ELECTRON RADIATION-INDUCED EFFECTS IN AUGER-ELECTRON SPECTROSCOPIC CHARACTERIZATION OF HIGH-T-C SUPERCONDUCTORS

The effect of radiation-induced changes on the surface and bulk compos itions of high-T-c Bi-Pb-Sr-Ca-Cu-O and Y-Ba-Cu-O superconducting syst ems produced by electron-beam irradiation at room temperature was stud ied by means of high-resolution Auger electron spectroscopy (AES). Ele ctrons of energies between 5 and 15 keV were used to investigate energ y-dependent decomposition phenomena for a wide range of electron radia tion doses up to about 10(28) electrons m(-2). In addition, irradiatio ns with scanned 10-keV electron beams were performed on YBa2Cu3O6.8 si ngle-crystal superconductors in order to investigate the radiation-ind uced effects on stoichiometric concentrations for oxygen and other ele mental constituents using AES multiplex and sputter depth profiling te chniques. The results indicate that there are significant changes in b oth the surface and the bulk compositions of the silver-sheathed Bi1.7 Pb0.3Sr2Ca2Cu3O10.2-10 wt.% Ag tape samples, e.g., up to surface conce ntrations of about 10 at.% for oxygen and about 12 and 15 at.% for cal cium and copper, respectively, whereas only small radiation-induced de composition effects are observed for epitaxially grown YBa2Cu3O7-x-SrT iO3 thin-film superconductors. YBa2Cu3O6.8 single crystals show relati vely strong changes in surface composition in the low radiation dose r ange, but also a damage recovery effect stimulated at higher electron radiation doses.