Xps Study Of Lithium Disilicate Glass Crystallisation

The failure of the classical nucleation theory to quantitatively describe crystal nucleation rates in glasses may be attributed to several causes. Some authors speculate that a possible reason for this discrepancy is the formation of metastable phases in the early stages of crystallisation prior to the equilibrium phase. This issue has been a subject of controversy for the last 40 years but recent TEM analysis clearly shows the precipitation of a second phase (lithium metasilicate) in addition to the stable phase lithium disilicate in a slightly hyper-stoichiometric lithium disilicate glass, heat treated.