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Page 14 of 19 Lee et al. Microstructures 2023;3:2023021 https://dx.doi.org/10.20517/microstructures.2023.08

Figure 9. Phase distribution for the (CsPbI ) (a ZIF-62) 0.75 composite fabricated with 300 °C sintering. (A) ADF-STEM image, (B)
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SED-STEM mapping, and (C) CsPbI crystal phase classification results for (CsPbI ) (a ZIF-62) 0.75 composite. (D) Volume rendering
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of tomographic reconstruction of (CsPbI ) (a ZIF-62) 0.75 and a single cross-sectional plane extracted from the volume. Color-coded
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arrows indicate the regions where electron diffraction data were collected. Scale bars, (A-D) 250 nm. Reprinted with permission [95] .
Copyright © 2021 American Chemical Society
scattering (SAXS) and wide-angle X-ray scattering (WAXS) could show the micro to atomic scale structures
and interactions of the composite materials. Recently, our group revealed the nanoparticle size,
homogeneity, and internal structure behaviour during the liquid phase sintering process of pure MOF to
MOF-glass and hybrid nanocomposite with perovskite, and MOF-glass using WAXS and SAXS
analysis [92,94] . Furthermore, pair distribution functions (PDFs) from the X-ray diffusion pattern could explain
the atomic structure formation, especially for composites with an amorphous matrix, as it can reveal
information that X-ray diffraction is unable to obtain.

Terahertz/far-infrared (THz/far-IR) spectroscopy is another powerful technique that should be considered
for investigating the dynamic properties of localised features within the composite. When paired with in-
situ investigation capabilities, THz/far-IR spectroscopy can effectively identify the dynamic structural
behaviour and emerging new chemical bonding between the guest and host materials. Hou et al.
successfully integrated this technique to identify halogenation reactions during the melting process of MOF
glass . Combined with thermal behaviour analysis and X-ray-based techniques, this spectroscopy can
[95]
reveal additional dynamic properties of QDs embedded in the microporous matrix and how they interface
internally.