A transmission electron microscopy (TEM) investigation was undertaken in order to elucidate the nature of the structural disorder in a tobelite specimen from the sedimentary rocks of the Armorican sandstones (western France). This structural disorder may be the origin of residual electron-density maxima in difference-Fourier maps reported previously in single-crystal XRD studies of tobelite. The TEM investigation of tobelite confirmed that it is the 2M2 polytype in subfamily-B, but the ordered sequence is interrupted by numerous stacking faults parallel to (001), for which the stacking vectors belong to both subfamilies-A and -B of mica polytypes, with a prevalence of the latter. Chemical heterogeneity depending on the Si/Al ratio and Na and Mg concentration was observed at the nanoscale among different mica lamellae in a single crystal. The observed variations are consistent with a change in mica chemistry leading to interlayer vacancies which may cause shortening of the interlayer separation, as revealed by the single-crystal structure refinements.
Capitani, G., Schingaro, E, L., M, M., & E, S. (2016). Structural anomalies in tobelite-2M2 explained by high resolution and analytical electron microscopy. MINERALOGICAL MAGAZINE, 80(1), 143-156 [10.1180/minmag.2015.079.7.14].
Citazione: | Capitani, G., Schingaro, E, L., M, M., & E, S. (2016). Structural anomalies in tobelite-2M2 explained by high resolution and analytical electron microscopy. MINERALOGICAL MAGAZINE, 80(1), 143-156 [10.1180/minmag.2015.079.7.14]. | |
Tipo: | Articolo in rivista - Articolo scientifico | |
Carattere della pubblicazione: | Scientifica | |
Presenza di un coautore afferente ad Istituzioni straniere: | No | |
Titolo: | Structural anomalies in tobelite-2M2 explained by high resolution and analytical electron microscopy | |
Autori: | Capitani, G; Schingaro; E, Lacalamita; M, Mesto; E, Scordari, F | |
Autori: | ||
Data di pubblicazione: | 2016 | |
Lingua: | English | |
Rivista: | MINERALOGICAL MAGAZINE | |
Digital Object Identifier (DOI): | http://dx.doi.org/10.1180/minmag.2015.079.7.14 | |
Appare nelle tipologie: | 01 - Articolo su rivista |