Novel phase of beryllium fluoride at high pressure

TL;DR

This paper predicts a new high-pressure phase of beryllium fluoride using evolutionary algorithms, revealing potential for synthesis and expanding understanding of BeF2's structural behavior under pressure.

Contribution

The study introduces a novel thermodynamically stable high-pressure phase of BeF2 predicted by USPEX, with detailed structural characterization and implications for related silica phases.

Findings

New stable phase of BeF2 at 18-27 GPa

Structure has C2/c symmetry with 18 atoms per cell

Metastable phase of SiO2 has comparable energy

Abstract

A previously unknown thermodynamically stable high-pressure phase of BeF$_{2}$ has been predicted using the evolutionary algorithm USPEX. This phase occurs in the pressure range 18-27 GPa. Its structure has $C2/c$ space group symmetry and contains 18 atoms in the primitive unit cell. Given the analogy between BeF$_{2}$ and SiO$_{2}$, silica phases have been investigated as well, but the new phase has not been observed to be thermodynamically stable for this system. However, it is found to be metastable and to have comparable energy to the known metastable phases of SiO$_{2}$, suggesting a possibility of its synthesis.