Small-angle X-ray scattering and Reyleigh scattering studies of the microstructure of some optical glasses

Several optical glass samples were studied by small-angle X-ray Scattering (SAXS) in order to verify the presence of inhomogeneity in the range (1-100 nm). The results were compared with Rayleigh scattering measurements in order to verify a possible correlation between microstructure and scattering losses. For most glasses investigated, the presence of phase separation was excluded and the Rayleigh scattering intensities were attributed to refractive index fluctuations. For glasses ZKN7 and SK11 evidence of phase separation, with size of about 8 nm and less than 2 nm respectively, was obtained using SAXS. The particle size was insensitive to annealing treatments in the case of SK11 and showed a continuous growth with annealing time at 610 °C in the case of ZKN7. For these two glasses the overall Rayleigh scattering intensity includes a contribution due to the presence of phase separated particles