CRYSTAL-STRUCTURES OF PB2SR2YCU3O8+DELTA(DELTA = 0 AND 1.67)

Crystal Structures of Pb2Sr2YCu3O8 + delta (delta = 0 and 1.67) were analysed by X-ray Rietveld method. The sample with delta = 1.67 obtained by an oxygen annealing has a tetragonal lattice. The analysis has been made with the assumption that absorbed oxygen atoms occupied the sites in the oxygen deficient Cu layer. We used the space group P4/mmm. The analysis of the sample with delta = 0 obtained by a quenching shows almost the same structure as the one presented previously. However, introduction of slight monoclinic distortion was found to give much better fit to the observed profile. The distance between the Cu and the Pb layers in the structure with delta = 1.67 was found to be longer than that with delta = 0.