Evidence of Critical Oxygen Concentration at y=6.7∼6.8 for 90 K Superconductivity in Ba<sub>2</sub>YCu<sub>3</sub>O<sub>y</sub>
M. TokumotoElectrotechnical Laboratory, Tsukuba Research CenterHideo IharaElectrotechnical Laboratory, Tsukuba Research CenterToshiya MatsubaraElectrotechnical Laboratory, Tsukuba Research CenterMasayuki HirabayashiElectrotechnical Laboratory, Tsukuba Research CenterNorio TeradaElectrotechnical Laboratory, Tsukuba Research CenterH. ŌyanagiElectrotechnical Laboratory, Tsukuba Research CenterKeizo MurataElectrotechnical Laboratory, Tsukuba Research CenterYoichi KimuraElectrotechnical Laboratory, Tsukuba Research Center
1987en
ABI
Annotatsiya
A study of precise oxygen concentration dependence of the superconducting volume fraction in Ba2YCu3Oy (6.22≤y≤6.96) revealed the phase diagram of this superconducting system. Three characteristic phases are found based on the oxygen concentration: (1) a nonsuperconducting tetragonal phase for 6.2<y<6.4, (2) a low-Tc (Tc= 55∼70 K) orthorhombic phase for 6.4≤y<6.8 and (3) a high-Tc (Tc=90 K) orthorhombic phase for 6.8≤y<7.0. Evidence for a distinct critical concentration at y=6.7∼6.8, necessary to sustain the bulk high-Tc (90 K) superconductivity, is presented.
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