Structure, structural relaxation and ion diffusion in sodium disilicate melts

We have investigated Na 2 Si 2 O 5 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 Å −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.