Summary
High resolution electron micrographs have been obtained from crystals of two types of tourmaline, aligned in a goniometer stage so that the electron beam is parallel to thec axis. Images having a resolution of about 3 Å taken out of focus show direct indications of the atomic arrangement; they suggest medium-range ordering of the metal atoms in buergerite and unexpectedh31l symmetry in elbaite-schorl solid solution. The appearance of ordering is tentatively explained in terms of electron-irradiation effects.
Zusammenfassung
Hochauflösende Elektronen-Mikrographien wurden von zwei Typen von Turmalinkristallen, die auf einer Goniometereinrichtung so orientiert waren, daß der Elektronenstrahl parallel zurc-Achse verlief, erhalten. Bilder mit einer 3 Å-Auflösung, die entfokusiert aufgenommen wurden, geben direkte Hinweise auf die Atomanordnung; sie deuten auf Ordnung mittlerer Reichweite der Metallatome in Buergerit und zeigen unerwarteterweiseh31l-Symmetrie bei Elbait-Schörl-Mischkristallen. Das Auftreten von Ordnung wird als vermutlicher Elektronenbestrahlungseffekt gedeutet.
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References
Barton, R., Jr., 1969: Refinement of the crystal structure of buergerite and the absolute orientation of tourmalines. Acta Cryst.B25, 1524–1532.
Cowley, J. M., 1971: Short-range ordering in crystals; in Advances in High Temperature Chemistry (LeRoy Eyring, ed.), New York: Academic Press, 35–85.
— andS. Iijima, 1972: Electron microscope image contrast for thin crystals. Z. Naturforsch.27, 445–451.
Gjønnes, J., andA. F. Moodie, 1965: Extinction conditions in the dynamic theory of electron diffraction. Acta Cryst.19, 65–67.
Hermon, E., D. J. Simkin, G. Donnay, andW. B. Muir, 1973: The distribution of Fe2+ and Fe3+ in iron-bearing tourmalines: a Mössbauer study. Tschermaks Min. Petr. Mitt.19, 124–132.
Iijima, S., 1971: High resolution electron microscopy of crystal lattice of titanium-niobium oxide. J. Appl. Phys.42, 5891–5893.
—, 1973: Direct observation of lattice defects inH-Nb2O5 by high resolution electron microscopy. Acta Cryst.A 29, 18–24.
Iijima, S. andJ. G. Allpress, 1973: Structural studies by electron microscopy: high resolution observation on 4Nb2O5·9WO3 and 2Nb2O5·7WO3. Acta Cryst. In press.
Iijima, S., S. Kimura, andM. Goto, 1973: Direct observation of point defects in Nb12O29 by high resolution electron microscopy. Acta Cryst. In press.
Tippe, A., andW. C. Hamilton, 1971: A neutron-diffraction study of the ferric tourmaline buergerite. Amer. Min.56, 101–113.
Tsang, T., A. N. Thorpe, G. Donnay, andF. E. Senftle, 1971: Magnetic susceptibility and triangular exchange coupling in the tourmaline mineral group. J. Phys. Chem. Solids32, 1441–1448.
Wagner, C. E., C. O. Pollard, R. A. Young, andG. Donnay, 1971: Texture variations in color-zoned tourmaline crystals. Amer. Min.56, 114–132.
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Iijima, S., Cowley, J.M. & Donnay, G. High resolution electron microscopy of tourmaline crystals. TMPM Tschermaks Petr. Mitt. 20, 216–224 (1973). https://doi.org/10.1007/BF01081921
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DOI: https://doi.org/10.1007/BF01081921