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Copper Deficiency - a Crystallochemical Nature of Ce-Doped Gd_2CuO_4 Phase. Part II

100%

Horyń R., Bukowska E., Sikora A., Wołcyrz M.

Acta Physica Polonica A

2004

vol. 106

issue 5

733-738

Two samples of nominal composition Gd_{1.80}Ce_{0.15}CuO_{4.0} and Gd_{1.85}Ce_{0.15}CuO_{4.075} were subjected for a long-term treatment in air at 1100°C, 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 Gd_2CuO_4 phase. Oxygen content reduction and further tests on the samples obtained are in progress.

Phase Relations in Gd_2O_3-CeO_2-CuO System at 980°C. Part I

100%

Horyń R., Sikora A., Bukowska E.

Acta Physica Polonica A

2004

vol. 106

issue 5

727-731

Phase equilibria in Gd_2O_3-CeO_2-CuO system were studied based on samples obtained from appropriate mixtures of the starting components, prepared by a conventional solid state reaction in air. The phase relations prevalent in this system have been deduced based on X-ray diffraction of well-equilibrated samples. An isothermal cross-section diagram through the system at 980°C is presented and chemical constitution of the Ce-doped Gd_2CuO_4 phase is proposed.

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2 Acta Physica Polonica A

2 2004

2 Bukowska E.

2 Horyń R.

2 Sikora A.

1 Wołcyrz M.

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Copper Deficiency - a Crystallochemical Nature of Ce-Doped Gd_2CuO_4 Phase. Part II

Phase Relations in Gd_2O_3-CeO_2-CuO System at 980°C. Part I