Deviatoric Stress Driven Formation of Large Single-Crystal PbS Nanosheet from Nanoparticles and in Situ Monitoring of Oriented Attachment

Abstract

Two-dimensional single-crystal PbS nanosheets were synthesized by deviatoric stress-driven orientation and attachment of nanoparticles (NPs). In situ small- and wide-angle synchrotron X-ray scattering measurements on the same spot of the sample under pressure coupled with transmission electron microscopy enable reconstruction of the nucleation route showing how enhanced deviatoric stress causes ordering NPs into single-crystal nanosheets with a lamellar mesostructure. At the same time that deviatoric stress drives SC(110) orientation in a face-centered-cubic supercrystal (SC), rocksalt (RS) NPs rotate and align their RS(200) and RS(220) planes within the SC(110) plane. When NPs approach each other along the compression axis, enhanced deviatoric stress drives soft ligands passivated at RS(200) and RS(220) surfaces to reorient from a group of SC(110) in-planes to the interspace of SC[110]-normal planes. While the internal NP structure starts a rocksalt-to-orthorhombic transition at 7.1 GPa, NPs become aligned on RS(220) and RS(200) and thus become attached at those faces. The transition-catalyzed surface atoms accelerate the inter-NP coalescing process and the formation of low-energy structure nanosheet. Above 11.6 GPa, the nucleated single-crystal nanosheets stack into a lamellar mesostructure that has a domain size comparable to the starting supercrystal.

Materials processing strategies for colloidal quantum dot solar cells: advances, present-day limitations, and pathways to improvement

“…annealing, [47][48][49] high-pressure treatments, [50] and plasma processing [51] -with the goal of regaining partial ordering. While enhanced electrical transport characteristics have been measured using these methods, a key challenge remains in the form of demonstrating superior device performance based on such films.…”

Synthesis and luminescence properties of Y2O3:Eu with flower-like microstructure

“…There are several crystal growth mechanisms in the solution system [38], including the classical Ostwald ripening process [39], the oriented attachment mechanism [40], and the self-sacrificed template mechanism based on Kirkendall effect [41]. For the formation of flower-like Y(OH) 3 :Eu microstructure, we believe the oriented attachment mechanism plays a key role.…”

Oriented attachment of nanoparticles to form micrometer-sized nanosheets/nanobelts by topotactic reaction on rigid/flexible substrates with improved electronic properties

“…This observation means that, on the given rigid/flexible substrates, the introduction of the strong surface adsorption of dodecanethiol ligands and inorganic ions, such as Cd 2+ , facilitates the coalescence of CQDs by pure in-situ OA growth to yield nanosheets. The rotation and alignment of the as-formed CQD domains eliminate high surface energy facets and interfaces between them, 26,27 resulting in their coalescence into quasi-sc nanosheets with lower surface energy facets exposed, as shown in Figure 4C. The polycrystalline state of Ag 2-δ X limits the following cation exchange reaction to rotate and align the CQD domains towards one growth direction due to different entropy-driven thermodynamics.…”