Application of electron backscatter diffraction to analytical challenges of asbestiform minerals.

摘要

In order to properly identify a mineral two pieces of information are required: chemical composition and crystal structure. A scanning electron microscope equipped with energy dispersive x-ray spectroscopy and electron backscatter diffraction allows for the characterization of both of these properties from micrometer (or smaller) sized crystals. In most cases, electron backscatter diffraction is performed on highly polished bulk materials. The application of electron backscatter diffraction to mineral particulates is uncommon, but a potentially very useful for phase identification.;Tests are presented that show that electron backscatter diffraction can be used to accurately identify mineral particulate. Polymorph minerals, minerals that are very similar in composition and structure, and unknown mineral identification cases are presented as a test of the method for phase identification of particulate specimens. These tests show that the method can successfully discriminate between structurally and compositionally similar phases in particulate form.;The ultimate goal of this dissertation was to determine the limits of electron backscatter diffraction for phase discrimination of asbestos and asbestiform minerals. The current standard methods employed for environmental monitoring of asbestos in air and bulk materials utilize transmission electron microscopy and selected area electron diffraction. This work represents the first thorough investigation of the application of electron backscatter diffraction to asbestos mineral identification.