Computational exploration of the structural stability, magnetic, optical, mechanical properties, and phonon spectra of novel perovskites CoXO3 (X = Rh, Ir) for optoelectronic applications

The exploration of suitable materials for energy-harvesting applications is a vital requirement in the present era of science and technology. In this work, we examine the structural, magnetic, optical, and mechanical properties, as well as the phonon spectra, of the perovskites CoXO3 (X = Rh, Ir) using the PBE+TB-mBJ functional implemented within the DFT-based WIEN2k code. In the cubic phase, the calculated lattice constants are 3.8436 Å for CoRhO3 and 3.8630 Å for CoIrO3, with lattice angles α = β = γ = 90°. CoRhO3 exhibits an indirect band gap of 2.29 eV, whereas CoIrO3, counterintuitively, shows metallic behavior. Total density-of-states analysis reveals that Co and O atoms predominantly contribute to the formation of both valence and conduction bands in these compounds. The elastic constants, derived using the Voigt–Reuss–Hill approximation, yield Young’s modulus values of 13.07 GPa for CoRhO3 and 13.64 GPa for CoIrO3. The Poisson’s ratio and elastic anisotropy indicate inherent ductility in both materials, ensuring considerable deformability before fracture. Additionally, the complex dielectric function, refractive index, extinction coefficient, absorption coefficient, optical conductivity, reflectivity, and energy-loss function have been evaluated. The appearance of imaginary frequencies in the phonon dispersion curves suggests that certain vibrational modes are dynamically unstable in the cubic phase. Overall, this comprehensive computational investigation highlights these compounds as promising candidates for future experimental synthesis and practical deployment in optoelectronic and related technologies.