Viscous Fingering and Dendritic Growth of Surface Crystallized Sr2TiSi2O8 Fresnoite

Abstract

During the quenching of a melt with the composition 2SrO·TiO2·2.75SiO2, cubic SrTiO3- and tetragonal Sr2TiSi2O8-crystals are formed at the surface. Subsequent crystal growth leads to dendritic fresnoite structures which become increasingly finer until the mechanism changes to viscous fingering during further cooling. In the final stages of this initial growth step, the crystal orientations of these dendrites systematically change. Due to a complete absence of bulk nucleation in this system, crystal growth is resumed upon reheating to 970°C and fractal growth with the c-axis tilted by about 45° from the main growth direction is observed. The results are interpreted to confirm the link between viscous fingering and dendritic growth in the case of a true crystallization process.

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.…”

Surface Crystallization of a MgO/Y2O3/SiO2/Al2O3/ZrO2 Glass: Growth of an Oriented β-Y2Si2O7 Layer and Epitaxial ZrO2

“…A link of all known growth mechanisms via a specific growth velocity has been proposed in ref. 39, but a more detailed discussion of this topic is beyond the scope of this article.…”

Growing Oriented Layers of Bi4Ti3O12 in Bi2O3/TiO2/SiO2/Nd2O3/Al2O3 Glass-Ceramics by Melt Quenching

“…continuous orientation changes in dendrites were also observed during the non-isothermal crystallisation of Sr-fresnoite 31 . Here the systematic orientation change was interpreted to correspond to a change of the growth mechanism from dendritic to what could be viscous fingering 31 during cooling. In the sample presented here, the microstructure and the orientation analysis indicate an increasing temperature during crystal growth with an increasing distance from the air/glass interface.…”

“…This is important because dendrites generally show a homogeneous orientation but e.g. continuous orientation changes in dendrites were also observed during the non-isothermal crystallisation of Sr-fresnoite 31 . Here the systematic orientation change was interpreted to correspond to a change of the growth mechanism from dendritic to what could be viscous fingering 31 during cooling.…”