Growth of RE–Ba–Cu–O thick film on metal substrate by liquid phase epitaxy process

Abstract

A liquid phase epitaxy (LPE) process on a metal substrate has been developed for the RE123 coated conductors. In order to prevent the reaction between the solvent and metal substrate, which is the first problem to be solved, for its development, an MgO buffer layer on the metal substrate was applied, since MgO is relatively stable in the liquid solvent. However, it disappeared when the substrate was dipped into the liquid. This phenomenon was clarified by a solubility measurement that was not due to melting but due to dissolution. Then, a combination of using a buffer layer and a saturated liquid by the MgO was considered to prevent the dissolution. Actually, the MgO buffer layer retained and it protects the Hastelloy substrate from the reaction. Additionally, it was clarified that there is little difference in Y 2O 3 solubility in the liquid with and without the MgO addition in the liquid. The Mg substituted Y123 LPE layer was grown at a similar growth rate even from MgO-saturated liquid under the same temperature conditions for the growth of Y123 from the solvent without MgO. Furthermore, the Y123 layer was grown from the liquid without MgO on the Mg substituted Y123 LPE layer to obtain the high superconducting characteristics. The double layered LPE film on MgO single crystal substrates revealed a high T c value of 90 K and a high J c value of 10 5 A/cm 2 at 77 K. Then, the new construction of RE123(LPE)/RE123–Mg(LPE)/MgO/Hastelloy was proposed for applying the LPE process to the coated conductor production. The fabrication of the construction on Hastelloy substrates was achieved.