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

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.