Process of Phase Separation in Sodium Borosilicate Glass as Studied by NMR
钠硼硅酸盐玻璃分相过程的NMR研究

29Si, 11 B, 23Na MAS NMR were employed to study the structure change of the Na2O-B2O3SiO2 glass in the process of thermal treatment of phase separation. The results show that oxygenatoms are deleted among the SiO4] structure units and the aggregation degree of Si increases inthe process of phase separation. In the meantime, the structure of boron atoms in silicon-richphase is transformed gradually from BO3] to BO4] and BO4] units enter into sodium-boronrich phase. The difference between the Compositions of the two phases gradually increases. Thephase separation is the result of diffusion and mass transfer. Moreover, the glass has a morerapid structure adjustment rate at a higher temperature of thermal treatment, thus can get to theequilibrium state faster.