Microstructure characterization of Bi 2Sr 2CaCu 2O x single crystal irradiated with 18 MeV Fe 8+ ions

Abstract

Bi 2Sr 2CaCu 2O x single crystals irradiated with 18 MeV Fe 8+ ions at a dose of 1 × 10 12 ions/cm 2 were studied by transmission electron microscopy both on plan- and cross-sectional views. It shows that the defects produced by ion irradiation with such an energy are ellipse-like amorphous defects embedded in the single crystal. The typical size of ellipse-like defects is about 10 nm × 6 nm along each axis. Most of the directions of long axes of ellipse-like defects are independent of the irradiated direction, which may be attributed to the collision between ions and atoms inside the crystal at the final stage of energy loss. The relative concentration of bismuth is greatly decreased inside the defects and a little bit increased around the amorphous defects. The antiphase boundary was occasionally found inside the single crystal, which was the preferential zone for the formation of ion irradiation defects. By observing along the c-axis of the single crystal, it was found that some defects had a tendency to form along small facets, such as the (100), (010) and (110) planes of Bi 2Sr 2CaCu 2O x , during ion irradiation. The density of the ion-irradiation defects is higher than the dose of Fe 8+ ion irradiation applied, which implies that one ion generates at least one defect. The enhancement of magnetization hysteresis in DC magnetization curves by irradiation of 18 MeV Fe 8+ ions strongly depends on the dose of the ion irradiation.