Lithium disilicate glass produced at high pressure: Characterization of structural, thermal and mechanical properties

Abstract

In this work, high‐density lithium disilicate (LS2) vitreous systems were produced by melting and quenching under high pressure (7.7 GPa) following two distinct experimental routes. In the first case, LS2 glass was remelted at 7.7 GPa and 1600°C and, then, quenched. In the second case, a stoichiometric mixture of precursor oxides (Li2O and SiO2) was melted at 1600°C and 7.7 GPa before quenching. A reference LS2 glass sample was produced at atmospheric pressure using conventional melting and quenching procedure. The samples were characterized by X‐ray diffraction, differential thermal analysis, and instrumented ultramicro hardness measurements. X‐ray diffraction confirmed that all samples were amorphous and thermal analysis suggests that different glassy structures were produced depending on the route of synthesis. Hardness and elastic modulus of the glasses produced under high pressure were higher than those of the reference glass, reflecting the irreversible densification effect induced by the high‐pressure processing.

Pressure‐driven homogenization of lithium disilicate glasses

“…In this context, we study the effect of pressure on the densification mechanisms of lithium disilicate glasses, and we provide a detailed analysis of the glass structure at both short‐ and medium‐range. The structural properties of the glass are compared with the experimental data of glasses similar to those prepared by Resende et al 28 . and analyzed through synchrotron X‐ray diffraction (XRD).…”

“…25 Another important result found in Buchner et al 26 work is the formation of a distinctive amorphous phase of densified LS 2 glass at a pressure of 7.7 GPa, wherein small distortions on the local arrangement of the initial structure cannot be used to explain its appearance. Moreover, Resende et al 28 showed that it is possible to produce lithium disilicate glasses at high pressure by melting and quenching them in situ at a pressure of 7.7 GPa. The results showed a significant increase in mechanical properties and completely different thermal properties compared to a reference glass sample conventionally prepared at atmospheric pressure.…”

“…work is the formation of a distinctive amorphous phase of densified $${\rm LS}_2$$ glass at a pressure of 7.7 GPa, wherein small distortions on the local arrangement of the initial structure cannot be used to explain its appearance. Moreover, Resende et al 28 . showed that it is possible to produce lithium disilicate glasses at high pressure by melting and quenching them in situ at a pressure of 7.7 GPa.…”