Study of chrysotile asbestos by a high resolution electron microscope

Examination of asbestos fibers by electron microscopical techniques enables the observer to distinguish among the fiber types by morphological and structural characteristics.Chrysotile asbestos fibers are composed of bundles of fibrils. Fibers are often curvilinear with splayed ends. Individual fibrils consist of a central capillary defined by an electron dense crystalline wall. With increasing time of electron bombardment, the capillary wail decreases in thickness, deforms, and is encapsulated in an electron translucent material. The change in electron opacity is considered to be a product of structural disruption brought about by dehydroxylation due to electron radiation. A well recognized sequential deformation pattern may be used for identification purposes.Amphibole fibers tend to be straight, splintery, and electron-opaque, although curved fibers are occasionally observed. Diffraction contrast figures are visible as dark bands moving parallel and at right angles to the fiber axis. Crocidolite forms the shortest and thinnest fibers, followed in size by amosite and anthophyllite. Size distribution characteristics of the amphibole fiber types are different.The selected area electron diffraction pattern for chrysotile is unique. Reflections range in forms from streaked to arcuate. Reflection intensity and shape are related to the degree of openness of the fiber bundle and the extent of physical degradation of the fiber. The amphibole asbestos fibers possess diffraction patterns having similar characteristics prohibiting individual identification. Microchemical analysis is required for identification in such cases.A discussion of the industrial hygiene threshold limit values for ampliphibole asbestos fibers is presented. The discussion is based on their differing size distribution characteristics.

show abstract

“…Occasionally, no central capillary is observed in the fibril, again reflecting conditions of growth (18).…”

Section: Morphology Of Chrysotile Asbestos Fibersmentioning

confidence: 99%

Electron Microscopical Investigation of Asbestos Fibers

Langer¹,

Mackler²,

Pooley³

1974

Environmental Health Perspectives

View full text Add to dashboard Cite

show abstract

“…While the scroll silicate chrysotile, Mg 3 Si 2 0 5 (OH) 4 P is a familiar item of commerce (it is one of the silicates commonly called asbestos) and 6 has been extensively studied, tube silicates and aluminosilicates are unfamiliar and have been investigated relatively little. They are interesting, however, because tube structures in which the tube bonds are primary bonds have received little attention.…”

Section: 5mentioning

confidence: 99%

Synthesis of the tube silicate litidionite and structural relationships between it and some other silicates

Hefter¹,

Kenney²

1982

Inorg. Chem.

View full text Add to dashboard Cite

“…Very thin oxide films for this type of work have been prepared by anodic oxidation of metal foils, followed by recrystallization in the electron beam of the microscope (Spyridelis, Delavignette & Amelinckx, 1967). Ultramicrotomy is of limited value for sectioning crystalline materials, although it has been profitably used by Yada (1967Yada ( , 1971 to examine the structure of chrysotile fibres. For many brittle materials, a very simple grinding technique has proved quite satisfactory.…”

Section: Specimen Thicknessmentioning

confidence: 99%

“…Yada (1967Yada ( , 1971 examined transverse sections of microfibres of chrysotile asbestos, and observed their concentric, spiral, or multispiral layer structures directly. Similarly, bent and distorted lattice fringes have been observed in partially graphitized carbon black (Heidenreich, Hess & Ban, 1968); in polyacrylonitrile-based carbon fibres (Johnson, 1970), and in films formed by the pyrolysis of methane and propane over nickel (Baird, Fryer & Grant, 1971).…”

Section: Historicalmentioning

confidence: 99%

The direct observation of the structure of real crystals by lattice imaging

Allpress¹,

Sanders²

1973

J Appl Cryst

159

View full text Add to dashboard Cite

The electron-microscope technique of lattice imaging can in favourable circumstances be used to observe the structure of materials directly. The technique is described, and examples of cases in which a direct correlation between image contrast and structural features has been established are given. Procedures for computing contrast in n-beam lattice images are outlined, and the important experimental parameters, thickness and orientation of the specimen, and spherical aberration and defocusing of the microscope objective, are discussed in some detail.

show abstract

Study of chrysotile asbestos by a high resolution electron microscope

Cited by 215 publications

References 1 publication

Electron Microscopical Investigation of Asbestos Fibers

Electron Microscopical Investigation of Asbestos Fibers

Synthesis of the tube silicate litidionite and structural relationships between it and some other silicates

The direct observation of the structure of real crystals by lattice imaging

Contact Info

Product

Resources

About