Electron backscatter diffraction (EBSD) in the SEM: applications to microstructures in minerals and rocks and recent technological advancements

Abstract

Electron backscatter diffraction (EBSD) is based on the principle that a beam of electrons generated in the scanning electron microscope (SEM) is the source of randomly scattered electrons in a specimen. The backscattered electrons (BSE) that escape the sample generate a Kikuchi pattern on a phosphor screen, which is linked to the specimen crystal structure. Different crystal orientations generate different EBSPs. EBSD provides orientation, misorientation and boundary measurements from a small area (>1 μm) in a crystal and automated EBSD analysis is applied to an increasingly large number of rock-forming minerals. Excellent results are obtained for example on calcite and quartz and recent achievements include successful automated indexing of low symmetry minerals such as feldspars and omphacite. The effective application of EBSD to mineralogy and petrology has increased and includes detailed studies of microstructures, twin boundaries, deformation mechanisms and metamorphic processes. A technique for in-situ high temperature tensile deformation of minerals and rocks is currently being developed.