J c and Composition Distribution of YBCO Coated Conductors Fabricated by the TFA-MOD Process

S Sakai,Y Tanaka,M Inoue,M Iwakuma,R Teranishi

doi:10.1109/tasc.2022.3156909

Abstract

The Trifluoroacetate-Metal Organic Deposition (TFA-MOD) process is one of the most promising fabrication processes for low-cost superconducting coated conductors (CCs) because of its high yield and non-vacuum system. However, in the doping and multi-coating process for the enhancement of critical current (Ic), degradation of Ic often occurs. In this study, to clarify the origin of Ic degradation, we have investigated the local critical current density (Jc) distribution, in-field Jc properties and the variation of composition for TFA-MOD processed YBa2Cu3Oy (YBCO) CCs. The local Jc distributions were measured by Scanning Hall-Probe Microscopy for confirming the location of the high/low-Jc regions. The CCs were then cut into 3 mm×3 mm or 3 mm×4 mm for dc magnetization measurement. The Tc of the all samples were about 87 K to 90 K. In-field Jc at 77 K was obtained from M-H measurements and all the samples were compared with each other. The in-field Jc of high-Jc sample showed about 100 times higher value than that of the low-Jc sample. Then we have observed the microchemistry and the variation of composition by SEM-EDS. In the high-Jc sample, the grains of the superconducting phase were large in size and were connected to each other. This means that superconducting current could form through the whole sample area and generate a large magnetic moment. On the other hand, in the low-Jc sample, though the superconducting phase could be observed, the grains were small in size and sparse. Therefore, the magnetic moment measured was small. However, it was also suggested that the intra-grain Jc would be almost the same as that of high-Jc sample.

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