High-Tc Superconductivity of La-Ba-Cu Oxides. II. –Specification of the Superconducting Phase

Occurrence of high- T c superconductivity with T c near 30 K is observed for the single phase of (La·Ba) 2 CuO 4- y by both magnetic susceptibility and resistivity measurements. This indicates that high- T c superconductivity in La-Ba-Cu oxide is realized in the K 2 NiF 4 -type structure, (La·Ba) 2 CuO 4- y .