X-Ray powder diffraction of mineralogical samples by X-Ray goebel mirrors

Résumé 0

Comparative studies are presented on a series of standard and mineralogical samples with X-ray powder diffraction methods, which have been made with a diffractometer possessing the traditional Bragg-Brentano geometry and a second one equipped with a parabolic Goebel mirror (parallel optics). The diffractometers with the Bragg-Brentano geometry are used extensively for the analysis of polycrystalline samples, the main drawback of which is the high expertise needed by the user in order to maintain an instrument in perfect alignment and the careful preparation of the studied samples. Samples measured with a Goebel mirror in parallel optics are free from displacement errors caused by the displacement of the surface or by the surface roughness of the samples. The advantages of the parallel optics are valuable in the case of study of mineralogical samples with the same structure and variable chemical composition (feldspars, amphiboles, pyroxenes, clays etc.) or samples with irregular shapes. Another advantage of Goebel mirrors is the high intensity.