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Title: Cation distribution in a Fe-bearing K-feldspar from Itrongay,Madagascar. A combined neutron- and X-ray single crystal diffractionstudy

Abstract

We determined the cation distribution and ordering of Si, Al and Fe on the tetrahedral sites of a monoclinic low-sanidine from Itrongay, Madagascar, by combined neutron- and X-ray single-crystal diffraction. The cation distribution was determined by means of a simultaneous refinement using neutron- and X-ray data, as well as by combining scattering densities obtained from separate refinements with chemical data from a microprobe experiment. The two methods give the same results and show that Fe is fully ordered on T1, whereas Al shows a high degree of disorder. Based on this and previously published temperature-dependent X-ray data, we conclude that it is preferential ordering of Fe on T1 even at high temperature, rather than a high diffusion kinetics of Fe, which causes this asymmetry in ordering behavior between Al and Fe. The preferential ordering of Fe3+ relative to Al3+ in T1 is consistent with its 25 percent larger ionic radius.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Director. Office of Science. Office of Basic EnergySciences
OSTI Identifier:
888754
Report Number(s):
LBNL-57466
R&D Project: A58189; BnR: KC0204016; TRN: US200622%%123
DOE Contract Number:  
DE-AC02-05CH11231
Resource Type:
Journal Article
Journal Name:
Schweizaerische Mineralogische und Petrographische Mitteilungen
Additional Journal Information:
Journal Volume: 84; Journal Issue: 3; Related Information: Journal Publication Date: 2004
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; ASYMMETRY; CATIONS; DIFFRACTION; DIFFUSION; DISTRIBUTION; KINETICS; MADAGASCAR; MONOCRYSTALS; SCATTERING; K-feldspar cation distribution neutron diffraction X-raydiffraction Cation distribution in a Fe-bearing K-feldspar

Citation Formats

Ackermann, Sonia, Kunz, Martin, Armbruster, Thomas, Schefer, Jurg, and Hanni, Henry. Cation distribution in a Fe-bearing K-feldspar from Itrongay,Madagascar. A combined neutron- and X-ray single crystal diffractionstudy. United States: N. p., 2005. Web.
Ackermann, Sonia, Kunz, Martin, Armbruster, Thomas, Schefer, Jurg, & Hanni, Henry. Cation distribution in a Fe-bearing K-feldspar from Itrongay,Madagascar. A combined neutron- and X-ray single crystal diffractionstudy. United States.
Ackermann, Sonia, Kunz, Martin, Armbruster, Thomas, Schefer, Jurg, and Hanni, Henry. 2005. "Cation distribution in a Fe-bearing K-feldspar from Itrongay,Madagascar. A combined neutron- and X-ray single crystal diffractionstudy". United States. https://www.osti.gov/servlets/purl/888754.
@article{osti_888754,
title = {Cation distribution in a Fe-bearing K-feldspar from Itrongay,Madagascar. A combined neutron- and X-ray single crystal diffractionstudy},
author = {Ackermann, Sonia and Kunz, Martin and Armbruster, Thomas and Schefer, Jurg and Hanni, Henry},
abstractNote = {We determined the cation distribution and ordering of Si, Al and Fe on the tetrahedral sites of a monoclinic low-sanidine from Itrongay, Madagascar, by combined neutron- and X-ray single-crystal diffraction. The cation distribution was determined by means of a simultaneous refinement using neutron- and X-ray data, as well as by combining scattering densities obtained from separate refinements with chemical data from a microprobe experiment. The two methods give the same results and show that Fe is fully ordered on T1, whereas Al shows a high degree of disorder. Based on this and previously published temperature-dependent X-ray data, we conclude that it is preferential ordering of Fe on T1 even at high temperature, rather than a high diffusion kinetics of Fe, which causes this asymmetry in ordering behavior between Al and Fe. The preferential ordering of Fe3+ relative to Al3+ in T1 is consistent with its 25 percent larger ionic radius.},
doi = {},
url = {https://www.osti.gov/biblio/888754}, journal = {Schweizaerische Mineralogische und Petrographische Mitteilungen},
number = 3,
volume = 84,
place = {United States},
year = {Mon May 02 00:00:00 EDT 2005},
month = {Mon May 02 00:00:00 EDT 2005}
}