Effect of titanium doping on the compositional homogeneity of hollow glass microsphere

Titanium doped hollow glass microspheres (HGMs) were fabricated by sol-gel method. There were two kinds of spheres, blue and colorless, in each batch of HGMs. To study the effect of titanium doping on the compositional homogeneity and the difference between the two classes of HGMs, titanium doped gel precursors and HGMs were characterized by XRD, XRF, SIMS, SEM and EDS. The results showed that precipitation of alkali chlorides reduced the uniformity of heavily doped gel precursors and increased the dispersions of doping concentration in batches of HGMs. Because of the movability and flowability at high temperature, the uniformities of alkali metals were relatively poor in all HGMs. The DSIMS depth profiles of HGMs showed that local loss and accumulation of glass network modifiers, especially alkali metals, occurred in the outer and inner surface layers in dozens of nanometers as a result of volatilization and migration in furnace. Titanium behaved as both glass network former and modifier and its uniformity was between that of alkali metals and silicon. In blue HGMs, crystallization and segregation of titanium oxide, furthermore, reduced the compositional homogeneity of blue spheres in comparison to that of the colorless one.