The Effect of Titanium Dioxide on the Crystallization Behavior of Silver Halides in Alkali Borosilicate Glasses

Ag-doped alkali borosilicate glasses with different TiO 2 contents were prepared by the melting method. The viscosity-temperature curves of the glass samples were fitted using the MYEGA equation, and it was found that the viscosity of the glass showed a gradual decrease with the increase of TiO 2 content in the interval of the crystallization temperature of the glass. The results of XPS analysis show that TiO 2 mainly enters the glass network in the form of [TiO 4 ] before the heat treatment of the glass samples. In contrast, after the heat treatment, the contents of [TiO 4 ] and [TiO 5 ] in the glass decreased significantly, and the content of [TiO 6 ] increased, which led to the separation of TiO 2 from the glass network. The microhardness of glass shows the same pattern. Raman spectral analysis shows that the introduction of TiO 2 promotes phase separation in glass. The reduction of glass viscosity facilitates the movement of particles within the glass, while the creation of phase separation promotes heterogeneous nucleation of grains. FE-SEM analysis reveals that the silver halide grains in the heat-treated glass are dispersed in the matrix in a spherical shape, and the average size of the silver halide grains tends to increase with the increase of TiO 2 content.