Effects of neutron irradiation on superconducting properties of Y-Ba-Cu oxides

The effects of fast neutron (E > 0.1 MeV) irradiation at reactor ambient (∼370 K) and low (∼20 K) temperatures on the superconducting properties of orthorhombic YBa2Cu3O7-y have been studied. Measurements were made on the superconducting critical temperature Tc, critical current Jc, Meissner effect and magnetic field dependence. On the samples irradiated at reactor temperature, the Tc drops and Jc increases with increasing fluence. On the other hand with the irradiation at low temperature, the Tc rises and Jc increases. The observation of Meissner effect is consistent with the behavior of Tc. From results of the magnetic field dependence of the Jc and diamagnetization, an enhancement of pinning force in the neutron irradiated superconductor were demonstrated. (author)