STRUCTURAL, DIELECTRIC AND A.C. CONDUCTIVITY STUDIES OF BaCe0.65 Zr0.2Y0.15O3-δ SOLID OXIDE FUEL CELL ELECTROLYTE BY CITRATE EDTA COMPLEXING SOL-GEL PROCESS.

Abstract

This paper reports on the effect of Zirconium doping on BaCe 0.85 Y 0.15 O 3-δ electrolyte prepared using the citrate-EDTA complexing modified sol-gel process at calcinations temperature T=1000°C. The phase formation, Thermal analysis, Morphology, Stability and Conductivity measurements were performed on the sintered powders through Thermogravimetric analysis (TGDTA), Xray diffraction (XRD), Scanning electron microscope (SEM), EDAX, FTIR, RAMAN and LCR measurements. The crystallite size of the ceramic powders calculated from Scherrer equation is 26.49nm and microstructure of the sintered powder revealed that the average grain size is in the range of 2-3m. Dense ceramic materials were obtained at 1300°C and the relative density is 90% of the theoretical density. The ionic conductivity of the pellet is investigated from room temperature to 500°C and is found to exhibit highest conductivity of 2.2x10 -3 S/cm and 2.76 x10 -3 S/cm at 500°C in dry air and wet air atmosphere with 3% relative humidity. Frequency dependence on the dielectric constant has been investigated at various temperatures which clarified that larger value of ε ′ is due to superposition of both electrolyte -electrode interfacial and space charge polarization originated from dopant-vacancies created. The conductivity increased as temperature increases with activation energy in the range 0.5eV and hence this composition is worth being an electrolyte.