Effect of chloride introduction on the optical properties in Eu³⁺-doped fluorozirconate glasses

Fluorozirconate glass containing Eu³⁺ ions and chloride ions are prepared by a meltquenching method. The luminescence behavior of Eu³⁺ affected by Cl ions is investigated. With increasing Cl ion concentration, the luminous intensity of Eu³⁺ is significantly enhanced and the quantum efficiency of fluorozirconate glass is improved. Meanwhile, the intensity parameter Ω₂ increases according to the Judd-Ofelt calculation, which indicates the decrease of local symmetry. The average lifetime of Eu³⁺ increases by introducing the Cl ions. Moreover, we find two kinds of sites for Eu³⁺ ions in a glass network by analyzing the fluorescence decay. The distribution of Eu³⁺ ions changes with increasing Cl ion concentration. In addition, the excessive Cl ions lead to the separation of the glass phase and the formation of the crystal phase, thus reducing the transmittance dramatically.