17th February 2021 | Author: Dr Simon Burgess
A lot has happened in the world since I last wrote a blog about quantitative analysis using EDS. These days most of my words come straight from my home office. Even my SEM operation and analysis has been mostly done from this desk over the past year, through two remote connections; one to the SEM PC and one to the AZtec PC.
Much of my work last year focused on the development of our AZtecWave software. This software is all about quantitative analysis and not just for WDS, as this is a combined WDS and EDS technique with the major elements relying on the speed and accuracy of EDS.
Currently I am editing a technical bulletin that Rosie Jones is writing, which combines information from Philippe Pinard’s recent paper: ‘Development and validation of standardless and standards-based X-ray microanalysis’, with more practical information. This document will describe the procedure we recommend you use to achieve the kind of high-quality compositional analysis we routinely report from our lab. We hope you will take the chance to see how we achieve good quant, and how you can achieve it too. Rosie and I are also preparing to present the information as a Webinar with Microscopy & Analysis at the end of March, so register now.
Quantitative analysis using EDS is increasingly established as a tool for accurate compositional determination of materials. With good method it can provide unique answers to numerous characterization challenges. For example, a recent letter published in Nature presented data that was collected with X-Max EDS detectors at Cardiff University and analysed using AZtec software:
Deep roots for mid-ocean-ridge volcanoes revealed by plagioclase-hosted melt inclusions by Bennett et al., 2019, Nature volume 572, pages 235–239
In this work small inclusions of glass contained within minerals have been analysed, using a dual large area EDS detector system. This allows beam sensitive materials to be measured at very low beam current, minimizing sample damage and loss of mobile elements such as Na and K. It was good to see the authors recognizing the need to validate their system (a subject of an earlier blog, and a favourite topic of mine). They published the results they obtained on two mineral standards in the supporting data to the letter. This shows that by collecting their own standards they were able to achieve accuracy for major elements well within the +/-2 % relative we expect from our standardless EDS method.
Whatever quant method, equipment and technique is used, the validation using materials of known and similar composition/matrix gives me high confidence in the quality of the data produced, and the findings of the research it informs.