Molecular dynamics studies of vitreous boron oxide

Positron lifetime spectroscopy of vitreous B2O3

“…To verify the proposed models, the slow cooled SC1 sample was re-heated to 500 (SCTF500 and SCTS500) and 600 K (SCTF600) then cooled to room temperature at different cooling rates. Re-heating the samples with a subsequent rapid quench should destroy, or at least diminish, the concentration of [22,23]. As expected, there was no significant difference observed in the s 1 lifetime and intensity for slow cooled samples, compare SC1 and SCTS500 in Table 1.…”

Neutron diffraction and reverse Monte Carlo modelling of v-B2O3 and 75B2O3–25Na2O glasses

“…Our result is in good agreement with the data obtained for the boroxol ring fraction <20% reported in Refs. [7][8][9][10][11] based on MD and RMC modelling, but contradicts others who report large number of boroxol rings from ND measurements 60% [1], 80% [2], from Raman spectroscopy [3,4], from NMR 70% [5] and from X-ray diffraction 75% [6]. The M(m) distribution, as displayed in Fig.…”

“…Table 1), which corresponds to the first neighbor distance of trigonal BO 3 units, in good agreement with the data reported in Refs. [1,2,8] and references therein. For the 75B 2 O 3 -25Na 2 O glass the B-O main peak is centred at 1.38 Å and a sub-peak appears at the higher r-side at about 1.55 Å, which corresponds to the sub-peak observed at $1.50 Å in the total RDF(r) (see Fig.…”

“…For v-B 2 O 3 it is generally accepted that the molecular building units are the planar 3-fold oxygen coordinated BO 3 groups with strong covalent bonding, however, the manner in which these units are connected to each other forming the network structure is question of debate in Refs. [1][2][3][4][5][6][7][8][9][10][11]. Several comprehensive neutron diffraction studies have shown [1,2] that the glassy network is formed by a mixture of large number of planar boroxol rings (B 3 O 6 ) and of a significantly smaller fraction of single BO 3 units.…”

“…From the above experimental probes typically f = 0.6-0.8 was revealed for the fraction of boroxol rings in the glassy network. On the other hand recent molecular dynamics (MD) calculations [7,8] and reverse Monte Carlo (RMC) modelling of neutron diffraction and X-ray experiments [9][10][11] could successfully simulate the experimental data only in that case if the fraction of boroxol ring was relatively low, typically less than 20%.…”