Insight into Physical and Thermodynamic Properties of X3Ir (X = Ti, V, Cr, Nb and Mo) Compounds Influenced by Refractory Elements: A First-Principles Calculation

Abstract

The effects of refractory metals on physical and thermodynamic properties of X3Ir (X = Ti, V, Cr, Nb and Mo) compounds were investigated using local density approximation (LDA) and generalized gradient approximation (GGA) methods within the first-principles calculations based on density functional theory. The optimized lattice parameters were both in good compliance with the experimental parameters. The GGA method could achieve an improved structural optimization compared to the LDA method, and thus was utilized to predict the elastic, thermodynamic and electronic properties of X3Ir (X = Ti, V, Cr, Nb and Mo) compounds. The calculated mechanical properties (i.e., elastic constants, elastic moduli and elastic anisotropic behaviors) were rationalized and discussed in these intermetallics. For instance, the derived bulk moduli exhibited the sequence of Ti3Ir < Nb3Ir < V3Ir < Cr3Ir < Mo3Ir. This behavior was discussed in terms of the volume of unit cell and electron density. Furthermore, Debye temperatures were derived and were found to show good consistency with the experimental values, indicating the precision of our calculations. Finally, the electronic structures were analyzed to explain the ductile essences in the iridium compounds.

Quasi-linear correlation between shear and young’s moduli in some polycrystalline ceramics

“…So, the maximum error (5.56 %) was found for MgO, while the minimum error (0.43 %) was reported for ZnO material. It is very important to that a quasi-linear correlation between Young's and shear moduli was also obtained for several intermetallic compounds: X3Ir (X = Ti, V, Cr, Nb and Mo) [5]. In the following section, we use our proposed model to predict the shear modulus G of some other polycrystalline ceramics based on their Young's modulus E values reported in the literature [19], [30], [31].…”

First-Principles Prediction of Structures and Properties in Crystals

“…In Reference [11], Chen et al study the properties of a class of metal-iridium compounds, X 3 Ir, for a set of early 3d and 4d transition metals. They focus on physical properties such as elastic moduli and sound velocities and are able to identify trends between the different metals, relate their calculations to experimental data, and correlate them to details of the electronic structures of the compounds.…”