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The oxidation of TiN in an oxygen flow at temperatures in the range 300-500·C has been studied by means of soft x-ray absorption spectroscopy. The analysis of the experimental results indicates that 0 progressively displaces N to form Ti0 2 . The process appears to be controlled by the temperature dependence of the oxygen diffusion. Some oxidation is observed to take place even at room temperature. No evidence of oxynitride formation was found in thermally oxidized TiN, instead complete phase separation is observed. The interface between Ti0 2 and TiN seems to be very abrupt. The appearance of a sharp absorption peak in the N Is spectrum of TiN is believed to be due to nitrogen atoms which are displaced during the oxidation process and remain unbounded within the Ti0 2 matrix. For temperatures above 400 ·C, this peak disappears as the interstitial N atoms migrate to the surface and desorb.

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