Keith Dicks
Applications, Oxford Instruments NanoAnalysis, High Wycombe, UK

Scanning electron microscopy (SEM) coupled with an Energy Dispersive Spectrometer (EDS) system is a routine analytical technique. EDS enables elemental analysis on the micro and nano scale within the chamber of the SEM. EDS is a powerful and incredibly useful technique, widely used in diverse fields of investigation and research. However, when characterising a sample in the SEM, it should be noted that EDS gives the quantity and distribution of the elements, rather than specific compounds, or oxidation states etc. EDS analysis is significantly enhanced by the addition of EBSD (Electron Backscattered Diffraction). This is a quantitative microstructure characterisation technique, which extends EDS to allow the study a wide range of material properties, and to identify and quantify compounds as opposed to the presence, association and quantity of elements. Thus EBSD is highly complimentary with respect to EDS.

Electron Backscatter Diffraction (EBSD) is a well established technique. It uses electron diffraction patterns to identify and quantify compounds or phases in a sample. Where EDS is used to display element distribution and can quantify composition, EBSD can identify specific compounds. These are characterised using crystallography. Therefore chemical compounds with distinct crystallography can be easily identified, discriminated, quantified and mapped.

In addition, EBSD benefits from higher spatial resolution than EDS, potentially with spatial resolution <100nm, dependant on the material and acquisition conditions.

EBSD can also be conducted in transmission, known as Transmission Kikuchi Diffraction (TKD). In this mode electron transparent TEM samples are analysed with significantly reduced lateral scattering which further improves the spatial resolution, to the order of 10’s of nanometres.

EBSD is simple and convenient to use on a SEM platform and brings a true surface analytical capability to compliment EDS. It extends the sphere of operation of your SEM to encompass work previously assigned to x-ray diffraction (texture, strain, phase) or TEM. The addition of EBSD transforms a SEM into a formidable, wide ranging analytical tool.

The talk introduces the theory and practice of EBSD and TKD, and gives applications examples to demonstrate the diverse range of applications and measures available. These include; phase and compound identification and distribution, grain size, grain boundary characterisation, crystallographic texture, and strain condition to name a few.

Powered by Eventact EMS