Masahiko Kai1, Atsushi Inoue2,, Saburo Hoshi1, Satoshi Koyama1, Teruo Izumi1, Kiyoshi Murata2 and Yuh Shiohara1
1Superconductivity Research Laboratory, International Superconductivity Technology Center, Tokyo 135-0062
Many applications of superconducting magnets using high-Tc oxide superconductors are expected to operate in the persistent current (PC) mode. For the PC mode operation, the PC switch (PCS) is considered to be an essential device. The special properties are required for the PCS material, which are not only high critical current but high electric resistance in the normal state in order to cut off the current flow efficiently through thermal switching.
We have studied to fabricate meander shaped REBa2Cu3Oy (RE123) LPE films to realize the high electric resistance in the normal state as a persistent current switch material. In the previous study, the meander shaped RE123 LPE films grown from the meander shaped seed films, in which an MgO bare surface exists, reveals low Tc and Jc. The reason for this phenomenon was recognized as that dissolved Mg from the bare MgO substrate was incorporated into the LPE film during growth. A BaZrO3 (BZO), which was confirmed to be stable to the Ba-Cu-O solution even at the high growth temperature, was deposited on the MgO substrate as a buffer layer in order to prevent the MgO dissolution into the solution. In this study, the size controllability of the Y-Yb123 LPE film on the BZO buffer layer was investigated and the control mechanism was discussed. It was found that the size would be controlled by the growth time due to low solutal diffusion flux for surface migration of the growth units on the BZO buffer layer. The size controlled Y-Yb123 LPE film on the BZO buffer layer revealed a high Tc of about 90 K, and the effect of the BZO buffer layer was confirmed from this result.
(Received December 3, 2002)
REBa2Cu3Oy, BaZrO3, liquid phase epitaxy, persistent current switch, meander shape
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