An Hypothesis On The Nature Of Griffith'S Cracks In Alkali Silicate And Silica Glasses

The nature of Griffith's cracks in alkali silicate glasses is considered. The modified random network model is reviewed and used to describe the distribution of network modifiers in alkali silicate glasses. The interdiffusion of the alkali metal ions with water, or hydroxonium ions is hypothisised to generate structural defects in such glasses which correspond to Griffith;s cracks. An extension of this hypothesis to cover fused silica is also considered. The aim is to stimulate a wider discussion on how a modified random network might be manifested in macroscopic glass properties.