In-situ High-temperature Crystallization of a Lithium Disilicate Glass
The effects on trace phase formation, crystallization kinetics and crystallographic evolution of Li2Si2O5 in glass-ceramics as a function of annealing temperature was determined using in-situ synchrotron X-ray diffraction.
Glass science and technology has been fundamentally important to the development of new glasses and glass-ceramics over recent decades.
Depending on the composition of lithium disilicate glass-ceramics, three types of reaction sequences may occur when forming the glass. Type I is the simultaneous nucleation of lithium metasilicate (LS) and lithium disilicate phases (LS2), followed by the transformation of LS to LS2 (1). In Type II, LS nucleates first and then transforms to LS2 at higher temperatures (2). While in Type III, LS2 nucleates directly without forming a LS phase (3).
In dental applications, glasses with type I or II are preferred (4) and using CAD/CAM technology it is possible to produce dental products with complex shapes. Due to the absence of LS, glasses of Type III reaction are not very common in the literature.
This study highlights the advantages of synchrotron radiation for determining the trace phase formation, crystallization kinetics and crystallographic evolution of lithium disilicate (Li2Si2O5) in a complex lithium disilicate glass (SiO2-Li2O-CaO-P2O5-ZrO2) (5). While X-ray diffraction measurements using a laboratory instrument were not capable of identifying the LS phase, the observation of the LS phase and other intermediate phases in trace quantities was successfully achieved using synchrotron radiation.
1. Höland, W., Apel, E., van t Hoen, C. & Rheinberger, V. Studies of crystal phase formations in high-strength lithium disilicate glass-ceramics. J. Non-Cryst. Solids 352. (2006), 4041-4050.
2. Hammetter, W.F. and Loehmann, R. E. Crystallization Kinetics of Complex Lithium Silicate Glass-Ceramic. J. Am. Ceram. Soc. 70. (1987), 577- 582.
3. Apel, E. et al. Inventors und Ivoclar Vivadent AG, assignee. Lithium disilicate glass ceramic. United States patent US 7,871,948 B2 18. January 2001.
4. Höland, W. et al. Future perspectives of biomaterials for dental restoration. J. eur. Ceram. Soc. 29. (2009), 1291-1297.
5. Saifang Huang, Zhaohui Huang, Wei Gao and Peng Cao. Trace phase formation, crystallization kinetics and crystallographic evolution of a lithium disilicate glass probed by synchrotron XRD technique. Scientific Reports. 5 : 9159, 2015.
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