A high pressure x-ray diffraction study of titanium disulfide

A high pressure angle dispersive synchrotron x-ray diffraction study of titanium disulfide (TiS₂) was carried out to pressures of 45.5 GPa in a diamond-anvil cell. We observed a phase transformation of TiS₂ beginning at about 20.7 GPa. The structure of the high pressure phase needs further identification. By fitting the pressure-volume data to the third-order Birch-Murnaghan equation of state, the bulk modulus, K_0T, was determined to be 45.9 ± 0.7 GPa with its pressure derivative, K'_0T, being 9.5 ± 0.3 at pressures lower than 17.8 GPa. It was found that the compression behavior of TiS₂ is anisotropic along the different axes. The compression ratio of the c-axis is about nine times larger than the a-axis when pressures are lower than 1 GPa. It suddenly decreases to three times larger at pressures of about 3 GPa. This ratio shows a linear decrease with a slope of negative 0.048 at pressures below phase transformation.