Limitations of asymmetric parallel-beam geometry
Contribuinte(s) |
G. Kostorz |
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Data(s) |
01/06/2004
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Resumo |
Bragg diffraction peak profiles and intensities in asymmetric (Omega-2theta) diffraction using a mirror-based parallel-beam geometry were compared with symmetric parallel-beam (theta-2theta) and conventional Bragg - Brentano (theta-2theta) diffraction for a powdered quartz sample and the NIST standard reference material (SRM) 660a (LaB6, lanthanum hexaboride). A comparison of the intensities and line widths (full width at half-maximum, FWHM) of these techniques demonstrated that low incident angles (Omega < 5&DEG;) are preferable for the parallel-beam setup. For higher &UOmega; values, if 2θ < 2Omega, mass absorption reduces the intensities significantly compared with the Bragg - Brentano setup. The diffraction peak shapes for the mirror geometry are more asymmetric and have larger FWHM values than corresponding peaks recorded with a Bragg - Brentano geometry. An asymmetric mirror-based parallel-beam geometry offers some advantages in respect of intensity when compared with symmetric geometries, and hence may be well suited to quantitative studies, such as those involving Rietveld analysis. A trial Rietveld refinement of a 50% quartz - 50% corundum mixture was performed and produced adequate results. |
Identificador |
http://espace.library.uq.edu.au/view/UQ:73307/UQ73307_OA.pdf |
Idioma(s) |
eng |
Publicador |
Blackwell Munksgaard |
Palavras-Chave | #Crystallography #Intensity Aberrations #Diffraction #Algorithm #Optics |
Tipo |
Journal Article |