Plasma-Assisted Synthesis and Properties of Na₃N

Abstract

Dark-blue sodium nitride, Na(3)N, was prepared by the reaction of metallic sodium or liquid Na-K alloy with plasma-activated nitrogen at low pressure. The compound crystallizes in the cubic anti-ReO(3)-type structure (space group Pm3m with a = 4.73301(6) Angstrom and Z = 1) according to powder and single-crystal X-ray diffraction data. Na(3)N decomposes above 104 degrees C into the elements, with DeltaH(f) estimated at +64(2) kJ/mol.

A Temperature‐dependent Structural Study of anti‐ReO3‐type Na3N: to Distort or not to Distort?

“…With the intention to avoid complications arising from partially occupied d states, aluminum fluoride was chosen as a model for ReO 3 . Standard DFT approach fails to reproduce a band gap in sodium nitride 5, which leads to numerical artifacts during geometry optimization. Even though use of self‐interaction‐corrected (SIC) pseudopotentials leads to a band gap opening in the electronic structure of Na 3 N 17, the applicability of the SIC approach in geometry optimization has not yet been sufficiently tested.…”

“…Sodium nitride was prepared by a reaction of plasma‐activated nitrogen with a liquid Na‐K alloy at room temperature as described earlier 5.…”

Structural phase transitions of sodium nitride at high pressure

“…4 For the synchrotron x-ray-diffraction measurements, the sample was ground to a fine powder and a small amount of it was transferred into the gasket of a diamondanvil cell ͑DAC͒ with all handling carried out under inert argon atmosphere. No pressure medium was added during loading in order to avoid possible chemical reactions.…”

“…3 Recently, a practical route to produce larger amounts of sodium nitride was developed. 4 It is based on the reaction between a liquid Na-K alloy and plasma-activated nitrogen at room temperature. The initially proposed cubic anti-ReO 3 -type ͑Pm3m , Z =1͒ structure was confirmed for Na 3 N based on x-ray diffraction data collected on powder and single crystals, and accessibility of the nitride on a laboratory scale allowed for further investigations of this unusual compound.…”

Structural Transformations in Na3N under High Pressure

“…The compound crystallizes in a rather open anti-ReO 3type structure with a very low density of 1.3 g/cm 3 , suggesting a possibility of structural transformations under high pressure. As larger amounts of Na 3 N became available by using the reaction between the elements under plasma conditions [2], diffraction experiments were carried out in diamond-anvil cells using synchrotron radiation at pressures up to 35 GPa. A number of high-pressure modifications were observed.…”