| Identification of the phase responsible for high-temperature superconductivity in $Y-Ba-Cu$ oxides (1987) | |||||||||
Abstract | |||||||||
| The discovery of $La-Ba(Sr)-Cu$ oxides of $K_2NiF_4$ structure exhibiting superconductivity in the 30-40 K region was reported early this year. The recent announcement of superconductivity above the temperature of liquid nitrogen in $Y-Ba-Cu$ oxides has belied all expectations. Unfortunately, all the $Y–Ba–Cu$ oxide compositions exhibiting this remarkable feature were biphasic or multiphasic. We have studied various compositions of the $Y_{3–x}Ba_{3+x}Cu_6O_{14}$ and now report the isolation of the pure oxide phase responsible for high $T_c$ superconductivity. This oxide has the composition $Y_{0.33}Ba_{0.67}CuO_{2.33}$, with an oxygen defect perovskite structure. The pure oxide shows the onset of superconductivity at 120 K, attaining zero resistance at 87 K. It also exhibits the highest Meissner effect of all the high-$T_c$ oxide superconductors. | |||||||||
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