Magnetic Field Dependence of Critical Current Density of TFA-MOD Processed YBCO Coated Conductors
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Magnetic Field Dependence of Critical Current Density of TFA-MOD Processed YBCO Coated Conductors
Yutaka Yamada, SeokBeom Kim, Takeshi Araki, Toyotaka Yuasa, Yasuo Takahashi, Haruhiko Kurosaki, Yuh Shiohara, Izumi Hirabayashi, Yasuhiro Iijima1 and Kaoru Takeda1 Superconductivity Research Laboratory, Mutsuno 2-chome 4-1, Atsuta-ku, Nagoya 456-8587, Japan 1 Fujikura Ltd.,1-5-1, Kiba, Koto-ku, Tokyo 135-8512,Japan
ABSTRACT YBCO films on LaAlO3 and IBAD (YSZ/Hastelloy) substrate were made by TFA-MOD (metalorganic deposition using trifluoroacetate) process. Improved coating solution resulted in high Jc at 77.3K and 0 T of 7 MA/cm2 and 1.7 MA/cm2 for LaAlO3 and IBAD substrates, respectively. The magnetic field dependence of Jc at 77.3K also showed superior property: 105 A/cm2 at 4T (B//c-axis) for the LaAlO3 substrate and at 3T (B//c-axis)) for IBAD substrate. Furthermore, the difference in Jc between single crystal LaAlO3 and IBAD was small up to 3T. The present results imply that TFA-MOD process is promising for the practical YBCO coated conductor process.
INTRODUCTION For the second generation superconducting wire, extensive work has been carried out by using various types of fabrication method. Among them, TFA-MOD (metalorganic deposition process using trifluoroacetate) process is considered to be promising from the point of low cost [1]. This process is carried out in a non vacuum atmosphere while other processes such as PLD, EB and CVD need a complicated vacuum system. Then, it is expected that the cost of the coated conductor will be reduced by the TFA-MOD process. Furthermore, this process also exhibited high critical current density, Jc, over 1 MA/cm2 at 77.3K [2]. For these reasons, TFA-MOD YBCO is now promising for the next generation superconducting wire. ASC group [3] is now intensively developing TFA-MOD YBCO wire using textured Ni or Ni-based alloys substrate. They attained 2.1 MA/cm2 (77.3K and 0T) for 0.4 micron thick film on Ni substrate and 5 MA/cm2 (77.3K and 0T) for 0.4 micron thick film and 2.5 MA/cm2 (77.3K and 0T) for 1.2 micron thick film on CeO2 buffered YSZ single crystal substrate. In our group, TFA process have been studied using the single crystal as substrate such as LaAlO3 ,SrTiO3 and CeO2 buffered YSZ. The obtained Jc was as high as 1 to 3 MA/cm2 at 77.3K and 0T [4]. Recently we obtained higher Jc values as high as 7 M MA/cm2 on LaAlO3 substrate by improving the purity of coating solution [5]. Much effort has been done for the development of TFA-MOD process as above. However, Jc-B characteristic is not yet studied in detail while the superconducting application needs this kind of data. For this purpose, we studied the magnetic field dependence of Jc for TFA-YBCO film on single crystal and metallic substrate. For the coated conductor development, we used IBAD tape consisting of YSZ buffer layers and Hastelloy developed by Iijima et al. [6]. In this case we used CeO2 buffer layer to avoid the reaction between YSZ and TFA-YBCO. As a result we obtained high Jc values for T
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