MECHANICAL RELAXATION MEASUREMENTS IN THE PROTONIC CONDUCTORS SRCEO3 AND SRZRO3

Several mechanical relaxation peaks have been observed in the ceramic proton conductors SrCe1-xYbxO3-alpha and SrZrt-xYbxO3-alpha (x=0.025, 0.05, 0.1). The spectra consist of a superposition of peaks which can be attributed to defect clusters containing both protons and dopant at oms. These peaks are positioned near 0 degrees C for a typical measuri ng frequency of 300 Hz. For the cerates another relaxation contributio n shows up near 100 degrees C. This can be related to oxygen vacancies near a dopant atom. Average activation energies of 0.5 eV for the pro ton related and 0.8 eV for the oxygen vacancy related local diffusion jumps are derived.