Fabrication of Large Gd–Ba–Cu–O Single Domains with Different Liquid Sources

Abstract

Top‐seeded infiltration and growth process (TSIG) is an effective way for the preparation of bulk REBa2Cu3O7−x (RE‐123) with finely dispersed RE2BaCuO5 (RE‐211) particles compared with the conventional melt growth method. In this article, large single‐domain Gd–Ba–Cu–O (GdBCO) bulk superconductors with a diameter 30 mm have been fabricated in air by the TSIG technique using liquid sources composed of RE2O3 (here, RE is the rare‐earth element Gd, Y, or Yb, respectively), BaCuO2, and CuO. After this processing, only two kinds of precursor powders involving Gd‐211 and BaCuO2 are needed to prepare for the whole TSIG flow, which can effectively shorten the experimental cycle and then advance the experimental efficiency. The growth character, microstructure, and performance of the GdBCO products were investigated in detail. The results indicate that all the liquid sources can be used to fabricate well‐textured large GdBCO single domains. Additionally, adopting the liquid source mixed by Y2O3 or Yb2O3 can raise the utilization rate of the liquid source powder, as well as can help to refine Gd‐211 particles.

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

“…The Y 2 BaCuO 5 (Y-211) and BaCuO 2 single-phase precursor powders were prepared by the conventional solid-state reaction method in air using raw materials Y 2 O 3 (99.99%), BaCO 3 (99%) and CuO (99%). Then, the powders of Y 2 O 3 , CuO, and BaCuO 2 were weighed according to the molar ratio Y 2 O 3 :CuO:BaCuO 2 = 1:6:10 and mixed thoroughly using the ball milling machine, as the liquid source powder for the IG process. The Y-211 powder, in batches of 12 g, was uniaxially pressed into cylindrical pellets of diameter 20 mm, while the liquid source powder in batches of 20 g was pressed into cylindrical pellets of 30 mm in diameter (i.e., using liquid source pellets with bigger diameters to infiltrate and grow smaller YBCO samples), which can increase the support ability of the liquid source pellet and enhance the experimental stability .…”

“…In order to simplify the process flow and enhance the experimental stability of the IG process, in our previous studies for fabricating single-grain Gd–Ba–Cu–O (GdBCO) bulk superconductors, a modified IG technique has been developed through changing the used liquid source composition and the pellet configuration pattern. − In this article, a series of single-grain Y–Ba–Cu–O (YBCO) bulk superconductors were successfully fabricated using our modified process, and the side surface morphology (SSM) associated with the inner crystallization structure of the produced bulk samples was investigated in detail.…”

Infiltration growth of Mg-doped Nd–Ba–Cu–O seed crystals for the fabrication of large grain RE–Ba–Cu–O bulk superconductors

“…The IG technique has been proved to be an effective way to prepare large REBCO bulks, and has attracted more and more attention recently because of its advantages compared with the MG method, such as fewer pores and cracks, negligible shrinkage and distortion in the final product, and especially the ability to provide fine-sized spherical RE 2 BaCuO 5 (RE-211) inclusions in the REBa 2 Cu 3 O 7−x (RE-123) matrix, which bring significant improvement in current density [21][22][23][24][25][26][27]. Moreover, in our recent studies, we improved this technique via modification of the liquid source composition and the pellet configuration pattern, in order to simplify the process flow and enhance the experimental stability [28][29][30].…”

Significant improvement of trapped flux in bulk Gd–Ba–Cu–O grains fabricated by a modified top-seeded melt growth process

“…A quench and melt growth (QMG) technology with advantages of fine size and homogeneous distribution of RE211 was developed at the Nippon Steel Corporation [39]; high performance and large size Gd-Ba-Cu-O single grains up to 150 mm in diameter have been reported [40]. The seeded infiltration and growth (SIG) process, possessing similar advantages, has gained considerable attention [41][42][43][44][45][46][47][48]. In the present work, we report a study of the SIG process of Gd-Ba-Cu-O bulk HTS by simply using a Y123 pressed pellet as the liquid source and the development of top-seeded melt growth (TSMG) technology by inserting a liquid source pellet under the pre-forms.…”