Photoluminescence and radioluminescence properties of Gd3+ and Dy3+ co-doped ZnO – BaO- TeO2 glasses for white-LED and scintillation applications

A series of Gd 3+ /Dy 3+ co-doped zinc barium tellurite glasses with composition (54-x)TeO 2 –10ZnO–35BaO–1Dy 2 O 3 –xGd 2 O 3 (x = 0, 2, 4, 6, 8, and 10 mol%) were successfully fabricated through the conventional melt-quenching technique. The optical and spectroscopic characteristics were systematically investigated, with emphasis on the Gd 3+ →Dy 3+ energy transfer process under both direct Gd 3+ excitation (275 nm) and direct Dy 3+ excitation (387 nm). The complete absence of Dy 3+ emission in the Gd-free sample under 275 nm excitation unambiguously confirms the essential role of Gd 3+ as a sensitizer ion. X-ray induced radioluminescence spectra were acquired to assess the suitability of the glass system for scintillation detector applications. The yellow-to-blue (Y/B) emission intensity ratio was evaluated under both excitation conditions as a function of Gd 3+ content to determine the white-light generation capacity of the host matrix. Judd-Ofelt (JO) intensity parameters extracted from optical absorption spectra yielded a trend of Ω 2 > Ω 6 > Ω 4 , reflecting a highly asymmetric ligand-field environment surrounding the Dy 3+ ion sites. The Gd 3+ →Dy 3+ energy transfer dynamics were further analyzed by applying the Inokuti-Hirayama (IH) model, from which the energy transfer parameter Q was quantitatively determined and shown to increase monotonically with Gd 3+ concentration. The overall results indicate that the 4 mol% Gd 2 O 3 -doped glass composition exhibits the most favorable luminescent properties, establishing it as a promising candidate for white-LED phosphor and scintillation detector applications.