Surface characterization of Fe₇₅B₂₀TM₅ (TM ≡ V, Co) amorphous ribbons by X-ray photoelectron spectroscopy

Abstract

X-ray photoelectron spectroscopy has been used to obtain surface composition and depth profiles of both ‘shiny’ and ‘dull’ sides of aged Fe₇₅B₂₀TM₅ (TM ≡ Co, V) amorphous ribbons prepared by melt spinning. Thick oxide films are found on both sides of the two ribbons, the dull side being always much more oxidized. The composition of the oxide layers strongly depends upon the nature of TM. The outermost layer of the dull sides is invariably composed of iron oxides while, on the shiny surfaces, boron oxides are also detected, mixed with TM oxides only when TM ≡ V. Depth profiles obtained by sputtering revealed large oxygen-induced segregation phenomena. Cobalt, which does not participate actively in the formation of the passive layer, is depleted, whereas a large enrichment is found for vanadium which contributed to the layer mostly as VO₂.