Effect of Cu Doping on the Crystal Structure of (Ru1-xCux)(Sr1.47Ba0.2Nd0.33)(NdCe)Cu2O10-δ

The structural effects of Cu doping in (Ru1-xCux) (Sr1.47Ba0.2Nd0.33)(NdCe)Cu2O10-delta (0 <= x <= 0.5) have been investigated by using X-ray and neutron diffraction. X-ray diffraction showed that the phase purity of the samples increased as the Cu-doping concentration increased and nearly-single-phase materials could be obtained for samples with x >= 0.25. The Rietveld refinements of the neutron diffraction data around 5 K for x = 0.25 and x = 0.5 samples show that the oxygen vacancies are located on both the O(1) site of the RuO2 basal plane and the O(4) site of the fluorite-type (Nd,Ce)O2-delta block, and the overall oxygen content is found to decrease with increasing Cu content x, mainly due to an increase in oxygen vacancies located on the O(1) site. It is also observed that the rotation angle of the RuO6 octahedra away from the crystallographic c-axis increases as the Cu content x increases.