Effects of P2O5 and heat treatment on crystallization and microstructure in lithium disilicate glass ceramics

Abstract This paper investigated the effects of P 2 O 5 content and heat treatment on the species of crystalline phase and microstructure of lithium disilicate glass ceramics. As P 2 O 5 increased from 0.0 to 4.0 mol.% (G0, G1P, G2P and G4P), the crystallization temperature decreased and nucleation density increased. Therefore, the microstructure was refined from plate-like polycrystalline aggregates to interlocking rod-shaped crystals and even spherical crystalline phases. Li 3 PO 4 crystals acted as the heterogeneous nucleation sites for Li 2 SiO 3 crystals, which could be the precursors of Li 2 Si 2 O 5 crystals. Furthermore, Li 2 Si 2 O 5 probably crystallized by epitaxial growth on Li 2 SiO 3 crystals. With increasing P 2 O 5 content, the relative content of Li 2 Si 2 O 5 crystals decreased and Li 2 SiO 3 and Li 3 PO 4 crystals increased in one- and two-stage treatments. Moreover, the precipitation of Li 2 Si 2 O 5 crystals was hampered during the one-stage treatment. Two-stage treatment was favorable for the growth of stable Li 2 Si 2 O 5 crystals.