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Further study of the cation ordering in phengite 3T by neutron powder diffraction

Published online by Cambridge University Press:  25 June 2018

A. Pavese ,
G. Ferraris ,
V. Pischedda  and
P. Radaelli
A. Pavese*
Affiliation:
Dipartimento di Scienze della Terra, Università di Milano, Via Botticelli 23, I-20133 Milano, Italy National Research Council, CNR, Centro di Studio per la Geodinamica Alpina e Quaternaria, Via Mangiagalli 34, 20133 Milano, Italy
G. Ferraris
Affiliation:
Dipartimento di Scienze Mineralogiche e Petrologiche, Università di Torino, Via Valperga Caluso 35, I-10125 Torino, Italy
V. Pischedda
Affiliation:
Dipartimento di Scienze Mineralogiche e Petrologiche, Università di Torino, Via Valperga Caluso 35, I-10125 Torino, Italy
P. Radaelli
Affiliation:
ILL Facility, Institut Laue-Langevin, 38042 Grenoble, France
*
*E-mail: pavese@p8000.terra.unimi.it
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Abstract

Phengite 3T (Dora-Maira massif, Italian western Alps), with chemical composition K0.96Na0.01Al1.44Mg0.56(Si3.59 Al0.41)O10(OH)2 has been investigated using powder neutron diffraction, at the ILL (Institut Laue-Langevin) Facility, on the D2B diffractometer. Data sets were collected at 293 and 873 K, and the present results are compared with those obtained previously using the time-of-flight (TOF) technique, on the same compound. In the octahedral sheet, Al tends to order into the M2 site, in accordance with the measurements mentioned above, whereas the Al/Si tetrahedral ordering we observe (i.e. Si fully into T1 site) is at variance with that determined previously. These discrepancies are ascribed to the presence of talc impurities in the sample used previously (∼6 wt.%), which affected the results obtained.

Keywords

neutron powder diffractionphengite 3TDora-Mairatetrahedral and octahedral orderRietveld refinement
Type
Research Article
Information
Mineralogical Magazine , Volume 64 , Issue 1 , February 2000 , pp. 11 - 18
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2000

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Footnotes

†

Present address: ISIS Facility, Rutherford Appleton Laboratory, Chilton-Didcot, Oxon OX11 0QX, UK

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