Spectroscopic properties and tunable color emission via Ce³⁺/Dy³⁺ energy transfer in K₂O–Al₂O₃–P₂O₅ glasses for solid-state lighting and scintillation applications

Abstract

The investigation of luminescent glasses has long aimed to improve emission intensity. Phosphate glasses doped with rare-earth (RE) ions are regarded as a promising high-gain laser material due to their favorable spectroscopic properties. In this study, a new series of glasses with the composition 15 K<inf>2</inf>O-20Al<inf>2</inf>O<inf>3</inf>-(64.5-X)P<inf>2</inf>O<inf>5</inf>-0.5CeF<inf>3</inf>-XDy<inf>2</inf>O<inf>3</inf>, where X = 0.0, 0.1, 0.3, 0.5, 1.0, and 2.0 mol%, were synthesized using the solid-state reaction method. The physicochemical and optical properties were characterized by using X-ray diffraction (XRD), optical absorption spectroscopy, photoluminescence (PL) analysis, Judd–Ofelt (J-O) parameterization, decay time measurements, and photoluminescence quantum yield (PLQY) determinations. XRD confirmed the amorphous nature of all samples. The absorption spectra revealed ten distinct bands, including a hypersensitive transition at ⁶H₉/₂ + ⁶F₁₁/₂, centered at 1278 nm. The glasses exhibited characteristic PL emissions in the blue (∼484 nm) and yellow (∼575 nm) regions. The J-O intensity parameters followed the order Ω2 > Ω6 > Ω4, indicating strong transitions. The ⁴F<inf>9/2</inf>→⁶H<inf>13/2</inf> transition of Dy³ ⁺ ions displayed a high stimulated emission cross-section (15.733 × 10⁻²² cm²), branching ratio (βᵣ; Exp. = 0.637, Cal. = 0.593), and radiative transition probability (583.1 s⁻¹). The measured decay time of Dy³ ⁺ emission at 574 nm (λₑₓ = 350 nm) decreased with increasing Dy³ ⁺ concentration, reaching a minimum of 0.52 ns at 2.0 mol%. Photoluminescence and X-ray luminescence spectra showed close agreement, both dominated by similar emission bands, confirming consistent radiative channels. Under UV excitation, Ce³⁺/Dy³⁺ co-doped glasses exhibited radiative energy transfer from Ce³⁺ to Dy³⁺, with emission intensity increasing as Dy³⁺ ion concentration increased. The highest PLQY value of 37.62 % was recorded for the 0.5Ce:0.1Dy glass sample. Additionally, the CIE coordinates (0.3895, 0.4332) and correlated color temperature (CCT) of 4100 K demonstrate that Ce³⁺/Dy³⁺ co-doped K₂O–Al₂O₃–P₂O₅ glasses are promising fluorescent materials for solid-state lighting devices.