Dy³⁺: B₂O₃–Al₂O₃–ZnF₂–NaF/LiF oxyfluoride glasses for cool white or day white light-emitting applications

Structural, thermal and optical characteristics of 0.5 mol% Dy³⁺-doped oxyfluoride zinc alumino borate glasses were studied by XRD, FTIR, DSC, optical absorption, and luminescence approaches. All FTIR spectra indicate the presence of functional groups like BO₄ and BO₃ units, and AlO₆ groups. Dy³⁺ shows emission bands at 483 nm (⁴F_9/2 → ⁶H_15/2 transition, blue), 575 nm (⁴F_9/2 → ⁶H_13/2 transition, yellow), and 663 nm (⁴F_9/2 → ⁶H_11/2 transition, weak red), respectively, under 350 nm excitation. Among all samples, 54.5B₂O₃–5Al₂O₃–10ZnF₂–30NaF–0.5Dy₂O₃ glass exhibits the highest intensity for all observed emission bands. The emission spectral data were used to compute yellow/blue (Y/B) ratios, color chromaticity coordinates (x, y), correlated color temperatures (CCT), D_uv, and color purity (CP) of the samples. The deduced color coordinates (0.345, 0.350), 5003 K CCT at −0.001 D_uv with 9% color purity for 54.5B₂O₃–5Al₂O₃–10ZnF₂–30NaF–0.5Dy₂O₃ sample hints it as a potential candidate for WLEDs application.