A structural model for B2O3 glass

The structural characteristics of four random network models of B2O3 glass are discussed, and their computed X-ray radial distribution functions are compared with experiment. A random network based on the boroxol ring hypothesis gives marginally the best agreement with the observed distribution function at low interatomic separations, but fails to reproduce the measured density of the glass satisfactorily. A locally layered random network model is proposed, in which adjacent layers are weakly bonded by the occasional overlapping of boroxol rings rotated relative to each other by π/3 rad. With an interlayer distance of 2·37 × 10−10 m, equal to the primary O–O separation in the BO3 triangle, the proposed model reproduces the experimental density very closely indeed, and accounts for observed peaks in the X-ray radial distribution function out to about 5 × 10−10 m.