PROGRESS IN MELT PROCESSING OF ND-BA-CU-O SUPERCONDUCTORS

Light rare earth (LRE)-Ba-Cu-O (LREBCO) bulk superconductors melt-proc essed in a reduced oxygen atmosphere are considered to be very materia ls for a high field application with the liquid nitrogen refrigeration because of their large critical current density (J(c)) in high magnet ic fields at 77 K, surpassing the limitation of an optimized Y-Ba-Cu-O (YBCO) bulk superconductor. For obtaining further improved J(c) and a large textured domain in the Nd-Ba-Cu-O system (Nd-system), we have a pplied the oxygen-controlled-melt-growth (OCMG) process to both direct ional and non-directional solidification techniques. At 77 K and for t he field parallel to the (H//c), while J(c) in low field apparently en hanced by refining the Nd4Ba2Cu2O10(Nd422) second phase particles trap ped in the NdBa2Cu3O7 (Nd123) matrix, J(c) in high field region princi pally depended on the location of the fishtail peak (H-pk) which was s ensitive to the P-O2 and thermal processing conditions during the melt growth. Problems related to the NdBCO domain enlargement are also dis cussed.