Effect of high-energy ion irradiation and electron irradiation on textured Bi2Sr2CaCu2Ox—180-MeV Cu11+ and Br11+ irradiations and 3-MeV electron irradiation

Abstract

180‐MeV Cu¹¹⁺ and Br¹¹⁺ irradiations and 3‐MeV electron irradiation were carried out on textured Bi‐2212 tapes and the effects of irradiation on the microstructure and superconducting properties were investigated. Ion irradiation, which creates linear tracks, is very effective in increasing both intragrain J_c and irreversibility field at temperatures below 60 K when field is parallel to the tracks. At 60 K, an order of magnitude higher B_irr is obtained for both Cu¹¹⁺ and Br¹¹⁺ irradiations. Electron irradiation which creates point defects, on the other hand, is not as effective as ion irradiation except for low temperatures of ∼4.2 K. Apparent pinning potential energy U₀ was increased by ion irradiation from ∼15 to ∼40 meV at 41.8 K, while U₀ was unchanged by the electron irradiation. However, even U₀ of the ion‐irradiated sample is still small. This small U₀ increases flux creep at temperatures above 60 K and makes ion irradiation less effective. A small increase of transport J_c was obtained by both ion and electron irradiation for small fluences. However, a significant decrease of transport J_c occurred at fluences which optimize intragrain J_c.