Optical Glass-Ceramics Based on Fe2+: MgAl2O4 Nanocrystals and Nucleated by TiO2 and ZrO2

Transparent glass-ceramics of magnesium aluminosilicate system based on Fe2+:MgAl2O4 spinel nanocrystals nucleated by a mixture of TiO2 and ZrO2 and doped with 0.6 mol% FeO were developed. The glass was melted at 1580 degrees C with stirring and heat-treated in the temperature range from 800 to 1300 degrees C. The structure and spectroscopic properties of the glass and glass-ceramics were studied by DSC and XRD methods, Raman and absorption spectroscopy. ZrTiO4 nanocrystals 6 nm in size precipitate during the nucleation heat-treatment at 800 degrees C. Spinel nanocrystals 9-14 nm in size are formed during heat-treatments at 850- 1000 degrees C. Intense absorption at similar to 2 mu m is observed due to Fe2+ ions in tetrahedral positions in these crystals. Iron-doped sapphirine crystallization in transparent glass-ceramics at 1000-1050 degrees C results in a decrease of absorption in this spectral range. The glass-ceramics are important for the development of saturable absorbers for the spectral range of 2-3 mu m.