A continuous random network approach to the structure of vitreous boron trioxide

Two models of a three-fold coordinated continuous random network (C.R.N), originally constructed to simulate the structure of amorphous arsenic have been converted by means of certain computer procedures into plausible structures of vitreous boron trioxide, B2O3. Using the original coordinates of the arsenic networks as a basis, oxygen sites were positioned at the midpoint of each arsenic bond and boron sites were located at the centre of each triangle, thereby forming interconnected planar BO3 units. Various structural parameters of the resulting model have been calculated, including radial distribution functions (RDFs), both total and partial, and bond angle distributions. The calculated RDF shows very reasonable agreement with experimental curves deduced from X-ray diffraction work, and reproduces satisfactorily the peaks that have previously been ascribed to six-membered boroxol rings. This is significant since the present model contains no boroxol rings whatsoever. (author)