Role of MgO in lowering glass transition temperature and increasing hardness of lithium silicate glass and glass-ceramics

Ultrahigh hardness Li2O–MgO–Al2O3–SiO2 glass–ceramics containing multiphase nanocrystals

“…The increasing glass transition and crystallization temperatures probably originated from better glass structure connectivity. Highly valance Mg 2+ ions connected [Si–O] structure unit and probably changed the role of Al 2 O 3 in glass from modifier to network former 35 . Moreover, the large glass transition and crystallization temperatures differences confirmed good glass‐forming abilities for all glass specimens.…”

“…The DSC diagrams of as-prepared glasses with different components (Figure 1) showed the glass transition temperatures (T g ) and crystallization temperatures (T c ) increased with higher MgO/Li 35 Moreover, the large glass transition and crystallization temperatures differences confirmed good glass-forming abilities for all glass specimens. In order to understand the glass structure changes with different MgO/Li 2 O ratios, furtherly for the effect on crystallization process, Raman spectra were presented in Figure 2.…”

“…[27][28][29][30][31][32][33] The crystallization processes, crystal phase, thermal expansion, and strength properties were determined by glass compositions of LAS glasses, which have been broadly investigated. [34][35] Chen et al 36 studied the effect of Li 2 O content in LAS glass on the crystal phase and CTE and found β-quartz solid solution-based crystal phases precipitation in glass-ceramics, and CTE in 30-300 • C range decrease with Li 2 O content increase. Lutpi et al 37 investigated the relationship between thermal treatment duration and thermal shock behavior of LAS glass, confirmed that the extension of thermal durations resulted in the growth of nanocrystals, from 0.55 to 0.67 μm, and induced microhardness increase, from 3.90 to 5.47 GPa.…”

“…In addition, the glass–ceramics also could be easily ion‐exchanged for further strength enhancement due to a suitable Li 2 O content 27–33 . The crystallization processes, crystal phase, thermal expansion, and strength properties were determined by glass compositions of LAS glasses, which have been broadly investigated 34–35 . Chen et al 36 .…”