White emission from Tm³⁺/Tb³⁺/Eu³⁺ co-doped fluoride zirconate under ultraviolet excitation

We synthesize Tm³⁺/Tb³⁺/Eu³⁺ triply-doped ZrF₄-BaF₂-LaF₃-AlF₃-NaF (ZBLAN) transparent glass by using a melt-quenching method. Under excitation of 365 nm, the white emission with Commission internationale deL'Eclairage (CIE) coordinates of (0.33, 0.33) is achieved at the Eu³⁺ concentration of 1.1 mol%. The mechanisms for white emission and the energy transfer process of Tb³⁺→Eu³⁺ are discussed in terms of the photoluminescence, photoluminescence excitation spectra, and the light emission decay curves. The nature for the Tb³⁺→Eu³⁺ energy transfer is described with the aid of an energy level diagram.