The stacking faults observed in the structure of the mineral lizardite 1T belonging to the polytype group A were investigated by using digital oblique-texture electron diffraction patterns, difference Fourier-potential maps, and model diffraction patterns for this compound. Numerical simulation of the diffraction profiles along the first (the 02l and 11l reflections) and second (the 20l and 13l reflections) ellipses in the oblique-texture electron diffraction patterns was performed for finite sequences of 10 layers using the Markovian statistical model in the quasi-homogeneous approximation. The specific features of the intensity distributions along the first and second ellipses were associated with the manifestation of translational (displacements of the layers by ±b/3) and orientational (rotations of the layers through an angle of 180°) defects of the layer stacking, respectively. For both ellipses, the experimentally observed intensity distributions were in best agreement with diffraction profiles calculated for stacking faults at a content of approximately 25%, a short-range order parameter of 1, and a maximum degree of ordering in the layer alternation. It was demonstrated that the irregularities revealed in the layer alternation in the structure of lizardite 1T (which was characterized by an identical orientation of the adjacent layers) arose from layer displacements by ±b/3 and, to a considerable extent, from the formation of sequences with opposite orientations of the adjacent layers. As a result, the structure of lizardite 1T nanocrystals involved a combination of layer sequences that were typical of structures belonging to the polytype groups A and D.

Electron Diffraction Study of Lizardite 1T with Stacking Faults. A.P.Zhukhlistov: Crystallography Reports, 2007, 52[2], 208-14