Structural and elastic properties of TlInSe2 at high pressure

The results of the structural study of chain-like structured TlInSe2 compound using powder synchrotron X-ray diffraction (XRD) experiments under the pressures up to P = 30.53 GPa and a first principle analysis of structural and elastic properties under the pressures up to P = 50 GPa are reported. The XRD data show the stability of the tetragonal phase in the whole investigated pressure range. Density Functional Theory (DFT) calculations also evidence that at zero pressure the lowest energy structure of TlInSe2 is tetragonal (space symmetry group I4/mcm). At pressures above P ≥ 38 GPa the symmetry of the lowest energy structure changes to face-centered cubic one (Fm-3m). It was shown that the experimentally and theoretically obtained pressure dependences of lattice parameters in tetragonal phase are in good agreement. The pressure dependences of elastic constants, acoustic wave velocities and other elastic parameters, such as bulk modulus, shear modulus, Young's modulus, Poisson's ratio have been calculated. [Display omitted] •We have explored the structural and elastic properties of TlInSe2 under hydrostatic pressure by XRD measurements up to P = 30.53 GPa and DFT calculations up to P = 50 GPa.•The DFT results point to a structural transition from the BCT to the HP cubic (Fm-3m) phase at a critical pressure P = 38 GPa. A small jump in the volume at P ~38 GPa indicates that there is the first-order phase transition.•The elastic constants and their related parameters were also investigated using the first-principles calculations.•The corresponding results suggest that c and a (b) axes of tetragonal phases are harder to compress and with increasing of pressure this hardiness becomes more significant.•The longitudinal acoustic waves propagate approximately two times faster than the transverse ones. Calculated elastic moduli show ductile character of TlInSe2.