MgSiO3 Perovskite: A HRTEM Study

Ishmael Hassan, Yasuhiro Kudoh, Peter R. Buseck and Eui Ito
Department of Geology, Faculty of Science, University of Kuwait, P. O. Box 5969, Safat, Kuwait, 13060
Department of Petrology, Mineralogy, and Economic Geology, University of Tohoku, Aobaku, Sendai 980, Japan
Departments of Geology and Chemistry, Arizona State University, Tempe, Arizona 85287, U.S.A.
Institute for Study of the Earth's Interior, Okayama University, Misasa, Tottori 682-02, Japan

Abstract: Selected-area electron diffraction patterns for the [110] zone of MgSiO3 perovskite are consistent with the orthorhombic unit cell obtained by X-ray diffraction (a = 4.775, b = 4.929, c = 6.897 Å). Various areas of a crystal fragment show diffuse streaking along c*, and well-developed satellite reflections that give a 3-fold repeat along [11¯0]*. Another fragment shows doubled cell dimensions when viewed down [1¯30]. The variable occurrence of the satellite reflectioncs and diffuse streaking indicate subtle variations in ordering, chemistry, or both. Images obtained by high-resolution transmission electron microscopy contain perfectly ordered regions, out-of-phase boundaries, and intergrowths of the two orthorhombic forms of perovskite.

Keywords: MgSiO3 perovskite • HRTEM • satellite reflections • intergrowth • out-of-phase boundaries

Mineralogical Magazine; October 1996 v. 60; no. 402; p. 799-804; DOI: 10.1180/minmag.1996.060.402.10
© 1996, The Mineralogical Society
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