# Growth and Morphology of PbSe Mesocrystals

## TL;DR

This paper studies the growth and surface features of PbSe mesocrystals using different methods, revealing insights into their crystal structure and defects.

## Contribution

The study demonstrates that PbSe mesocrystals grow following classical crystal growth principles, with notable exceptions like the absence of spiral growth.

## Key findings

- Mesocrystals up to tens of micrometers in size were successfully grown using vapor in-diffusion of an antisolvent.
- Surface features like twinning, growth steps, and striations were observed using scanning and atomic force microscopy.
- The absence of spiral growth in PbSe mesocrystals contrasts with classical crystal growth models.

## Abstract

This work describes the growth, (surface) morphology,
and defect
structure of mesocrystals composed of lead selenide (PbSe) nanocrystals
enveloped by a corona of oleate ligands. Three crystal growth methods
are explored to reproducibly obtain mesocrystals up to tens of micrometers
in size. The best results are obtained by vapor in-diffusion of a
suited antisolvent into a PbSe nanocrystal suspension. This yields
octahedral and trigon-shaped cubic close-packed (fcc) crystals composed
of partially oriented nanocrystals. The morphology and surface structure
of the mesocrystals are investigated by scanning electron microscopy
and atomic force microscopy. This reveals a wealth of features, including
various kinds of single and multiple {1 1 1} twinning, monolayer,
and multilayer growth steps, the lower ones often being undulated
by impurity blocking, ⟨1 2 1⟩ and ⟨1 1 0⟩
striations formed by a postgrowth phase transformation, linear growth
faults, slip lines, and cracks. These observations show that the growth
and defect structure of PbSe mesocrystals, for the most part, follow
the classical crystal growth concepts, which are based on molecular
or atomic growth units. The absence of spiral growth is a notable
exception.