The incommensurately modulated structures of low-temperature labradorite feldspars: a single-crystal X-ray and neutron diffraction study
Labradorite feldspars of the plagioclase solid solution series have been known for their complicated subsolidus phase relations and enigmatic incommensurately modulated structures. Characterized by the irrationally indexed e -reflections in the diffraction pattern, e -labradorite shows the largest v...
Published in: | Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials |
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Online Access: | http://www.osti.gov/servlets/purl/1631226 https://www.osti.gov/biblio/1631226 https://doi.org/10.1107/S2052520619017128 |
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ftosti:oai:osti.gov:1631226 2023-07-30T04:03:55+02:00 The incommensurately modulated structures of low-temperature labradorite feldspars: a single-crystal X-ray and neutron diffraction study Jin, Shiyun Xu, Huifang Wang, Xiaoping Jacobs, Ryan Morgan, Dane 2021-01-29 application/pdf http://www.osti.gov/servlets/purl/1631226 https://www.osti.gov/biblio/1631226 https://doi.org/10.1107/S2052520619017128 unknown http://www.osti.gov/servlets/purl/1631226 https://www.osti.gov/biblio/1631226 https://doi.org/10.1107/S2052520619017128 doi:10.1107/S2052520619017128 36 MATERIALS SCIENCE 2021 ftosti https://doi.org/10.1107/S2052520619017128 2023-07-11T09:43:10Z Labradorite feldspars of the plagioclase solid solution series have been known for their complicated subsolidus phase relations and enigmatic incommensurately modulated structures. Characterized by the irrationally indexed e -reflections in the diffraction pattern, e -labradorite shows the largest variation in the incommensurate ordering states among the e -plagioclase structures. The strongly ordered low-temperature e -labradorite is one of the last missing pieces of the e -plagioclase puzzle. Nine plutonic and metamorphic labradorite feldspar samples from Canada, Ukraine, Minnesota (USA), Tanzania and Greenland with compositions ranging from An 52.5 to An 68 were studied with single-crystal X-ray diffraction. Two crystals from Labrador, Canada, and Duluth, MN, USA, with wide enough twin lamellae were analyzed with single-crystal neutron diffraction. The incommensurately modulated structures of e -plagioclase are refined for the first time with neutron diffraction data, which confirmed that the T—O distance modulation in the low-temperature e -plagioclase results from the Al–Si ordering in the framework. Detailed configurations of the M site are also observed in the structures refined from neutron diffraction data, which were not possible to see with X-ray diffraction data. The relation between the q -vectors and the mole% An composition is revealed for the entire compositional range of e -plagioclase, from An 25 to An 75 . The previously proposed two-trend relation depending on the cooling rate and phase transition path is confirmed. A new classification of e -plagioclase ( e α , e β and e γ ) is proposed based on the q -vector of the structure, which makes it an independent character from the presence/absence of density modulation. New parameters are proposed to quantify the ordering states of these complicated aperiodic structures of e -plagioclases, such as the difference between $\langle$T 1 o—O$\rangle$ and $\langle$T 1 m—O$\rangle$ at phase t = 0.2 or the normalized intensity of the (071\bar 1) ... Other/Unknown Material Greenland SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) Canada Greenland Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 76 1 93 107 |
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SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) |
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36 MATERIALS SCIENCE |
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36 MATERIALS SCIENCE Jin, Shiyun Xu, Huifang Wang, Xiaoping Jacobs, Ryan Morgan, Dane The incommensurately modulated structures of low-temperature labradorite feldspars: a single-crystal X-ray and neutron diffraction study |
topic_facet |
36 MATERIALS SCIENCE |
description |
Labradorite feldspars of the plagioclase solid solution series have been known for their complicated subsolidus phase relations and enigmatic incommensurately modulated structures. Characterized by the irrationally indexed e -reflections in the diffraction pattern, e -labradorite shows the largest variation in the incommensurate ordering states among the e -plagioclase structures. The strongly ordered low-temperature e -labradorite is one of the last missing pieces of the e -plagioclase puzzle. Nine plutonic and metamorphic labradorite feldspar samples from Canada, Ukraine, Minnesota (USA), Tanzania and Greenland with compositions ranging from An 52.5 to An 68 were studied with single-crystal X-ray diffraction. Two crystals from Labrador, Canada, and Duluth, MN, USA, with wide enough twin lamellae were analyzed with single-crystal neutron diffraction. The incommensurately modulated structures of e -plagioclase are refined for the first time with neutron diffraction data, which confirmed that the T—O distance modulation in the low-temperature e -plagioclase results from the Al–Si ordering in the framework. Detailed configurations of the M site are also observed in the structures refined from neutron diffraction data, which were not possible to see with X-ray diffraction data. The relation between the q -vectors and the mole% An composition is revealed for the entire compositional range of e -plagioclase, from An 25 to An 75 . The previously proposed two-trend relation depending on the cooling rate and phase transition path is confirmed. A new classification of e -plagioclase ( e α , e β and e γ ) is proposed based on the q -vector of the structure, which makes it an independent character from the presence/absence of density modulation. New parameters are proposed to quantify the ordering states of these complicated aperiodic structures of e -plagioclases, such as the difference between $\langle$T 1 o—O$\rangle$ and $\langle$T 1 m—O$\rangle$ at phase t = 0.2 or the normalized intensity of the (071\bar 1) ... |
author |
Jin, Shiyun Xu, Huifang Wang, Xiaoping Jacobs, Ryan Morgan, Dane |
author_facet |
Jin, Shiyun Xu, Huifang Wang, Xiaoping Jacobs, Ryan Morgan, Dane |
author_sort |
Jin, Shiyun |
title |
The incommensurately modulated structures of low-temperature labradorite feldspars: a single-crystal X-ray and neutron diffraction study |
title_short |
The incommensurately modulated structures of low-temperature labradorite feldspars: a single-crystal X-ray and neutron diffraction study |
title_full |
The incommensurately modulated structures of low-temperature labradorite feldspars: a single-crystal X-ray and neutron diffraction study |
title_fullStr |
The incommensurately modulated structures of low-temperature labradorite feldspars: a single-crystal X-ray and neutron diffraction study |
title_full_unstemmed |
The incommensurately modulated structures of low-temperature labradorite feldspars: a single-crystal X-ray and neutron diffraction study |
title_sort |
incommensurately modulated structures of low-temperature labradorite feldspars: a single-crystal x-ray and neutron diffraction study |
publishDate |
2021 |
url |
http://www.osti.gov/servlets/purl/1631226 https://www.osti.gov/biblio/1631226 https://doi.org/10.1107/S2052520619017128 |
geographic |
Canada Greenland |
geographic_facet |
Canada Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_relation |
http://www.osti.gov/servlets/purl/1631226 https://www.osti.gov/biblio/1631226 https://doi.org/10.1107/S2052520619017128 doi:10.1107/S2052520619017128 |
op_doi |
https://doi.org/10.1107/S2052520619017128 |
container_title |
Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials |
container_volume |
76 |
container_issue |
1 |
container_start_page |
93 |
op_container_end_page |
107 |
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1772815055047360512 |