High pressure study of structural and elastic properties of barium chalcogenides

The structural and elastic properties of barium chalcogenides (BaX; X = S, Se, Te) under high pressure have been investigated by using a two body inter-ionic potential approach with modified ionic charge (Z(m)e). The equation of states in NaCl type to CsCl type structural phases for BaX has been depicted and found that the volume collapses at the phase transition pressures. The phase transition pressures 7.2 GPa, 6.1 GPa, 5.0 GPa respectively for BaS, BaSe, and BaTe obtained by us, are in close agreement with experimental data (6.5 GPa, 6.0 +/- 0.2 GPa, 4.8 +/- 0.3 GPa). The bulk modulus, pressure derivatives, second order elastic constants (SOEC) and third order elastic constants (TOEC) at high pressure have been calculated, which show predominantly ionic nature of these compounds. The variation of second order elastic constants (C-11, C-44) with pressure has been presented.