Interaction of oxygen with TiN (001): N↔O exchange and oxidation process
|Author||Graciani Alonso, Jesús
Fernández Sanz, Javier
Rodríguez, José A.
|Editor||Fernández Sanz, Javier|
|Department||Universidad de Sevilla. Departamento de Química Física|
|Abstract||This work presents a detailed experimental and theoretical study of the oxidation of TiN(001) using a combination of synchrotron-based photoemission and density functional theory (DFT). Experimentally, the adsorption of ...
This work presents a detailed experimental and theoretical study of the oxidation of TiN(001) using a combination of synchrotron-based photoemission and density functional theory (DFT). Experimentally, the adsorption of O2 on TiN(001) was investigated at temperatures between 250 and 450K. At the lowest temperature, there was chemisorption of oxygen (O2,gas→2Oads) without significant surface oxidation. In contrast, at 450K the amount of O2 adsorbed increased continuously, there was no evidence for an oxygen saturation coverage, a clear signal in the Ti 2p core level spectra denoted the presence of TiOx species, and desorption of both N2 and NO was detected. The DFT calculations show that the adsorption/dissociation of O2 is highly exothermic on a TiN(001) substrate and is carried out mainly by the Ti centers. A high oxygen coverage (larger than 0.5 ML) may induce some structural reconstructions of the surface. The exchange of a surface N atom by an O adatom is a highly endothermic process (ΔE=2.84eV). However, the overall oxidation of the surface layer is thermodynamically favored due to the energy released by the dissociative adsorption of O2 and the formation of N2 or NO. Both experimental and theoretical results lead to conclude that a TiN+mO2→TiOx+NO reaction is an important exit channel for nitrogen in the oxidation process.
|Funding agencies||Ministerio de Educación y Ciencia (MEC). España
Junta de Andalucía
U.S. Department of Energy. United States
Nippon Foundation for Materials Science. Japan
|Citation||Graciani Alonso, J., Fernández Sanz, J., Asaki, T., Nakamura, K. y Rodríguez, J.A. (2007). Interaction of oxygen with TiN (001): N↔O exchange and oxidation process. The Journal of Chemical Physics, 126 (24), 244713.|