Revealing the local properties of β-HP4N7, a promising candidate for high pressure synthesis of new materials
Abstract
Acomputational investigation of β-HP4N7 system is accurately performed using the density functional theory formalism coupled with quantum theory of atoms in molecules. The aim of this work is to understand the behavior of β-HP4N7 under compression.
At ambient conditions, theN atoms occupy around 81% of the unit cell volume; for this reason the Natoms are the ones contributing significantly to the bulk properties. The particular tetrahedron (PN4) connection promotes high flexibility to this structure.
The atoms composing the solid show significant differences in their compressibilities. The high compressibility (or low resistence to pressure) of theNatoms indicates that the reorganization of these atoms is the key in the densification process that takes place when pressure is increased.
When compresing the β-HP4N7 from 0 to 130 GPa the formation of PN6 units is observed, leading to a phase transition. The analysis of the elastic constants reveals the stability of this new phase at 110 GPa.
This study shows that β-HP4N7 could be a potential candidate for high pressure synthesis of new phases where P atoms would be 6-fold coordinated.