Original paper

Powder neutron diffraction study of 2M1 muscovite at room pressure and at 2 GPa

Catti, Michele; Ferraris, Giovanni; Hull, Steve; Pavese, Alessandro

European Journal of Mineralogy Volume 6 Number 2 (1994), p. 171 - 178

16 references

published: Mar 31, 1994
manuscript accepted: Dec 21, 1993
manuscript received: Jun 7, 1993

DOI: 10.1127/ejm/6/2/0171

BibTeX file

ArtNo. ESP147050602001, Price: 29.00 €

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Abstract

Abstract A powder sample of 2M\ muscovite, (K0.90Na0.07)(Al1.63Fe0.23Mg0.16Ti0.83)(Si3.20Al0.80)O10(OH)2, was studied by time-of-flight neutron diffraction at 1 bar and at 2(± 0.1) GPa. Rietveld refinements of the crystal structure were performed, varying all atomic coordinates in the room-pressure case (profile i?w = 0.013, Bragg intensities Rw = 0.040) and only the z coordinates of basal O atoms plus xyz of O and H of the OH group at 2 GPa (profile i?w = 0.035, Bragg intensities Rw = 0.181). In both cases the lattice constants were refined: a = 5.2108(4), b = 9.0399(8), c = 20.021(2) Å, β = 95.76(1)° (1 bar), a = 5.187(2), b = 8.995(4), c = 19.502(4) A, β = 95.78(2)° (2 GPa). The unit-cell compression shows deviations from linear elastic behaviour. Inter-layer K-O bonds are compressed along z more than the c lattice constant. The O-H group forms an angle of 85(1)° with c* and establishes three very loose contacts (H..O from 2.62 to 2.67 A) with neighbouring O atoms. This environment does not change appreciably at 2 GPa.

Keywords

muscovitehigh-pressureneutron diffraction