First-principles study on B2 based XAl(X = Rh, Ru)compounds

Abstract

In this study, to see pressure effects on optical, thermodynamic, structural, elastic, electronic properties, charge density, and phonon frequencies of the XAl (X:Rh, Ru) compounds in B2 structure, the first-principles methods were used. The ground-state properties of these compounds were determined and compared with experimental and theoretical data. High Young’s and shear modulus showed these compounds to be hard materials. The investigated compounds have ductile property according to the Paugh criterion and Poisson’s ratio calculated from elastic constants. The electronic band structure showed that these compounds have a metallic nature. Dynamic stability using phonon distribution curves was determined under pressure. The bond properties between Rh-Al and Ru-Al atoms were evaluated in detail by Mulliken Atomic Populations and charge density analysis. Also, the optical properties are examined in detail. We think that this theoretical work contributes greatly to engineering applications due to the electronic, thermodynamic, and optical behavior of XAl (X: Rh, Ru) compounds.

Mechanical, vibration, and optical properties of IrAl intermetallic compound via DFT calculations: high-pressure effect

“…It was observed that the intensity of DOS decreased with the effect of pressure. The same effect was seen in NiBe, and XAl(Rh, Ru) intermetallic compounds [26,30]. The pressure effect narrows the bond length between atoms and the bond interaction between atoms increases.…”

“…Examination of these stability criteria employing the calculated pressure dependent elastic constants (table 1) suggests that this compound is elastically stable at all pressures up to 60 GPa. At all pressures, the C 11 value of the IrAl compound can be interpreted as greater resistance of the compound to unidirectional compression [30]. Therefore, the Bulk modulus(B) values are greater than the Shear modulus(G) values (figure 2) [31] andthe same behavior prevails in the values in the literature [10].…”

“…Hybridity in the pseudogap near the Fermi level results from covalent bonding. This gap represents the larger Bulk modulus and the smaller Poisson's ratio [30]. This gap gets smaller with increasing pressure, and the Bulk modulus and Poisson ratio increase.…”

“…The IrAl intermetallic compound is elastically ductile as it satisfies all three criteria. Various Al-based cubic structures of ductile nature have been reported in the literature [30,35]. Cauchy pressure, B/G ratio, and Poisson ratio increase with the increase in pressure.…”

“…The values of DOS f at the Fermi level are 1.21, 0.98 and 0.84 at 0 GPa, 30 GPa and 60 GPa, respectively. A value of DOS f at the Fermi level other than zero is indicative of metallicity [30]. With the increase in pressure, the DOS f value at the Fermi level decreases.…”