Electrical properties and crystal structure of Y123, Y358 and Y257/Y211 composite bulk superconductors

Abstract

The Y123, Y358 and Y257 bulk superconductors mixed with various ratio of non-superconducting Y211 (Y 2 BaCuO 5 ) were synthesized by solid state reaction. The physical properties of pellets were investigated by d.c. four-probes measurement. The crystal structure was determined using powder X-ray diffraction and the characteristic peaks were determined using the Rietveld full-profile analysis method. Results showed that the T c onset and T c offset decreased with the increasing of Y211 doping. The samples consist of both superconducting phase and the non-superconducting phase. The lattice parameter of Y211 doped samples showed lower c direction than pure samples. The superconducting phase decreased with increasing Y211 content. The non-superconducting phases consists of Pccm (Ba 2 Cu 3 O 6) and Im-3m (BaCuO 2 ) respectively. According to the percentage of superconducting phase, the anisotropy increased with Y211 contents.

Investigate Oxygen Content in YBa₂Cu₃O_7-_δ Superconductors

“…The values obtained of experimental oxygen content and critical temperature are reported in Table .5 Oxygen content increased with time of sintering. This raise the critical temperature of the sample because the oxygen addition may pump more holes from the Cu-O chains [10]. By optimizing the duration of the heat treatment , Y123 phase has higher critical temperature.…”