Transparent oxyfluoride glass ceramics with composition of 45SiO(2)-25Al(2)O(3)-5CaCO(3)-10NaF-15CaF(2)-0.5ErF(3) (in mol%) were developed through controlled crystallization of melt-quenched glass. Non-isothermal crystallization kinetics investigation showed that the average apparent activation energy E-a and Avrami exponent n are about 283 kJ/mol and 2.22, respectively, indicating the crystallization a three dimensional crystal growth process controlled by the diffusion with a decreasing nucleation rate. X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM) observation revealed the precipitation of CaF2 crystallites sized about 15 mu among the glass matrix after heat-treatment at 650 degrees C for 2 h. For as-made glass, no upconversion signals were detected when excited with a 30 mW diode laser at 980 nm, while strong upconversion emissions at 545, 660 and 800 nm were obtained for transparent glass ceramic under similar excitation condition. (C) 2005 Elsevier Ltd. All rights reserved.