Chemical effects in TiO₂ and titanates due to bombardment with Ar⁺ and O ⁺₂ ions of different energies (3.5-10 keV)

Abstract

Compositional and chemical changes in TiO₂ and Ph, Ni, Al and Ba titanates induced by bombardment with Ar⁺ and O ⁺₂ ons of different energies have been studied quantitatively by XPS. An increase of preferential loss of oxygen and, in case of PbTiO₃, of lead has been observed when increasing the Ar+ ion energy from 3.5 to 10 keV. Because of oxygen loss, Ti⁴⁺ species reduce to Ti³⁺ and Ti²⁺. In addition, the loss of oxygen from PbTiO₃ and NiTiO₃ leads to the metallic state of nickel and lead, whereas aluminium and barium in Al₂TiO₅ and BaTiO₃ maintain their chemical state (i.e., Al³⁺ and Ba²⁺). Bombardment with OZ ions of PbTiO₃ and NiTiO₃ leads to a partial reduction of Pb and Ni. This metallization and the preferential loss of lead are more efficient at higher ion energies for both, O ⁺₂ and Ar⁺ bombardment. The results are discussed in terms of chemical stabilities and the possibility of oxygen diffusion in the bombarded oxides.