Thermal and light emission properties of rare earth (Eu3+, Dy3+ and Er3+), alkali (Li+, Na+ and K+) and Al3+-doped barium tellurite and boro-tellurite glasses

Abstract

The effects of rare earth, alkali and Al ions on the thermal, short-range structure, optical absorption and emission properties of barium tellurite and barium boro-tellurite glasses are studied. The glass transition temperature and density correlate with the average single bond energy of the glass network and the molecular mass of the constituents, respectively. Glasses containing Eu³⁺ shows strong red emission peaks at 613 nm and 595 nm. The emission spectra of Dy³⁺-doped glasses show two peaks due to ⁴F_9/2 → ⁶H_13/2 (578 nm) and ⁴F_9/2 → ⁶H_11/2 (668 nm) transitions. The downconversion spectra of Er³⁺-doped glasses (excited at 380 nm) have emission bands due to ²H_11/2 → ⁴I1_5/2 (524 nm), ⁴S_3/2 → ⁴I_15/2 (545 nm), and ⁴F_9/2 → ⁴I_15/2 (657 nm) transitions. The addition of B₂O₃ in the tellurite network does not produce any significant modification in the emission intensity, but it enhances the thermal stability and optical transparency of glasses. The photoluminescence intensity shows strong quenching effects with an increase in Dy₂O₃ and Er₂O₃ concentrations from 1 to 7 mol%, however these effects were not found in Eu₂O₃ containing glasses, which on the contrary show a continuous enhancement in luminescence intensity with an increase in Eu₂O₃ concentration. Raman studies show that the addition of metal oxides produces short-range structural transformation: TeO₄ → TeO₃ units in the tellurite glass network.