Boroxol Rings in Liquid and Vitreous B2O3 from First Principles.
We investigate the structural and vibrational properties of glassy B2O3 using first-principles molecular dynamics simulations. In particular, we determine the boroxol rings fraction f for which there is still no consensus in the literature. Two numerical models containing either a low or a high level of boroxol rings are tested against a gamut of experimental probes (static structure factor, Raman, 11B and 17O NMR data). We show that only the boroxol-rich model (f=75%) can reproduce the full set of observables. Total-energy calculations show that at the glass density, boroxol-rich structures are favored by about 6 kcal/(mol boroxol). Finally, the liquid state is explored in the 2,000-4,000 K range and a reduction of f to 10%-20% is obtained.
Ferlat
Guillaume
G
IMPMC, CNRS-IPGP-Universités Paris 6 et 7, 140, rue de Lourmel, Paris, France.
Charpentier
Thibault
T
Seitsonen
Ari Paavo
AP
Takada
Akira
A
Lazzeri
Michele
M
Cormier
Laurent
L
Calas
Georges
G
Mauri
Francesco
F