Performance of cubic ZrO2 doped CeO2: First-principles investigation on elastic, electronic and optical properties of Ce1−x ZrxO2

The structural, elastic, electronic and optical properties of Ce1−x ZrxO2 (x = 0, 0.25, 0.5, 0.75, 1) fluorite type oxides are studied by researchers using the method of density functional theory (DFT) + U method. The calculated equilibrium lattice parameter, cell volume, elastic and optical properties for CeO2 and ZrO2 are all in good agreement with the available experimental data and other theoretical results. It is found that Ce substituted by Zr leads to the formation of the pseudo-cubic fluorite-type structure. With doping concentration × increasing, the lattice parameter, cell volume and the bond length of dCe−O and dZr−O decrease linearly. It is interesting to find that the hardness of materials increase with Zr concentration increasing. For Ce0.75 Zr0.25 O2, we also find that its ductility is good. Meanwhile, the range of the conduction band energy in the doped system becomes wider than that in the undoped system. The overlapping band phenomenon occur for all substitutions in Ce1−x ZrxO2 (from x = 0.25 to x = 0.75), especially for the structure of Ce0.5 Zr0.5 O2 and Ce0.25 Zr0.75 O2, its second band gaps almost disappear. Based on the dielectric functions obtained, it is shown that the static dielectric constant ε0 and refractive index n0 obviously decrease with Zr concentration increasing. After discussing, we know that CeO2 is suitable as a useful high-refractive index film material in single and multilayered optical coatings, whereas ZrO2 can be used as gate-dielectric materials in metal-oxide semiconductor (MOS) devices, in metallurgy and as a thermal barrier coating in engines.