Glass-forming ability and ZrO2 saturation limits in the magnesium aluminosilicate system

Glass formation and devitrification behavior of alkali (Li, Na) aluminosilicate melts containing TiO2

“…1-b). All in all, a decrease in overall SiO 2 content and an enrichment in Al 2 O 3 appear beneficial for the obtainment of homogeneous aluminosilicate glasses doped with TiO 2 , in agreement with recent results on ZrO 2 -bearing (magnesium) aluminosilicate glasses [28]. Our observations may indeed seem counterintuitive in the light of the available geochemical models [47,48], which predict higher solubility of TiO 2 in peralkaline melts at a given temperature.…”

“…The starting compositions for this study (Fig. 1 All samples were synthesized by aerodynamic levitation coupled to CO 2 laser heating (ADL); the experimental setup has been described elsewhere [28]. Laboratory-grade Li 2 CO 3 (99%, Aldrich), Na 2 CO 3 (99.5+%, Strem Chemicals) SiO 2 (99.999%, Strem Chemicals), Al 2 O 3 (99.999%, Strem Chemicals) and TiO 2 (99.5%, Evonik P25) were thoroughly mixed in a hand mortar with the help of some ethanol and pressed into pellets of 1 g. Small chunks of these pellets were then melted by ADL in an O 2 flow, increasing the laser power until achieving a fully liquid spherical droplet.…”

A chemical threshold controls nanocrystallization and degassing behaviour in basalt magmas

“…A sufficiently long dwell at medium-to-deep undercooling can therefore induce nucleation and growth of Fe-Ti-oxide crystals simply due to their melt oversaturation, which will ultimately be more pronounced in a FeO-and TiO 2 -richer melt. This explanation is supported by fundamental studies of devitrification and crystal nucleation in aluminosilicate melts containing nucleating agents (e.g., TiO 2 and ZrO 2 ): differences by only a few wt.% typically mark the transition between unchallenging glass quenchability and extensive crystal precipitation 163,164 .…”

Glass-forming ability and structural features of melt-quenched and gel-derived SiO2-TiO2 glasses

“…Melt-quenched glasses were prepared by aerodynamic levitation coupled to CO2 laser heating (ADL), using a setup described in a previous work [64]. SiO2 (Chempur, 99.9%) and TiO2 (Evonik, Aeroxide TiO2 P 25, 99.5%) powders were mixed thoroughly in an agate mortar and pressed into pellets of approximately 1 g. Small chunks of the pellets weighing from 10 to 50 mg were then melted using O2 as a levitation gas, gradually increasing the laser power until reaching 1900-2100 °C (as recorded by two pyrometers).…”

“…SiO2 (Chempur, 99.9%) and TiO2 (Evonik, Aeroxide TiO2 P 25, 99.5%) powders were mixed thoroughly in an agate mortar and pressed into pellets of approximately 1 g. Small chunks of the pellets weighing from 10 to 50 mg were then melted using O2 as a levitation gas, gradually increasing the laser power until reaching 1900-2100 °C (as recorded by two pyrometers). The levitated droplet was left at this temperature for a few seconds and then quenched by cutting the laser power; the cooling rate is estimated to be in the order of 300 K s -1 or more [64]. Using this method, several glassy beads containing 0, 0.5, 1, 2, 4, 6, 8 and 10 mol% could be prepared; they were accordingly named T0m, T0.5m, T1m, T2m, T4m, T6m, T8m, T10m (-m for melt-quenched).…”