Structural, thermal, optical properties and simulation of white light of titanium-tungstate-tellurite glasses doped with dysprosium

Graphical abstract: CIE coordinate diagram of different concentrations of the Dy³⁺-doped TTWD glasses with coordinates in the white light region. - Highlights: • Radiative lifetime of ⁴F_9/2 level of Dy³⁺ ions is longer in the tellurite glass. • Quantum efficiency is found to be high. • These glasses are suitable materials for generating white light. - Abstract: Structural, thermal, optical properties and simulation of white light of Dy³⁺-doped tellurite glasses of composition TTWD: (75 − x)TeO₂ − 10TiO₂ − 15WO₃ − xDy₂O₃ (x = 0, 0.1, 0.5, 1.0 and 2.0 mol%) were investigated. Raman spectra revealed that the glass contains TeO₄, TeO₃, WO₄ and WO₆ units. Differential scanning calorimetry (DSC) measurements were carried out to measure the glass transition temperature of all the glasses. From the optical absorption spectra, luminescence spectra and using the Judd–Ofelt (JO) analysis, we estimated the radiative transition probabilities, emission cross-sections, branching ratios and radiative lifetimes. The decay curves at lower concentrations are exponential while they show a non-exponential behavior at higher concentrations (≥0.5 mol%) due to energy transfer processes. The effective lifetime for the ⁴F_9/2 level decreases with increase in Dy₂O₃ concentration for the glasses under investigation. The non-exponential decay curves could fit well to the Inokuti–Hirayama (IH) model with S = 6, indicating that the nature of interaction responsible for energy transfer is of dipole–dipole type. Simulation of white light is examined with varying concentration and the results indicate that these glasses are suitable for white light emitting diode applications