Electronic Resource
[S.l.]
:
International Union of Crystallography (IUCr)
Acta crystallographica
37 (1981), S. 754-762
ISSN:
1600-5724
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
A new type of satellite has been observed in plagioclases CaxNa1 - x[Al1 + xSi3 - xO8] with 0.5 ≤ x ≤ 1. Their intensities are such that they could be observed only by applying a special focusing technique. They appear in the neighbourhood of some strong reflections with h + k = 2n, l = 2n. It is shown that the new satellites are most probably caused by a three-dimensional array of domains of two structures, differing only by small displacements of the atoms. Since the translation lattices of the two structures have the same geometry it is concluded that the two structures are twins of an acentric plagioclase correlated with a centre of symmetry. The size of the domains is 80 Å approximately. The diffraction of such submicroscopically intergrown twins is calculated for lamellae and blocks and compared qualitatively with the experimental results. The approximate periodicity of the domains could be destroyed by very long exposure to X-rays.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0567739481001642
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