Topochemistry of Bowtie- and Star-Shaped Metal Dichalcogenide Nanoisland Formation

• Published in: Nano letters Vol. 16; no. 6; pp. 3696 - 3702
• Main Authors: Artyukhov, Vasilii I, Hu, Zhili, Zhang, Zhuhua, Yakobson, Boris I
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 08-06-2016
• Subjects: synthesis; Wulff construction; grain boundaries; transition metal dichalcogenides; chemical vapor deposition; 2D materials
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.6b00986

A large number of experimental studies over the past few years observed the formation of unusual highly symmetric polycrystalline twinned nanoislands of transition metal dichalcogenides, resembling bowties or stars. Here, we analyze their morphology in terms of equilibrium and growth shapes. We propose a mechanism for these complex shapes’ formation via collision of concurrently growing islands and validate the theory with phase-field simulations that demonstrate how highly symmetric structures can actually emerge from arbitrary starting conditions. Finally, we use first-principles calculations to propose an explanation of the predominance of high-symmetry polycrystals with 60° lattice misorientation angles.