Group connectivity in binary silicate glasses

The medium range order of binary alkali-silicate glass is studied in terms of the groups Qn,a1,…,anQn,a1,…,an, where n stands for the number of bridging oxygen atoms, and a1, … ,an indicate type of the connected Qn units. The Random Connectivity Model describing interconnections of Qn units in silicate glass was proposed and compared with the available experimental DQ 29Si nuclear magnetic resonance (NMR) data and with data obtained from molecular dynamics (MD) simulations. Analysis of NMR revealed that basic connectivity conditions are not fulfilled. The connectivity distribution in glass prepared by MD was found to be random.