Phase separation and crystallization in glasses of the lithium silicate system xLi2O · (100 − x)SiO2 (x = 23.4, 26.0, 33.5)

Role of dynamic heterogeneities in crystal nucleation kinetics in an oxide supercooled liquid

“…The red line, τ R (T), was calculated as a VFT regression to the values of viscosities reported by several authors. 13,48,[62][63][64][65][66] The blue straight line is a linear regression to the τ N (T) reported by several authors. 34,37,39,44,45 The two curves intersect at a temperature of about 656 K. The green vertical dashed lines represent the uncertainties in the T X value, and the yellow vertical dashed line corresponds to experimental T max value.…”

Critical assessment of the alleged failure of the Classical Nucleation Theory at low temperatures

“…( 10). Both plots were built using reported values of J0 and a regression of viscosity data from the literature [12,14,[40][41][42][43][44][45], shown in Figure 2c, which gave an average viscosity for this particular supercooled liquid. The deviation from linearity observed on the low temperature side in both Figure 2a and Figure 2b is the so-called nucleation "breakdown" (not to be confused with the breakdown of the Stokes-Einstein equation, often reported in the analyses of crystal growth rates [46][47][48][49]).…”

Crystallization‐induced suppression of intumescence in aqueous alkali silicates

“…The mobility of the network is reduced a lot in the case of Li‐silicates. This stems from the fact that the starting compositions studied here lie in the phase separation regime (already evidenced in the starting solutions that become whitish at rather lower temperatures, that is, below 150°C as shown in Figure S5) when compared with the reported data for binary Li 2 O–SiO 2 glass systems 23,27,32 indicating the formation of an almost pure SiO 2 phase. Although we do not have access to the phase separation diagram in the ternary system, including water, it is likely that protons are mostly found in the Li‐rich phase, because it is thermodynamically more favorable to cluster together network modifiers.…”

“…Li-silicates (especially glass-based compositions), on the other hand, have been widely reported to exhibit crystallization upon thermal treatment [21][22][23][24][25][26][27] with the formation of Li 2 SiO 3 and Li 2 Si 2 O 5 as the most frequently observed phases depending upon the starting composition. Crystallization has also been observed for Li-silicate powders synthesized from gels; at room temperature 28 and upon thermal treatments above 500 • C 29,30 without any indication of intumescence or extensive macroscopic structural changes.…”

“…Crystallization has also been observed for Li-silicate powders synthesized from gels; at room temperature 28 and upon thermal treatments above 500 • C 29,30 without any indication of intumescence or extensive macroscopic structural changes. In addition to crystallization, phase separation 23,27,31,32 is a characteristic property of Lisilicates, the thermal behavior of which has not been fundamentally explored; rather some studies on the mixture of solutions involving Li-silicates have been communicated where the addition of Li into K-silicates tends to reduce the extent of intumescence. 9, 14 Li-silicates are suggested to have little to no intumescence 9,33 even on keeping the system under a humid atmosphere followed by thermal treatment to 500 • C. This is considered to be the result of Li ions forming strong cross-links between polysilicate particles with the formation of Li 2 Si 2 O 5 crystals in the process.…”