ENHANCEMENT OF CRITICAL CURRENT-DENSITY IN FAST-NEUTRON IRRADIATED MELT-TEXTURED YBA2CU3O7-X

The critical current density in melt-textured samples obtained by the powder melting process was determined from magnetization measurements. Linear dependence between the width of the hysteresis loop and sample size was observed for both unirradiated and irradiated samples. This indicates that the critical current is circulating through the whole sample and is not disconnected by weak links, even when a magnetic field is applied in the irradiated sample. After fast neutron irradiation with fluences from 5 x 10(16) to 6 x 10(17) n CM-2 (E > 0.5 MeV), significant enhancement of the critical current density, j(c), was observed. Critical current density, determined from magnetization measurements, for magnetic field perpendicular to the a-b plane, j(c)ab, reaches almost-equal-to 10(5) A cm-2 at 77 K in 1 T. For H parallel to the a-b plane, j(c)c along the c-axis reaches 5 X 10(3) A cm-2. An increase in the anisotropy of the critical current was observed after fast neutron irradiation in the temperature range 60 - 80 K.