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Orientational order of liquids and glasses via fluctuation diffraction

Liquids, glasses and other amorphous matter lack long-range order, which makes them notoriously difficult to study. Local atomic order is partially revealed by measuring the distribution of pairwise atomic distances, but this measurement is insensitive to orientational order and unable to provide a...

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Autor principal: Martin, Andrew V.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: International Union of Crystallography 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5331463/
https://www.ncbi.nlm.nih.gov/pubmed/28250939
http://dx.doi.org/10.1107/S2052252516016730
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author Martin, Andrew V.
author_facet Martin, Andrew V.
author_sort Martin, Andrew V.
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description Liquids, glasses and other amorphous matter lack long-range order, which makes them notoriously difficult to study. Local atomic order is partially revealed by measuring the distribution of pairwise atomic distances, but this measurement is insensitive to orientational order and unable to provide a complete picture of diverse amorphous phenomena, such as supercooling and the glass transition. Fluctuation scattering with electrons and X-rays is able provide this orientational sensitivity, but it is difficult to obtain clear structural interpretations of fluctuation data. Here we show that the interpretation of fluctuation diffraction data can be simplified by converting it into a real-space angular distribution function. We calculate this function from simulated diffraction of amorphous nickel, generated with a classical molecular dynamics simulation of the quenching of a high temperature liquid state. We compare the results of the amorphous case to the initial liquid state and to the ideal f.c.c. lattice structure of nickel. We show that the extracted angular distributions are rich in information about orientational order and bond angles. The diffraction fluctuations are potentially measurable with electron sources and also with the brightest X-ray sources, like X-ray free-electron lasers.
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spelling pubmed-53314632017-03-01 Orientational order of liquids and glasses via fluctuation diffraction Martin, Andrew V. IUCrJ Research Papers Liquids, glasses and other amorphous matter lack long-range order, which makes them notoriously difficult to study. Local atomic order is partially revealed by measuring the distribution of pairwise atomic distances, but this measurement is insensitive to orientational order and unable to provide a complete picture of diverse amorphous phenomena, such as supercooling and the glass transition. Fluctuation scattering with electrons and X-rays is able provide this orientational sensitivity, but it is difficult to obtain clear structural interpretations of fluctuation data. Here we show that the interpretation of fluctuation diffraction data can be simplified by converting it into a real-space angular distribution function. We calculate this function from simulated diffraction of amorphous nickel, generated with a classical molecular dynamics simulation of the quenching of a high temperature liquid state. We compare the results of the amorphous case to the initial liquid state and to the ideal f.c.c. lattice structure of nickel. We show that the extracted angular distributions are rich in information about orientational order and bond angles. The diffraction fluctuations are potentially measurable with electron sources and also with the brightest X-ray sources, like X-ray free-electron lasers. International Union of Crystallography 2017-01-01 /pmc/articles/PMC5331463/ /pubmed/28250939 http://dx.doi.org/10.1107/S2052252516016730 Text en © Andrew V. Martin 2017 http://creativecommons.org/licenses/by/2.0/uk/ This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.http://creativecommons.org/licenses/by/2.0/uk/
spellingShingle Research Papers
Martin, Andrew V.
Orientational order of liquids and glasses via fluctuation diffraction
title Orientational order of liquids and glasses via fluctuation diffraction
title_full Orientational order of liquids and glasses via fluctuation diffraction
title_fullStr Orientational order of liquids and glasses via fluctuation diffraction
title_full_unstemmed Orientational order of liquids and glasses via fluctuation diffraction
title_short Orientational order of liquids and glasses via fluctuation diffraction
title_sort orientational order of liquids and glasses via fluctuation diffraction
topic Research Papers
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5331463/
https://www.ncbi.nlm.nih.gov/pubmed/28250939
http://dx.doi.org/10.1107/S2052252516016730
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