Using density functional theory (DFT) via the all-electron, full-potential linearized augmented plane wave (LAPW) approach implemented in the ELK code, we investigate the electronic structure and optical properties of bulk Co₈Cr₁₆O₂₄ along with its doped derivatives Co₈Cr₁₅BiO₂₄ and Co₈Cr₁₅ZrO₂₄. The bulk material exhibits intrinsic semiconductor behavior with an effective band gap of roughly 0.7 eV, arising from distinct spin-polarized contributions—where the spin-up states dominate the valence band and the spin-down states define the conduction band. In the bismuth (Bi)-substituted compound, the band gap narrows and becomes indirect, as the conduction band edge shifts to the L point and the valence band edge to the Γ point, while the Fermi level remains centrally positioned. In contrast, zirconium (Zr) substitution not only further reduces the band gap but also shifts the Fermi level towards the conduction band, inducing n-type behavior by acting as an electron donor. Optical analyses indicate that although all samples show comparable refractive index behavior at wavelengths below 800 nm, significant differences emerge at longer wavelengths. Specifically, Bi doping enhances both the refractive index and reflectance, while Zr doping initially lowers the refractive index before it rises markedly in the infrared range. These findings illustrate that selective doping effectively tailors the electronic and optical properties of Co₈Cr₁₆O₂₄ based materials, presenting promising routes for advanced semiconductor and optoelectronic applications.

PDF (Download Full text)

Download Citation (XML)