Optical and electrical conductivity properties of rare earth elements (Sm, Y, La, Er) co-doped CeO2

In this research, un-doped CeO2 and Ce0.85La0.10M0.05O2 (M: Sm, Er, Y) compounds were synthesized by hydrothermal method and the multi-functional properties are reported. Oxygen defects were created with the additives of rare earth ions. The electrical and luminescence behaviors of the synthesized compounds were investigated in accord with the types of additives. The synthesized products were characterized by X-ray diffraction (XRD) analysis, Brunauere–Emmette–Teller (BET) measurement, UV–vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy and electrochemical impedance spectroscopic (EIS). All synthesized compounds are found to be nano-structured and have cubic phase. The total conductivity of all samples was calculated. Hence, the total conductivity of un-doped CeO2, Ce0.85La0.10Y0.05O2, Ce0.85La0.10Er0.05O2 and Ce0.85La0.10Sm0.05O2 is found to be 2.07 × 10−10, 5.70 × 10−4, 1.0 × 10−3 and 0.0747 S/cm, respectively. Also, bandgap energy (Eg) of these samples calculated from UV visible absorption spectra is discussed, and the optical results show variation between 3.2 and 2.15 eV. Additionally, the luminescence properties of the compounds were investigated and different emissions occur depending on the additive type. Accordingly, photoluminescent emission spectra of Ce0.85La0.10Y0.05O2, Ce0.85La0.10Er0.05O2 and Ce0.85La0.10Sm0.05O2 phosphors indicate that these phosphors have red, green and orange-red colors, respectively.