Results 131 to 140 of about 33,137,902 (193)

Structure of α-polypivalolactone: a refinement based on the Rietveld method

Polymer, 1988
Abstract A comparative study is carried out on the structure of the α form of polypivalolactone obtained (i) from the analysis of oriented-fibre X-ray diffraction diagrams, (ii) from conformational energy calculations and (iii) by refining the first two models through best fitting on the powder X-ray diffraction profile according to the Rietveld ...
BRUCKNER S., MEILLE, STEFANO VALDO, PORZIO W.   +2 more
exaly   +3 more sources

Simultaneous structure and size-strain refinement by the Rietveld method

Journal of Applied Crystallography, 1990
A new procedure for simultaneous refinement of structural and microstructural disorder parameters for polycrystalline materials is proposed. It is based on the Rietveld method combined with Fourier analysis for broadened peaks. Crystallite size and shape and r.m.s.
L. Lutterotti, P. Scardi
semanticscholar   +3 more sources

Quantitative phase analysis using the Rietveld method

Journal of Applied Crystallography, 1988
Quantitative phase analysis of multicomponent mixtures using X-ray powder diffraction data has been approached with a modified version of the Rietveld computer program of Wiles & Young [J. Appl. Cryst. (1981), 14, 149–151]. This new method does not require measurement of calibration data nor the use of an internal standard; however, the approximate ...
D. Bish, S. A. Howard
semanticscholar   +2 more sources

Crystal structure of LaVO3 by Rietveld refinement method

Materials Letters, 2004
Abstract Structure refinement of LaVO 3 was carried out using the whole pattern fitting or Rietveld method, which is a powerful technique for extracting structural information from powder diffraction data. The crystal structure refinement was done using powder X-ray diffraction data measured on a conventional diffractometer.
J Bashir
exaly   +2 more sources

Quantitative and structural analysis of minerals in soil clay fractions developed under different climate zones in China by XRD with Rietveld method, and its implications for pedogenesis

Applied Clay Science, 2018
Mineral compositions and structures in soil clay fractions can reflect the pedogenesis and the pedoenvironments of the natural soils. However, the simultaneous quantification and structural analysis of all phases in soils by X-ray diffraction are ...
Wei Zhao, W. Tan
semanticscholar   +1 more source

An analysis of the Rietveld refinement method

Journal of Applied Crystallography, 1979
An analysis of the Rietveld profile refinement method used in the interpretation of neutron or X-ray powder diffraction patterns has been carried out. It is shown that the values obtained for the structural parameters are not exactly the same as those obtained from an integrated intensity refinement of the same data and that the standard deviations of ...
M. Sakata, M. J. Cooper
openaire   +1 more source

The structure of neutral polythiophene. An application of the rietveld method

Die Makromolekulare Chemie, 1988
AbstractThe crystal structure of polythiophene is analyzed by the Rietveld whole‐fitting method on the X‐ray diffraction powder profile. Experimental data allow only a bidimensional characterization of the structure in the plane orthogonal to the chain axis with a pgg symmetry (a = 7,79; b = 5,53 Å).
Brückner S, Porzio W
openaire   +2 more sources

An alternative to the Rietveld profile refinement method

Zeitschrift für Kristallographie - Crystalline Materials, 1981
Abstract A new method (SCRAP) has been used for the analysis of neutron powder diffraction data as an alternative to the Rietveld profile refinement method, which has been shown to give incorrect values for the standard deviations of the parameters.
M. J. Cooper, K. D. Rouse, M. Sakata
openaire   +2 more sources

Domain Size Analysis in the Rietveld Method

Materials Science Forum, 2010
The implementation of a physically-sound size broadening model for peak profiles in the Rietveld method is presented. TOPAS macros are provided and the results compared with analogous modelling performed according to advanced analysis methods such as the Whole Powder Pattern Modelling.
W. I. F. David, Leoni, Matteo, Scardi, Paolo   +2 more
openaire   +2 more sources

The validity of the Rietveld method

Zeitschrift für Kristallographie - Crystalline Materials, 1983
Abstract The values of the estimated standard deviations given by the Rietveld profile refinement method are formally invalid, since the method does not take into account systematic errors which are introduced into the residuals by the constraints of the model from which the calculated intensities are derived.
openaire   +1 more source