Sharp microfaceting of (001)-oriented cerium dioxide thin films and the effect of annealing on surface morphology

Cerium dioxide, CeO2, is a chemically stable oxygen-ion-conducting material , which has been extensively used as an additive or support in oxidation ca talysts. The fact that catalytic behaviour is often surface structure sensi tive and/or edge atom dependent suggests that different surfaces might be d iscernible in associated redox processes. Thus, it is desirable to realise CeO2 films with a well-defined microstructure and with crystallographically uniform surfaces. In this paper we present evidence of extremely sharp mic rofaceting on the surface of thin CeO2 films grown by r.f. magnetron sputte ring, and the effect of annealing on the formed sharp ridges. The results s how that nominally designated crystallographic surfaces may in fact not coi ncide with the surfaces exposed as-grown. Thus, there is a clear risk for e rroneous interpretation of various orientation-dependent surface properties . Carefully controlled annealing of these films can be utilised as a method for tailoring the resulting surface morphology on the atomic scale. (C) 19 99 Elsevier Science B.V. All rights reserved.