crystallography Crystallography is the branch of science devoted to the study of molecular and crystalline structure and properties. The word ''crystallography'' is derived from the Ancient Greek word (; "clear ice, rock-crystal"), and (; "to write"). In J ...

, a Greninger chartIt is named after Alden Buchanan Greninger (17 September 1907,

Glendale, Oregon Glendale is a city in Douglas County, Oregon, United States. The population was 874 at the 2010 census. History After construction of a railroad line south from Roseburg in 1881–83, Solomon Abraham, the local right-of-way agent, platted th ...

20 April 1998). is a

chart A chart (sometimes known as a graph) is a graphics, graphical representation for data visualization, in which "the data is represented by symbols, such as bars in a bar chart, lines in a line chart, or slices in a pie chart". A chart can repres ...

that allows angular relations between zones and planes in a

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

to be directly read from an

x-ray diffraction X-ray diffraction is a generic term for phenomena associated with changes in the direction of X-ray beams due to interactions with the electrons around atoms. It occurs due to elastic scattering, when there is no change in the energy of the waves. ...

photograph. The Greninger chart is a simple trigonometric tool to determine ''g'' and ''d'' for a fixed sample-to-film distance. (If one uses a 2-d detector the problem of determining ''g'' and ''d'' could be solved mathematically using the equations which generate the Greninger chart) A new chart must be generated for different sample to detector distances. (2''s'' is 2''q'' for the diffraction peak and tan ''m'' is ''x''/''y'' for the Cartesian coordinates of the diffraction peak.) The Greninger chart gives directly the two angles needed to plot poles on the

Wulff net In mathematics, a stereographic projection is a perspective projection of the sphere, through a specific point on the sphere (the ''pole'' or ''center of projection''), onto a plane (the ''projection plane'') perpendicular to the diameter thr ...

. It is critical to keep track of the relative arrangement of the sample to the film, if photographic film is used then this is achieved by cutting the corner of the film. For Polaroid film one must make a note of the arrangement of the face of the film in the camera.

References

Sources

* Greninger A. B. (1935). ''Zeitschrift für Kristallographie'' 91: 424.

External links

* http://www.answers.com/topic/greninger-chart * http://www.eng.uc.edu/~gbeaucag/Classes/XRD/Labs/Lab3Laue.html {{Webarchive, url=https://web.archive.org/web/20100618150942/http://www.eng.uc.edu/%7Egbeaucag/Classes/XRD/Labs/Lab3Laue.html , date=2010-06-18 * http://www-xray.fzu.cz/xraygroup/www/grchart.html Trigonometry X-rays Diffraction

See also

References

Sources

External links