Infiltration Growth and Crystallization Characterization of Single-Grain Y–Ba–Cu–O Bulk Superconductors

Abstract

A series of single-grain Y–Ba–Cu–O (YBCO) bulk superconductors were fabricated using a modified infiltration growth (IG) technique, and the morphology feature associated with the inner crystallization structure of the samples was investigated in detail. Experimental observations indicated that YBCO single grains grew much larger with the increasing slow-cooling time. A bended a/c growth sector boundary was observed in the cross section of the YBCO sample grown for 48 h, which resulted from the variations in the R a /R c ratio during the slow-cooling growth process, where R a and R c represent the growth rate in the a axis and c axis direction, respectively. In addition, different side surface morphology (SSM) patterns were presented for the samples fabricated with different processings, which originated from the difference in the crystallization structure of the YBCO single grains and could be divided into four groups. On the other hand, for a defined inner-crystallization structure, the changes of sample size (diameter or thickness) could also lead to various SSM styles. Finally, it was concluded that the comparison relationship between the ratio of sample radius and thickness with the ratio of R a /R c determined the final SSM pattern of the sample.

A Reliable Method for Recycling (RE)‐Ba‐Cu‐O (RE: Sm, Gd, Y) Bulk Superconductors

“…The composition of the liquid phase pellet was Yb 2 O 3: CuO: BaCuO 2 = 1: 6: 10 in molar ratio, corresponding to the composition reported for the infiltration and growth process . A pressed pellet of this composition was placed directly beneath the failed sample, as shown in Fig.…”

“…Unfortunately, the success rate of these recycling methods has not been reported specifically, although, from our experience, the recycling success rate is typically ~20%. Inspired by the infiltration growth method, we have developed a reliable method for recycling any failed (RE)BCO sample by replenishing the liquid phase lost during the primary growth process without first reprocessing the failed samples into powders. To date, we have successfully recycled 58 bulk (RE)‐Ba‐Cu‐O (RE: Sm, Gd, Y) samples (including 16 YBCO, 1 GdBCO, 16 GdBCO‐Ag, and 25 SmBCO‐Ag) of diameters up to 31 mm using this new technique.…”

Microstructure and Composition of Primary and Recycled Single Grains of YBCO, GdBCO‐Ag, and SmBCO‐Ag Bulk Superconductors

“…The recycling technique is based on the TSMG process in air, which is used widely for primary single grain processing. The TSMG technique has drawn inspiration from the infiltration growth process . The initial stage of the recycling process involves infiltration growth, which involves placing a precursor pellet of the liquid‐rich phase composition beneath the failed sample to provide additional liquid phase at elevated temperature.…”

“…The TSMG technique has drawn inspiration from the infiltration growth process. 11,12 The initial stage of the recycling process involves infiltration growth, which involves placing a precursor pellet of the liquid-rich phase composition beneath the failed sample to provide additional liquid phase at elevated temperature. This, in turn, enables a small amount of infiltration growth to occur during recycling to replenish liquid lost in the failed primary grown process.…”

A Coated Infiltration Growth Technique for Fabricating Single‐Grain Y–Ba–Cu–O Bulk Superconductor

“…Recently, the TSIG technique is attracting considerable attentions because of its encouraging advantages compared with the TSMG method . In the regular TSIG process, a RE 2 BaCuO 5 (RE‐211) preform pressed with RE‐211 solid phase and a liquid source pellet containing Ba–Cu–O‐rich phase are necessary, which have the same diameter.…”