Study On Ionic Liquid Assisted Synthesis And Multifunctional Application Of Calcium-Based Fluorinated Phosphor

Rare earth ion and Bi3+ion-doped inorganic luminescent materials are experiencing growing popularity in recent years due to their excellent optical properties.Rare earth ion and Bi3+doped inorganic luminescent materials have the advantages of exhibit high biocompatibility,high physical and chemical stability,tunable luminescent characteristics,and low toxicity,etc.,which have broad application prospects in the fields of bioimaging,lasers,lighting and optical anti-counterfeiting.However,how to effectively synthesize rare earth ion and Bi3+ion-doped inorganic luminescent materials and control their morphology through simple and environmentally friendly techniques is the current challenge.At present,the green and mild ionic liquid assisted preparation method is an effective means to solve this problem.Ionic liquids,consisted of organic cations and inorganic anions,can have their physical and chemical properties widely adjusted by selecting appropriate cation-anion combinations,making them superior to traditional organic solvents.Furthermore,through carefully selecting combinations of cations and anions,the physical and chemical properties of ionic liquids can be controlled,allowing them to serve as end-capping agents,reactants,and reaction media.Therefore,the development of multifunctional phosphors through the assistance of ionic liquids holds significant research significance.Focusing on the selection and design of ionic liquids and synthesis methods,this thesis studied the luminescence properties of a series of calcium-based fluorinated phosphor doped with rare earth ions and Bi3+and explored their potential applications.The main research contents are as follows:1.CaF2:Yb3+,Ho3+phosphors were synthesized via hydrothermal method with the assistance of ionic liquid[Omim]PF6.The influence of adjusting the amount of ionic liquid,reaction time,and Gd3+doping concentration on the size of CaF2:Yb3+,Ho3+nanoparticles was investigated,and the formation mechanism was proposed.With the introduction of Gd3+ions,the upconversion luminescence of CaF2:Yb3+,Ho3+was significantly improved,and the mechanism for enhancing upconversion luminescence was discussed.In addition,the green and red upconversion luminescence intensities of CaF2:Yb3+,Ho3+,Gd3+displayed different trends with increasing temperature,indicating the potential application of CaF2:Yb3+,Ho3+,Gd3+phospors in temperature sensing.Additionally,the seven unpaired 4f electrons of Gd3+are unaffected by crystal field,and Gd3+doped CaF2:Yb3+,Ho3+nano-crystals exhibit paramagnetic behavior.Therefore,Gd3+doped CaF2:Yb3+,Ho3+nanomaterials have potential applications in bioseparation and magnetic resonance imaging.2.Ca5(BO3)3F:Bi3+/Eu3+nanofibers and microspheres were synthesized by ionic liquid[Omim]BF4 assisted electrospinning.The influence of the molecular weight of PVP on the morphology of Ca5(BO3)3F was studied,and the formation mechanism was analyzed.The luminescent properties of Ca5(BO3)3F:Bi3+,Eu3+were systematically investigated.Due to the different thermal response emissions of Bi3+and Eu3+,the luminescent color of Ca5(BO3)3F:Bi3+,Eu3+phosphor changed significantly with temperature,demonstrating good temperature sensing performance.The response of Bi3+ions to pressure was discussed,as the peak shift occurred initially towards blue and then red,which can be ascribe to the the crystal field splitting effect and multi-site effect of Ca5(BO3)3F.The phosphor exhibited a noticeable visual color change(from blue to cyan),significant pressure response(4.76 nm/GPa),and a high-pressure limit(24.2 GPa),indicating its potential for optical pressure sensing.3.Eu2+and Eu3+co-doped Ca5(PO4)3F phosphor was prepared by ionic liquid[Omim]PF6 assisted electrospinning method,microsphere and fiber structures of Ca5(PO4)3F:Eu2+/3+were synthesized by varying the solution viscosity,and the formation mechanism was studied.The luminescent properties of Ca5(PO4)3F:Eu2+/3+samples were thoroughly studied,and the effects of excitation wavelength,temperature,and pressure on their luminescent behavior were examined.Based on the coloration behavior of Ca5(PO4)3F:Eu2+/3+phosphors dependent on the excitation wavelength,the Ca5(PO4)3F:Eu2+/3+/PVA composite films displayed red and blue emission under excitation at 254/365 nm,respectively.The temperature sensitivity and pressure sensitivity of Ca5(PO4)3F:Eu2+/3+phosphors were investigated as Eu2+and Eu3+exhibited different luminescent response behaviors to temperature and pressure stimulation.Therefore,this multifunctional material holds potential for applications in anti-counterfeiting,temperature sensing and pressure sensing.In summary,this study provides a new synthesis approach for fluorapatite and offers a simple scheme for integrating multiple functionalities into a single system.