Читать книгу Amorphous Nanomaterials - Lin Guo - Страница 26

With the recent developments in hardware attachments to achieve both probe- and image-corrected microscope geometries so as to obtain a sub-Angstrom resolution, the spherical aberration-corrected transmission electron microscopy (Cs-TEM) is nowadays recognized as a powerful tool for study condensed matter physics and materials science. These advantages are meeting the growing demand of nanosciences and nanotechnology for atomic-scale characterization of materials and also for inspiring people to explore the expected functions of nanosynthesized products and devices. The instrumentation developments have played an important role in advancing the imaging and analytical capability, bringing both opportunities and challenges for the electron microscopy community. In addition, when equipped with electron energy filters and electron energy loss spectrometers, this advanced instrument could study not only morphology of microstructures but also their elemental composition and chemical bonding. The application of atomic resolution imaging and spectroscopy has rapidly expanded into many scientific areas to investigate many different types of semiconductors, metals, oxides, ceramics, and even a single-dopant atom.

In this chapter, we will first review the history and introduce the working mechanism of Cs-TEM, where two important imaging modes, high-resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy (STEM) will be described throughly. Next, we will discuss how electron energy loss spectroscopy (EELS) works with Cs-TEM to study the adsorption and reaction of molecules on metal oxide surface and to characterize the single-atom impurities or defects, which are important issues in heterostructure catalyst study. In the end, we will discuss the application of in situ transmission electron microscopy (TEM) that involves various stimuli to nanomaterials with high-resolution imaging and spectroscopy, for instance, in studying reaction mechanisms in metal-ion batteries, gas-phase reactions, and the phase transformation from amorphous to crystalline under electron beam irradiation.