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In the h-c notation, used by Pauling12, Wyckoff13 and Jagodzinski14, one specifies each layer in terms of the orientation of layers above and below it. A layer is said to be in hexagonal configuration and is denoted as `h` if it is surrounded on either side by layers in similar orientations. A layer is said to be in cubic configuration and is denoted as `c` if it is surrounded on either side by layers in different orientations. Thus the 6H SiC structure with stacking sequence ABCACB can be written as hcchcc in the h-c notation. This notation is specially useful in dealing with X-ray diffraction effects from faulted structures and for calculating stacking fault energies15.
It is quite easy to transform from one notation to another. For this it is convenient to write first the complete ABC sequence of the structure and then express this in the desired notation. Some close-packed structures expressed in different notations are listed in Table 2.
|Ramsdell notation||ABC sequence||Zhdanov number||h-c notation|
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