Mass spectrometry of secondary negative ions emitted from low-energy sputtered YBCO ceramics

Mass spectra of negative secondary ions emitted from the surface of a stoichiometrical superconducting YBa 2 Cu 3 O 7-x ceramic bombarded by 250 eV positive argon and oxygen ions were measured. The results show that the reduction of the primary ion energy reduces the yield of heavy secondary ions. It was observed that the supply of oxygen to the sample bombarded by Ar + ions enhances the yield of secondary negative ions, although this yield is further enhanced by switching to positive oxygen primary ions. Moreover, the bombardment of a YBCO ceramic sample by oxygen ions is characterized by a particular enhancement of the yield of barium and barium-containing molecular ions.