Structural and elastic properties of TlInSe2 at high pressure

Abstract

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.