# High‐Pressure Synthesis of Antimony Nitride Sb3N5 and Polynitride Sb2N8 Featuring Single‐Bonded N8 10− Chains

## TL;DR

Scientists created new antimony nitride compounds under high pressure, including one with unique nitrogen chains.

## Contribution

Discovery of two new antimony nitrides, including the first oligonitride with twisted single-bonded N8 chains.

## Key findings

- Synthesis of mP20-Sb2(N8) with twisted single-bonded (N8)10− chains confirmed by X-ray and Raman.
- Identification of oC32-Sb3N5 at 51 GPa with structural and compressional analysis.
- Demonstration of antimony's ability to stabilize unusual nitrogen structures under high pressure.

## Abstract

High‐pressure high‐temperature synthesis in laser‐heated diamond anvil cells provides a direct pathway to stabilize polymeric and oligomeric nitrogen units, often inaccessible under ambient conditions due to the stability of the N2 molecule. Here we report the high‐pressure reactivity of antimony with molecular nitrogen, leading to the discovery of two distinct binary nitrides. At megabar pressures, we synthesized and structurally characterized mP20‐Sb2(N8), the first pnictogen oligonitride containing unprecedented twisted single‐bonded (N8)10− chains. The compound was identified by single‐crystal x‐ray microdiffraction and Raman spectroscopy, supported by density functional theory calculations. At lower pressures of ∼ 50 GPa, we observed the formation of oC32‐Sb3N5, complementing recent reports of this phase by the studies of its compressional behavior and stability field. These results significantly expand the interpnictogen chemistry and demonstrate the ability of antimony to stabilize unusual extended nitrogen fragments at high pressures.

High‐pressure reactions between Sb and molecular nitrogen in a laser‐heated diamond anvil cell led to the formation of oC32‐Sb3N5 (51(1) GPa) and mP20‐Sb2(N8), (> 100 GPa). Both phases were identified by single‐crystal x‐ray microdiffraction and are fully corroborated by density functional theory calculations. mP20‐Sb2(N8) is the first oligonitride to contain previously unknown twisted single‐bonded (N8)10− chains, whose characteristic vibrations were additionally identified by Raman spectroscopy.