γ-irradiation dose effect on the critical current density in aBi1.6Pb0.4Sr2Ca2Cu3O10 polycrystal

Abstract

The effect of different γ-irradiation doses on the critical current density,Jc, ina Bi1.6Pb0.4Sr2Ca2Cu3O10 superconducting polycrystal has been investigated under several valuesof applied magnetic field and at temperatures from 80 to 105 K usingI–V measurements.Two doses of γ-irradiation were used: 50 and 300 MR. The specimen was preparedusing the solid-state reaction technique. We found that forγ-irradiation dose of50 MR the values of Jc were enhanced through the whole temperature range for all applied fields. This enhancement ofJc values is significant at low temperatures. We also found that for aγ-irradiationdose of 300 MR Jc values were suppressed at all temperatures for all applied fields. This reduction ofJc values is significant at low temperatures. At high temperatures both doses ofγ-irradiation were found to have a very small effect onJc values.These results are discussed in terms of the effect of defects produced byγ-rays and grain boundaries on the vortex pinning forces in the samples.