Electrochemical and thermal characterization of doped ceria electrolyte with lanthanum and zirconium

Nanocomposites electrolytes consisting of La3+ and Zr4+ doped with ceria labelled as La0.2 Ce0.8 O2-δ (LDC), Zr0.2Ce0.8O2-δ (ZDC) and Zr0.2La0.2Ce0.6O2-δ (ZLDC) have been synthesized via a co-precipitation route. DC conductivity was studied with a four-probe method in the range of temperature 450-650 °C and maximum conductivity was found to be 0.81 × 10−2 S.cm−1 (LDC) > 0.32 × 10−2 S.cm−1 (ZLDC) > 0.15 × 10−2 S.cm−1 (ZDC) at a temperature of 650 °C, respectively. Further, electric behavior of doped and co-doped ceria electrolytes was investigated by A.C electrochemical impedance spectroscopy (frequency range ~ 0.1 Hz‒4 MHz). The phase/structural identification of the material prepared was studied using X-ray diffraction and found ceria to possess a cubic fluorite structure. Scanning electron microscopy (SEM) was carried out to study its morphology and particle size (~ 90-120 nm). Thermal behavior on its change in weight and length with the temperature were studied by thermogravimetric analysis (TGA) and dilatometry respectively. Furthermore, thermal expansion coefficients (TECs) of prepared electrolytes are calculated and found as follows: 13.4 × 10−6 °C−1, 13.6 × 10−6 °C−1and 15.3 × 10−6 °C−1 for LDC, ZDC and ZLDC, respectively, in the temperature range 150-1150 °C.