We show that targeted energy input from an electron beam in a transmission electron microscope (TEM), often combined with concurrent heating in a MEMS holder, drives atomic defect formation and phase transitions across four classes of low-dimensional materials: (1) few-layer transition metal phosphorus trichalcogenides (TMPTs), (2) graphene sandwich structures encapsulating either lithium droplets (2a) or a benzenehexathiol-based two-dimensional conjugated metal-organic framework (2b), (3) platinum nanocrystals on graphene, and (4) noble metals confined within carbon nanotubes.
In (1), controlled heating around 600 °C induces phase transitions to MnS, MnSe, and NiSe, with ab initio calculations predicting orientation- and thickness-dependent magnetic properties. In (2a), graphene vacancies nucleate polycrystalline lithium growth during lithiation, while interstitial oxygen inhibits delithiation via lithium oxide formation. Despite high beam resistance, Cu₃(BHT) (2b) transforms thermally into a crystalline CuS phase between 480 °C and 620 °C as well as under high electron flux. For (3), we resolve the solid–liquid phase transition of Pt nanoclusters and identify a mechanism where stationary Pt atoms corral molten nanodroplets, halting crystallization. Finally, in (4), we reveal contrasting bonding behaviors of Re and Kr atoms within fullerenes inside carbon nanotubes, driven by differences in electronic structure and confinement.
These findings are enabled by the Cc/Cs-corrected SALVE (Sub-Ångström Low-Voltage TEM) platform, highlighting its potential for atomic-scale in situ phase engineering.