Introduction to electron crystallography

Abstract

Everything in Nature, macroscopic or microscopic, inorganic, organic or biological, has its specific properties. Most properties of matter depend on the atomic structures, and many techniques have been developed over the centuries for structure analysis. The greatest of them all, structure analysis of single crystals by X-ray diffraction, X-ray crystallography, was founded in 1912, and remains the most important technique for studying structures of periodically ordered objects at atomic resolution. Electron diffraction of single crystals was discovered fifteen years later by Thomson, Davisson and Germer. The wave property of electrons was exploited in the invention of the electron microscope by Knoll and Ruska in 1932. Since then, electron microscopes have been used in many fields as a tool for exploring and visualising the microscopic world in all its beauty. Between the first blurred images and today's sharp atomic resolution lies seventy years of untiring engineering. More recently, the unprecedented power of computers has made it possible to analyse quantitatively, and even further improve, these images. The amalgamation of electron diffraction and atomic resolution electron microscopy with crystallographic image processing has created a new powerful tool for structure analysis -electron crystallography.

Puzzling Intergrowth in Cerium Nitridophosphate Unraveled by Joint Venture of Aberration-Corrected Scanning Transmission Electron Microscopy and Synchrotron Diffraction

“…The diversity of three-dimensional frameworks is, in theory, infinite, and a general task of modern synthetic chemistry is to combine new structural motifs and complex elemental compositions in order to realize increasingly sophisticated materials. But as the materials become more numerous, structure elucidation frequently encounters various challenges including microcrystalline heterogeneous samples, pseudosymmetry, and weak superstructures. − Through technological advances, methods for solving these latter problems like aberration-corrected transmission electron microscopy (TEM), application of third generation synchrotrons, and refractive X-ray lenses producing microfocused beams for X-ray diffraction became available. − Atomic resolution Z -contrast scanning TEM (STEM) now enables the direct observation of vacancies or superstructures to derive atom positions and first structure models. − …”