Microstructure of Transparent Strontium Fresnoite Glass-Ceramics

Abstract

Glass-ceramics grown from a glass of the composition Sr2TiSi2.45O8.9 (STS 45) are analyzed by scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). Oriented nucleation with the c-axes preferably perpendicular to the surface is detected. A very strong 001-texture is observed after only 10 μm of growth into the bulk, making this the first system in which an orientation preferred during nucleation prevails during growth into the bulk in glass-ceramics. Piezoelectric measurements are performed and d33-values presented and discussed. The obtained results are critically viewed with respect to the two growth models describing Sr2TiSi2O8 growth in glasses.

The influence of TiO 2 and ZrO 2 on microstructure and crystallization behavior of CRT glass

“…The lack of bulk crystallization allowed us to conclude that nucleation occurred solely on the surfaces. This seems to be in contradiction to the crystallization of BTS reported in [19], but comparable with data shown by W. Wisniewski for the surface crystallization of Sr 2 TiSi 2 O 8 fresnoite [39][40][41]. The EDX spectra of samples support the above XRD results.…”

Oriented Nucleation of both Ge-Fresnoite and Benitoite/BaGe4O9 during the Surface Crystallisation of Glass Studied by Electron Backscatter Diffraction

“…also observed in STS containing glass-ceramics3839. Polarization micrographs of cross sections have been published24 and indicate a strong optical anisotropy.…”

“…001 textures have also been indicated by XRD in BTS4041 and STS38 glass-ceramics, but the application of EBSD showed that the topmost layer shows a different orientation in the case of BTS40 which is affected by the annealing temperature40. Actually, the analysis of surface crystallized STS from the composition STS+0.45 SiO 2 provided the first case where the texture detected at the immediate surface also prevailed during growth39 while a texture change is observed more often33404243. Hence the assumption of a randomly oriented nucleation in BTG24 must be questioned.…”

“…The application of electron backscatter diffraction (EBSD) to the surface crystallization of glass-ceramics containing BTS4041 and STS383942 has significantly altered the understanding of occurring crystal orientations and textures in these systems. For example, the observation of oriented nucleation in these glass-ceramics3839404142, also observed e.g.…”

Pockels effect of silicate glass-ceramics: Observation of optical modulation in Mach–Zehnder system

“…In surface crystallization, direction of evolved nuclei is basically randomly oriented and the orientation starts during the growth process owing to geometric selection30. However, Wisniewski et al found that in case of the PSC the crystal nuclei roughly orient at the nucleation stage, i.e., orientation nucleation31. The strong orientation of crystallized fresnoite phase and its dense texture are considered to be due to the orientation nucleation.…”