Characterization of Atomic Structures of Nanosized Intermetallic Compounds Using Electron Diffraction Methods

Abstract

In metallurgy, many intermetallic compounds crystallize as nanosized particles in metallic matrices. These particles influence dramatically the physical properties of engineering materials such as alloys and steels. Since properties and crystal structure are intimately linked, characterization of the atomic model of these intermetallides is crucial for the development of new alloys. However, this structural information usually cannot be attained using traditional X-ray diffraction methods, limited by the small volume and size of the precipitates. In these cases, electron diffraction (ED) is the most suitable method. In the last few decades, ED has experienced a tremendous leap forward. Many structures, including intermetallides, are solved using these methods. The class of intermetallides should be discussed independently since these phases do not comprise regular polyhedrals; moreover, the interatomic distances and angles vary drastically even in the same compositional system. These facts point to difficulties that have to be overcome during the solution path. Furthermore, intermetallic compounds can be of high complexity-possessing hundreds of atoms in the unit cell. Here, this topic is expanded with an emphasis on novel developments in the field.

Materials Modelling of π‐Phase Monochalcogenides

“…The small size of the particles and their small fraction in the product precluded use of x-ray diffraction to characterize the phase. Instead, advanced electron diffraction methods [17] were applied and uncovered a simple cubic structure with a 64-atom unit-cell and space group P2 1 3. This novel phase was denoted as the π-phase.…”

Type‐II Red Phosphorus: Wavy Packing of Twisted Pentagonal Tubes

“…Electron crystallography has recently emerged as an alternative method to conventional X-ray crystallography tools. [35][36][37] In particular, the sample size required for electron crystallography is much smaller ( � 10 nm) than that required for single-crystal XRD. This merit is critical for the investigation of type-II RP because large-sized single crystals are unavailable to date.…”

Type‐II Red Phosphorus: Wavy Packing of Twisted Pentagonal Tubes

“…We employed 3D electron diffraction to obtain unit cell information on type‐II RP. Electron crystallography has recently emerged as an alternative method to conventional X‐ray crystallography tools [35–37] . In particular, the sample size required for electron crystallography is much smaller (≈10 nm) than that required for single‐crystal XRD.…”