Efficient energy transfer from Ce3+ to Tb3+ in BaF2: green-emitting phosphors for potential applications in the detection of Cu2+ ions

Abstract

A succession of Ce³⁺ and Tb³⁺ co-doped BaF₂ nanoparticles were synthesized by co-precipitation and hydrothermal methods. The structure, morphology, elemental composition and photoluminescence characteristics of the doped samples were studied by X-ray diffractometry (XRD), transmission electron microscopy (TEM), X-ray energy spectrometry (EDX), photoluminescence emission spectroscopy (PL) and photoluminescence excitation spectroscopy (PLE). The phosphor has a cubic structure. According to the energy level relationship between Ce³⁺ and Tb³⁺, the energy transfer mechanism of Ce³⁺ and Tb³⁺ co-doped BaF₂ samples was analyzed. Ce³⁺, Tb³⁺ co-doped BaF₂ shows a strong green emission, and its fluorescence emission intensity is about 9 times higher than that of Tb³⁺ single doped BaF₂. The energy transfer efficiency from Ce³⁺ to Tb³⁺ was calculated using a formula, and it was found that the energy transfer efficiency could reach up to 88.22%. The detection solution was prepared by uniformly dispersing the phosphor in absolute ethanol. Through a comparative study of a series of metal ions, it was found that the detection solution has a peculiar sensitivity to aqueous solutions containing Cu²⁺. At the same time, the relationship between the fluorescence intensity of the detection solution and the concentration of Cu²⁺ was studied, and the cause of fluorescence quenching caused by Cu²⁺ ions was analyzed from the perspective of energy transfer. From this work, it is considered that the phosphor has a great potential application in the determination of Cu²⁺ in practical wastewater.