High pressure phase-transition, elastic and thermal properties of uranium chalcogenides: A model study

Uranium chalcogenides crystallize in Fm (3) over barm space group at ambient condition and transform to Pm (3) over barm space group under pressure. We have investigated the elastic and thermo-physical properties of uranium mono-chalcogenides using modified charge-transfer potential model. This model incorporates long-range Coulomb effects and charge-transfer (Coulomb screening due to f-electrons of U) effect modified by covalency and short-range repulsive interaction extended up to next-nearest neighbours. This model is capable of explaining the Cauchy-discrepancy. Calculated values of the phase-transition pressure (P(T) = 79.50, 19.60 and 9.50 GPa) and relative volume collapse (4.69, 7.95 and 7.88%) are in good agreement with experimental data. The equation of state has been plotted to get phase diagram. (C) 2010 Elsevier B.V. All rights reserved.