Superconductivity and structural characteristics of ceramic Pr2Ba4Cu7O15−δ prepared by ambient pressure synthesis using citrate pyrolysis method

Sintered material of Pr2Ba4Cu7O15−δ (Pr247) was synthesized at ambient pressure condition by using citrate pyrolysis precursor method, and the superconductivity caused by oxygen reduction treatment has been confirmingly observed and examined.By resistivity and magnetization experiments, it has been found that the critical temperature Tc of the reduced samples could reach about 10 K higher than previously reported data for pure Pr247. Besides, from TEM observations, the present material was found to be heterogeneous system containing Pr247, Pr124 and novel stacking structure phases rich in CuO single chains. These results have suggested that oxygen–reduction at such region rich in the CuO single chains may affect the superconductivity of the adjacent crystal region containing CuO double chains, and might enhance the superconductive critical temperature.