This paper investigated the effects of P_2O_5 content and heat treatment on the species of crystalline phase and microstructure of lithium disilicate glass ceramics. As P_2O_5 increased from 0.0 to 4.0 mol. percent (GO, G1P, G2P and G4P), the crystallization temperature decreased and nuclcation density increased. Therefore, the microstructure was refined from plate-like polycrystalline aggregates to interlocking rod-shaped crystals and even spherical crystalline phases. Li_3PO_4 crystals acted as the heterogeneous nucleation sites for Li_2SiO_3 crystals, which could be the precursors of Li_2Si_2O_5 crystals. Furthermore, Li_2Si_2O_5 probably crystallized by epitaxial growth on Li_2SiO_3 crystals. With increasing P_2O_5 content, the relative content of Li_2Si_2O_5 crystals decreased and Li_2SiO_3 and Li_3PO_4 crystals increased in one- and two-stage treatments. Moreover, the precipitation of Li_2Si_2O_5 crystals was hampered during the one-stage treatment. Two-stage treatment was favorable for the growth of stable Li_2Si_2O_5 crystals.
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