Electron radiation-induced effects in Auger electron spectroscopic characterization of high-Tc superconductors

The effect of radiation-induced changes on the surface and bulk compositions of high-Tc Bi-Pb-Sr-Ca-Cu-O and Y-Ba-Cu-O superconducting systems produced by electron-beam irradiation at room temperature was studied by means of high-resolution Auger electron spectroscopy (AES). Electrons of energies between 5 and 15 keV were used to investigate energy-dependent decomposition phenomena for a wide range of electron radiation doses up to about 1028 electrons m−2. In addition, irradiations with scanned 10-keV electron beams were performed on YBa2Cu3O6.8 single-crystal superconductors in order to investigate the radiation-induced effects on stoichiometric concentrations for oxygen and other elemental constituents using AES multiplex and sputter depth profiling techniques. The results indicate that there are significant changes in both the surface and the bulk compositions of the silver-sheathed Bi1.7Pb0.3Sr2Ca2Cu3O10.2-10 wt.% Ag tape samples, e.g., up to surface concentrations of about 10 at.% for oxygen and about 12 and 15 at.% for calcium and copper, respectively, whereas only small radiation-induced decomposition effects are observed for epitaxially grown YBa2CugO7−x-SrTiO3 thin-film superconductors. YBa2Cu3O6.8 single crystals show relatively strong changes in surface composition in the low radiation dose range, but also a damage recovery effect stimulated at higher electron radiation doses.