# Difference between revisions of "Weiss parameters"

### From Online Dictionary of Crystallography

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− | The '''Weiss parameters''', introduced by Christian Samuel Weiss in | + | The '''Weiss parameters''', introduced by Christian Samuel Weiss in 1817, are the ancestors of the [[Miller indices]]. They give an approximate indication of a face orientation with respect to the crystallographic axes, and were used as a symbol for the face. |

Weiss parameters are the reciprocal of Miller indices, each followed by the corresponding axis symbols. | Weiss parameters are the reciprocal of Miller indices, each followed by the corresponding axis symbols. | ||

'''Example'''. Weiss parameters 2a:3b:1c indicate that a face intercepts the '''a''' axis at twice the a<sub>o</sub> units and the '''b''' axis at three times b<sub>o</sub> units as it cuts the '''c''' axis in c<sub>o</sub> units. The first plane of the family to which this face belongs has intercepts at 1/3, 1/2 and 1/6 on '''a''', '''b''', and '''c''' respectively, so that the corresponding Miller indices are (326). | '''Example'''. Weiss parameters 2a:3b:1c indicate that a face intercepts the '''a''' axis at twice the a<sub>o</sub> units and the '''b''' axis at three times b<sub>o</sub> units as it cuts the '''c''' axis in c<sub>o</sub> units. The first plane of the family to which this face belongs has intercepts at 1/3, 1/2 and 1/6 on '''a''', '''b''', and '''c''' respectively, so that the corresponding Miller indices are (326). | ||

+ | |||

+ | === Reference === | ||

+ | Weiss, C.S. (1817). Ueber eine verbesserte Methode für die Bezeichung der verschiedenen Flächen eines Krystallisationssystemes; nebst Bemerkungen über den Zustand von Polarisierung der Seiten in den Linien der krystallinischen Structur. ''Abhandlungen der Königlichen Akademie der Wissenschaften in Berlin'', 286-336 ([https://babel.hathitrust.org/cgi/pt?id=umn.31951d00016117y;view=1up;seq=304 digitized version available online]). | ||

[[Category:History of crystallography]] | [[Category:History of crystallography]] | ||

[[Category:Morphological crystallography]] | [[Category:Morphological crystallography]] |

## Revision as of 12:07, 12 April 2017

Paramètres de Weiss (*Fr*). Weiss-Parameter (*Ge*). Parámetros de Weiss (*Sp*). Параметры Вайс (*Ru*). Parametri di Weiss (*It*). ワイスパラメーター (*Ja*)

The **Weiss parameters**, introduced by Christian Samuel Weiss in 1817, are the ancestors of the Miller indices. They give an approximate indication of a face orientation with respect to the crystallographic axes, and were used as a symbol for the face.

Weiss parameters are the reciprocal of Miller indices, each followed by the corresponding axis symbols.

**Example**. Weiss parameters 2a:3b:1c indicate that a face intercepts the **a** axis at twice the a_{o} units and the **b** axis at three times b_{o} units as it cuts the **c** axis in c_{o} units. The first plane of the family to which this face belongs has intercepts at 1/3, 1/2 and 1/6 on **a**, **b**, and **c** respectively, so that the corresponding Miller indices are (326).

### Reference

Weiss, C.S. (1817). Ueber eine verbesserte Methode für die Bezeichung der verschiedenen Flächen eines Krystallisationssystemes; nebst Bemerkungen über den Zustand von Polarisierung der Seiten in den Linien der krystallinischen Structur. *Abhandlungen der Königlichen Akademie der Wissenschaften in Berlin*, 286-336 (digitized version available online).