Preparation and electrical characterization of ruthenia-doped yttria-stabilized zirconia ceramics

Samples belonging to the [(ZrO2)(0.92)(Y2O3)(0.08)](1-x)(RuO2)(x) system, where 0 less than or equal to x 0.1 (mol), hale been synthesized by a polymeric sol-gel route and sintered in air at 1400 degrees C for 2 h, The RuO2-YSZ solid solution limit is found at x = 0.05 at 1400 degrees C by X-ray diffraction and electrochemical impedance spectroscopy measurements. The electrical conductivity of the studied materials decreases with ruthenia additions. At high temperature (700-850 degrees C) and low oxygen partial pressure, these materials behave as mixed oxygen ion-electronic conductors, The electronic conductivity as a function of P-o2 shows a dependence of - 1/4 and an activation energy of 0.98 eV, The electronic contribution is explained on the basis of redox equilibrium between trivalent Ru3+ and divalent Ru2+. The EPR spectra of polycrystalline sintered samples confirm the presence of Ru3+. (C) 1998 Academic Press.