Structural, Elastic, Electronic, Magnetic, and Thermoelectric Characteristics of MgEu₂X₄ (X = S, Se) Spinel Compounds: Ab‐Initio Calculations

Abstract

The structural, elastic, electronic, magnetic, and thermoelectric properties of MgEu2X4 (X = S and Se) spinel compounds are investigated computationally. Calculations are performed using the full‐potential linearized augmented plane wave (FP‐LAPW) method within the Perdew, Burke, and Ernzerhof generalized gradient approximation (PBE‐GGA), GGA + U, and modified Becke–Johnson (mBJ‐GGA) approximations. The band structure and density of states results from the three exchange‐correlation approximation methods (mBJ, GGA + U, and PBE) show that these spinel compounds are fully spin‐polarized. Also, they possess a half‐metallic character in the spin‐down channel with a direct bandgap (Γ–Γ) of about 3.44, 2.712, and 2.472 eV for MgEu2S4 and 2.89, 2.285, and 2.017 eV for MgEu2Se4, respectively. The formation of both compounds is energetically favorable based on the results of the total energy and cohesive energy calculations. Furthermore, the two compounds are chemically and mechanically stable, as concluded from cohesive energy and elastic calculations. The elastic calculations reveal that both spinel compounds are ductile materials. The ionic bonds are predominant. The quasi‐harmonic model has also been used to investigate the influences of temperature and pressure on thermal characteristics. The thermoelectric behavior is studied using the BoltzTraP code. Both systems show good thermoelectric properties for the spin‐down channel.

Mechanical, magneto-electronic and thermoelectric properties of Ba2MgReO6 and Ba2YMoO6 based cubic double perovskites: an ab initio study

“…As detailed in equation (7), Cauchy's pressure, derived from the difference between C 12 and C 44 , can offer insights into the dominant type of bonds in a compound. When C 12 is smaller than C 44 (resulting in a negative C″), covalent bonds tend to dominate; otherwise, ionic bonds are more prominent [61]. Accordingly, the calculated Cauchy's pressure for both compounds is positive, signifying the prevalence of ionic bonds in their structures.…”

“…The outcomes obtained through the Voigt Reuss Hill approximations (VRH) [59][60][61] have been consolidated in table 3. It's important to highlight that currently, there exist no existing experimental or prior theoretical findings to serve as a basis for comparison with our attained results.…”

A DFT calculation of electronic structures, magnetic, and thermoelectric properties of the new equiatomic quaternary Heusler alloy RuTiCrSi

“…The thermoelectric properties are calculated using Boltzmann's quasi‐classical theory under constant relaxation time ($$$ \tau \approx {10}^{-14}\ s $$$), relying on the BoltzTraP code [65–67]. The TDOS, Seebeck coefficient S , power factor PF, and figure of merit ZT versus different chemical potential ($$$ \upmu -{E}_{\mathrm{F}} $$$) and three temperatures, 300, 500, and 800 K, are represented in Figure 8.…”

Hydrogen Storage Capacity of Lead-Free Perovskite NaMTH3 (MT=Sc, Ti, V): A DFT Study

“…Mechanical characteristics are interlinked with the elastic constants denoted as C ij . The elastic constants of a material can define how it behaves under applied stress from the outside and offer important information about its bonding properties and structural stability [40]. For the compounds NaVH 3 , NaTiH 3 , and NaScH 3 , the computed values of the elastic constants C 11 , C 12 , and C 44 for cubic single-crystalline structures are presented in Table 3.…”