Raman spectroscopy and X-ray diffraction of pressure-induced reversible structure change in K2OsO2(OH)4

High-pressure structural evolution of K2OsO2(OH)(4), a potassium osmate dihydrate, has been studied by high-pressure Raman spectroscopy and angle dispersive X-ray diffraction. A pressure-induced reversible structure change is observed at approximately 8 GPa, evidenced by the splitting of Raman modes and the addition of X-ray diffraction peaks. The splitting of phonon generally occurs in the Raman modes with smaller Gruneisen parameters. The pressure-induced structural change is correlated with the relatively isolated arrangement of Os-O polyhedron. In addition, the zero-pressure bulk modulus B-0 = 46(1) GPa and zero-pressure Gruneisen parameters gamma of K2OsO2(OH)(4) are given and discussed.