X-ray nanodiffraction is applied to study the formation and correlation of domain boundaries in mesocrystalline superlattices of PbS nanocrystals with face-centered cubic structure. Each domain of the superlattice can be described with one of two mesocrystalline polymorphs with different orientational order. Close to a grain boundary, the lattice constant decreases and the superlattice undergoes an out-of-plane rotation, while the orientation of the nanocrystals with respect to the superlattice remains unchanged. These findings are explained with the release of stress on the expense of specific nanocrystal-substrate interactions. The fact that correlations between adjacent nanocrystals are found to survive the structural changes at most grain boundaries implies that the key to nanocrystal superlattices with macroscopic domain sizes are strengthened interactions with the substrate.
@article{arxiv.1904.02408,
title = {Revealing Grain Boundaries and Defect Formation in Nanocrystal Superlattices by Nanodiffraction},
author = {Nastasia Mukharamova and Dmitry Lapkin and Ivan A. Zaluzhnyy and Alexander André and Sergey Lazarev and Young Y. Kim and Michael Sprung and Ruslan P. Kurta and Frank Schreiber and Ivan A. Vartanyants and Marcus Scheele},
journal= {arXiv preprint arXiv:1904.02408},
year = {2019}
}