The acceleration of crystal growth of gold-doped glasses within the system BaO/SrO/ZnO/SiO2

Glasses with the base composition 8 BaO center dot 8 SrO center dot 34 ZnO center dot 50 SiO2 were studied with respect to the crystallization of a phase with the composition Ba0.5Sr0.5Zn2Si2O2. Some glasses were doped with gold and/or antimony oxide. All glasses exhibited solely surface crystallization. If the glasses contained both antimony and gold, they showed red coloration after different heat treatments and the crystal growth velocities were enhanced, depending on the chosen temperature, by around a factor of 30. Crystals were proven to be oriented statistically, while in all other glasses of the system under consideration, i.e., in those which did not contain both gold and antimony, an orientation of the crystals with their c-axes perpendicular to the surface was obtained. This effect is explained by a continuous nucleation in front of the growing crystals.