The pressure dependence of the static and dynamic properties of liquid boron oxide was studied using ab initio molecular dynamics simulations. Planar BO3 units were found to be scarcely deformed under pressures up to about 3GPa. Under further compression, the number of tetrahedral BO4 units increased gradually, and approximately 90% of the boron atoms had fourfold coordination near to 100GPa. The self-diffusion coefficients of boron and oxygen exhibited a maximum at a pressure of about 10GPa. It was found that, under pressures above 20GPa, the diffusivity of boron became about two times larger than that of oxygen, while the former was 10 to 20% smaller than the latter at lower pressures. The microscopic origin of this anomalous pressure dependence of the diffusivity was revealed.

Anomalous Pressure Dependence of Self-Diffusion in Liquid B2O3: an ab initio Molecular Dynamics Study. Ohmura, S., Shimojo, F.: Physical Review B, 2009, 80[2], 020202