Ramsdell notation

Ramsdell notation Zhdanov notation Stacking sequence ... 

From the examples above it is evident that 1) the homo-octahedral approximation corresponds to applying to a polytype the relation of homomorphy 2) in micas, the classical Ramsdell notation rigorously applies to homo-octahedral polytypes only. 

TABLE 1 Seven of the most simple SiC polytypes with four notations (R = Ramsdell notation, J = Jagodzinski notation, Z = Zhadanov notation). They are listed by increasing percent hexagonality. 

Notice the use of the Ramsdell notation. This example is more complicated than in Section 6.13 because the chemistry is also changing. 

The layer sequence of the 111 plane is ABCABCABC which means that every third layer is identical (Fig. 7.3).1 1 This gives a Ramsdell notation of 3C SiC where the numeral 3 refers to the number of layers of carbon atoms and silicon atoms necessary to produce a unit cell and C indicates cubic symmetry. It is analogous to the diamond structure and is also the structure of cubic boron nitride (see Ch. 12). 

Structure Strukturbericht Stacking sequence Lattice parameters Ramsdell notation... 

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