It was recalled that internal friction maxima were observed in Cu3Ba2YO7-x over a wide range of temperatures, with the peak temperatures for 1Hz being: I (50 to 110K), II (200 to 250K), III (500K) and IV (850 to 950K). Maximum I consisted of 3 sub-maxima: IA (62K), IB (74K), IC (45K). These maxima were studied in detail here. Maximum IB was restricted to the orthorhombic phase, maximum IA decreased continuously with O deficiency and was absent at x = 1. Maximum IC appeared within a narrow composition range in the tetragonal phase (x greater than 0.7). All of the maxima were governed by thermally activated atomic jumps (as indicated by their frequency shift) with the relaxation parameters, IA: H = 0.12eV (6.8 x 10-12s); IB: H = 0.18eV (1.0 x 10-13s); IC: H = 0.08 (1.6 x 10-10s). Models which were based upon O jumps via vacancies were considered to be less probable, since it was now established that loss-maximum III was linked to O diffusion. It was concluded that maxima IA and IB were connected with the hopping of polarons.

M.Weller: Materials Science Forum, 1993, 119-121, 667-80