New method of producing fine Y₂BaCuO₅in the melt-textured Y-Ba-Cu-O system: attrition milling of YBa₂Cu₃O_y-Y₂BaCuO₅powder and CeO₂addition prior to melting

Abstract

A new process yielding fine Y211 particles in melt-textured Y-Ba-Cu-0 was developed by combining attrition milling of Y123-YZll powder and CeOz 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,) in the Y123-YZ11 powder mixture, (2) it produces nanocrystaliine 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 calcinationlsintering 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 (Jc) at 77 K of the melt-textured Y1.8 sample containing fine Y211 (less than 1 pm) was 2.0 x 1 0 ' A cm-* and 1.16 x lo4 A twice the Jc of 1.1 x lo4 A cnr2 (at 1 T) and 0.56 x lo4 A cm+ (at 2 T) of the Y1.8 sample containing coarse Y211 (-5 p m in average size). at 1 T and 2 T, respectively, which is

Enhancement of critical current density of liquid-infiltration-processed Y–Ba–Cu–O bulk superconductors using milled Y2BaCuO5powder

“…Another important factor in increasing J c is the precursor powder size, which has been reported in many research papers [11,[13][14][15][16][17]. The enhancement of J c by controlling the size of the starting powder was first reported in the MTG-processed Y123 superconductors obtained using the milled Y123-Y211 precursor [13]. The Y211 refinement and improvement in J c were achieved by milling the starting powder with an addition of CeO 2 .…”

The peak effect in bulk Y–Ba–Cu–O superconductor with CeO2doping by the infiltration growth method

“…Study of the IG technique also reveals that the Y211 inclusions are relatively small without adding precursor powders (like CeO 2 , Pt or PtO 2 ); however, the J c of YBCO samples fabricated by the IG process are generally rather low. Some previous studies on increasing the J c of YBCO by using additives are listed in table 1 [13][14][15]. Pinol et al [13] reported that TSMT-YBCO samples containing Y211 particles with an average size of 1.1 μm by CeO 2 addition obtained a critical current density above 10 5 A cm −2 at 77 K under zero field.…”

Growth of large bulk Y–Ba–Cu–O with multi-seeding

“…We thus added 1 wt% of CeO 2 , which is known to be effective in refining the size of the Y-211 particle, and thereby leading to higher field trapping abilities [11,12]. Sample E with 1 wt% of CeO 2 was melt-processed using the same thermal schedule as that of sample D. We could successfully obtain the sample in that four large grains grew in the entire bulk body as shown in figure 7.…”