Structure analysis of the YBCO layer in Ag/YBCO/metal oxide buffer/Hastelloy composite tape before and after 107 MeV Kr17+ irradiation

The effects of 107 MeV 84Kr17+ ion irradiation on YBa2Cu3O7−x-based second-generation coated conductors were investigated using a combination of transmission electron microscopy, diffraction and X-ray energy dispersive spectrometry. Defects 3–5 nm in diameter formed due to irradiation with relatively low fluences (∼2 × 1010 and ∼6 × 1010 cm−2). Analysis of electron microscopy images and spectrometry data led to the conclusion that radiation defects are voids approximately 3 nm in diameter. Heavy ion irradiation results in the significant enhancement of YBCO/buffer oxides adhesion to the Hastelloy substrate, the reduction of stresses and the formation of a crack-free structure in the YBCO layer. The use of low-dose irradiation enables the critical current to be increased without lowering the transition temperature.