Internal friction and dynamic Young's modulus measurements were carried out on polycrystalline Cu3Ba2YO7-x at temperatures ranging from 300 to 900K, by using a vibrating-reed (0.1 to 10kHz) and an inverted torsional pendulum (1 to 30Hz). Two relaxation damping peaks, with activation energies of 1.3 and 1.55eV, were found. The relaxation strength depended upon the temperature and the O stoichiometry. A marked modulus softening, indicating a phase transition, was detected for x = 0.55; both during isothermal modulus measurements and during constant heating tests, where DTG measurements revealed a corresponding maximum in the O desorption rate. On the basis of these results, a model was developed for O short-range mobility, twinned interface mobility and O out-diffusion.

E.Bonetti, E.G.Campari, V.Luprano, S.Mantovani, S.Casagrande, P.Cammarota: Materials Science Forum, 1993, 119-121, 689-94