes a phase transition at ∼6 GPa to a mixture of a disordered ambient pressure phase and a new high pressure phase. The new phase resembles the triclinic mixed-valence phase of uranium orthophosphate (U(UO2)(PO4)2). On release of pressure the initial phase is not retrieved.

Graphical abstractThe high pressure behavior of U2O(PO4)2 has been investigated with the help of Raman scattering and X-ray diffraction measurements up to ∼14 and 6.5 GPa, respectively. The observed changes in the Raman spectra as well as the X-ray diffraction patterns suggest that U2O(PO4)2 undergoes a phase transition at ∼6 GPa to a mixture of a disordered ambient pressure phase and a new high pressure phase. The new phase resembles the triclinic mixed-valence phase of uranium orthophosphate (U(UO2)(PO4)2). On release of pressure the initial phase is not retrieved.Figure optionsDownload full-size imageDownload as PowerPoint slide