Conductivity studies of sol-gel prepared BaCe0.85-xZr xY0.15O3-´ solid electrolytes using impedance spectroscopy

A systematic investigation on doped barium cerate perovskites on conductivity was performed by means of ac electrochemical impedance spectroscopy technique. BaCe0.85-xZrxY0.15O3-d powders (x=0, 0.1, 0.2, 0.3, 0.4) were prepared by a modified sol-gel Pechini method and sintered at 1250°C -1450°C, depending of Zr content, to obtain good densities (93-97 % of the theoretical ones). The measured total conductivities for these solid solutions in three different atmospheres were reported: in dry oxygen, in dry nitrogen and wet (0.5 bar H2O) hydrogen (5%H2/Ar) atmospheres. Arrhenius plots recorded in dry oxygen as well as in dry nitrogen showed some residual hydration which remained in the specimens upon initial heating. The compositions with x=0.3 and 0.4 gave conductivities close to 10-2 S/cm in 5%H2/Ar /H2O atmosphere at 600°C. The isothermal conductivities values showed a little variation for x from 0.2 to 0.4 between 500 and 800°C.