Microstructural characterization and crystallization of (1 - x)TeO₂-xCdF₂ (x = 0.10, 0.15, 0.25 mol) glasses

The differential thermal analysis (DTA), X-ray diffractometer and scanning electron microscopy/energy dispersive spectrometer (SEM/EDS) techniques were used to investigate the microstructural characterization and the thermal behavior of the three (1 - x)TeO₂-xCdF₂ (x = 0.10, 0.15, 0.25 mol) glasses. The effect of the heating rate, annealing temperature and CdF₂ content on the thermal and the microstructural properties of TeO₂-CdF₂ binary glasses were enquired. DTA analysis has shown that as the CdF₂ content in the glass composition increases, the value of the glass transition and the peak crystallization temperatures shift to higher values. SEM/EDS investigations have shown that the crystal formation of α-TeO₂, γ-TeO₂ and CdTe₂O₅ crystal phases were observed when the 0.90TeO₂-0.10CdF₂ and the 0.85TeO₂-0.15CdF₂ glass samples were annealed to temperatures above the crystallization temperatures. X-ray diffraction (XRD) results illustrated clearly the transformation of the metastable γ-TeO₂ phase to stable α-TeO₂ crystalline phase as the annealing temperature was increased from 385 to 425 °C for the 0.75TeO₂-0.25CdF₂ glass.