Surface oxygen chemistry of a gas-sensing material:M. Batzill1, A. M. Chaka2 and U. Diebold1
1 Department of Physics, Tulane University - New Orleans, LA 70118, USA
2 Chemical Science and Technology Laboratory, National Institute of Standards Gaithersburg, MD 20899-8380, USA
(Received 29 July 2003; accepted in final form 14 October 2003)
Experimental techniques and density-functional theory have been employed to identify the surface composition and structure of . The stoichiometric surface is only stable at high oxygen chemical potential. For lower oxidizing potential of the gas phase a bulk termination is favored. These two surfaces convert into each other without reconstruction by occupying and vacating bridging oxygen sites. This variability of the surface composition is possible because of the dual valency of and may be one of the fundamental mechanisms responsible for the performance of this material in gas-sensing devices.
68.47.Gh - Oxide surfaces.
82.65.+r - Surface and interface chemistry; heterogeneous catalysis at surfaces.
68.37.Ef - Scanning tunneling microscopy (including chemistry induced with STM).
© EDP Sciences 2004