Photoluminescence properties and energy transfer in γ-irradiated Dy3+, Eu3+-codoped fluoroaluminoborate glasses

The photoluminescence (PL) properties of singly doped (Dy 3+ ) and codoped (Dy 3+ , Eu 3+ ) fluoroaluminoborate glasses, with an emphasis on the white light generation, are studied. The γ-irradiation led to the formation of defects in Dy 3+ -doped glasses and photoreduction of Eu 3+ to Eu 2+ in codoped (Dy 3+ , Eu 3+ ) glasses. The electron paramagnetic resonance spectra confirm the presence of divalent europium ions and defects in Dy 3+ , Dy 3+ –Eu 3+ -doped glasses. The FTIR spectra mainly establish the compaction of glass network due to γ-irradiation. From the PL spectra, the intensity ratio of Dy 3+ emission bands yellow to blue ( 4 F 9/2 – 6 H 13/2 / 4 F 9/2 – 6 H 15/2 ) defines the site symmetry, covalency, and feasibility of extracting white light. The existence of an energy transfer (ET) from Dy 3+ to Eu 3+ ions are established due to the decrease in intensity of Dy 3+ peaks with an increase of Eu 2 O 3 content. Moreover, the non-exponential nature of decay curves was well fitted with the generalization of Yokota–Tanimoto model for electric dipole-quadrupole ( S = 8) interaction that is responsible for ET process from sensitizer (Dy 3+ ) to activator (Eu 3+ ).