Melt processing and characterization of bulk NdBaCuO

Abstract

Nd 1+x Ba 2−x Cu 3 O 7−δ (Nd123) bulk superconductors have been synthesized under air and by the oxygen-controlled melt growth method (OCMG). We have studied the effects of Nd 4 Ba 2 Cu 2 O 10 (Nd422) additions, processing rates and doping effects on the microstructure and the superconducting properties in the OCMG-processed samples. Unlike the YBCO system, platinum doping or Nd422 additions do not refine the Nd422 secondary phase inclusions. On the other hand, Ce doping is effective in Nd422 refinement as in the YBCO system. The nucleation window has been determined for growth conditions in air, and was found to be in a very narrow temperature range. The effectiveness of the MgO single crystal used as seed, the occurrence of solid solution and the oxygen content are also examined. Good superconducting properties were obtained in OCMG samples while poor properties occurred in the air-textured sample and cerium-doped samples.

MgO buffer-layer-induced texture growth of RE–Ba–Cu–O bulk

“…The particle size of Nd422 embedded in the matrix is much larger than Gd211. One possible explanation is that the platinum doping does not refine the Nd422 particles during the growth [24].…”

“…The melting point of MgO is sufficiently high; there is no T max limit for this method. The cold-seeding growth of Nd-Ba-Cu-O single grains, which is largely limited by the high T p [12][13][14][15], is realized by the present method.…”

Nd-422 content dependence of superconductivity in a large-sized single-domain Nd-system superconductor

“…Kojo et al [7] investigated the magnetic field dependence of J c for the oxygen-controlled melt-growth (OCMG)-processed Nd-system bulks with a different volume fraction of the Nd 4 Ba 2 Cu 2 O 10 (Nd-422) phase. Monot-Laffez et al [8] reported on the effects of Nd-422 addition, platinum and Ce doping on the microstructure and the superconducting properties in the OCMG-processed samples. A detailed study of grain growth in a Nd-system superconductor was performed and a schematic phase diagram was constructed in the peritectic solidification region at various temperatures [9].…”