Effect of high pressure and high temperature on the Na2O · 2CaO · 3SiO2 glass-ceramic’s structural properties

Abstract In this study, the Soda-lime-silicate system, with the Na 2 O · 2 CaO · 3 SiO 2 ( N 1 C 2 S 3 ) composition, was used to study the effect of high pressure on structural properties of this glass-ceramic. Samples were produced and submitted to a single stage crystallization heat treatment at 720 °C for 30 min simultaneously in atmospheric pressure, 2.5 GPa, 4.0 GPa or 7.7 GPa. All characterizations were performed ex-situ. The major crystalline phase obtained is the Combeite, regardless of the pressure used, with indications of a β − CaSiO 3 or Cristobalite-II phase transition happening due to the high pressure. Raman and Infrared spectroscopy showed that the phase transition could be a CaO precipitation on the material, due to the breaking of Si–O bonds and presence of Ca–O vibrational modes present on the high pressure samples. All results point to the Combeite crystalline phase being highly stable under pressures up to 7.7 GPa.