Ba-Ca-Cu-O COMPOSITIONS SUPERCONDUCTING AT UP TO 126K AND METHODS FOR MAKING SAME

摘要

A material having a superconducting transition temperature (Tc) of 126K under ambient pressure has been identified. The superconducting material belongs to a Ba-Ca-Cu-O compound family where the cation ratio of Ba : Ca : Cu is 2 : 2.5 ± 0.5 : 3.5 ± 0.5. The superconducting material is produced from precursor oxides having nominal formula Ba2Can-1+xCun+yOz wherein n=3 or 4 and x is 0.4 to 1.0 and y is 0 to 0.8 using high-pressure synthesis. Final synthesis temperature was maintained at less than 950 °C. Formation of the superconducting material is sensitive to the state of the precursor oxides, the carbon content of the precursor, and the synthesis temperature, pressure and time.