Improvements of microstructural and superconducting properties of Aghyphen;Bi2Sr2CaCu2Oxscreenhyphen;printed tape by controlled oxygen partial pressure during cooling procedure

摘要

The effect of different cooling procedures, after sintering, on the microstructural and superconducting properties of Bi2Sr2CaCu2Ox(Bhyphen;2212) screenhyphen;printed tapes has been investigated. It was found that the amorphous phase originally present in grain boundaries at the sintering temperature undergoes a conversion to the Bihyphen;2212 phase during slow cooling. However, the excess oxygen absorbed during slow cooling (in 21percnt; oxygen) disturbs the order and ordering process of Bihyphen;2212 crystals, but if the slow cooling process is conducted under monotonically reduced oxygen partial pressure, to ensure that the optimum oxidation state at sintering temperature of the Bihyphen;2212 phase can be retained during the cooling procedure, tapes are then characterized by narrow grain boundaries and the highestJcvalue gsim;104A/cm2at 77 K and 0 T.