CHEMICAL-CHANGES IN TITANATE SURFACES INDUCED BY AR+ ION-BOMBARDMENT

The reduction effects and compositional changes induced by 3.5 keV Ar+ bombardment of several titanates (i.e. SrTiO3, Al2TiO5 and NiTiO3) have been quantitatively investigated by XPS. In all the samples studied here the original Ti4+ species were reduced to lower oxidation states (i.e. Ti3+ and Ti2+), although to a lesser extent than in pure TiO2. On the contrary, whereas Sr2+ and Al3+ seem to remain unaffected by Ar+ bombardment. in agreement with the behaviour of the respective oxides (i.e. SrO and Al2O3), Ni2+ appears more easily reducible to NiO in NiTiO3 than in NiO. In addition, other specific differences were observed between the titanates, which reveal the existence of interesting chemical effects related to the presence of the different counter-ions in the titanates. In the case of Al2TiO5, its Ar+ -induced decomposition to form TiO2 + Al2O3 could be, followed by XPS.