Electron diffraction studies of the structure of amorphous and polycrystalline materials

The technique of energy selected electron diffraction allows reduced density function analysis to be carried out not only on small volumes of amorphous and polycrystalline material, but at the same time on volumes of material which can be investigated in parallel by high-resolution microscopy and by energy loss and X-ray spectrometry. The technique gives nearest neighbour distances to an accuracy of better than 0.02 Angstrom, and, in the case of single-element materials, first-shell co-ordination numbers accurate to 5%. The importance of and methods for overcoming, multiple scattering are discussed. The possibility of using convergent probes, by deconvolution of the probe from the diffraction pattern, offers promise of highly localised analysis from small amorphised volumes and intergranular phases.