New method of producing fine Y<sub>2</sub>BaCuO<sub>5</sub> in the melt-textured Y-Ba-Cu-O system: attrition milling of YBa<sub>2</sub>Cu<sub>3</sub>O<sub>y</sub>-Y<sub>2</sub>BaCuO<sub>5</sub> powder and CeO<sub>2</sub> addition prior to melting
Chan-Joong Kim; Hai-Woong Park; Ki-Baik Kim; Gye-Won Hong; Chan-Joong Kim; Superconductivity Res. Lab., Korea Atomic Energy Res. Inst., Taejon, South Korea; Hai-Woong Park; Superconductivity Res. Lab., Korea Atomic Energy Res. Inst., Taejon, South Korea; Ki-Baik Kim; Superconductivity Res. Lab., Korea Atomic Energy Res. Inst., Taejon, South Korea; Gye-Won Hong; Superconductivity Res. Lab., Korea Atomic Energy Res. Inst., Taejon, South Korea
Журнал:
Superconductor Science and Technology
Дата:
1995-08-01
Аннотация:
A new process yielding fine Y211 particles in melt-textured Y-Ba-Cu-O was developed by combining attrition milling of Y123-Y211 powder and CeO<sub>2</sub> addition prior to the partial melting. Beneficial points of the attrition milling are as follows: (1) it allows uniform distribution of the Y211 refiner (CeO<sub>2</sub>) in the Y123-Y211 powder mixture, (2) it produces nanocrystalline Y123 powder with large surface area per unit volume which increases the possibility of Y211 nucleation during incongruent melting and (3) it controls the number and the size of Y211 particles preformed at the calcination/sintering stage from the off-stoichiometric powder of Y1.8 composition. The Y211 particles of the melt-textured Y123 sample which was prepared from the attrition-milled powder were of submicrometre scale and their distribution was quite uniform. The critical current density (J<sub>c</sub>) at 77 K of the melt-textured Y1.8 sample containing fine Y211 (less than 1 mu m) was 2.0*10<sup>4</sup> A cm<sup>-2</sup> and 1.16*10<sup>4</sup> A cm<sup>-2</sup> at 1 T and 2 T, respectively, which is twice the J<sub>c</sub> of 1.1*10<sup>4</sup> A cm<sup>-2</sup> (at 1 T) and 0.56*10<sup>4</sup> A cm<sup>-2</sup> (at 2 T) of the Y1.8 sample containing coarse Y211 ( approximately 5 mu m in average size).
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