Coupling Experiments with Theory: Effect of Size and Topography on Structural Dynamics and Energetic Reactions of Metal Oxides
EMSL Project ID
30200
Abstract
Metal oxides represent various and fascinating classes of material that are widely applied and cover the entire range from insulators to semiconductors. Their surfaces play a crucial role in an extremely wide range of phenomena including the environmental degradation of high-Tc superconductors and catalysis. They are also increasingly important in processes such as the passivation of metal surfaces and gas sensing for pollution monitoring and control or as constituents of microelectronic devices and optical coatings.Many oxidic systems belong to the class of rock-salt solids that can be prepared in the form of very high surface area polycrystalline samples, which exhibit large numbers of very reactive coordinatively unsaturated ions such as steps, edges and corner sites[7]. Among these we can mention MgO, CaO, SrO, BaO, NiO and CoO. Due to their simple crystal structure and to the fact that the most commonly exposed face is (001), they represent an ideal family of solids for the investigation of the surface properties of both cations (M2+) and oxygen anions (O2-) in different local environments. For both cation and anion we can distinguish among regular five coordinated sites on flat (001) faces, four coordinated sites on steps and edges, and three coordinated sites on corners. When the size of metal oxides approaches the nanometer length scale - as in a case of high surface area polycrystallines - the shape sets the ratio of the different terminating surface planes and determines the relative concentration of coordinatively unsaturated ions. Moreover, morphology of these particles can vary not only in shape and particle size but also in surface structure and their properties sensitively depend on all of these three parameters[8,9]. These can be controlled by a judicious choice of the synthesis process.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2008-10-01
End Date
2009-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members