Neutron irradiation studies on Y-123 thick films deposited by liquid phase epitaxy on single crystalline substrates

The influence of neutron irradiation on the angular, field and temperature dependence of the critical transport current density J(c) of YBa2Cu3O7-delta (Y-123) thick films, as well as on the irreversibility fields was investigated. The specimens were deposited by liquid phase epitaxy either directly on NdGaO3 or on seeded (100)MgO substrates with a final Y-123 layer thickness of I and 5-10 mum, respectively. XRD of the superconducting layers proves good in-plane and out-of-plane alignments with FWHM's below 2degrees. The specimens showed excellent irreversible properties with critical current densities of up to 3 x 10(9) A/m(2) at zero field and 77 K and irreversibility fields above 7 T at 77 K for Hparallel toc prior to neutron irradiation, which was performed in fast neutron fluence steps of 10(21) m(-2), corresponding to 5 x 10(21) defect cascades per m(3) per step. J(c) enhancements by 100% and an anisotropy reduction by a factor of 2 are achieved at the optimum neutron fluence. (C) 2003 Elsevier B.V. All rights reserved.