International
Tables for
Crystallography
Volume H
Powder diffraction
Edited by C. J. Gilmore, J. A. Kaduk and H. Schenk

International Tables for Crystallography (2018). Vol. H, ch. 2.1, pp. 26-27

Section 2.1.3.1.1. Film cameras

A. Kerna*

aBruker AXS, Östliche Rheinbrückenstrasse 49, Karlsruhe 76187, Germany
Correspondence e-mail: arnt.kern@bruker-axs.de

2.1.3.1.1. Film cameras

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Powder diffraction analysis started with the development of simple film cameras, right after von Laue formulated his basic diffraction theory and the Braggs, father and son, laid down the foundations of crystal structure analysis, in the years 1912–1914. The first and simplest cameras were developed independently by Debye & Scherrer (1916[link]) and Hull (1917[link]), using a film to detect the scattered X-rays, with the instrument geometry termed `Debye–Scherrer geometry'. The basic drawback of Debye–Scherrer cameras was their lack of resolution. Consequently, since standard X-ray tubes readily produce divergent beams, the next evolutionary step was to employ self-focusing geometries, as first proposed independently by Seemann (1919[link]) and Bohlin (1920[link]), termed `Seemann–Bohlin geometry'. In addition to significantly improved resolution, the intensity was also greatly increased by using a para-focusing arrangement using an X-ray source and specimen with finite width (line focus). Guinier (1937[link]) extended the Seemann–Bohlin geometry using an incident-beam monochromator. Although the monochromator significantly reduced the intensity, this disadvantage was overcompensated for by improved beam conditioning, leading to unparalleled resolution at that time and elimination of the Kα2 component of the radiation. This made the Guinier camera the best-performing film camera at that time and it therefore enjoyed high popularity.

The idea of using powder diffraction for phase identification of substances in pure form or in mixtures, originally suggested by Hull (1919[link]) and then formalized by Hanawalt et al. (1938[link]), attracted enormous interest, and developed into the powder diffraction method, making it a fundamental tool for material scientists. However, while classic film cameras laid down the historical foundation for the success of polycrystalline diffraction, their use was mostly limited to phase identification, semi-quantitative phase analysis and macroscopic stress measurements. Inherent difficulties included, but were not limited to, obtaining reliable intensities (because of film grain size and nonlinearity of the film response), very limited flexibility in terms of hardware extensions such as non-ambient specimen stages, and lack of diffracted-beam conditioning (e.g. the use of diffracted-beam monochromators).

Detailed descriptions of the many camera types as well as their use are given in a large number of texts. The interested reader is specifically referred to the textbook of Klug & Alexander (1974[link]), which also contains an extensive bibliography.

References

Bohlin, H. (1920). Eine neue Anordnung für röntgenkristallographische Untersuchungen von Kristallpulver. Ann. Phys. 366, 421–439.Google Scholar
Debye, P. & Scherrer, P. (1916). Interference of X-rays, employing amorphous substances. Phys. Z. 17, 277–283.Google Scholar
Guinier, A. (1937). Arrangement for obtaining intense diffraction diagrams of crystalline powders with monochromatic radiation. C. R. Acad. Sci. Paris, 204, 1115–1116.Google Scholar
Hanawalt, J. D., Rinn, H. W. & Frevel, L. K. (1938). Chemical analysis by X-ray diffraction. Ind. Eng. Chem. Anal. 10, 457–512.Google Scholar
Hull, A. W. (1917). A new method of X-ray crystal analysis. Phys. Rev. 10, 661–696.Google Scholar
Hull, A. W. (1919). A new method of chemical analysis. J. Am. Chem. Soc. 41, 1168–1175.Google Scholar
Klug, H. P. & Alexander, L. E. (1974). X-ray Diffraction Procedures for Polycrystalline and Amorphous Materials, 2nd ed. New York: Wiley.Google Scholar
Seemann, H. (1919). Eine fokussierende röntgenspektroskopische Anordnung für Kristallpulver. Ann. Phys. 364, 455–464.Google Scholar








































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