MICROSTRUCTURAL AND PHYSICAL-PROPERTIES OF YBA2CU3O7-DELTA SUPERCONDUCTORS PREPARED BY THE FLAME-QUENCH-MELT-GROWTH (FQMG) METHOD

The microstructural and physical properties of YBCO-123 superconductor s prepared by the flame-quench-melt-growth (FQMG) method have been inv estigated in terms of XRD, optical, SEM and AC susceptibility measurem ents. Samples were prepared under various heat treatments in a flowing oxygen atmosphere. Optimum preparation conditions have been determine d for good quality samples with a high degree of order in large grain alignment leading to high J(c) values for YBCO-123 at short heat treat ments. T-c and J(c) values have been determined by inductive methods. T, values are less sensitive to the heat treatment conditions while J, values increased considerably for samples grown at 1050 degrees C for 20 h. High values of J, can be attributed to several various AC loss mechanisms related with flux pinning. (C) 1997 Elsevier Science B.V.