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Stress analysis of polycrystalline thin films and surface regions by X-ray diffraction

PANalytical and the Max Planck Institute for Metals Research, Stuttgart, have cooperated on a thin film stress research program.

The study initially focused on obtaining a full overview of the various thin film stress methods that have been published in scientific literature. Following intensive discussions, and additional research by Prof. E.J. Mittemeijer's department, an extensive review was published in the Journal of Applied Crystallography with the title 'Stress analysis of polycrystalline thin films and surface regions by X-ray diffraction' [U. Welzel et al. J.Appl.Cryst. (2005). 38, 1-29].

Several thin film stress diffraction methods had been published but, prior to this study, a full and up-to-date overview did not exist. This invaluable article is available free of charge.

The review article describes these methods in a structured way: that classical residual stress methods use only a single reflection; and that analysis strategies depend on the complexity of the stress state. Typically, in the case of thin films, multiple reflections are used and are combined with the non-conventional collection of data (for example employing grazing incidence diffraction). Both characteristics have consequences for the complexity of the analysis. In particular, reflection-dependent elastic behavior must be taken into account.

The article also summarizes the effects of elastic behavior on a macro-scale, which depends on the nature of the specimen. Texture is known to affect elastic behavior, and another recently discovered factor is the restricted dimension of a thin film. The inclusion of these topics, which are still under investigation by the scientific community, makes the review completely up to date.

Diffraction stress analysis of materials with differing structures and elastic properties

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