Effects of size and volume fraction of the Nd4Ba2Cu2O10 (Nd422) second phase on the critical current density (Jc) were studied for the Nd-Ba-Cu-O bulk superconductors fabricated by an oxygen-controlled-melt-growth (OCMG) process. The size of the Nd422 second phase trapped in NdBa2Cu3Oy (Nd123) superconducting matrix was controlled using two different precursors of Nd123-Nd422 powders and the melt-quenched powders. Finer Nd422 second phase with an average diameter of 1-2μm was obtained in the sample fabricated from the mixture of Nd123-Nd422 precursors when the initial Nd422 powders of less than 1μm was employed. The Jc was significantly improved especially in low field by refining the Nd422 second phase. While a small amount of Nd422 addition increases the Jc in low field without sacrificing the Jc near the fishtail peak, the peak effect was drastically depressed by increasing the volume fraction.
|ジャーナル||Superlattices and Microstructures|
|出版ステータス||Published - 1997 1月 1|
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