Nitride Spinel: An Ultraincompressible High-Pressure Form of BeP2 N4.

Owing to its outstanding elastic properties, the nitride spinel γ-Si3 N4 is of considered interest for materials scientists and chemists. DFT calculations suggest that Si3 N4 -analog beryllium phosphorus nitride BeP2 N4 adopts the spinel structure at elevated pressures as well and shows outstanding elastic properties. Herein, we investigate phenakite-type BeP2 N4 by single-crystal synchrotron X-ray diffraction and report the phase transition into the spinel-type phase at 47 GPa and 1800 K in a laser-heated diamond anvil cell. The structure of spinel-type BeP2 N4 was refined from pressure-dependent in situ synchrotron powder X-ray diffraction measurements down to ambient pressure, which proves spinel-type BeP2 N4 a quenchable and metastable phase at ambient conditions. Its isothermal bulk modulus was determined to 325(8) GPa from equation of state, which indicates that spinel-type BeP2 N4 is an ultraincompressible material.