White light emission from Dy3+-doped ZnO + Bi2O3 + BaF2 + B2O3 + TeO2 glasses: Structural and spectroscopic properties.

The ZnO + Bi2O3 + BaF2 + B2O3 + TeO2 (ZnBiBaBFTe) host glass was prepared by melt quenching technique with the aim of achieving white light emission from Dy3+ ions. Their structural and spectroscopic properties were systemically investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Visible absorption, emission spectra and decay times. Judd-Ofelt (JO) parameters (Ωλ) evaluated from absorption spectrum were utilized to calculate the radiative parameters for 4F9/2 level of Dy3+ ions. The optical band gap energy of as-prepared glasses were calculated for the indirect, (αhυ)1/2 and direct, (αhυ)2 allowed transitions. The emission spectra of Dy3+:ZnBiBaBFTe glasses showed two intense peaks at 575 nm (4F9/2→6H13/2) and 481 nm (4F9/26H15/2) upon 386 nm excitation. The highest emission intensity was observed at 1.0 mol% of Dy3+ for 4F9/2→6H13/2 transition and the results are used in conjunction with lifetime measurements to derive spectroscopic parameters for the stimulated emission cross-section (25.2 × 10-22 cm2), gain bandwidth (5.86 × 10-28 cm3), and favourable quantum efficiency (74.2%). Moreover, white light can be realized with a CIE coordinates by adjusting the concentration of Dy3+ ions in ZnBiBaBFTe host glass. Efficient spectroscopic values and realizable white lighting in Dy3+-doped ZnBiBaBFTe glasses may have potential applications in laser illumination devices.