A DFT study of the structural, electronic and optical properties of transition metal doped fluorite oxides: Ce0.75M0.25O2Ce0.75M0.25O2 (M=Fe, Co, Ni)

• The structural, electronic and optical properties of Ce1−xMxO2Ce1−xMxO2 (M=Fe, Co, Ni; x=0, 0.25) fluorite type oxides are studied.
• The calculated equilibrium lattice parameter, cell volume, bulk modulus and optical properties for CeO2 are in good agreement with the available experimental data and other theoretical results.
• Compared with the undoped CeO2, the doped system has steep absorption peaks ranging from 1.0 eV to 2.0 eV at lower energy, and it can be used for visible light absorption applications.
• Ce0.75Co0.25O2Ce0.75Co0.25O2 is suitable as a useful high-refractive index film material in single and multilayered optical coatings.

The structural, electronic and optical properties of Ce1−xMxO2Ce1−xMxO2 (M=Fe, Co, Ni; x=0, 0.25) fluorite type oxides are studied by using the method of density functional theory (DFT) + U method. The calculated equilibrium lattice parameter, cell volume, bulk modulus and optical properties for CeO2 are in good agreement with the available experimental data and other theoretical results. The lattice parameter, cell volume, bulk modulus and bond length of Ce–O decreased after substituting Ce atom with Fe (or Co, Ni). Meanwhile, the band-gap (Eg) reduction is observed. It is interesting to find that doping of Fe (or Co, Ni) in CeO2 obviously decreases the O 2p-Ce 4f transition intensity and the covalent character of the Ce–O bond. On the contrary, the static dielectric constant ε0 and refractive index n0 for the doped system increased. Compared with the undoped CeO2, the doped system has steep absorption peaks ranging from 1.0 eV to 2.0 eV at lower energy, and it can be used for visible light absorption applications. The Ce0.75Co0.25O2Ce0.75Co0.25O2 has a high refractive index and reflectivity, therefore it is suitable as a high-refractive index film material in single and multilayered optical coatings.