Abstract
As part of an electron microscopic study of plagioclase, displacement vectors for b- and c-domains have been determined from contrast experiments and calculations. In lunar anorthite from breccia 15459 (An 94.9), b-domains could be imaged in dark field with b-reflections and c-domains with c-reflections. The vector corresponding to these contrast conditions is 1/2[110] for b-domains and 1/2[111] for c-domains. The face centering vector 1/2 [110] relates two domains with a reverse Al/Si arrangement. The body-centering vector 1/2[111] relates domains of identical Al/Si distribution but different atomic coordinates. Fringe patterns for c-domains have been obtained for Pasmeda anorthite. Calculated intensity profiles applying multi-beam dynamic theory and a 1/2[111] displacement vector are in agreement with the observations.
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Müller, W.F., Wenk, H.R., Bell, W.L. et al. Analysis of the displacement vectors of antiphase domain boundaries in anorthites (CaAl2Si2O8). Contr. Mineral. and Petrol. 40, 63–74 (1973). https://doi.org/10.1007/BF00371764
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DOI: https://doi.org/10.1007/BF00371764