Structure, Structural Relaxation and Ion Transport in Sodium Disilicate Melts

We have investigated Na2SiO5 melts with inelastic neutron scattering at temperatures up to 1600K. The Si-O network relaxes on a time scale of ns, whereas the Na ion relaxation dynamics are found on a time scale of 10ps. The elastic structure factor exhibits at ~0.9A-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.