program abstracts
Friday, 2E-05, -
Improvement of Production Rate by Modified TFA-MOD Starting Solution
H. Ichikawa
K. Nakaoka, H. Hirano, M. Miura, Y. Sutoh, T. Ito, Y. Takahashi, H. Tobita, M. Yoshizumi, T. Izumi, Y. Yamada, Y. Shiohara
Superconductivity Research Laboratory, ISTEC, 1-10-13, Shinonome, Koto-Ku, Tokyo, 135-0062 Japan
Phone: +81-3-3536-5711 Fax: +81-3-3536-5717 e-mail: ichikawa.hiro@istec.or.jp
Long YBCO coated conductors with high Ic values over 200A/cm-width have been fabricated by the advanced metal organic deposition using the trifluoroacetates (TFA-MOD) process. Concerning the future mass-production stage, a high production rate is definitely required, which also leads to low cost.
In the TFA-MOD process, there are two steps; coating / calcination and crystallization steps. In our previous work, when the coated films were calcined at a high heating rate, which is necessary for a high production rate, the film quality was degraded and the Ic values became low. It was found that the degradation is caused by the high out-gas rate of HF from the coated films in the calcination step. In the worse cases, the gases were bubbled and a part of films disappeared. Based on the understandings, a new solution including F-free salt of Y was developed. The damages, such as bubbling, could not be recognized in the films after calcination using the new solution at a high heating rate. However, the films which revealed high Jc values of about 1.5MA/cm2 are limited under the conditions only at lower heating rates than 2°C/min in the crystallization step. Then, the heat-treatment conditions in the calcination step, including the heating time and the maximum temperature, have been well investigated and controlled to realize a high heating rate in the crystallization step with high Ic values.
Through the investigation, it was found that the increment of the maximum temperature in the calcination step could improve the critical heating rate in the crystallization for the high superconducting properties. As a result, high Jc values of 1.4MA/cm2 was confirmed in the film heat-treated for the crystallization with the high heating rate of 70°C/min.
This work was supported by the New Energy and Industrial Technology Development Organization (NEDO) as the project of Collaborative Research and Development of Fundamental Technologies for Superconductivity Applications, and the project of Development of Materials & Power Applications of Coated Conductors, (M-PACC).
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