Oxyfluorotellurite glasses doped by dysprosium ions. Thermal and optical properties

•(65 − x)TeO2–20ZnF2–12Pb2O5–3Nb2O5–xDy2O3 (x = 0.5, 2, 5 mol%) glasses were prepared.•Thermal and optical properties of new oxyfluorotellurite glasses were investigated.•Material combines good thermal stability with desirable spectroscopic parameters.

The paper shows results of investigation of thermal and optical properties of oxyfluorotellurite (65 − x)TeO2–20ZnF2–12Pb2O5–3Nb2O5–xDy2O3 (x = 0.5, 2 and 5) glass systems. Thermal stability and the onset of crystallization of the materials were monitored by differential thermal analysis (DTA). It was found that characteristic parameters, namely glass transition temperatures (Tg), onset of crystallization temperatures (Tc) and thermal stability criteria ΔT and H’ increased with increasing Dy2O3 content indicating that the incorporation of dysprosium ions improves substantially thermal stability of glass system under study.Optical absorption and emission spectra of Dy3+ ions in oxyfluorotellurite glass were investigated at room temperature in the visible (VIS) and near-infrared (NIR) region. Oscillator strengths, phenomenological Judd–Ofelt (JO) intensity parameters Ω2,4,6, radiative transition probabilities, branching ratios and radiative lifetimes of luminescent levels were determined. Decay curves of the 4F9/2 luminescence of incorporated Dy3+ ions were recorded and analysed. Lifetimes and the luminescence dynamics were studied as a function of the Dy2O3 concentration. It was concluded that good thermal stability combined with desirable spectroscopic parameters of investigated dysprosium-doped oxyfluorotellurite glass point at the suitability of this material for the design of UV-excited visible phosphors.