Structural Complexities in Sodium Ion Conductive Antiperovskite Revealed by Cryogenic Transmission Electron...

Area of Science:

• Materials Science
• Solid-State Chemistry
• Electron Microscopy

Background:

• Antiperovskite materials are promising solid electrolytes.
• Their atomic-scale structure is crucial for performance but challenging to study.
• Electron beam sensitivity limits traditional imaging techniques.

Purpose of the Study:

• To investigate the atomic-scale structure of antiperovskite Na2NH2BH4.
• To assess the utility of low-dose cryogenic transmission electron microscopy (cryo-TEM) for sensitive materials.
• To identify structural ordering phenomena in the solid electrolyte.

Main Methods:

• Low-dose cryogenic transmission electron microscopy (cryo-TEM) was employed.
• Quantitative analysis of electron beam damage using selected area electron diffraction.
• Comparison of experimental cryo-TEM images with simulated potential maps.

Main Results:

• Cryo-TEM imaging demonstrated a 6-fold improvement in beam stability.
• A novel long-range-ordered supercell with doubled unit cell dimensions (9.4 Å) was discovered.
• The supercell structure was attributed to ordered sodium atom vacancies.

Conclusions:

• Cryo-TEM is effective for studying air- and electron-beam-sensitive antiperovskite solid electrolytes.
• The discovered supercell structure provides new insights into Na2NH2BH4.
• This imaging approach advances the understanding of solid electrolyte atomic structures.