Influence of CaF2 on the spectroscopic studies of Dy–Eu co-doped fluoroborate glass for lighting applications

Abstract

To investigate novel glass materials applicable to W-LED, we designed and prepared a series of glasses with varying compositions. The compositions of the glasses were (64-x)B2O3–15Al2O3–10Na2O–10Bi2O3-xCaF2-0.5Dy2O3-0.5Eu2O3 (x = 0, 5, 10, 15, 20, 25). The glasses were synthesized using the melting quenching method. The effect of CaF2 on the structural feature of fluoroborate glass was studied by infrared spectroscopy analyses. Determination of fluorine content in glass by 19F NMR inversion spectroscopy. The absorbance of glass increased as the CaF2 content increased in the visible and ultraviolet light ranges. The optical band gap of the prepared glasses was obtained from the absorption spectrum, which confirmed the existence of nonbridging oxygen (NBO) in the glass network structure. The fluorescence lifetime of the glass increases with increasing CaF2 content, and the quantum yield of the glass first increases and then decreases. In addition, fluoroborate glass had a lower Urbach energy, indicating that its network structure was relatively uniform and stable. In contrast, the increase in Urbach energy is due to the substitution of CaF2, leading to more defects. By adjusting the excitation wavelength and CaF2 content, the color temperature (1598–3346 K) and color rendering index (36–63) of fluoroborate glass can be effectively adjusted. These results show that the prepared Dy/Eu co-doped fluoroborate glasses have a potential application in white lighting.