Fig. 1. (a) XRD patterns; (b) Enlarged XRD patterns; (c) the change relations between cell parameters and doped ions of nanosized Ce_0.95M_0.05O₂ (M=Fe, Nd, Eu) solid solutions

Fig. 2. (a) the UV-Vis absorption spectra; (b) the band gap fitting patterns, inset shows the value of band gap energies of nanosized Ce_0.95M_0.05O₂ (M=Fe, Nd, Eu) solid solutions

Fig. 3. The PL spectra of nanosized Ce_0.95M_0.05O₂ (M=Fe, Nd, Eu) solid solutions

Fig. 4. (a) Cycle stabilities curves, inset displays the maximum discharge capacities; (b) the capacity retentions of ball milled Mg₂Ni-Ni-5%Ce_0.95M_0.05O₂

Fig. 5. Semilogarithmic curves of anodic current vs. time responses of typical sample Mg₂Ni-Ni-5%CeO₂ and inset shows the diffusion coefficient D of different samples