Copper deficiency -: a crystallochemical nature of Ce-doped Gd2CuO4 phase.: Part II

Two samples of nominal composition Gd1.80Ce0.15CuO4.0 and Gd1.85Ce0.15CuO4.075 were subjected for a long-term treatment in air at 1100degreesC, comprised with a precise control of their weights vs. time of the treatment applied. The gravimetric analysis and the iodometric titration, both showed a deficiency on Cu-site, steadily increasing vs. time with a slight tendency to a saturation. The X-ray analysis of the resulting products showed that even after 272 h of sintering, the samples remained single phase of the "214" structure type. Refinement of their crystal structures as well as density measurements, both allowed confirming Cu deficient structure constitution of these samples. Results of dc-magnetization measurements, performed prior to reduction of the sample's overall oxygen content, did not show any sign of superconductivity down to 4.2 K. These preliminary results indicate that copper deficiency, developing during synthesis, may occur to be a decisive factor for the reported lack of superconductivity in Ce-doped Gd2CuO4 phase. Oxygen content reduction and further tests on the samples obtained are in progress.