The crystallization of yttrium aluminum garnet (YAG) doped with Ce3+ from alkali free glasses in the system Y2O3/Al2O3/SiO2/AlF3 has been investigated with and without the addition of ZrO2 and/or TiO2 as nucleation agents. X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analysis (DTA) were used to characterize the crystallization process. Fluorescence microscopy and fluorescence spectroscopy were used to investigate optical properties. Thermal annealing of the glass was carried out at temperatures in the range from 1100 to 1400 degrees C. In all samples studied, crystallization at temperatures >= 1300 degrees C lead to the formation of YAG as the main crystalline phase. If the glass contained TiO2, the crystallization of YAG occurred at lower temperatures; here, already at 1150 degrees C, YAG was the main crystalline phase. After annealing at 1300 degrees C, the only crystalline phase formed was YAG. The fluorescence intensity showed a maximum at a wavelength of 532 nm and was largest in the sample solely doped with 5 mol% TiO2. This proves that Ce3+ was incorporated into the YAG crystals. (C) 2011 Elsevier B.V. All rights reserved.