Pinning of magnetic flux lines in Y-Ba-Cu-O superconductors by neutron irradiation and chemical route

The increase of critical magnetization current due to pinning of magnetic f lux lines in Y-Ba-Cu-O superconductors has been investigated. The methods u tilized were either irradiation by fast neutrons or addition of yttria incl usions prior to processing. The Y-Ba-Cu-O superconductors were prepared as plates (20 to 40 cm in length) using melt texturing method. Samples were ir radiated using doses of 2x10(21) to 5x10(22) neutrons pr. sq, m, According to magnetization measurements, the critical current density is improved sim ilar to 3 and similar to 12 times at magnetic fields of 0.07 and 1 tesla re spectively. Thus, at 1 tesla the critical current density was improved from 290 to 3500 A/cm(2) by an irradiation of 1x10(22) neutrons.m(-2) Addition of yttria results in formation of 1 to 20 pm large inclusion of Y2BaCuO5 in the superconducting material. The critical current characteristics show a peak-effect at 1 to 2 tesla, with critical currents comparable to irradiate d samples. Melt textured single crystals have equal high critical current d ensities at these applied magnetic fields.