Structural and superconducting properties of YBaCuO superconductors at different atomic compositions

Mixing of Y2O3, BaCO3 and CuO in proper amounts to yield a net composition of YBaCu2Ox reveals superconductivity above 90 K without the requirement of any post-annealing under oxygen flow. Advantage of this starting composition is observed as the samples take sufficient amount of oxygen during calcination process. We found that oxygenation does not change the crystal structure and the transition temperature but it seems to be effective for improvement of the superconducting properties of intergrain regions. The Jc values of as-sintered samples, which were calculated from the M–H curves, approach to the order of 106 A/cm2 at 10 K. Oxygenated samples even take Jc values higher than 106 A/cm2, which is mainly due to the improvement of intergrain regions.