Preparation,Color-Tunable And Energy Transfer Of Bi-Based Rare Earth Fluorescent Materials

Bi-based rare earth luminescent materials have gained intensive attention in the fields of devices and biomedicine due to their unique optical properties.In order to achieve multicolor tunable luminescence and meet the demand for nanomaterials in the biomedical field,bismuth-based rare earth luminescent materials doped with rare earth ions have become a research hotspot.In this thesis,BiPO₄,NaBiF₄ and K_0.3Bi_0.7F_2.4 were used as matrix materials to synthesize phosphors doped with a variety of rare earth ions(Dy³⁺,Sm³⁺,Tb³⁺,Eu³⁺),the crystal structure,morphology,fluorescence properties,and energy transfer were systematically analyzed.The main contents are as follows:1.Monoclinic phase BiPO₄:Tb³⁺,Sm³⁺phosphor was synthesized by hydrothermal method.The prepared samples are all rod-like structures,and the morphology does not change with the increase of doping ions concentration.Fluorescence spectra show that BiPO₄:Tb³⁺phosphor exhibits green emission under excitation of 378 nm ultraviolet light,and BiPO₄:Sm³⁺phosphor exhibits orange red emission under 403 nm excitation.There is energy transfer between Tb³⁺and Sm³⁺in BiPO₄:Tb³⁺,Sm³⁺phosphor,and the energy transfer mechanism is determined to be dipole-dipole interaction.The CIE chromaticity coordinates show that the luminescent color of phosphor can be tuned from red and green to white,which indicates that the multi-color tunable luminescence can be achieved by adjusting the doping ratio of Tb³⁺and Sm³⁺.2.NaBiF₄:Tb³⁺,Eu³⁺phosphor was quickly synthesized by precipitation method at room temperature.The synthesized NaBiF₄ crystal has a hexagonal phase,and the introduction of Tb³⁺and Eu³⁺ions do not change the crystal structure of NaBiF₄.Fluorescence spectra show that NaBiF₄:Tb³⁺phosphor exhibits green emission under excitation of 352 nm ultraviolet light,and NaBiF₄:Eu³⁺phosphor exhibits orange red emission under 395 nm ultraviolet light excitation.In NaBiF₄:Tb³⁺,Eu³⁺phosphors,there is energy transfer process from Tb³⁺ions to Eu³⁺ions.The energy transfer mechanism is dipole-dipole interaction.Under 352 nm UV excitation,NaBiF₄:Tb³⁺,Eu³⁺sample can achieve white light emission.3.The K_0.3Bi_0.7F_2.4:Dy³⁺,Tb³⁺phosphors were quickly synthesized by precipitation method at room temperature.Fluorescence spectra show that K_0.3Bi_0.7F_2.4:Dy³⁺phosphor exhibits blue emission under excitation of 388 nm ultraviolet light,and K_0.3Bi_0.7F_2.4:Tb³⁺phosphor exhibits green emission under 378 nm ultraviolet light excitation.There is energy transfer process from Dy³⁺ions to Tb³⁺ions,and the energy transfer mechanism is dipole-dipole interaction.