The Synthesis And Property Investigations Of Magnetic Rare-earth Ions Doped Yttrium Oxide Nanocomposites

Materials science developing to the present, the material with a single function or property is no longer able to meet the needs of current applications, especially in biochemistry fields. Now, the emergence of a nanocomposites with magnetic and fluorescence properties makes the development of functional materials entering a new world. The magnetic fluorescent bifunctional nanocomposites can not only be manipulated by external magnetic field, and can conduct real-time fluorescence imaging and also can be used in other functional applications. More research found that they could be used in many applications, including magnetic targeting, especially in cancer detection. In this paper, we synthesized several complexes with different magnetic cores and different colors fluorescent shells. And these are able to show more excellent magnetic and fluorescent properties.In the introduction, we detailedly described the composition, structural features, a simple classification and special properties of composite materials, functional materials, especially magnetic-fluorescent materials. Also, this chapter takes Y₂O₃ and Fe3O4 as an example and incorporates the main content of this article to briefly introduce the principles of fluorescent and magnetic properties. In the introduction the end, we introduced the research and application prospects of the fluorescent magnetic multifunctional materials.Firstly, this article synthesize Eu³⁺doped nano-Y₂O₃ luminescent materials by hydrothermal and solvothermal method. Their composition and structure and optical properties were studied in detail. By comparing different doping concentrations' fluorescence spectra, obtained the best doping concentration:9% using hydrothermal method and 13% using solvothermal method. When the doping concentration exceeds these concentration values, due to concentration quenching effect the samples' luminescence would weaken. This article also investigated the property of Y₂O₃'s precursor synthesized by hydrothermal and solvothermal method, and found that the composition may be the orthorhombic yttrium carbonate (Tengerite) containing crystalline structure of water. Chemical formula may be Y₂(CO₃)₃·H₂O. We also use it as light-emitting substrate, and synthesize the precursor of the Y₂O₃:Ce³⁺,Tb³⁺ through Ce³⁺. Tb³⁺ co-doped by hydrothermal and solvothermal methods. By analysis of different fluorescence spectra doping 4% Ce³⁺ we obtained the optimum doping concentration of Tb³⁺:12% using hydrothermal method and 10% using solvothermal method. Through the fluorescence spectroscopy of the optimal doping concentration we found in this substrate the energy transfer between Ce³⁺ and Tb³⁺ has a very good role and. we briefly discussed process of the energy transfer and proposed a simple energy transfer mechanism.We have introduced a hydrothermal carbonization reaction of glucose to synthesize Fe₃O₄@C, and obtained Fe@C composite through high-temperature calcination. We also discussed the condition of Fe₃O₄-reduction by amorphous C during high temperature.we obtained when the addition of Fe₃O₄ is 2.0g Fe₃O₄ can be completely reduced to body-centered cubic a-Fe. Also:only by increasing the addition of Fe₃O₄ to reduce the relative amount of coating C layer, not by reducing the temperature of hydrothermal reaction of glucose or reduce the hydrothermal reaction time or reduce the amount of glucose reactant to reduce the amount of coating C layer, otherwise it will have other iron oxide impurity phase (such as Fe₃O₄, FeO and Fe₂O₃) generation.In this paper, on the basis of the above experiment, we prepared magnetic-fluorescent bifunctional complexes microspheres Fe@C@Y₂O₃:Eu³⁺. and characterized their nature through different testing methods. We have found that the composite has high Ms (47.4emu/g). low Mr (1.5emu/g) and He (95Oe). and has a good red light emission (610nm) under UV irradiation. This article also adopted a similar approach to synthesize the Fe@Y₂O₃:Eu³⁺ composite, and its property has been characterized. We also found that the compound has good magnetic and photoluminescence properties, through comparison between the Fe@C@Y₂O₃:Eu³⁺ composite and Fe@Y₂O₃:Eu³⁺ composite, we found that the magnetic and photoluminescence properties of Fe@Y₂O₃:Eu³⁺ composite is weaker than that of Fe@C@Y₂O₃:Eu³⁺, which proves the C layer played a crucial role in reducing the quenching effect of magnetic on the fluorescence. The magnetic field generated by the magnetic core can significantly limit the f-f transition of Eu³⁺, but the restrictions on the CTB transition of Eu³⁺ is significantly weaker than that.In this paper, using a simple two-step synthesis, we synthesis Fe₃O₄@Y₂O₃ precursor:Ce³⁺,Tb³⁺ and Fe₃O₄@C@Y₂O₃ precursors:Ce³⁺,Tb³⁺ complex with magnetic and can emit green fluorescence under 294nm excitation light hydrothermal and solvothermal method, respectively. And found that in the composites, the energy transfer between Ce³⁺ and Tb³⁺ also has the role, and the presence of nuclear magnetic has not impact this energy transfer Ce³⁺-Tb³⁺. In the resulting bifunctional magnetic-fluorescent compound Fe₃O₄@Y₂O₃-P:Ce³⁺,Tb³⁺ and Fe₃O₄@C@Y₂O₃-P:Ce³⁺.Tb³⁺, the magnetic field generated by the magnetic core can significantly limit the f-f transition of Tb³⁺. but the restrictions on the f-d transition of activator Tb³⁺ is significantly weaker than that. Based on the further analysis of the fluorescence spectras, we found in magnetic-fluorescent composites Fe@Y₂O₃:Eu³⁺ and Fe@C@Y₂O₃:Eu³⁺, or Fe₃O₄@Y₂O₃-P:Ce³⁺,Tb³⁺ and Fe₃O₄@C@Y₂O₃-P:Ce³⁺.Tb³⁺synthesized by hydrothermal or solvothermal method, the presence of the middle C layer greatly reduced the quenching effect of magnetic on light-emitting layer. And compared with SiO₂,C layer is more suitable for acid, alkali or sol environment, which expands the scope of application of bifunctional composite material. In addition, though the further analysis, we found that the limits generated by the nuclear's magnetic field to the charge transition is different between different activator ions of light-emitting layer: the magnetic field produced by magnetic core can significantly limit the f-f transition of rare earth activator ion (Eu³⁺ and Tb³⁺). But the limit to the CTB between the matrix and the activator (Y₂O₃:Eu+) and the limit to the f-d transition of the activator ion (Y₂O₃:Tb³⁺) are significantly weaker.Through the effort, we prepared different bifunctional materials with different colored fluorescent shell and magnetic core. The magnetic type of fluorescent compound has been expanded, which lays a solid foundation for future applications. We believe that multi-functional magnetic fluorescent materials will be better tomorrow.