Atomistic Simulation of the Equation of State of SrF2 Using Electron Gas Interionic Potentials

Author： Francisco E. Blanco M.A. Palacios P.

ISSN： 0895-7959

Source： International Journal of High Pressure Research, Vol.22, Iss.1, 2002-01, pp. : 227-230

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Abstract

We have determined the equation of state (EOS) of SrF₂ in the cubic (C1, Fm3m) and orthorhombic (C23, Pbnm) phases using Electron Gas Interionic Potentials (EGIP) that incorporate many-body energy components. Thermal effects are included by means of a quasi-harmonic Debye model. The zero pressure unit cell length (a₀), lattice energy (E_latt), bulk modulus (B₀), and EOS of the C1 phase are predicted in good agreement with the observed data. Moreover, the computed EOS satisfy very well the empirical Vinet EOS. Fittings of η/η₀−p data (η=a, b, c) to linear forms of the Vinet EOS reveal that SrF₂ (C23) is more compressible along the b and c axes than along the a direction. Finally, the {rm C1}rightleftharpoons {rm C23} transition is predicted to occur at p_t=3.92 GPa, which is between the observed direct (p_t=5.0 GPa) and reverse C1 (p_t=1.7 GPa) phase transitions.