Oxide electronics

Abstract:

The effect of environmental factors such as moisture and temperature on the critical current of sintered YBCO was systematically investigated. The degradation rate of materials with different characteristics was also analysed. The synthesis procedure used, powder grain size, silver oxide addition, sintering conditions and final density were all considered as possible factors affecting the material's sensitivity to ageing. The transport critical current was measured using the d.c. four probe technique, with and without magnetic field, on wire specimens, and with an a.c. contactless method with no field on moulded rings. Complex susceptibility measurements were also carried out to further qualify the material's behaviour, especially in cases where the macroscopic Ic had dropped to zero. The results showed qualitatively similar Ic versus time behaviour for the various samples, but with strong quantitative differences, which were correlated to the above factors. © 1990.

Abstract:

A sintering process of Bi-Ca-Sr-Cu-O superconductor is reported. The electrical and microstructural analysis of the pellets shows the coexistence of B and C phases with transition temperatures of about 85 K and 105 K, respectively. © 1989 Società Italiana di Fisica.

Abstract:

In this work a procedure followed for the preparation of superconducting compounds in the Bi-Ca-Sr-Cu-O system using the cytrate polymer precursor route is reported. A preliminary characterization of the structure and superconducting properties of the samples so obtained is given through X-ray diffraction analysis, resistivity and a.c. susceptibility measurements. All the samples so obtained showed the presence of superconducting phases at 80 K and 110 K beyond other non superconducting ones.