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Magnesium aluminosilicate glass-ceramics are one of the important glass-ceramics with good mechanical performance. However, most of these magnesium aluminosilicate glass-ceramics are colored and non-transparent. In this work, transparent magnesium aluminosilicate glass-ceramics containing ZrO 2 are investigated. Devitrification of these magnesium aluminosilicate glass-ceramics is investigated using thermal analysis, X-ray diffraction, Raman spectroscopy, transmission electron microscope, transmission spectra, and Vickers hardness. It is found that crystals precipitated in these glasses and transparency of the glass-ceramics are strongly affected by the concentration of ZrO 2. Magnesium aluminosilicate glass-ceramics are found to be nontransparent when the ZrO 2 concentration is lower than 6.45 mol.%. With the increase in heat-treatment temperature ZrO 2 nanocrystals, MgAl 2 O 4 nanocrystals, and Al 6 Si 2 O 13 nanocrystals are sequentially precipitated, and Vickers hardness as high as 9.2 GPa are realized in glass-ceramics containing 7.19 mol.% ZrO 2. [ABSTRACT FROM AUTHOR]

Sodium-calcium-silicate glasses are the most widely used glasses in architectures, photovoltaics, etc. Development of highly transparent sodium-calcium-silicate glass-ceramics is important to extend the application areas. This work investigates the effect of glass composition on the crystallization and transmittance of sodium-calcium-silicate glasses containing ZrO 2. It is found that concentration of Na 2 O in the glasses has large effect on the crystallization behaviors and transmittance of the glass-ceramics obtained. Higher concentration of Na 2 O in glasses leads to lower glass transition temperature and crystallization activation energy, facilitating the bulk crystallization. Lower concentration of Na 2 O in glasses results in the surface crystallization of glasses. Similarity in composition of crystalline grains and glass improves the transmittance of glass-ceramics up to above 75 % in the visible region, even when the grain size is as large as ∼150 µm. Results reported in this work are full of significance for the development of transparent sodium-calcium-silicate glass-ceramics. • Na 2 O-CaO-SiO 2 glass-ceramics with large grain size, high transparency, and good mechanical properties were obtained. • Effect of Na 2 O content on crystallization kinetics and mechanism was investigated. • The change of Na 2 O contents can result in a transition from bulk crystallization to surface crystallization. • The transmittance was 75.5 % at 400 nm and 78.8 % at 550 nm, respectively, when the average grain size reaches 150 µm. [ABSTRACT FROM AUTHOR]

ZnAl 2 O 4 nanocrystals (NCs) embedded transparent glass-ceramics containing relatively large amount of alkali oxide were prepared and effects of the crystallization on ion-exchange properties of glass-ceramics were investigated. Precipitation of ZnAl 2 O 4 NCs not only improves the Vickers hardness of the glass-ceramics, but also reduces the content of zinc and aluminum with concomitant increase in the content of sodium in the residual glassy phase. These changes in the residual glassy phase decrease the activation energy of K–Na ion-exchange and enhance the diffusion coefficient of potassium, resulting in the large ion-exchange depth and significantly improved Vickers hardness of the ion-exchanged glass-ceramics. These results show that glass-ceramics containing non-alkali nanocrystals have promising applications in fields of covers for optoelectronic devices. • ZnAl 2 O 4 NCs were precipitated in transparent aluminosilicate GCs containing large amount of alkali oxides. • Crystallization of ZnAl 2 O 4 NCs can improve ion exchange properties. • Compositional changes in residual glassy phase in GCs was responsible for the enhanced ion-exchange. [ABSTRACT FROM AUTHOR]

Transparent glass-ceramics have particular properties compared with their precursor glasses, and have promising potential applications in many fields. Titanium-relative phases are frequently employed as nucleation agents for crystallization of glass-ceramics, and rarely been precipitated as functional nanocrystalline phases in glass-ceramics. In this work, transparent glass-ceramics containing Zn 2 TiO 4 and/or α-Zn 2 SiO 4 nanocrystals are investigated. It turns out that Vickers hardness of these glass-ceramics increases with the precipitation of Zn 2 TiO 4 and α-Zn 2 SiO 4 nanocrystals. Despite the blocking effect of nanocrystals precipitated in the glass-ceramics, structural and compositional modification of the residual glass induced by the precipitation of these nanocrystalline phases facilitates the K-Na ion-exchange, leading to the enhanced depth of layer and further improved Vickers hardness of the glass-ceramics. [ABSTRACT FROM AUTHOR]