XRD investigation of metastable phase formation in Li 2O–2SiO 2 glass

Abstract

Metastable crystal phase formation in lithium disilicate glass has been a subject of controversy for many years. However, recent evidence mainly obtained via the use of electron microscopy has provided strong evidence for formation of metastable phases during the early stages of crystallization in this composition. Very recently, however, a study has appeared which suggests that these metastable phases are long-lived and can be detected with the aid of XRD. Here, we present XRD results obtained for lithium disilicate glasses which were heated for various time periods at several temperatures in the nucleation regime. In no case do we find any evidence for metastable phase formation. Possible causes for the discrepancy between the present and previous experimental results are discussed.