Novel Dry Dispersions for Automated Scanning Electron Microscopy: Energy and Wavelength Dispersive X-RAY Spectrometry (ASEM-EDS/WDS)

Abstract

In recent years, the need for more precise size and chemical analysis of materials has been stressed since these features can have major effects on product performance. Historically, optical and manual scanning electron microscopy, the latter in combination with energy and wavelength dispersive x-ray spectrometry (SEM-EDS/WDS), have been used in our laboratory to size and identify the chemical composition of materials. In recent years, automated SEM-EDS/VDS methods have been developed and are likewise used for similar measurements, especially where large sets of particle information are desired.The inherent success of ASEM-EDS/WDS critically depends on sample preparation. Particle dispersion criteria include: 1) a smooth substrate, free of defects, 2) a uniform distribution of particles, and 3) proper density of particle loading. Traditionally, particles have been suspended and homogenized in liquid media and then either filtered through membrane filters or aliquots directly dispersed onto highly polished carbon planchets. While wet dispersions are applicable to a wide array of materials, in the case of complex materials, alternative dry dispersion protocols are necessary.