The high-pressure phase transition of TiS2 from first-principles calculations

The structural stability of TiS2 under high pressures has been investigated by using first-principles plane-wave pseudopotential density functional theory within the local density approximation (LDA). The obtained results predict that TiS2 undergoes a pressure-induced first-order phase transition from its trigonal 1T-type structure to orthorhombic cotunnite-type structure at 16.20 GPa. The calculated transition pressure agrees quite well with the experimental finding of 20.7 GPa. The equation of state determined from our calculated results yields bulk moduli of 58.91 and 118.10 GPa for the 1T-type and cotunnite-type phases, respectively. This indicates higher incompressibility of the high-pressure phase of TiS2. In addition, the electronic structures of the two phases of TiS2 are also calculated and discussed. The results suggest the structural phase transition of TiS2 at high pressure is followed by a semimetal to metal electronic transition.

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