Trace phase formation, crystallization kinetics and crystallographic evolution of a lithium disilicate glass probed by synchrotron XRD technique.

Saifang Huang,Wei Gao,Zhaohui Huang,Peng Cao

doi:10.1038/srep09159

Abstract

X-ray diffraction technique using a laboratory radiation has generally shown limitation in detectability. In this work, we investigated the in situ high-temperature crystallization of a lithium disilicate glass-ceramic in the SiO2–Li2O–CaO–P2O5–ZrO2 system with the aid of synchrotron radiation. The formation of lithium metasilicate and other intermediate phases in trace amount was successfully observed by synchrotron X-ray diffraction (SXRD). The crystallization mechanism in this glass was thus intrinsically revised to be the co-nucleation of lithium metasilicate and disilicate, instead of the nucleation of lithium disilicate only. The phase content, crystallite size and crystallographic evolutions of Li2Si2O5 in the glass-ceramic as a function of annealing temperature were studied by performing Rietveld refinements. It is found that the growth of Li2Si2O5 is constrained by Li2SiO3 phase at 580–700°C. The relationship between the crystallographic evolution and phase transition was discussed, suggesting a common phenomenon of structural response of Li2Si2O5 along its c axis to other silicon-related phases during glass crystallization.

Highlights

Trace phase formation, crystallization kinetics and crystallographic evolution of a lithium disilicate glass probed by synchrotron XRD technique
We investigated the in situ high-temperature crystallization of a lithium disilicate glass-ceramic in the SiO2–Li2O–CaO–P2O5–ZrO2 system with the aid of synchrotron radiation
We examined the phase transformation of a complex LS2 glass in the SiO2–Li2O–CaO– P2O5–ZrO2 glass system using both in situ and ex situ laboratory-based XRD techniques[14]

Summary

Introduction

Trace phase formation, crystallization kinetics and crystallographic evolution of a lithium disilicate glass probed by synchrotron XRD technique. We investigated the in situ high-temperature crystallization of a lithium disilicate glass-ceramic in the SiO2–Li2O–CaO–P2O5–ZrO2 system with the aid of synchrotron radiation. The kinetics and thermodynamics of nucleation are described by several theories including the classical nucleation theory (CNT) and Johnson–Mehl–Avrami–Kolmogorov (JMAK) theory[1] Thermoanalytic techniques, such as differential scanning calorimetry (DSC) or differential thermal analysis (DTA), have been used to study the non-isothermal crystallization kinetics[2,3,4]. We have successfully applied the state-of-the-art synchrotron radiation to study the mechanism, kinetics and crystallographic change during the crystallization of lithium disilicate glasses[5,6,7]. It has been well known that there are three types of reaction sequence occurring in the fabrication of lithium disilicate glass-ceramics, depending on glass composition[5]. The results from this study may shed insight on the understanding of crystallisation in glass-ceramics

Methods

Results

Conclusion