TEM-Based Materials Characterization

Connecting nanoscale structure, composition, and phase evolution across functional materials.

I use transmission electron microscopes (TEM) to connect local structure and chemistry with the behaviour of functional materials—from carbon and plasmonic nanostructures to ferroelectrics and halide perovskites, thereby elucidating on the structure-property relationships.

Visual highlights

Three-dimensional plasmonic near-field observation of a chiral gold nanoparticle — Three-dimensional plasmonic near-fields resolved around a chiral gold nanoparticle.

Strain analysis of beam-sensitive nanoparticles — Nanoscale strain analysis of a CsPbBr3 nanoparticle.

Data-driven analysis of bonding variation in amorphous carbon — Data-driven EELS analysis connects local bonding variation with amorphous-carbon structure.

in situ biasing TEM investigation of hafnium zirconium oxide — Microscopy analysis of local phase behaviour in hafnium zirconium oxide.

Nanoscale heterogeneity analysis in lead-halide perovskites — Spatially resolved analysis of nanoscale heterogeneity and phase evolution in lead-halide perovskites.

Selected outputs

J. Ryu, et al., Correlative study between the local atomic and electronic structures of amorphous carbon materials via 4D-STEM and STEM-EELS, Applied Physics Letters (2022).
J. Jo, J. Ryu, et al., Direct three-dimensional observation of the plasmonic near-fields of a nanoparticle with circular dichroism, ACS Nano (2024).
Q. Zeng, et al., A hierarchical shell locks and stabilizes perovskite nanocrystals with near-unity quantum yield, Science (2026).
S. Lee, J. Ryu, et al., In situ transmission electron microscopy visualization of electric-field-induced phase transitions at the morphotropic phase boundary in Hf0.5Zr0.5O2, ACS Nano (2026).
J. Ryu, et al., Resolving nanoscale heterogeneities in lead halide perovskites through low dose concurrent 4D-STEM-EDX mapping, Advanced Materials (2026).