A diffraction study of SiO2 glass

The neutron structure factor for SiO2 glass at 22.0+-0.50C was determined in the range of Q, 1.0-25.5 A-1, by means of the time-of-flight (TOF) neutron diffraction method using the electron linear accelerator (LINAC). An analysis of neutron and X-ray diffraction data was carried out by using a general procedure of analysis of structure factors based on a theoretical viewpoint of liquids. Excellent agreement between the calculated structure factor curves and the observed ones over the whole range of Q has ascertained that the structure of SiO2 glass can be explained as a liquid-like structure which is an aggregate of randomly packed clusters consisting of five SiO2 'molecules'. Within the cluster one central 'molecule' is tetrahedrally surrounded by four peripheral 'molecules' with a random orientation about the Si-O bond direction. (author)