Rivalry Under Pressure – The Coexistence of Ambient‐pressure Motifs and Close‐packing in Silicon Phosphorus Nitride Imide SiP2N4NH

Non‐metal nitrides such as BN, Si3N4 and P3N5 meet numerous demands on high‐performance materials and their high‐pressure polymorphs exhibit outstanding mechanical properties. Herein, we present the silicon phosphorus nitride imide SiP2N4NH featuring six‐fold coordinated Si. Using the multianvil technique, SiP2N4NH was obtained from high‐pressure high‐temperature synthesis at 8 GPa and 1100 °C with in situ formed HCl acting as a mineralizer. Its structure was elucidated by combination of single‐crystal X‐ray diffraction and solid‐state NMR measurements. Moreover, SiP2N4NH was characterized by energy‐dispersive X‐ray spectroscopy and (temperature‐dependent) powder X‐ray diffraction. The highly condensed Si/P/N framework features PN4 tetrahedra as well as the rare motif of SiN6 octahedra and is discussed in the context of ambient‐pressure motifs competing with close‐packing of nitride anions, representing a missing link in high‐pressure chemistry of non‐metal nitrides.

from A via a.sfakia on Inoreader http://bit.ly/2Hjkq6b