Effects of Nano scale Y2O3 Additions on Sm–Ba–Cu–O Materials

概要

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To enhance the critical current density ($J_{\text{c}}$) of Sm–Ba–Cu–O (SmBCO) superconductors, a small number of Y2O3 particles of nano scale (nmY2O3) were used. The $J_{\text{c}}$–$H$ (the applied magnetic field) results show that the increase in $J_{\text{c}}$ using nmY2O3 occurs mainly in high fields. In addition, by increasing the number of nmY2O3 particles, the flux pinning force-reduced magnetic field ($F_{\text{p}}$–$h$) curves shift to the right. The above results indicate the formation of $\delta T_{\text{c}}$ pinning centers. The microstructure results show that Y2O3 particles react with the 211 (Sm2BaCuO5), 123 (Sm1Ba2Cu3O7) and liquid phases at high temperatures. Both the high solubility of Sm in the liquid and the inter-diffusion of Sm and Y at high temperatures result in compositional fluctuations [(Sm,Y)–Ba–Cu–O]. It is considered that these compositional fluctuations contribute to $\delta T_{\text{c}}$ pinning. Finally, to determine the effect of compositional fluctuation caused by a different method, these results were also compared with those of the nano sized Y211 (nmY211)-doped samples.
2006-11-15