Prediction study of the structural, elastic and high pressure properties of Yttrium chalcogenide

The full-potential linearized augmented plane-wave plus local orbitals method with the generalized gradient approximation for the exchange–correlation potential (FP-APW + lo-GGA) is used to predict the structural, elastic and high pressure properties of YX with X = S, Se and Te. Ground state properties such as lattice constant, bulk modulus and its pressure derivative are obtained. The pressures at which these compounds undergo structural phase transition from NaCl-type to CsCl-type phases are calculated. The elastic constants and their pressure dependence are calculated using the total energy variation with strain technique. The shear modulus, Young’s modulus, Poisson’s ratio and Lamé’s coefficients are estimated in framework of Voigt–Reuss–Hill approximation for polycrystalline YX aggregates. The Debye temperature is estimated from the average sound velocity. To our knowledge this is the first quantitative theoretical prediction of the elastic and high pressure properties for these compounds and still awaits experimental confirmations.