Pressure-Stabilized Zinc Trifluoride.

By combining the particle swarm optimization algorithm with first-principles calculation, the high-pressure phase diagram of Zn-F binary compounds was established. An unexpected stoichiometry of ZnF3 with space group Cccm is thermodynamically stable above 183 GPa. The new structure is fascinating with the appearance of Zn2+[F3]2- units. The stability of the new phase stems from the mixed ionic and covalent chemical bonding in ZnF3. The electronic properties indicate that Zn has a tendency to form high oxidation states under higher pressure. Our work is an important step in understanding the bonding behavior of Zn under extreme conditions and provides a valuable reference for experimental synthesis and identification of ZnF3.