Quantifying the Local Structure of Nanocrystals, Glasses, and Interfaces Using TEM-Based Diffraction

Abstract

Although order is a defining characteristic of crystals, disordered structuresespecially near interfacesoften govern a material’s performance. For example, the interfaces in batteries, coatings, or catalysts exemplify systems in which disorder plays a critical role. Despite this importance, characterization of local structure in disordered materials remains a challenge. To solve this challenge, the electron pair distribution function (ePDF) method has given insight into the local structure of many complex samples because the technique can be applied to disordered materials containing as few as tens or hundreds of atoms. The ePDF method takes a transmission electron microscope (TEM) diffraction pattern and transforms this into information about the bond lengths present in a material. This information can then be used to create a 3D, atomic-scale model of local chemical structure. In this review, we introduce the theory behind ePDF, describe common methods for data acquisition, and highlight recent advances in the ePDF technique, including its combination with cryo-electron microscopy, ultrafast TEM, and precession electron diffraction. We also show how ePDF has been applied to important classes of materials, including 2D heterostructures, nanoscale interfaces, and materials fabricated by atomic layer deposition. Finally, we review how ePDF can be combined with other techniques to provide a comprehensive understanding of a material. Because ePDF can be performed on most TEMs, it is beginning to emerge as a routine method for the analysis of complex, disordered structures in technologically important materials.

White Light Generating Molecular Materials: Correlation Between the Amorphous/Crystalline Structure and Nonlinear Optical Properties

“…The key for understanding and enhancing any desirable features, in general, is understanding the microscopic structure, or rather, the absence thereof in such materials. [7] Such an endeavor is particularly challenging as diffraction based techniques rely at least on pseudo-periodicity, and, commonly, lack sufficient spatial resolution indispensable in light of the continuous trend towards miniaturization. These challenges demand developing and applying advanced materials characterization procedures suitable for understanding aperiodic matter with sufficient spatial resolution while preserving the structure of the amorphous solid without causing extreme (radiation) damage during investigation.…”

“…The amorphous materials show widely superior properties compared to their crystalline counterparts in their respective applications. The key for understanding and enhancing any desirable features, in general, is understanding the microscopic structure, or rather, the absence thereof in such materials [7] . Such an endeavor is particularly challenging as diffraction based techniques rely at least on pseudo‐periodicity, and, commonly, lack sufficient spatial resolution indispensable in light of the continuous trend towards miniaturization.…”

Adamantanes as White-Light Emitters: Controlling the Arrangement and Functionality by External Coulomb Forces

“…Figure S4). The scattering shows characteristic deviations from the average atomic form factor of the constituents, indicating deviations from random atom positions and hence distinct correlations of atomic sites . These features underline the existence of molecules in random orientations.…”

“…The scattering shows characteristic deviations from the average atomic form factor of the constituents, indicating deviations from random atom positions and hence distinct correlations of atomic sites. 45 These features underline the existence of molecules in random orientations. We carry out molecular dynamics (MD) simulations using the OPLS-AA force field of a large number of molecules (1728) in a supercell to model an amorphous arrangement (cf.…”

Impact of bridging oxygens formation on optical properties of Fe3+ doped Li2O–Al2O3–SiO2–TiO2 glasses

“…Accordingly, interaction of EW in each region could be attributed to the resonance or absorption of EW by electrons, atoms, molecules, spin of electrons etc. Each of them could be interpreted for the structural evaluation [5][6][7][8]. In advanced technologies, heavy doped materials are utilized for production of the small, high power optical devices [9,10].…”