** Next:** Examples of Some Close-Packed Structures
**Up:** Notations Used for Representing Close-Packed Structures
** Previous:** (c) Zhdanov notation

In the h-c notation, used by Pauling^{12}, Wyckoff^{13} and
Jagodzinski^{14}, 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 6*H* 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 energies^{15}.

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 |

2H |
AB | (11) | h |

3C |
ABC | c | |

4H |
ABCB | (22) | hc |

6H _{1} |
ABCACB | (33) | hcc |

6H _{2} |
ABCBAB | (2211) | hchchh |

9R |
ABACACBCB | (12) | hhc |

**Copyright © 1981, 1997 International Union of
Crystallography**