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Controlled Synthesis And Properties Of Rare Earth Carbonate And Phosphate Micro/Nano Particles

Posted on:2014-02-11Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y L WuFull Text:PDF
GTID:1261330401971821Subject:Micro and Nano Materials Science and Engineering
Abstract/Summary:PDF Full Text Request
Rare Earth Luminescent materials have attracted more attention due to their abroad applications in displaying, lighting, bioimaging, solar photoelectric conversion, laser and biological engineering, In order to meet the demand of the resource-saving society, rare earth luminescent materials are also developing to the direction of multi-functionallization, nanocrystllization and spheroidization. Meanwhile, the nanosacle rare earth luminescent material has the potential application value in biosensing, immunoassay, biological imaging, and drug loading. The aim of this study was to prepare Ln3+doped Gd2(CO3)3magnetic-fluorescent bifunctional nanoparticles through different synthesis methods and LaPO4:Ce,Tb(LAP) green fluorescent powders with small size and high emission brightness via simple chemical methods for industrial application. The concrete content includes:[1]A simple reverse microemulsion method and coating process was introduced to synthesize silica-coated Gd2(CO3)3:Tb nanoparticles. The morphology and particle size of the nanoparticles were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), energy spectrum(EDS), and infrared spectrum(IR). The results showed that nanoparticles have obvious core-shell structure and perfect spherical morphology. The particles with an average diameter of16nm, including8-10nm of Gd2(CO3)3:Tb core and3-5nm of SiO2shell, can be dispersed well in water. As in vitro cell imaging of the nanoprobe shows, the nanoprobe accomplished delivery to gastric SGC7901cancer cells successfully in a short time, as well as NCI-H460lung cancer cells. Furthermore, it presents no evidence of cell toxicity or adverse affect on kidney cell growth under high dose, which makes the nanoprobe’s optical bio-imaging modality available. The possibility of using the nanoprobes for magnetic resonance imaging is also demonstrated, and the nanoprobe diplays a clear T1-weighted effect and could potentially serve as bimodal T1-positive contrast agent. Therefore, the new nanoprobe formed from carbonate nanoprobe doped with rare earth ions provides the dual modality of optical and magnetic resonance imaging. A new type of dual modal nanoprobe to combine optical and magnetic resonance bioimaging was developed.[2] Ln3+doped Gd2O(CO3)2nanoparticles with uniform particle size have been prepared via urea homogeneous precipitation. The properties of as-prepared nanoparticles were characterized by SEM, TEM, XRD and IR. The fluorescent properties and magnetic resonance relaxivity were measured and the effect of the sedimentation time on the morphology and particle size was examined. The results showed that the morphology of the nanoparticles was changed from spherical to diamond with reflux time increased from2h to10h, and the size was growing too. The spherical Gd2O(CO3)2:Tb@pvp emit bright green light at about543nm under274nm excitation, and would be a good T1MRI contrast agent in solution and a good optical imaging agent in cell environment. The sensitivity and accuracy of detection of the tumor cells would be improved through combining these two functions. It indicated that Gd2O(CO3)2:Tb nanoparticles provides the dual modality of optical and magnetic resonance imaging. At the same time, nanosized spherical Gd2O3:Fu fluorescent powder could be obtained by calcination of the Gd2O(CO3)2:Fu precipitate at800℃.[3] Spherical Ln3+doped Gd2(CO3)3nanoparticles with uniform particle size were prepared by a simple hydrothermal method. The morphology and particle size of the as prepared particles were characterized by SEM, TEM, XRD and IR. The results showed that the morphology, phase structure, particle size and the properties of the nanoparticles would be changed with the hydrothermal conditions. The hydrothermal crystallization mechanism of the nanoparticles was preliminary discussed.[4] LaPO4:Ce,Tb phosphor was prepared by a rreduction calcination of the precursor obtained by the simple mechanical grinding method. The results of SEM, XRD and FL showed that the luminance and morphology of the phosphors were affected by the synthesis conditons including grinding time, calcination temperature, washing method and the cosolvent used. The as-prepared nanosized green LaPO4:Ce,Tb phosphors showed higher brightness and smaller size than the current commercial aluminate green powder (CAT). This method provides potential applicaton in large scale industrial production because of its characterization of simple, mild, and environment friendly. [5] LaP04:Ce,Tb phosphor was prepared by a reduction calcination of the precursor obtained by a simple co-precipitation method. The results of SEM, XRD and FL showed the luminescence and morphology of the phosphors were also influenced by the aging time, feeding mode, ionic concentration and pH value.
Keywords/Search Tags:Nanomaterials, Magnetic, Fluorescence, Rare earth, Gd2(CO3)3Reverse microemulsion, Precipitation method, Hydrothermal method, LaPO4:Ce,Tb
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