SURFACE PHASE DECOMPOSITION IN Bi₂Sr₂CaCu₂O_7-y SINGLE CRYSTALS UNDER NITROGEN IONS IRRADIATION

The influence of irradiation by 30 keV nitrogen ions with a fluence 1×10¹⁸N⁺·cm^-2 on the crystal structure of single crystal Bi₂Sr₂CaCu₂O_7-y was investigated by means of X-ray photoelectron spectroscopy and X-ray diffraction. The irradiation caused a transformation from Bi₂Sr₂CaCu₂O_7-y (2212 phase) to Bi₂Sr₂CuO_5-x (2201 phase). It was observed that. a small amount of metallic bismuth with an average thickness of about 6.3nm appeared after the irradiation. The possible reaction mechanism under nitrogen-ion irradiation was discussed.