Controlling the physics and chemistry of binary and ternary praseodymium and cerium oxide systems

摘要

Rare earth praseodymium and cerium oxides have attracted intense research interest in the last fewdecades, due to their intriguing chemical and physical characteristics. An understanding of the correlationbetween structure and properties, in particular the surface chemistry, is urgently required for their applicationin microelectronics, catalysis, optics and other fields. Such an understanding is, however, hampered by thecomplexity of rare earth oxide materials and experimental methods for their characterisation. Here, we reportrecent progress in studying high-quality, single crystalline, praseodymium and cerium oxide films as well asternary alloys grown on Si(111) substrates. Using these well-defined systems and based on a systematic multi-technique surface science approach, the correspondingphysical and chemical properties, such as the surfacestructure, the surface morphology, the bulk–surface interaction and the oxygen storage/release capability, areexplored in detail. We show that specifically the crystalline structure and the oxygen stoichiometry of theoxide thin films can be well controlled by the film preparation method. This work leads to a comprehensiveunderstanding of the properties of rare earth oxides and highlights the applications of these versatile materials.Furthermore, methanol adsorption studies are performed on binary and ternary rare earth oxide thinfilms, demonstrating the feasibility of employing such systems for model catalytic studies. Specifically forceria systems, we find considerable stability against normal environmental conditions so that they canbe considered as a ‘‘materials bridge’’ between surface science models and real catalysts.