37 / 2026-03-13 11:19:36

Pressure-Induced Phase Transformations of Alkali-Metal Carbon-Nitride Compounds

material characterization,phase transition

高压物理与材料科学 > 静高压物理与材料科学

The growing demand for sustainable energy solutions and the increasing environmental challenges necessitate significant advancements in energy storage technologies. Recent studies highlight carbon-nitride-based materials as promising candidates due to their high capacitance, low cost, and minimal volumetric expansion upon alkali-metal doping, making them viable for high-energy-density applications [1-3]. We explored alkali-metal carbon-nitride compounds (AMCNC) as potential battery materials, combining the advantages of both alkali metals and carbon-nitrides to enhance battery performance.

Previous studies provide compelling evidence that the properties of materials can undergo significant alterations when subjected to high pressure. It is worth noting that most materials from AMCNC family haven’t been explored under high pressure. Motivated by these findings, we aim to investigate whether compressing AMCNC, specifically LiC₄N₃ and NaC₄N₃, under moderate pressure of a few tenths of gigapascal (GPa), to yield materials that are applicable as new battery materials with better efficiency. We note that both the LiC₄N₃ and NaC₄N₃ compounds, that are the subject of this study, are molecular solids and distinct from the conventional Li- and Na-intercalated g-C₄N_3.

We performed a high-pressure Raman spectroscopy on LiC₄N₃ up to 20 GPa, and an in-situ synchrotron Wide-Angle X-ray Scattering (WAXS) measurements up to 30 GPa using a diamond anvil cell (DAC). These results documented that the C≡N bonds were transformed into C=N extended bonds. The quenched material remained metastable and metallic after fully releasing the pressure and reacted with the air several hours after exposing to atmospheric conditions.

NaC₄N₃ has also been studied under high pressure using Raman spectroscopy and WAXS at synchrotron sources up to 32 GPa. At around 6 GPa and 20 GPa, two crystalline-to-crystalline phase transformations were observed, and it was also concluded that the C≡N triple bonds were transformed into extended double bond alike LiC₄N₃.



References:

[1] GM. Veith et al., Chem. Mater, 25(3) 503-508 (2013).

[2] M. Wu et al., J. Phys. Chem. C, 117(12), 6055-6059 (2013).

[3] A. Kraytsberg et al., J. Solid State Electrochem., 21, 1907-1923 (2017).