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- Title
The modulated structure of labradorite.
- Authors
Boysen, Hans; Kek, Stefan
- Abstract
The crystal structure of labradorite is characterized by two modulation waves with largely different periods of about 1500 Å and 50 Å, giving rise to s- and e-satellites, respectively. The problems to determine the true structure by diffraction methods are discussed. Since each s-lamella has its own e-modulation, common experiments are not sufficient. Using only s-satellites around main reflections assumes e-averaged structures of the s-lamellae. On the other hand, using only averaged e-satellites and main reflections integrated over the s-satellites leads to a hypothetical, idealised structure such as if there were no s-modulation. For this reason the analysis of an extensive data set, including e-satellites up to third order, cannot resolve the Ca/Na modulation unambiguously, although the Si/Al modulation can be determined consistently from directly refined occupancies and T-O bond lengths.
- Subjects
STRUCTURAL analysis (Engineering); MODULATION spectroscopy; SILICON compounds; LAMELLARIIDAE; ALUMINUM
- Publication
Zeitschrift für Kristallographie. Crystalline Materials, 2015, Vol 230, Issue 1, p23
- ISSN
2194-4946
- Publication type
Article
- DOI
10.1515/zkri-2014-1749