Effectively promoting the crystallization of lithium disilicate glass-ceramics by free oxygen in the glass

Lithium disilicate glass-ceramics were prepared with SiO2-Al2O3-Li2O-CeO2-P2O5-R2O as the base system through the traditional melting method and modified with K2O, Rb2O, Cs2O, and Tb4O(7). The microstructure of the lithium disilicate glass-ceramics was characterized through differential thermal analysis, X-ray diffraction and scanning electron microscopy. The whiteness and fracture strength of the lithium disilicate glass-ceramics were investigated to validate their potential applications as dental materials. Results indicated that the mixed alkali effect exerted by the introduction of K2O, Rb2O, and Cs2O greatly improved the fracture strength of the modified lithium disilicate glass-ceramics. Furthermore, X-ray photoelectron spectroscopy and whiteness analysis proved that free oxygen increased through the introduction of larger alkali metal ions and terbium element in the glass-ceramics. The increase in free oxygen content through the introduction of Rb2O or Cs2O into the lithium disilicate glass-ceramics could effectively promote the formation of lithium disilicate crystals and the crystallization of lithium disilicate glass-ceramics. Research results indicated that lithium disilicate glassceramics with high fracture strength under pressureless sintering had been successfully fabricated.