First-Principles Prediction of Structural, Mechanical Stability, Thermodynamic Performance and Phonon Dispersion in an Emerging VRhTe and VRuSb Heusler Materials

Abstract

This work investigated the structural, mechanical, thermodynamic, and phonon characteristics of Vanadium-Rhodium-Tellurium (VRhTe) and Vanadium-Ruthenium-Antimony (VRuSb) compounds by first-principles calculations grounded on density functional theory (DFT). The computations were performed under the generalised gradient approximation (GGA) utilising the Perdew–Burke–Ernzerhof (PBE) functional as processed in the Quantum ESPRESSO software package. The optimised structures indicated that both compounds crystallise in cubic Heusler-type (Fm–3m) symmetry and display thermodynamic stability, as proved by their negative formation energy and absence of structural distortions. The lattice parameter of VRuSb was slightly higher than that of VRhTe owing to the larger atomic radius of Sb. The results revealed that the Pugh's ratio for VRhTe is 11.94, whereas for VRuSb has the value 2.67, this demonstrates the compounds VRhTe, and VRuSb are ductile. The Poisson's ratio is 0.45 and 0.33 for VRhTe and VRuSb which is greater than the evalution value 0.30 (ⱱ > 0.30) signifies the metallic bonding characteristics ductility of the materials. This agree with the outcome of the Pugh‘s ratio. The thermal conductivity of a substance is been determined by the debye temperature. The materials suggest improved thermal conductivity at the debye temperature. Meanwhile, at high temperature the Dulong and Petit law agrees with the specific heat capacity of the heusler materials and adheres to the T3 rule as the temperature decreases. The heusler compounds reveals phonon dynamical stability as the frequencies and the phonon density of states are positives.