True effects of microstructure and oxygen contents on flux-pinning properties of Y123 melt-solidified bulks

We have investigated the relationship between microstructure and pinning properties of Y123 melt-solidified bulks having systematically controlled oxygen contents. The subgrain structure was developed along crystal growth direction in the a-growth region. while it was not observed in the c-growth region. The formation of such subgrains could be explained by an elastic property of the edge dislocations and RE123 crystal growth process. Through evaluations on the second peak effects of J(c)-B curves and irreversibility fields, it was found that Y123/Y211 interfaces do not act as the predominant pinning centers under high fields against the reported theoretical predictions. Furthermore, our results suggested that the precipitation of Y211 particles decreases J(c) in high fields. The resulting pinning properties of Y123 melt-solidified bulks were discussed in relationship to the subgrain structure. (C) 2008 Published by Elsevier B.V.