DIRECTIONAL SOLIDIFICATION OF BULK ND1-XCU3P7+(XBA2)-DELTA/

An innovative procedure for melt-texturing Nd1+xBa2-xCu3O7+/-delta in Ar-1% O-2 was developed. The precursor bars were allowed to crystalliz e from semisolid under the strong thermal gradient created by a moving thermal shield with micrometric displacement. The advantages are in t he possibility of varying the thermal profile on the sample and proces sing long bars. The procedure allows to obtain large domains with a sa tisfactory control on the stoichiometry. The problems of bar deformati on and reactivity with the support were definitely solved. Additional evidence of a spiral growth mechanism of the platelets stacked in the domains is shown. A.C. susceptibility measurements show T-c onset=95.5 K and full diamagnetism below 88K in 0.01 mT applied field. J(c) value , determined from magnetization hysteresis loops by application of the standard critical state model, is: 6.5.10(5) A/cm(2) at 5 K and mu(0) H = 1T, revealing the strong pinning typical of textured materials.