Pseudo-orthogonal cell

The rather limited crystallinity of PPP produced by the Kovacic route, which can be increased to 60% by annealing above 400°C, has been an obstacle to the determination of the unit cell. Well-oriented diffraction patterns have only been obtained in electron diffraction studies. Nonetheless, Kovacic et al. [169] have laid down the basic aspects of the structure and its problems in their very original work, which included an x-ray study. Their indexing scheme for the reflections has been verified in several later studies. The authors propose a pseudo-orthogonal cell with two chains passing through, and dimensions o = 7.81 A, h =... 

Figure 19. Projection onto the (001) plane of the primitive, conventional (double, monoclinic), pseudo-hexagonal (triple), Ci (sextuple, pseudo-orthohexagonal) and pseudoto c axis of the orthogonal cell-rhombohedral (primitive) cells of Class b polytypes.

N number of layers in the unit cell of the (pseudo)-orthohexagonal setting N = N for orthogonal polytypes, TV = 3TV for non-orthogonal polytypes T, character ( 0 5 ) indicating the mica OD packet orientation... 

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