Photoemission and thermoluminescence characteristics of Dy³⁺-doped zinc sodium bismuth borate glasses

The present study reports preparation and characterization of Dy³⁺-doped PbO free alkali-heavy-metal-borate glasses for luminescent applications. The amorphous nature of the glasses and the presence of various structural groups like BiO₆, BO₃ and BO₄ were confirmed through XRD and FTIR measurements. The Oscillator strength of Dy³⁺ absorption transitions as well as the bond formed with the O²⁻ ion in the glass network were determined using the absorption spectra. Radiative parameters extracted from Judd-Ofelt theory proved the degree of suitability of prepared glasses for lasing applications. The photoluminescence spectra exhibited the emission characteristics of Dy³⁺ ions and used to calculate the branching ratio, stimulated emission cross-section and radiative lifetime. Metastable lifetimes of Dy³⁺ ions were obtained through exponential fitting of respective decay profiles. The luminescence quenching phenomena was reasoned using Inokuti-Hirayama (I–H) model. The optical gain and quantum efficiency values clearly suggested Dy³⁺ doping at 0.3 mol% was optimum for 587 nm lasing action. Further, CIE chromaticity plot indicated the possible applications in solid state lighting devices. The thermoluminescence glow curves of 0.3 mol% Dy³⁺-doped glasses were considered for gamma irradiation and kinetic parameters of the same were evaluated using Computerized Glow Curve Deconvolution (CGCD) technique.