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Multigrain indexing of unknown multiphase materials

A multigrain indexing algorithm for use with samples comprising an arbitrary number of known or unknown phases is presented. No a priori crystallographic knowledge is required. The algorithm applies to data acquired with a monochromatic beam and a conventional two-dimensional detector for diffractio...

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Detalles Bibliográficos
Autores principales: Wejdemann, Christian, Poulsen, Henning Friis
Formato: Online Artículo Texto
Lenguaje:English
Publicado: International Union of Crystallography 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4815876/
https://www.ncbi.nlm.nih.gov/pubmed/27047308
http://dx.doi.org/10.1107/S1600576716003691
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author Wejdemann, Christian
Poulsen, Henning Friis
author_facet Wejdemann, Christian
Poulsen, Henning Friis
author_sort Wejdemann, Christian
collection PubMed
description A multigrain indexing algorithm for use with samples comprising an arbitrary number of known or unknown phases is presented. No a priori crystallographic knowledge is required. The algorithm applies to data acquired with a monochromatic beam and a conventional two-dimensional detector for diffraction. Initially, candidate grains are found by searching for crystallographic planes, using a Dirac comb convoluted with a box function as a filter. Next, candidate grains are validated and the unit cell is optimized. The algorithm is validated by simulations. Simulations of 500 cementite grains and ∼100 reflections per grain resulted in 99.2% of all grains being indexed correctly and 99.5% of the reflections becoming associated with the right grain. Simulations with 200 grains associated with four mineral phases and 50–700 reflections per grain resulted in 99.9% of all grains being indexed correctly and 99.9% of the reflections becoming associated with the right grain. The main limitation is in terms of overlap of diffraction spots and computing time. Potential areas of use include three-dimensional grain mapping, structural solution and refinement studies of complex samples, and studies of dilute phases.
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spelling pubmed-48158762016-04-04 Multigrain indexing of unknown multiphase materials Wejdemann, Christian Poulsen, Henning Friis J Appl Crystallogr Research Papers A multigrain indexing algorithm for use with samples comprising an arbitrary number of known or unknown phases is presented. No a priori crystallographic knowledge is required. The algorithm applies to data acquired with a monochromatic beam and a conventional two-dimensional detector for diffraction. Initially, candidate grains are found by searching for crystallographic planes, using a Dirac comb convoluted with a box function as a filter. Next, candidate grains are validated and the unit cell is optimized. The algorithm is validated by simulations. Simulations of 500 cementite grains and ∼100 reflections per grain resulted in 99.2% of all grains being indexed correctly and 99.5% of the reflections becoming associated with the right grain. Simulations with 200 grains associated with four mineral phases and 50–700 reflections per grain resulted in 99.9% of all grains being indexed correctly and 99.9% of the reflections becoming associated with the right grain. The main limitation is in terms of overlap of diffraction spots and computing time. Potential areas of use include three-dimensional grain mapping, structural solution and refinement studies of complex samples, and studies of dilute phases. International Union of Crystallography 2016-03-24 /pmc/articles/PMC4815876/ /pubmed/27047308 http://dx.doi.org/10.1107/S1600576716003691 Text en © Wejdemann and Poulsen 2016 http://creativecommons.org/licenses/by/2.0/uk/ This is an open-access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
spellingShingle Research Papers
Wejdemann, Christian
Poulsen, Henning Friis
Multigrain indexing of unknown multiphase materials
title Multigrain indexing of unknown multiphase materials
title_full Multigrain indexing of unknown multiphase materials
title_fullStr Multigrain indexing of unknown multiphase materials
title_full_unstemmed Multigrain indexing of unknown multiphase materials
title_short Multigrain indexing of unknown multiphase materials
title_sort multigrain indexing of unknown multiphase materials
topic Research Papers
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4815876/
https://www.ncbi.nlm.nih.gov/pubmed/27047308
http://dx.doi.org/10.1107/S1600576716003691
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