In-column Synthesis and Atomic-resolution Electron Microscopic Analysis of Metastable Reactive Nitrides
Year: 2026
Type: preprint
Abstract: Metastable and air-sensitive compounds are challenging to synthesize and characterize because their formation often requires harsh conditions and their structures can rapidly evolve upon exposure to the environment. Here, we demonstrate that a high-vacuum environment inside a transmission electron microscope (TEM) column can serve simultaneously as a reaction platform and an atomic-scale analytical tool for generating and interrogating such materials. Electron-beam irradiation on sodium azide (NaN3) produces crystalline sodium nitride (Na3N) at room temperature, despite the conventional decomposition of NaN3 into sodium and nitrogen. The formation of Na3N is supported by high-resolution TEM, electron diffraction, and energy dispersive X-ray spectroscopy, which reveal correlated structural and compositional changes through irradiation. The resulting Na3N subsequently undergoes oxidation through an amorphous intermediate to form polycrystalline Na2O. The high-vacuum environment sufficiently suppresses this reaction to resolve its otherwise unachievable microscopic mechanisms. Extending this approach to potassium azide (KN3), we observe a transient crystalline phase that is most consistently indexed as K3N, a nitride known to be thermally unstable even under room temperature. Its transient appearance and decay indicate a dynamic balance between electron-beam-induced formation and degradation. These results establish in-column electron-beam chemistry as a route to metastable nitride formation while enabling multimodal characterization of highly reactive products. More broadly, this strategy offers a means of exploring nonequilibrium metastable compounds that are difficult to access using conventional synthesis and characterization workflows.
Source: ChemRxiv
Language: English
Subfield: Structural Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7214764940