X-ray study of lithium disilicate glass: High pressure densification and polyamorphism

• Published in: Journal of non-crystalline solids 2014-03, Vol.387, p.112-116
• Main Authors: Buchner, Silvio, Pereira, Altair Soria, de Lima, João Cardoso, Balzaretti, Naira Maria
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Densification; Exact sciences and technology; Glasses (including metallic glasses); High pressure; High-pressure and shock-wave effects in solids and liquids; Lithium disilicate; Materials science; Mechanical and acoustical properties of condensed matter; Physics; RDF; Specific materials; X-ray diffraction
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2014.01.003

We have investigated the structural changes induced by high-pressure in lithium disilicate glass with stoichiometric composition Li2O.2SiO2 (LS2). Using toroidal type high-pressure chambers, glass samples were processed at 2.5GPa, 4GPa, 6GPa and 7.7GPa at room temperature. Synchrotron X-ray diffraction measurements were used to obtain the radial distribution functions (RDF) in order to follow the structural changes induced after processing at high pressure. Compared to a pristine sample, the main change observed for the samples processed up to 6GPa was associated to the distortion of the SiO4 tetrahedral structure. However, for the sample processed at 7.7GPa, a drastic change in the RDF indicated the formation of a distinct amorphous phase. The observed polyamorphism is important for a better understanding of the nucleation kinetics of crystalline phases under high pressure. •Synchrotron X-ray diffraction measurements were used to obtain the RDF.•Densification of LS2 glass at room temperature•Irreversible modifications of the glass structure under high pressure•Drastic change in the RDF indicated the formation of a distinct amorphous phase.