Thermal and microstructural characteristics of (1 - x)TeO2-xPbF(2) (x = 0.1, and 0.25) optical glasses were investigated. A differential thermal analysis technique was used to determine the glass transitions, crystallization and melting temperatures of each composition. Each sample shows only one crystallization peak at 355 and 322 degrees C for 0.1 and 0.25 mol PbF2 content, respectively. Microstructural analysis of the samples was carried out after the samples annealed above their crystallization temperatures. The X-ray diffraction pattern of the sample containing 0.1 mol PbF2 content predicts that the PbTe3O7, and gamma-TeO2 crystalline phases are present. The micrographs of the samples, and the elemental analysis of the crystalline phases observed were recorded using an optical microscope (OM). These results verify the existence of the crystalline phases determined from the X-ray diffraction patterns. (c) 2006 Elsevier Ltd. All rights reserved.