High pressure structural study of β-Ti3O5: X-ray diffraction and Raman spectroscopy

The structural stability of β-Ti3O5 (C2/m) has been investigated by X-ray diffraction and Raman spectroscopy with diamond anvil cells. β-Ti3O5 is stable up to about 26 GPa at room temperature. Isothermal pressure–volume relationship of β-Ti3O5 is well presented by the third-order Birch–Murnaghan equation of state with V0=348.6(8) Å3 and B0=216(9) GPa. Axial compressibility presents obvious anisotropy. The a-axis and c-axis are more compressible than b-axis due to the different crystal structure arrangement of β-Ti3O5 along b-axis and perpendicular to b-axis direction. The Grüneisen parameters of thirteen observed Raman modes are 0.79–1.74, whose mean is 1.32.