Analysis of chemical composition and morphology of linear radiation defects created by Kr and Xe ions with energies of 0.04–0.8 MeV/nucleon in YBa2Cu3O6+δ and in secondary phase precipitates: experiment and application of the analytical thermal spike model

Abstract

TEM, electron diffraction, energy dispersive X-ray spectrometry and electron energy loss spectroscopy characterization of a multilayer composite Ag/YBa2Cu3O6+δ/LaMnO3/MgO/Y2O3/Al2O3/Hastelloy after exposure to Xe and Kr ions with energies from E ≅ 0.04 to E ≅ 0.8 MeV/nucleon was carried out. Changes in the chemical composition, morphology and sizes of linear radiation defects, tracks, in the YBa2Cu3O6+δ and secondary phase precipitates were investigated. It was found that all radiation defects had amorphous structure regardless the ion energy, while the change in chemical composition was dependent on atomic radius (or mass) of stopping ion and atoms in samples. The diameters of linear defects remain constant for each material in the ion energy range used and distance passed by ions in the samples, about 1 μm, and correlate with the material parameters. The largest track diameters of 10–12 nm were registered in the YCuO2 phase, which has the lowest density, low melting point and the lowest threshold of electronic stopping power of track formation among all the studied compounds. The experimentally measured track diameters in YBCO and secondary phase precipitates were compared with the predictions of the analytical thermal spike model. It is shown that for dielectrics such as simple yttrium oxide and yttrium-copper oxide, with the stopping power of ions exceeding 10 keV/nm, the measured diameters agree with the calculated values within the experimental error or the deviation does not exceed 10%. The discrepancy between the sizes of the observed and calculated tracks at lower stopping powers, as well as the contradiction in the qualitative behavior of the track radius depending on the energy losses, may be due to the inaccuracy of the thermal spike model associated with the underlying significant assumptions.