High-performance single grain Y–Ba–Cu–O bulk superconductor fabricated by seeded infiltration and growth

Large single grains of Y–Ba–Cu–O (YBCO) bulk superconductor of up to 32 mm in diameter have been fabricated by a seeded infiltration and growth (IG) technique. Small Y2BaCuO5 (Y-211) particles are observed in the seeded IG sample microstructure, albeit with a rather inhomogeneous distribution in the superconducting YBa2Cu3Oy (Y-123) phase matrix. Values of magnetic critical current density, Jc, measured in self-field along the a and c growth sectors of the bulk samples prepared by seeded IG appear higher than the corresponding values for samples fabricated by conventional top seeded melt growth (TSMG), despite the inhomogeneous distribution of Y-211 particles in the former. A maximum trapped field of 0.42 T at 0.2 mm above the sample surface was observed at liquid nitrogen temperature (the actual mean temperature during measurement was around 78 K) in samples fabricated by seeded IG due to the increased Jc, despite the relatively small YBCO grain size (25 mm diameter × 7.4 mm thickness). This value of trapped field is almost two times greater than that of samples fabricated by TSMG and of a similar size.