Effect of La2O3 on the physical and crystallization properties of Co2+-doped MgO–Al2O3–SiO2 glass

Abstract The physical and crystallization properties of MgO–Al 2 O 3 –SiO 2 glasses with various La 2 O 3 additions (0–10 wt.%) were studied by means of density, hardness and coefficient of thermal expansion (CTE), differential thermal analysis (DTA), in situ high temperature XRD, room temperature XRD, and absorption spectrum. Density, hardness and CTE were found to increase with adding La 2 O 3 content. The slight variation of transformation temperature ( T g ) observed between different LMAS glass compositions can be attributed to the relatively strong La O bonds. La 2 O 3 was found to hardly influence the nucleation and crystallization processes of Co 2+ -doped MgO–Al 2 O 3 –SiO 2 glasses when lower than 5 wt.%, while the nucleation of the glass was hindered and MgAl 2 O 4 spinel cannot be formed with the La 2 O 3 content greater than 5 wt.%. Transparent glass-ceramics were synthesized by heat-treating glasses with 0–5 wt.% La 2 O 3 at 760 °C/12 h + 930 °C/4 h; the changes in absorption spectra reflected that Co 2+ ions entered into MgAl 2 O 4 nanocrystals precipitated in the glass-ceramics and occupied tetrahedral coordinated site.