Synthesis And Luminesecence Properties Of Rare-earth Phosphates&Rare-earth Doped Compound Nano-materials

Nanoscale luminescent materials exhibit superior luminescence properties,especially, rare earth doped luminescent materials have many advantages such asattracted considerable interest for their potential applications in the fieldsof high-performance luminescence devices, catalysts, time resolved fluorescencelabels for biological detection. This paper mainly has two parts, study of the rare earthphosphate nanorods synthesis and luminescent properties was showed the first part,Chapter2statements the main research content and results of rare earth phosphate, thesecond part is the study of rare earth doped nano-compound synthesis and luminescenceproperties, and make a statement on the main research content and results in Chapter3,4and5.In Chapter1, we briefly introduced the basic theories of luminescent materials，including the definition and classification of luminescent materials，the luminescencetheories and properties of rare earth luminescent nanomaterials，and the preparationmethods and current investigation of rare earth luminescent materials．In Chapter2, hexagonal phase CePO₄have been prepared by facile hydrothermalmethod using EDTA as chelating agents with various pH values. The as-preparedproducts were characterized by means of x-ray diffraction （XRD）, transmission electronmicroscopy （TEM）, high-resolution transmission electron microscopy （HRTEM） andphotoluminescence （PL） spectra, XRD and TEM show that all of the as-prepared ceriumphosphate products have rod-like shape, and the sizes of nanorods, crystallinity anduniformity are subjected to the pH of starting solution. Successful doping with terbiumphosphors shows their characteristic emission under ultraviolet excitation due to theefficient energy transfer from Ce³⁺to Tb³⁺.In Chapter3, AlPO₄nanorods were synthesized by a self-assemble hydrothermalmethod with urea as additive. The morphology of rod-like AlPO₄can be controlled byvarying the amount of urea, the reaction time and temperature. With the increase of ureaconcentrations, AlPO₄gradually changed from nanoparticles to dispersed nanorods.When prolonging the reaction time, the nanorods grew along the （101） plane to about85nm, Improving the reaction temperature, the morphology turned nanopartiles, tonanosphere and to nanorods. Under excitation at466nm, Eu³⁺doped AlPO₄nanorodsexhibited strong red emission, corresponding to the characteristic transition of⁵D0â†'⁷F₂of Eu³⁺. For Eu³⁺ion doped AlPO₄samples,the effect of Eu³⁺concentration on thephotoluminescence intensity was investigated. The optical properties of these aluminumphosphate nanorods were strongly dependent on their crystal structures and morphologies.In Chapter4, AlPO₄: Ce, Tb nanorods were synthesized by a faceile self-assemblehydrothermal method. The morphology of rod-like AlPO₄can be controlled by varyingurea concentrations, AlPO₄gradually changed from nanosheets to dispersed nanorods,and urea provides the hydroxyl anion （OH-） in the aqueous solution to prepare themonodispersed nanoparticles in hydrothermal conditions. The emission intensity ofnanorods increased significantly compared to that of nanosheets without adding urea.AlPO₄: Ce, Tb nanorods providing a novel redox luminescent switch on the basis of thereversible switching of the Ce³⁺/Ce⁴⁺redox couple. The turn-off luminescence sensingsystem was quenched by KMnO₄, and the turn-on luminescence sensing system wasadded by ascorbic acid, and the mechanism of the energy transfer and electronictransition between Ce³⁺and Tb³⁺in the host material of AlPO₄nanorods also explored.In Chapter5, Hexagonal CaTiO₃:Eu³⁺nanosheets were prepared by a supercriticalfluid method. The samples were characterized by X-ray diffraction （XRD）, transmissionelectron microscopy （TEM）, high-resolution transmission electron microscopy（HRTEM） and luminescence spectrometer （LS）. Under466nm excitation, the CaTiO₃:Eu³⁺nanoheets showed a strong red （616nm） emission corresponding to⁵D0â†'⁷F₂transition of Eu³⁺. The effect of Eu³⁺concentration was investigated, among thesesamples,0.2mol%Eu³⁺doped CaTiO₃nanosheets showed the strongest luminescentintensity. Compared with nanoparticles, the nanosheets showed better luminescenceproperty. Growth mechanism of hexagonal CaTiO₃nanosheets was also discussed.