Spectroscopic and radiative properties of Dy3+: BBCZFB glass suitable for solid-state yellow laser and W-LEDs applications

Abstract

Dysprosium ions (Dy3+) doped barium bismuth calcium zinc fluoroborate (Dy3+: BBCZFB) glass with the chemical composition of (70-x) H3BO3 + 10 BaCO3 + 5 Bi2O3 + 7.5 CaF2 + 7.5 ZnO + x Dy2O3 (where x = 0.05, 0.1, 0.3, 0.5, 1 and 2 in wt. %, standing for the concentration of Dy3+ ions) was prepared with melt quenching technique. X-ray diffraction pattern confirmed its amorphous nature. Scanning electronic microscope revealed its undefined shape showing its aperiodic nature. Its optical behaviour was explored with absorption, excitation, photoluminescence and decay time spectral analyses. Its direct allowed and indirect allowed transitions and bandgap values were obtained with Tauc’s plots. The Judd-Ofelt intensity parameters (Ωλ = 2, 4 and 6) were calculated from the absorption spectra to determine the glass’s radiative parameters. Its photoluminescence spectrum showed two intense emission bands, one ascribed to 4F9/2→6H15/2 transition around 483 nm (blue), the other to 4F9/2→6H13/2 transition around 575 nm (yellow), and showed one feeble band at 663 nm (red) of 4F9/2→6H11/2 transition. The emission colour was identified with CIE 1931 colour chromaticity diagram. The colour coordinates (x, y) were calculated, showing that the emission was in the near white region. The calculated correlated colour temperature was in the range of 4475–4916 K, indicating that the emission belonged to cool white light. The measured decay curves for the exited state of 4F9/2 exhibited non-exponential nature. The efficient energy transfer between Dy3+ ions were explored with Inokuti-Hirayama model. The glass’s density and refractive index, as well as the absorption coefficient in the NIR region, increased with the concentration of Dy3+ ions; while its emission intensity increased first and reached the maximum value at 1.0 wt% concertation then decreased. Among the prepared samples, 1DyBBCZFB exhibited the most competing comprehensive optical property and was suitable for solid-state yellow laser and W-LEDs applications.