Analytical Transmission Electron Microscopy and Scanning Transmission Electron Microscopy Techniques for the Characterization of Nanomaterial Composition, Phase and Crystallinity

The production and use of manufactured nanomaterials (NMs) have been increasing dramatically for the past few years. Because there are nearly unlimited possibilities for the types of NMs that may be created, heterogeneity and complexity in both composition and structure are expected. In addition, manufactured NMs undergo compositional and structural transformation processes in response to the interaction(s) with their surrounding environment, as well as with that environment as it changes through time. In this chapter, we will introduce and discuss how to identify and characterize chemical composition and crystal structure (and therefore the exact phase or phases) of manufactured NMs (parent forms) as well as their transformed ones (daughter forms) by using analytical transmission electron microscopy (analytical TEM) and scanning transmission electron microscopy (STEM). For this specific purpose, in this chapter, we discuss TEM and STEM techniques for compositional and structural analyses, the applications and limits, the data acquisition and analysis methods, as well as sample preparation procedures in detail.

The purpose of this chapter is to make these instruments and techniques much more accessible and familiar to nonexperts in electron microscopy. Manufactured NMs, such as TiO2, metals and metal oxides and sulphides will be used for examples throughout this chapter. In addition, examples of naturally occurring NMs will be used for crystal structural analyses, as well as crystal structure refinements.