THE STRUCTURE OF SOME SIMPLE AMORPHOUS NETWORK SOLIDS REVISITED

The amorphographic relationships between the structures of a number of single component amorphous network solids are discussed. New neutron diffraction data are introduced for several of the materials including vitreous P2O5 which has not previously been studied by neutron diffraction. These data suggest that network connectivity is more important than structural unit stereochemistry in determining intermediate range order. Previous neutron data for amorphous Ge and vitreous SiO2 are compared with both random network and crystal based models and criteria are proposed for the minimum size of model required to accurately predict the shape of the first diffraction peak, which for a number of amorphous network solids is found to be Lorentzian. It is concluded that new computer modelling techniques are capable of generating models in good agreement with modern diffraction data and should considerably enhance present understanding of the structure of amorphous solids.