Pressure and temperature stability range of crystalline lithium metasilicate in a binary Li2O·2SiO2 glass

• Published in: The Journal of physics and chemistry of solids Vol. 74; no. 8; pp. 1179 - 1183
• Main Authors: Buchner, Silvio, Balzaretti, Naira Maria
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.08.2013
• Subjects: A. Glasses; C. High pressure; C. Raman spectroscopy; C. X-ray diffraction; D. Phase transitions; C. Raman spectroscopy; D. Phase transitions; C. High pressure; A. Glasses; C. X-ray diffraction
• ISSN: 0022-3697; 1879-2553
• DOI: 10.1016/j.jpcs.2013.03.024

The aim of this work was to investigate the formation of lithium metasilicate (Li2SiO3) under high pressure and high temperature starting from lithium disilicate glass with the stoichiometric composition Li2O·2SiO2 (LS2). Monolithic LS2 glass samples were processed at 4.25GPa, 4.5GPa, 5GPa, 5.5GPa, 6GPa and 6.5GPa and submitted, simultaneously, to heat treatment for nucleation and growth of the crystalline phases. The crystallization of the samples was investigated by X-ray diffraction, Raman spectroscopy and optical microscopy. In the pressure and temperature range investigated, crystalline Li2Si2O5 remained stable up to 6GPa and the formation of the metasilicate phase Li2SiO3 started at 4.25GPa coexisting with quartz and coesite up to 6.5GPa. The segregation of SiO2 phases during the crystallization of Li2SiO3 was a consequence of the lithium deficiency of the starting LS2 composition. •Lithium metasilicate was observed during thermal treatment from 4.25 to 6.5GPa.•A large crystallization of the orthorhombic phase was observed at 5.5GPa.•Quartz and coesite formation were consistent with stoichiometric restrictions.