XPS and ISS study of NiTiO 3 and PbTiO 3 subjected to low‐energy ion bombardment. I. Influence of the type of ion (Ar + and O)

Compositional and chemical changes in PbTiO 3 and NiTiO 3 induced by 3.5 keV Ar + and O 2 + ion bombardment have been studied quantitatively by XPS and ISS. Whereas in NiTiO 3 the Ti/Ni ratio determined by XPS remained practically constant, a preferential loss of lead was observed in PbTiO 3 during ion bombardment. In that case, Ar + removed lead more effectively than O 2 + ions. Argon ion bombardment induced strong chemical changes in both titanates: Ni 2+ and Pb 2+ species were nearly totally reduced to the metallic state, while Ti 4+ species were partially reduced to Ti 3+ and Ti 2+ oxidation states. This reduction is more efficient in PbTiO 3 than in NiTiO 3 . The preferential loss of lead in PbTiO 3 and the removal at equivalent rates of Ti and Ni in NiTiO 3 are discussed within the context of the chemical stability and physical constants of the compounds by assuming a chemically guided lattice relaxation of the bombarded targets. The possibility that solid‐state reactions play a role in the control of some of the results is stressed. Other possible effects, such as agglomeration or surface enrichment, are discussed by using the ISS results.