1D to 2D Transition in Tellurium Observed by 4D Electron Microscopy

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 16; no. 49; pp. e2005447 - n/a
• Main Authors: Londoño‐Calderon, Alejandra, Williams, Darrick J., Ophus, Colin, Pettes, Michael T.
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.12.2020; Wiley
• Subjects: 2D materials; 4D‐scanning transmission electron microscopy (4D‐STEM); Crystallites; Crystallography; Datasets; four dimensional-scanning transmission electron microscopy (4D-STEM); Image transmission; material science; MATERIALS SCIENCE; microwave synthesis; Nanomaterials; Nanoribbons; Nanotechnology; Nanowires; Parameters; peak profile analysis; Scanning transmission electron microscopy; Structural analysis; Synthesis; tellurene; Tellurium; Transmission electron microscopy; X-ray diffraction
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202005447

A new microwave‐enhanced synthesis method for the production of tellurium nanostructures is reported—with control over products from the 1D regime (sub‐5 nm diameter nanowires), to nanoribbons, to the 2D tellurene regime—along with a new methodology for local statistical quantification of the crystallographic parameters of these materials at the nanometer scale. Using a direct electron detector and image‐corrected microscope, large and robust 4D scanning transmission electron microscopy datasets for accurate structural analysis are obtained. These datasets allow the adaptation of quantitative techniques originally developed for X‐ray diffraction (XRD) refinement analyses to transmission electron microscopy, enabling the first demonstration of sub‐picometer accuracy lattice parameter extraction while also obtaining both the size of the coherent crystallite domains and the nanostrain, which is observed to decrease as nanowires transition to tellurene. This new local analysis is commensurate with global powder XRD results, indicating the robustness of both the new synthesis approach and new structural analysis methodology for future scalable production of 2D tellurene and characterization of nanomaterials. Microwave chemistry is demonstrated to be an efficient means to produce 2D tellurium. More impressively, a new characterization technique and analysis methodology are developed which are capable of observing the dimensional transition locally. This transition is evidenced in a marked reduction in nanostrain and recovery of the isotropic strain profile.