Advances in enlargement of melt-textured Gd–Ba–Cu–O superconductors

Abstract

We investigated the fabrication of melt-textured Gd–Ba–Cu–O bulk superconductors with the employmentof a Gd2BaO4 (Gd210)–BaCuO2–CuO precursor. This enabled us to synthesize a very large Gd–Ba–Cu–O bulksuperconductor, 140 mm in diameter. The trapped field distribution measured at 77 Krevealed that the sample had no serious cracks, and the maximum field was 2.3 T. Theformation behaviour and depressing mechanism of cracking were studied using sinteredGd210-containing precursors. The Ba–Cu–O component in the precursor melted at around900 °C. The formation of such a liquid phase enhanced the densification of the precursor by liquidphase sintering. The mechanical strength of the sintered precursor was increased comparedto the conventional Gd123–Gd211 precursor. This will be effective in preventing crackformation in the texturing process of large single-grain samples. The superconductingproperties of the bulk sample fabricated from Gd210-containing precursor have beendiscussed.