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Use of XAS and chemical probes to study the structural damage induced in oxide ceramics by bombardment with low‐energy ions
Author(s) -
Caballero A.,
Leinen D.,
Espinós J. P.,
Fernández A.,
GonzálezElipe A. R.
Publication year - 1994
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740210617
Subject(s) - xanes , x ray absorption spectroscopy , extended x ray absorption fine structure , x ray photoelectron spectroscopy , titanium , adsorption , oxide , ion , analytical chemistry (journal) , sulfur , absorption spectroscopy , chemistry , x ray absorption fine structure , spectroscopy , materials science , inorganic chemistry , chemical engineering , metallurgy , physics , organic chemistry , chromatography , quantum mechanics , engineering
A preliminary study by x‐ray absorption spectroscopy (XAS) of the structural modifications induced in mixed oxides by low‐energy (1–5 keV) Ar + bombardment is presented in this paper. The analysis of the extended x‐ray adsorption fine structure (EXAFS) and x‐ray adsorption near‐edge structure (XANES) spectra recorded for bombarded Al 2 TiO 5 and BaTiO 3 has shown the randomization of the atomic network and the formation of TiO 2 in the outermost layers of these materials. On the other hand, SO 2 is proposed as a probe molecule to asess semiquantitatively the extent of structural damage in the surface layers of bombarded oxides. The incorporation of sulphur into this zone has been proved by depth profiling with XPS and Ar + ions of 0.5 keV. In BaTiO 3 the incorporation of sulphur increases with the energy of the primary ions. This fact suggests that the concentration of defects increases with the energy of the Ar + beam and that the most disordered surface layers are more reactive towards SO 2 . A similar effect is not observed with TiO 2 and Al 2 TiO 5 because in these materials, where a considerable reduction of titanium to Ti n + ( n < 4) species is produced by the preferential removal of oxygen, an overlay of elemental sulphur is formed by the reaction of SO 2 with these species. This overlay prevents the diffusion of SO 2 and therefore the incorporation of sulphur into the damaged layer of those samples.