NEW METHOD OF PRODUCING FINE Y2BACUO5 IN THE MELT-TEXTURED Y-BA-CU-O SYSTEM - ATTRITION MILLING OF YBA2CU3OY-Y2BACUO5 POWDER AND CEO2 ADDITION PRIOR TO MELTING

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 CeO2 addition prior to the partial melting. Beneficial points of the attrition milling are as follows: (1) it allows uniform distribution of the Y211 refiner (CeO2) 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(c)) at 77 K of the melt-textured Y1.8 sample containing fine Y211 (less than 1 mu m) was 2.0 x 10(4) A cm(-2) and 1.16 x 10(4) A cm(-2) at 1 T and 2 T, respectively, which is twice the J(c) of 1.1 x 10(4) A cm(-2) (at 1 T) and 0.56 x 10(4) A cm(-2) (at 2 T) of the Y1.8 sample containing coarse Y211 (similar to 5 mu m in average size).