We have observed nonorthogonal twinning in thin film oxide perovskites. This twinning geometry is equivalent to a 60° rotation of the twinned crystallites about the [111] direction in an [001] oriented film. This twinning is not detectable by the standard x-ray tests for film quality (a radial θ–2θ scan and a φ scan at a chi of 45°). In this study we observe this twinning in films of PbZrxTi1−xO3, BaTiO3, and SrRuO3 grown by sputtering and MOCVD on MgO and SrTiO3. These twins are observed in films deposited on a substrate with which there is a large lattice mismatch and in films that are deposited in an oxygen deficient environment. We propose that these twins result from plastic deformation associated with misfit accommodation and discuss the twin geometry and the nature of the twin interface.

We present a high-resolution synchrotron X-ray diffraction study of xenon adsorbed on single-crystal graphite for coverages of two, three and six monolayers. We observe the evolution of the lattice mismatch between the xenon overlayer and a square root 3* square root 3R30 degrees structure commensurate with the underlying substrate. In the case of the bilayer we see a first-order incommensurate-commensurate (IC-C) phase transition at 62.0 K+or-1.2 K, which we demonstrate is consistent with the layer closest to the substrate having locked into the commensurate sites. The role of substrate quality is discussed and we conclude that previous studies on relatively poorer substrates may have favoured equilibrium structures strongly influenced by the surface imperfections. The risk of an insufficiently equilibrated adsorbate is discussed in the context of the very slow kinetics we observe for multilayer xenon on high-quality substrates. For the three- and six-layer adsorbates we observe a systematic increase in lattice mismatch with film thickness and no indication of an incommensurate-commensurate transition. We conclude that the trilayer system consists of many distinct domains approximately 500 AA across, each of which has a random close packed structure.

The thermomechanical behavior of Pt thin films was studied using the substrate curvature technique. Films of identical thickness but different grain size were prepared by sputtering directly onto a thermally grown SiO2 layer on a (100) Si wafer. Predictions from a thin-film version of the deformation mechanism map model and the diffusional wedge are compared to the experimental results. The diffusional wedge model most accurately predicts the onset of diffusion-controlled stress relaxation in columnar Pt films. The use of an effective film thickness equal to the grain size improves the match to noncolumnar microstructures.

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