F. Esaka et al., Composition dependence of the initial oxidation behaviour of Ti1-xAlxN (x=0.20, 0.45, 0.65) films studied by XAS and XPS, SURF INT AN, 27(12), 1999, pp. 1098-1106
The difference in the initial oxidation behaviours of Ti1-xAlxN (x = 0.20,
0.45, 0.65) films was studied by x-ray absorption (XAS) and by x-ray photoe
lectron spectroscopy (XPS) using synchrotron radiation (SR-XPS), The N It-e
dge XAS results indicated rapid decreases in the relative ratio of AI-N rel
ative to the total nitride with surface oxidation for all the Ti1-xAlxN fil
ms, The SR-XPS analysis of O, Ti and Al species with different photon energ
ies disclosed the formation of Al2O3 at an upper layer and TiO2 at a lower
layer in oxidized Ti1-xAlxN films with x = 0.20 and 0.45. In contrast, a mi
xed Al2O3 and TiO2 surface layer was formed in tie oxidized Ti1-xAlxN him w
ith high aluminium content (x = 0.65), In addition, N-2 molecules, which we
re formed as an intermediate species during the oxidation, were concentrate
d in the interface of Al2O3 and TiO2 in the oxidized Ti0.55Al0.45N and Ti0.
80Al0.20N films, whereas they occurred near the surface in the oxidized Ti0
.35Al0.65N film. From these results, it was concluded that the high surface
oxidation-resistant properties of Ti1-xAlxN film with low aluminium conten
t originated from the rapid formation of a surface Al2O3 layer that prevent
ed inward diffusion of oxygen as wed as outward diffusion of molecular nitr
ogen. Copyright (C) 1999 John Wiley & Sons, Ltd.