Structural information in diffuse diffraction patterns

Our plain-English summary of Structural information in diffuse diffraction patterns, by J.H. Konnert (Environmental Health Perspectives, 1974).

The study

• Author: J.H. Konnert
• Journal: Environmental Health Perspectives
• Published: 1974;9:137-8
• Read it: PubMed · Publisher · Free full text

Abstract

The radiation diffraction pattern for amorphous materials requires special analysis for information on atomic groupings. Powdered crystalline material may also give diffuse patterns requiring this type of analysis. Absence of a sharp diffraction pattern does not necessarily indicate absence of the material. Examples are given for chrysotile and powdered chrysotile.

In plain English

This two-page technical note described how x-ray diffraction patterns can be analyzed when a material gives only blurred ("diffuse") patterns instead of sharp ones. It did not study people or disease. The author first used silica glass as an example, drawing on earlier published work. A mathematical method (Fourier analysis giving a "radial distribution function") can recover distances between atoms from such patterns. One example was a sharp feature at 1.61 angstroms, which represents bonded silicon-oxygen distances. The author then showed x-ray powder diffraction patterns, collected in the author's laboratory, for chrysotile and for chrysotile ground under toluene for 1 hour. Grinding made the pattern more diffuse, and further grinding made it progressively more so. Preliminary microscopy indicated this was due not only to smaller particles but also to disorder within the fibrils. The author suggested that micron-size chrysotile particles might give diffuse patterns because of slight misalignment of atomic layers. The author concluded that the lack of a sharp diffraction pattern does not necessarily mean the material is absent.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: short technical/methods note on analyzing diffuse x-ray diffraction patterns, with illustrative laboratory examples (not a study of people)
• Who was studied: no human subjects; material samples: silica glass (as a worked example, drawing on earlier work) and chrysotile samples whose patterns were collected in the author's laboratory at the Naval Research Laboratory, Washington, D.C.
• Exposure: chrysotile, unground and ground under toluene for 1 hour (and further grinding), examined by x-ray powder diffraction
• Main results:
  • For silica glass, the radial distribution function showed features ranging from very sharp maxima at 1.61 angstroms (bonded silicon-oxygen distances) to broad features at about 18 angstroms
  • The chrysotile diffraction pattern became progressively more diffuse with further grinding
  • Preliminary microscopy indicated the broadening was due not only to reduction in particle size but also to disorder within the fibrils
  • The author suggested that micron-size chrysotile particles may give diffuse patterns due to slight misalignment of the atomic layers
• The authors' conclusion: The author concluded that caution is needed when identifying easily disordered materials from diffraction patterns, because lack of a sharp pattern does not necessarily indicate the material is absent. The author also concluded that the method could be used to probe, at the atomic level, the effects of grinding and chemical treatment on asbestos.
• Limitations the authors state:
  • The author noted that analyzing diffuse patterns has difficulties arising from limits of the experimental data, namely the restricted range of scattering angle and accuracy
  • The microscopy findings on chrysotile were described as preliminary

Topics

Medical terms in this study, explained in our Lexicon: Crystalline, Chrysotile.

Related studies

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• Effect of heat on the identification of asbestos by x-ray diffraction — C. Plowman (1973)
• Electron diffraction patterns of U.I.C.C. asbestos samples — M.I. Skikne, J.H. Talbot, et al. (1971)
• Explanation for the insensitivity to tilts of the electron diffraction patterns of amphibole asbestos fibers — K. Seshan (1977)
• The nature of electron diffraction patterns of amphibole asbestos and their use in identification — J.L. Hutchison, E.J. Whittaker (1979)
• Quantitative X-ray diffraction analysis of crocidolite and amosite in bulk or settled dust samples — J.V. Crable, M.J. Knott (1966)

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