Enhanced flux pinning in lithium doped melt grown YBCO by low fluency neutron irradiation

A substantial increase in flux pinning has been reported in Li doped YBCO 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 fission of 6Li. In this study we report preliminary measurements on the effect of irradiating Li doped melt grown YBCO with thermal neutrons. A single grain was divided into two samples, one of which was then irradiated with ≈ 1017 neutrons. VSM measurements have revealed that the irradiated sample is far superior at low fields (at best a factor of five increase in Jc at 77 K), but at high fields the magnetic moments become very similar and the irreversibility field remains the same. The absence of fishtail irradiation suggests the introduction of an additional low field pinning mechanism.