Abstract: Alkali-aluminosilicate glasses with different (Al₂O₃+P₂O₅) concentrations were prepared by the melting-quenching method, and their structural characteristics and crystallization behavior were studied by Raman spectroscopy, X-ray diffraction spectroscopy, and scanning electron microscopy. It is found that as the concentration of (Al₂O₃+P₂O₅) decreases, the concentration of Na₂O increases, resulting in the glass transition temperature decreases from 685 ℃ to 622 ℃. When the (Al₂O₃+P₂O₅) concentration decreases to 22% (mole fraction), a crystallization peak appears and the onset crystallization temperature gradually decreases. The intensity of the Raman vibration band corresponding to Q⁴_P becomes lower and gradually shifts towards low frequency, indicating that the Na₂O as a network modifier gradually depolymerizes the structure of silicate glass and enhances the crystallization ability of the glass. The results show that there is a crystalline transformation after heat treatment when the concentration of (Al₂O₃+P₂O₅) is 22% (mole fraction). The main precipitation crystals are NaAlSiO₄ nepheline at 700 ℃ for 2 h while it transforms to Na_6.8Al_6.3Si_9.7O₃₂ nepheline crystals at 900 ℃ for 2 h. When the concentration of (Al₂O₃+P₂O₅) is 21% and 20% (mole fraction), Na₃PO₄ and Na_6.8Al_6.3Si_9.7O₃₂ crystals are precipitated after heat treatment. After heat treatment, phosphorus-rich phase and Na₃PO₄ crystals with poor acid corrosion resistance are precipitated, resulting in poor chemical stability.

Key words: Na₂O-Al₂O₃-SiO₂-P₂O₅ glass, glass-ceramics, aluminosilicate glass, cover glass, crystallization, melting-quenching method, nepheline