2006 年 41 巻 10 号 p. 428-438
We have reported high-Jc Sm1+xBa2-xCu3Oy (SmBCO) films prepared by a low-temperature growth (LTG) technique. The LTG-SmBCO films showed a Jc of 0.28 MA/cm2 (77 K, B//c, B=5 T). However, the Jc of these films in the magnetic fields above 5 T dropped and were lower than that of NbTi wire (4.2 K). In this study, we introduced nanoparticles with low Tc (low-Tc-nanoparticles) into LTG-SmBCO films to improve the Jc at the high magnetic field. The LTG-SmBCO + 1.4 vol.% nanoparticle film result in a Jc of 0.37 MA/cm2 (77 K, B//c, B = 5 T) and 0.10 MA/cm2 (77 K, B//c, B = 8 T). Furthermore, the Jc at 65 K in a field of 16 T (B//c) reached 0.05 MA/cm2. Elemental mapping clarified that LTG-SmBCO + 1.4 vol.% nanoparticle film had nanosized low-Tc particles with an x of 0.15-0.30 and low-Tc network with an x of 0.05-0.15, which were dispersed in the high-Tc matrix. We speculate that the Jc under high magnetic field conditions depends not only on the distribution and size of low-Tc regions, but also on the Sm/Ba composition within the low-Tc regions.