Investigation of structural, electronics, and optical characteristics of cubic SrZr_1−xRu_xO₃ perovskites: first-principles study

This work addresses the effect of substituting Zr atoms with Ru atoms at different concentrations in perovskite SrZrO₃ on the widening of the band gap and the change in the electronic and magnetic states of the material. Density functional theory (DFT) based on the all-electron full-potential linearized augmented plane-wave method was used for the calculations. The results obtained for the energy gap show that their values gradually decreased from 4.20 eV in the parent SrZrO₃ to zero with 50% Zr substitution by Ru, accompanied by a linear decrease in the lattice constant from 4.177 to 4.085 Å. This trend is consistent with Vegard’s law. The introduction of Ru induces a ferromagnetic state, with the total magnetic moment reaching 1.25 μB at a concentration of x = 0.5. The SrZr_1−xRu_xO₃ series compounds showed good thermal properties, as their coefficient of thermal expansion is low, and their lattice thermal conductivity does not exceed 4.0 W m⁻¹ K⁻¹ at room temperature, and under pressure reached 30 GPa. The involvement of the oxygen 2p states with the 4d−t_2g states of both ruthenium and zirconium is critical in the optical transitions observed in SrZr_1−xRu_xO₃ compounds. These findings demonstrate that Ru-doped SrZrO₃ is a promising candidate for spintronics, photovoltaics, and sustainable energy technologies due to its tunable band gap, robust magnetism, and exceptional thermal stability.