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Rietveld refinement

About: Rietveld refinement is a(n) research topic. Over the lifetime, 12836 publication(s) have been published within this topic receiving 271353 citation(s).
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Journal ArticleDOI
Abstract: A structure refinement method is described which does not use integrated neutron powder intensities, single or overlapping, but employs directly the profile intensities obtained from step-scanning measurements of the powder diagram. Nuclear as well as magnetic structures can be refined, the latter only when their magnetic unit cell is equal to, or a multiple of, the nuclear cell. The least-squares refinement procedure allows, with a simple code, the introduction of linear or quadratic constraints between the parameters.

13,024 citations

Journal Article
Abstract: Introduction to the Rietveld Method 1. The early days: a retrospective view 2. Mathematical aspects of Rietveld refinement 3. The flow of radiation in a polycrystalline material 4. Data collection strategies: fitting the experiment to the need 5. Background modelling in Rietveld analysis 6. Analytical profile fitting of X-ray powder diffraction profiles in Rietveld analysis 7. Crystal imperfection broadening and peak shape in the Rietveld method 8. Bragg reflection profile shape in X-ray powder diffraction patterns 9. Restraints and constraints in Rietveld refinement 10. Rietveld refinement with time-of-flight powder diffraction data from pulsed neutron sources 11. Combined X-ray and neutron Rietveld refinement 12. Rietveld analysis programs Rietan and Premos and special applications 13. Position - constrained and unconstrained powder-pattern-decomposition methods 14. Ab initio structure solutions with powder diffraction data

3,085 citations

Journal ArticleDOI
Abstract: 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.

2,329 citations

Journal ArticleDOI
A. Le Bail1, H. Duroy1, J.L. Fourquet1Institutions (1)
Abstract: The crystal structure of LiSbWO6 is solved from X-ray powder diffraction data. The cell is orthorhombic (space group Pbcn, Z = 4) with a = 4.6664(1) A , b = 17.4435(5) A , c = 4.9941(2) A . Initial positional parameters for antimony and tungsten were obtained from direct methods applied on 307 reflexions which were derived from a modified Rietveld analysis working without structural model. The structure was refined using Rietveld profile refinement principles ; the final reliability factors (%) are Rx = 2.1, RWP = 6.5. The structure derives from PbO2-α by a tripling of the b axis of PbO2 with a full cationic order, unlike the columbite structure which is related to PbO2-α by a tripling of the a-axis.

2,152 citations

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