The crystallographic stability and anisotropic compressibility of C54-type TiSi2 under high pressure

In situ synchrotron X-ray powder diffraction experiment on TiSi2 has been performed using a diamond anvil cell at ambient temperature. The present experimental results showed that the structure of C54-type TiSi2 is stable in the experimental pressure range up to around 52 GPa. The compressibility of C54-type TiSi2 under high pressure presents anisotropic behavior. The compressibility along the a-, b- and c-axes has an approximate ratio of 6:5:4. And the anisotropic compressibility of the studied crystal is discussed in terms of the crystallography stacking. The c/a and b/a axial ratios both increase as the pressure increases. With pressure increasing, the c/a shows a tendency of approaching the ideal value, but the b/a deviates from the ideal value. The pressure-volume data of C54-type TiSi2 were fitted to a Birch-Murnaghan equation of state, which yielded a bulk modulus of B0=155 (2) GPa.