ELECTRON-BEAM-INDUCED STRUCTURAL-CHANGES IN BI2SR2CACU2O8-ELECTRON EMISSION(X STUDIED BY CATHODOLUMINESCENCE MICROSCOPY AND SECONDARY)

Bi2Sr2CaCu2O8+x superconducting ceramics have been irradiated in the s canning electron microscope (SEM), and the irradiation-induced effects investigated by cathodoluminescence (CL), secondary electron emission (SEE) and X-ray microanalysis. Electron beam irradiation causes a sli ght Bi depletion and an inhomogeneous Ca distribution. A higher CL int ensity emission is found in the irradiated areas, where besides an enh ancement of the oxygen content related 2.4 eV band, another CL bands p robably related to new non-superconducting phases induced by irradiati on can be observed. SEE yield measurements allow to detect an oxygen d epleted region surrounding the irradiated areas. X-ray microanalysis s hows that this intermediate region retains the cationic composition of the unaffected material. CL spectra from bright zones inside the same area also show a dominant 2.4 eV emission band, which supports its re lation with oxygen deficiency or rearrangement in high-T-c superconduc tors.