A continuous random network model for vitreous boron trioxide

The structure of glassy boron trioxide B2O3 is a subject of debate since it is not yet established which of two possibilities, either -BO3 triangles or -B3O6 ‘boroxol’ rings, forms the structural unit of a continuous random network describing the structure. We describe the construction of the first hand-built ‘ball-and-stick’ structural model to simulate the structure of glassy B2O3. It is composed solely of -BO3 triangles with no boroxol rings whatsoever; the calculated scattering properties of the model agree very well with experimental X-ray and neutron data, although the density of the model is some 17 % higher than the experimental value. This might be reduced either by relaxing the constraint placed during construction that the model be made as dense as possible, or by incorporating a small proportion of boroxol units.