Eur. Phys. J. B (2022) 95: 106
https://doi.org/10.1140/epjb/s10051-022-00370-5

Regular Article - Solid State and Materials

First principles study of structural, elastic, and thermodynamic properties of LiAl₂X (X = Rh, Pd, Ir and Pt) intermetallic compounds

¹ Département des Sciences et Techniques, Faculté des Sciences et de la Technologie, Université Mohamed Elbachir El Ibrahimi de Bordj Bou Arreridj, 34000, Bordj Bou Arreridj, Algérie
² Laboratoire Matériaux et Systèmes Electroniques, Faculté des Sciences et de la Technologie, Université Mohamed Elbachir El Ibrahimi de Bordj Bou Arreridj, 34000, Bordj Bou Arreridj, Algérie
³ Laboratory of Materials Physics and Its Applications, University of M’sila, 28000, M’sila, Algeria

^c n_bouarissa@yahoo.fr

Received: 11 March 2022
Accepted: 19 June 2022
Published online: 5 July 2022

Abstract

The equilibrium structural parameters, thermodynamic properties, elastic constants, and several other related properties of LiMAl₂ (M = Rh, Pd, Ir and Pt) ternary intermetallic compounds have been investigated, employing the projected augmented wave pseudopotentials (PAW) approach in the framework of the density functional theory (DFT) as implemented in the Quantum Espresso code. Our findings on the lattice parameters of LiMAl₂ (M = Rh, Pd, Ir and Pt) compounds agree well with the experimental ones, while our obtained results of the elastic constants are in general slightly higher than the theoretical ones reported previously in literature. Our results concerning the mechanical stability criteria indicate that all LiMAl₂ (M = Rh, Pd, Ir and Pt) are mechanically stable at equilibrium, while the analyses of both Zener anisotropy factor and elastic anisotropy index show that all these compounds are highly anisotropic in their elastic properties. According to Mukhanov et al.’s (Philos. Mag. 89:2117, 2009) model, the Vickers hardness H_V of LiMAl₂ (M = Rh, Pd, Ir and Pt) increases gradually and almost linearly with increasing pressure. The Debye temperature θ_D as well as the melting point T_m of the aggregate materials are calculated using two different empirical expressions. The obtained values of θ_D are around 499.5 (546.4) K for LiRhAl₂, 478.7 (520.6) K for LiPdAl₂, 411 (451) K for LiIrAl₂, and 417.3 (455.2) K for LiPtAl₂ compound, respectively; while those of T_m are found to be around 1566 (1448) K for LiRhAl₂, 1436 (1316) K for LiPdAl₂, 1650 (1502) K for LiIrAl₂, and 1615 (1489) K for LiPtAl₂, respectively. Our calculated data show that the behavior of the thermodynamic properties with increasing temperatures is monotonic for all our materials of interest.