Effect of Bi2O3 on the structural and optical features of Co-doped Dy3+/Eu3+ borofluorbismuth glass for white LED

In this study, 50B2O3–(25–x)Al2O3–10Na2O–xBi2O3–15CaF2–0.5Dy–0.5Eu（x = 0，5，10，15，20，25 mol%）multi-component oxide glass was investigated. The non-crystallinity of the fluoroborate glass has been verified by X-Ray diffraction. The FTIR spectra show that the structural properties of the glass were characterized by the stretching and vibrating groups of various boric groups. The absorption spectrum of fluoroborate glass mainly had four absorption bands. The optical band gap measurements have proved the presence of unbridged oxygen (NBOs) in the prepared glass samples. In addition, the refractive index of fluoroborate glass enhances with the increase of Bi2O3 content. Photoluminescence spectra show strong emission at the transitions of 4F9/2→6H15/2 (blue) and 4F9/2→6H13/2 (yellow) for Dy3+ ions, and 5D0→7F2 (red) for Eu3+ ions. The chromaticity coordinates (x, y), color temperature (Tc), color rendering index (Ra), and color purity (CP) of fluoroborate glass were calculated by photoluminescence emission spectra. By adjusting the Bi2O3 content and excitation wavelength, the white light of glass can be realized. Therefore, fluoroborate glass is suitable for white light-emitting diodes (WLEDs).