Conductivity studies of sol-gel prepared BaCe0.85-xZrxY0.15O3-δ 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-delta powders (x = 0, 0.1, 0.2, 0.3, 0.4) were prepared by a modified sol-gel Pechini method and sintered at 1,250 degrees C-1,450 degrees C, depending on 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%H-2/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%H-2/Ar/H2O atmosphere at 600 degrees C. The isothermal conductivities values showed a little variation for x from 0.2 to 0.4 between 500 and 800 degrees C.