Ab initio study of the thermodynamic properties of rare-earthmagnesium intermetallics MgRE (RE=Y, Dy, Pr, Tb)

TL;DR

This study uses ab initio methods to analyze the thermodynamic properties of MgRE intermetallics with CsCl structure, revealing phonon behavior, thermal expansion, and electronic effects on heat capacity.

Contribution

It provides a comprehensive first-principles analysis of thermodynamic properties of MgRE intermetallics, including phonon and electronic contributions, using density functional theory and quasiharmonic approximation.

Findings

RE atoms dominate phonon frequencies

Thermal expansion and heat capacity are temperature-dependent

Electronic contributions significantly affect specific heat

Abstract

We have performed an ab initio study of the thermodynamical properties of rare-earth-magnesium intermetallic compounds MgRE (RE=Y, Dy, Pr, Tb) with CsCl-type B2-type structures. The calculations have been carried out the density functional theory and density functional perturbation theory in combination with the quasiharmonic approximation. The phonon-dispersion curves and phonon total and partial density of states have been investigated. Our results show that the contribution of RE atoms is dominant in phonon frequency, and this character agrees with the previous discussion by using atomistic simulations. The temperature dependence of various quantities such as the thermal expansions, bulk modulus, and the heat capacity are obtained. The electronic contributions to the specific heat are discussed, and found to be important for the calculated MgRE intermetallics.