Pressure dependent mechanical properties of europium mono chalcogenides under high pressure

A theoretical study of the elastic properties in EuX (X = O, S, Se, Te) using an effective interionic interaction potential in which long-range Coulomb as well charge transfer interactions, Hafemeister and Flygare type short-range overlap repulsion extended up to the second neighbor ions and van der Waals interactions are considered. Emphasis is on the evaluation of the pressure dependent Poisson’s ratio ν, the ratio RG/B of G (shear modulus) over B (bulk modulus), anisotropy parameter, Shear and Young’s modulus, Lame constant, Klein man parameter, elastic wave velocity and thermodynamical property as Debye temperature. The Poisson’s ratio behavior infers that europium chalcogenides are brittle in nature. To our knowledge this is the first quantitative theoretical prediction of the pressure dependence of elastic, and thermodynamical properties explicitly the ductile (brittle) nature of EuX and still awaits experimental confirmations.

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► EuX (X = O, S, Se, and Te) semiconducting chalcogens are brittle in nature.
► Pressure dependence of θD infers the softening of lattice with increasing pressure.
► The αth.exp decreases nonlinearly with pressure for both rock salt and CsCl phase.
► The elastic anisotropic parameter γ12 decreases with enhanced pressure.