First-principle calculations to investigate the elastic and thermodynamic properties of RBRh₃ (R = Sc, Y and La) perovskite compounds

Abstract

We have performed first-principle calculations using the full-potential linear augmented plane wave (FP-LAPW) method within density functional theory (DFT) to investigate the structural, elastic and thermodynamic properties of the cubic perovskite RBRh₃ (R = Sc, Y and La) compounds. The exchange-correlation potential is treated within the generalized gradient approximation of Perdew–Burke–Ernzerhof (GGA-PBE). Single-crystal elastic constants are calculated using the total energy variation versus strain technique, then the shear modulus, Young's modulus, Poisson's ratio and anisotropic factor are derived for polycrystalline RBRh₃ using the Voigt–Reuss–Hill approximations. Analysis of the calculated elastic constants and B/G ratios shows that these compounds are mechanically stable and ductile in nature. Using the quasi-harmonic Debye model, the effect of pressure P and temperature T on the lattice parameter a ₀, bulk modulus B ₀, thermal expansion coefficient α, Debye temperature and the heat capacity C _v for these compounds are investigated for the first time. The computed structural and elastic constants are in good agreement with the available experimental and theoretical data.

Keywords:

• perovskite borides
• first-principle calculations
• elastic constants
• thermodynamic properties
• Debye temperature

Acknowledgements

This work was supported by FRGS grants Nos. 9003-00249 and 9003-00255. R.K., A.B. and S.O. extend their appreciation to the Deanship of Scientific Research at King Saud University for funding the work through the research group project No. RGP-VPP-088. Y.A. would like to acknowledge TWAS, Italy, for full support of his visit to JUST, Jordan, under a TWAS-UNESCO Associateship.