Stability of the TeO_2 phase in the binary and ternary TeO_2 glasses

摘要

The stability of TeO_2 phase was studied in binary TeO_2–WO_3, TeO_2–CdO and ternary TeO_2–WO_3–CdO glasses. The samples were prepared by heating high purity powder mixtures of TeO_2, WO_3 and/or CdO to 800 ℃ in a platinum crucible with a closed lid, holding for 30 min and quenching in water bath. Differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were used to characterize the thermal, phase and microstructural properties of theδ- TeO_2 phase. The addition of CdO into the tellurite glasses increased the stability range of the δ-TeO_2 phase up to higher temperature values and expanded the compositionalδ- TeO_2 formation range. The formation ofδ- TeO_2 phase in the binary systems was observed for samples containing 5–10 mol% WO_3 and 5–15 mol% CdO. However, for the ternary TeO_2–WO_3–CdO system the formation of δ-TeO_2 phase was determined in a wider compositional range.