Semiempirical equation of the levitation-force density for (Sm123) 1-x(Yb211) x superconducting samples

Abstract

After the preparation of Sm123 and Yb211 by melt-powder-melt growth and solid-state-reaction, respectively, the nominal compositions of (Sm123) 1-x(Yb211) x for x = 0.00, 0.05, 0.10, 0.15, 0.20 and 0.25 were prepared to examine experimentally and theoretically the effect of x in the composition on the levitation-force density. Although the amount of Yb211 increased on increasing the content x, the levitationforce density increased because the Yb211 phase structure decomposed into Yb123 and liquid phase. Owing to the fact that Yb123 welded the Sm123 grains under a slow-cooling regime, the increasing of the interaction between Sm123 grains gave rise to high potential barriers of the flux pinning and resulted in increasing of the levitation-force density with the content x. The results of the obtained general functions of the levitation-force density for all samples are in good agreement with the experimental data. This new formulation of the levitation-force density is very useful for material optimization to other researchers. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA.