P₂O₅ AS AN EFFECTIVE NUCLEATING AGENT OF LITHIUM DISILICATE GLASS-CERAMICS

Abstract

The objective of the study was to control the nucleation and main crystal formation of lithium disilicate, Li₂Si₂O₅, by an effective nucleating agent to develop high-strength, translucent glass-ceramics.The authors used P₂O₅ as nucleating agent to precipitate lithium disilicate in glasses derived from the SiO₂-Li₂O-Al₂O₃-K₂O-ZrO₂ system. The concentration of P₂O₅ was up to approx. 3 wt.%. Additives of P₂O₅ allowed the control of bulk crystallization. Nucleation was catalyzed by Li₃PO₄ phases. Li₃PO₄ is the heterogeneous catalyst. The final glass-ceramic is characterized by a dense microstructure with a high crystalline content of more than 70 vol.%.The mechanical strength was determined as biaxial flexural strength of approx. 740 MPa and Weibull factor of 11.3. The glass-ceramic shows the potential to be applied as a biomaterial for dental restorations. The authors conclude the effectiveness of P₂O₅ as nucleating agent on the basis of a heterogeneous nucleation of nanophases and precipitating main crystal phases by epitaxial growth.