<p>Defect engineering
can enhance key properties of metal-organic frameworks (MOFs). Tailoring the
distribution of defects, for example in correlated nanodomains, requires characterization
across length scales. However, a critical nanoscale characterization gap has
emerged between the bulk diffraction techniques used to detect defect
nanodomains and the sub-nanometre imaging used to observe individual defects. Here,
we demonstrate that the emerging technique of scanning electron diffraction
(SED) can bridge this gap. We directly image defect nanodomains in the MOF
UiO-66(Hf) over an area of ca. 1 000 nm and with a spatial resolution ca. 5 nm to
reveal domain morphology and distribution. Based on these observations, we suggest
possible crystal growth processes underpinning synthetic control of defect
nanodomains. We also identify likely dislocations and small angle grain
boundaries, illustrating that SED could be a key technique in developing the
potential for engineering the distribution of defects, or “microstructure”, in
functional MOF design.</p>