Structure, structural relaxation and ion diffusion in sodium disilicate melts

We have investigated Na2Si2O5 melts with inelastic neutron scattering at temperatures up to 1600 K. The Si-O network relaxes on a time scale of ns, whereas the Na ion relaxation dynamics are found on a time scale of 10 ps. The elastic structure factor exhibits at 0.9 A−1 an emerging prepeak which becomes more pronounced with increasing temperature. The prepeak is caused by the formation of sodium-rich regions in the partially disrupted Si-O tetrahedral network.