1987/04/01 by Paul Thompson, P. Thompson, D. E. Cox +1 · 2,768 citations
Materials Science · Physics and Astronomy · #Computational physics #Condensed matter physics #Debye #Diffraction #Electron and X-Ray Spectroscopy Techniques #Gaussian #Monochromator #Optics #Physics #Resolution (logic) #Rietveld refinement #Synchrotron #Synchrotron radiation #X-ray Diffraction in Crystallography #X-ray Spectroscopy and Fluorescence Analysis
paper · doi:10.1107/s0021889887087090
published in Journal of Applied Crystallography 20(2), 79-83 (Wiley)
openalex publication_date 1987/04/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The application of the Rietveld refinement technique to synchrotron X-ray data collected from a capillary sample of Al2O3 in Debye–Scherrer geometry is described. The data were obtained at the Cornell High Energy Synchrotron Source (CHESS) with an Si(111) double-crystal monochromator and a Ge(111) crystal analyzer. Fits to a number of well resolved individual peaks demonstrate that the peak shapes are very well described by the pseudo-Voigt function, which is a simple approximation to the convolution of Gaussian and Lorentzian functions. The variation of the Gaussian and Lorentzian half widths, ΓG and ΓL, with Bragg angle can be approximated quite closely by the functions V tan θ and X/cos θ which represent the contributions from instrumental resolution and particle-size broadening respectively. Rietveld refinement based on this model yields generally satisfactory results. The refined values of V and X are consistent with the expected vertical divergence (≃0.1 mrad) and the nominal particle size (≃ 0.3μm). In particular, the use of a capillary specimen virtually eliminates preferred orientation effects, which are highly significant in flat-plate samples of this material.