Sodium Pentazolate: a Nitrogen Rich High Energy Density Material

TL;DR

This paper reports the discovery of sodium pentazolates as high energy density materials stabilized at high pressures, with potential for energy storage applications, supported by first-principles calculations and experimental Raman spectrum analysis.

Contribution

The study introduces sodium pentazolates NaN5 and Na2N5 as new nitrogen-rich high energy density materials stabilized by sodium cations at high pressures, revealing their formation and stability mechanisms.

Findings

NaN5 and Na2N5 are stabilized at pressures above 20 GPa.

NaN5 becomes metastable upon pressure release.

Calculated Raman spectra match experimental data.

Abstract

Sodium pentazolates NaN5 andNa2N5, new high energy density materials, are discovered during first principles crystal structure search for the compounds of varying amounts of elemental sodium and nitrogen. The pentazole anion N5- is stabilized in the condensed phase by sodium Na+ cations at pressures exceeding 20 GPa, and becomes metastable upon release of pressure. The sodium azide (NaN3) precursor is predicted to undergo a chemical transformation above 50 GPa into sodium pentazolates NaN5 and Na2N5. The calculated Raman spectrum of NaN5 is in agreement with the experimental Raman spectrum of a previously unidentified substance appearing upon compression and heating of NaN3.