Energy-transfer Er3+ to Eu3+ and frequency upconversion visible emission in PbGeO3:PbF2:CdF2 glass

Highlights: • Efficient Er³⁺-to-Eu³⁺ energy-transfer. • Efficient frequency upconversion in a new glass matrix. • Enhancement of Eu³⁺ emissions using Er³⁺ and/or Er³⁺/Yb³⁺ sensitizing ions. Er³⁺ to Eu³⁺ energy-transfer and frequency upconversion in PbGeO₃:PbF₂:CdF₂ glass are reported. Emission spectra excited at 980 nm was obtained for Er³⁺-doped samples, while Eu³⁺ emissions only occurred for double-doped (Er³⁺/Eu³⁺) or triple-doped (Yb³⁺/Er³⁺/Eu³⁺) samples. Codoped samples' spectra exhibit bands around 520 (²H_11/2 – ⁴I_15/2), 545 (⁴S_3/2 – ⁴I_15/2), 590 (⁵D₀ – ⁷F₁), 610 (⁵D₀ – ⁷F₂), 660 (⁴F_9/2 – ⁴I_15/2) and 700 (⁵D₀ – ⁷F₄) nm. The Er³⁺ green emissions' lifetimes were examined as a function of Eu³⁺ content evidencing Er³⁺-to-Eu³⁺ energy-transfer. The addition of Yb³⁺ enhanced the Eu³⁺ ions' emissions suggesting potential application for upconversion-based white light phosphor.