A TEM study of long-period mica polytypes: determination of the stacking sequence of oxybiotite by means of atomic resolution images and Periodic Intensity Distribution (PID).
In this study it is shown that the stacking sequences in long-period mica polytypes (including a rare example of a mixed-rotation polytype, with a 36-layer long periodicity) can be unambiguously determined using atomic resolution images recorded down two zone axes separated by 30 degrees (e.g. [100] and [31;0]) at the same area. Uniformity of these stacking sequences in a large area is further confirmed by the correspondence between computed and observed Periodic Intensity Distributions (PIDs) in electron diffraction patterns. The appearance of long-period polytypes containing layers with different orientation parity may be explained by the coalescence of two small crystals during crystal growth.
Kogure
T
Mineralogical Institute, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. kogure@min.s.u-tokyo.ac.jp
Nespolo
M