Evaluation of Gadolinium Doped Barium Zirconate Electrolyte for Solid Oxide Fuel Cell

High proton conductivity perovskites can be utilized in many important applications. In this work gadolinium doped barium zirconate ([gadolinium oxide] = 0, 5, 10, 15 and 20% mol) was prepared by Pechini method from nitrates precursors. The powders were studied by simultaneous thermal analysis, X-ray diffraction, and scanning electron microscopy. These powders were then uniaxially pressed at 1 ton/cm² in cylindrical discs (diameter = 10 mm and thickness ~ 1 mm) and theirs geometrical densities were determined. These pellets were sintered at temperatures of 1773 K/1 h and 1523 K/1 h with and without amounts of boric acid as sintering aid respectively, follow by geometrical and Archimedes density measurements. Phase analysis was carried out by X-ray diffraction, and fracture and polished samples surfaces were observed in scanning electron microscopy. The parallel faces of each sample was painted with platinum paste and electrical characterized by impedance spectroscopy in the frequency range from 32 MHz to 1 Hz, under static air and standard mixture (3% hydrogen/97% nitrogen) flow, in the RT up to 1273 K. The main results indicate that dense (>96 % of theoretical density) barium zirconate perovskite phase was obtained for samples liquid phase sintered with high electrical conductivity.