Transparent Spinel Glass‐Ceramics With Varied MgO: Structure, Performance, and Ion‐Exchange Behavior

ABSTRACT ZnO–MgO–Al 2 O 3 –SiO 2 (ZMAS) transparent glass‐ceramics were prepared by the melting method. The effects of MgO content (4–10 mol%) on the network structure, crystallization mechanism, microstructure, and ion‐exchange enhanced mechanical properties were investigated. As the MgO content increases, the conversion of [AlO 5 ] to [AlO 4 ] is promoted, thereby enhancing the polymerization degree of the glass network. Additionally, Mg 2+ ions can participate in the formation of spinel crystals; thus, the increasing MgO content enhances the crystallinity of spinel and further enhances the mechanical properties of glass‐ceramics. When the addition of MgO is 4–6 mol%, the mean crystal sizes are ∼35 nm, maintaining high transparency. Increasing the MgO content further resulted in larger grain sizes, which in turn reduced transparency. The glass with 6 mol% MgO nucleated at 800°C for 6 h and then crystallized at 960°C for 2 h exhibited optimal comprehensive properties, a Vickers hardness of 830 kgf/mm 2 , approximately 70% visible light transmittance, an elastic modulus of 103 GPa, and the three‐point flexural strength of 171 MPa. These transparent glass‐ceramics were conducted on a two‐step ion‐exchange process, leading to the increasing of Vickers hardness to 920 kgf/mm 2 and the three‐point flexural strength to 600 MPa. It is indicated that the spinel glass‐ceramic can be chemically strengthened through ion‐exchange, showing a high potential in the applications of protective covers for cell phones, displays, and some precision lens.