ENHANCED FLUX-PINNING IN LITHIUM-DOPED MELT GROWN YBCO BY LOW FLUENCYNEUTRON-IRRADIATION

A substantial increase in flux pinning has been reported in Li doped Y BCO grains following thermal neutron irradiation. This effect observed in sintered YBCO was attributed to the increased number of defects in the crystal lattice produced by the particles emitted from the fissio n of Li-6. In this study we report preliminary measurements on the eff ect of irradiating Li doped melt grown YBCO with thermal neutrons. A s ingle grain was divided into two samples, one of which was then irradi ated with approximate to 10(17) neutrons. VSM measurements have reveal ed that the irradiated sample is far superior at low fields (at best a factor of five increase in J(c) at 77 K), but at high fields the magn etic moments become very similar and the irreversibility field remains the same. The absence of fishtail irradiation suggests the introducti on of an additional low field pinning mechanism. (C) 1998 Published by Elsevier Science S.A. All rights reserved.