Surface Morphology of Heat‐Treated Ceramic Thin Films

The morphology of surfaces of several ceramic materials has been examined using transmission electron microscopy. The approach used was to prepare a sample for examination in the microscope, carefully clean it, and then heat‐treat it. In the case of the oxides studied (alumina and spinel) the samples were heated in air; the non‐oxides (α‐SiC and β‐SiC) were annealed under vacuum. The morphology in all but one case was such that the surface faceted parallel to the nearest low‐index plane to give well‐defined terraces; these were separated by ledges which also tended to facet parallel to the traces of low‐index planes. The exception was the {1100} alumina surface, which appears to be unstable in air at temperatures close to 1400°C. A computer program using a multislice approach was used to estimate the height of the steps on the (0001) surface; the step heights appear to be multiples of the c lattice parameter. A reconstruction of this surface as a result of this heat treatment is also proposed. Copyright © 1992, Wiley Blackwell. All rights reserved