Luminescence and structural properties of Eu³⁺-doped calcium fluoride-bismuth oxide-phosphate glasses

Calcium fluoride-bismuth oxide-phosphate glass of (60-x)P₂O₅–25Bi₂O₃–14CaF₂–1Sb₂O₃-xEu₂O₃ (PBCFS), (x = 0, 0.25, 0.5, 0.75, and 1 mol%) was manufactured by melt-quenching technique. XRD and FT-IR spectra were obtained to characterize the PBCFS glass structure. The glass density, molar volume, refractive index, and thermal properties were determined. The absorption spectra of the PBCFS glass had three absorption peaks. The absorption peak with the highest intensity corresponded to the electronic transition of ⁷F₀→⁵L₆ (~392 nm), and the electronic transition starting from the first excited state (⁷F₁) was also found. The excitation spectra corresponding to the ⁵D₀→⁷F₂ transition of Eu0.5 at 612 nm was obtained. When excited by a λ_ex = 392 nm xenon lamp, the strongest orange-red emission occurred at 612 nm (⁵D₀→⁷F₂). According to the CIE1931 chromaticity coordinates, the chromaticity coordinates of the PBCFS glass with different Eu₂O₃ contents were determined by the emission spectra. The decay curve of Eu³⁺ ions with ⁵D₀→⁷F₂ (612 nm) transition was obtained by monitoring the excitation at λ_ex = 392 nm, which was compared with other Eu³⁺-doped luminescent glass. The color tunability of the orange-red light emission of the Eu³⁺ ions indicated that Eu³⁺-doped PBCFS glass may be suitable for LEDs and display device applications.