Influence of magnetic entropy on stability and thermodynamic properties of Laves phase Fe2Mo from first principles

Abstract

The thermodynamic and physical properties of the Laves phase Fe2Mo have been investigated using the finite-temperature quantum mechanical calculations within the frame of the density functional theory (DFT). All relevant free energy contributions including electronic, vibrational and magnetic excitations are considered. The quasi-harmonic Debye - Gruneisen theory is used. In this work, a new method of searching a thermal expansion path of compounds is proposed. It allows to reduce the problem to a one-dimensional case and minimize the free energy in one variable, in volume. The heat capacity, thermal expansion, elastic constants and bulk modulus are modelled. The calculated results analyzed and are in an agreement with the available experimental data. It is shown that magnetic entropy must be considered on equal footing with vibrational and electronic energies to reliably predict stability of Fe2Mo.