Modulation/Satellite Reflections
due to Mutually Commensurate Mismatch
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An example of misfit layer chalcogenides with NaCl-type H layer is La1.2CrS3.2 [1 - 2] with a periodical stacking of  H (CrS2) and Q (LaS) layers. The repeat distance along the a axis, i.e. along the misfit direction, is different for each layer, being the coincidence unit cell 3 × aQ = 5 × aH as indicated in the electron diffraction pattern in Figure 3466a. Their mutual mismatch induces a modulation (i.e. represented by the satellite reflections), in this commensurate case, shown by the small arrows.

Electron diffraction pattern from a crystal of LaCrS3 oriented along the [001] zone axis

Figure 3466a. Electron diffraction pattern from a crystal of LaCrS3 oriented along the [001] zone axis. [3]

 

 

 



[1] Kato, K., Kawada, I., Takahashi, T., 1977. Die Kristallstruktur von LaCrS3. Acta Cryst. B 33, 3437 - 3443.
[2] Otero-Díaz, L.C., Fitzgerald, J.D., Williams, T.B., Hyde, B.G., 1985. On the monoclinic binary-layer compound `LaCrS3'. Acta Cryst. B 41, 405 - 410.
[3] A.R. Landa-Cánovas, A. Gómez-Herrero, L. Carlos Otero-Díaz, Electron microscopy study of incommensurate modulated structures in misfit ternary chalcogenides, Micron 32 (2001) 481 - 495.

 

 

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