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Accuracy of pair distribution function analysis applied to crystalline and non-crystalline materials

Accuracy of pair distribution function analysis applied to crystalline and non-crystalline materials Pair distribution function (PDF) analysis of neutron or X-ray powder diffraction data is a useful technique for analysis of short-range structure in both amorphous and crystalline materials. Errors in PDF determinations may arise from several sources: termination of the Fourier transform, lack of instrument resolution, counting statistics and inaccurate corrections for experimental artifacts. Estimates of the amount of error from termination and instrument resolution are computed using a model structure. A general method for estimating the expected contribution of statistical error to the PDF is introduced for the first time. The effect of termination varies with the type of material and with the amplitude of lattice vibrations but, in general, termination with Q > 30 A produces minimal errors. Broadening of the diffraction pattern produces negligible effect for conventional instrumentation. With moderate data-collection times, the statistical errors can be reduced to reasonable levels. Pulsed-neutron diffraction can provide accurate and precise PDF measurements, as is demonstrated in this work by the agreement between model and experimental results for polycrystalline aluminium. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Acta Crystallographica Section A: Foundations of Crystallography International Union of Crystallography

Accuracy of pair distribution function analysis applied to crystalline and non-crystalline materials

Accuracy of pair distribution function analysis applied to crystalline and non-crystalline materials


Abstract

Pair distribution function (PDF) analysis of neutron or X-ray powder diffraction data is a useful technique for analysis of short-range structure in both amorphous and crystalline materials. Errors in PDF determinations may arise from several sources: termination of the Fourier transform, lack of instrument resolution, counting statistics and inaccurate corrections for experimental artifacts. Estimates of the amount of error from termination and instrument resolution are computed using a model structure. A general method for estimating the expected contribution of statistical error to the PDF is introduced for the first time. The effect of termination varies with the type of material and with the amplitude of lattice vibrations but, in general, termination with Q > 30 A produces minimal errors. Broadening of the diffraction pattern produces negligible effect for conventional instrumentation. With moderate data-collection times, the statistical errors can be reduced to reasonable levels. Pulsed-neutron diffraction can provide accurate and precise PDF measurements, as is demonstrated in this work by the agreement between model and experimental results for polycrystalline aluminium.

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References (12)

Publisher
International Union of Crystallography
Copyright
Copyright (c) 1992 International Union of Crystallography
ISSN
0108-7673
eISSN
1600-5724
DOI
10.1107/S0108767391011327
Publisher site
See Article on Publisher Site

Abstract

Pair distribution function (PDF) analysis of neutron or X-ray powder diffraction data is a useful technique for analysis of short-range structure in both amorphous and crystalline materials. Errors in PDF determinations may arise from several sources: termination of the Fourier transform, lack of instrument resolution, counting statistics and inaccurate corrections for experimental artifacts. Estimates of the amount of error from termination and instrument resolution are computed using a model structure. A general method for estimating the expected contribution of statistical error to the PDF is introduced for the first time. The effect of termination varies with the type of material and with the amplitude of lattice vibrations but, in general, termination with Q > 30 A produces minimal errors. Broadening of the diffraction pattern produces negligible effect for conventional instrumentation. With moderate data-collection times, the statistical errors can be reduced to reasonable levels. Pulsed-neutron diffraction can provide accurate and precise PDF measurements, as is demonstrated in this work by the agreement between model and experimental results for polycrystalline aluminium.

Journal

Acta Crystallographica Section A: Foundations of CrystallographyInternational Union of Crystallography

Published: May 1, 1992

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