Synthesis, Characterization And Properties Of Rare Earth Phosphate Superstructure

Rare earth phosphate is an important kind of rare earth compounds. Because of their excellent physical and chemical properties such as good chemical stability and heat stability, unique structural features and special magnetic, photocatalytic activity, sensitive characteristics, electric conductivity, good gas sensitivity, thet have been extensively used in optical materials, laser material, magnetic light material, magnetic resistance materials, dielectric material, adsorption materials, catalyst, chemical sensor, and so on. The properties of nanomaterials depend greatly on their size and morphology. In recent years, the controlled preparation of rare earth phosphate nanomaterials has received intensive attention. However, few papers have appeared on the preparation of rare earth phosphate superstructures and it is difficult to fabricate their superstructures by a facile method in an extensive broad.In this paper, phosphate ester was used as phosphate source and a series of rare earth phosphate superstructures with different structures were prepared via a mixed-solvothermal synthesis. The as-obtained products were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), energy disperse spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), TG-DTA, photoluminescence (PL). The properties and formation process of the products were systematically investigated. The main content of this thesis is as following:1. Preparation and maganetic properties of DyPO4 superstructures3D flower-like DyPO4 superstructures have been successfully synthesized by a mixed-solvothermal method with tributyl phosphate (TBP) and dysprosium chloride as starting materials. SEM results show that the 3D flower-like nanostructures have an average diameter of ca.500nm. One-dimensional (1D) dysprosium coordination polymer wires can be prepared at different reaction temperature in the early stage. The effect of reaction temperature on the sample morphology and luminescent intensity was tested by SEM and fluorescence spectrometer. Results showed that with the extention of reaction time, the luminescent intensity of the obtained wires increased. The dosage of tributyl phosphate, reaction time and surfactant on the preparation of the DyPO4 superstructures were systematically investigated. It turned out that the dosage of tributyl phosphate had slight effect on the morphology of the product. However, the reaction temperature and surfactant influence the morphology of the products significantly. Rice-like macroprous DyPO4 superstructures were obtained with the assistance of lauryl sodium sulfate (SLS). The effect of the reaction time and the amount of the SLS on the morphology of product was also investigated. Furthermore, the possible formation mechanism of the DyPO4 superstructure and rice-like macroprous DyPO4 superstructure was preliminarily disccussed, their luminescent and magnetics properties were also studied.2. Preparation and photoluminescence properties of EuPO4 superstructuresOne-dimensional (1D) europium coordination polymer wires and walnut-like EuPO4 superstructure were prepared using tributyl phosphate (TBP) as phosphorus source and europium chloride as the reactant. The effect of reaction time and the dosage of tributyl phosphate on the morphology of the product were systematically investigated. On the other hand, the luminescent properties of the products were also studied. Under similar conditions, EuPO4 micro/nanostructures with novel morphology and structure were obtained using different phosphate ester as phosphate source.3. Preparation of other rare earth phosphate micro/nanostructuresA series of rare earth phosphates LnPO4 micro/nanostructure (Ln denotes La, Ce, Pr, Nd, Er, Yb, Y or Tb) have been successfully synthesized via a simple mixed-solvothermal route. XRD and SEM have been employed to characterize the as-prepared samples. The results show that all of the products have similar morphology. While the light rare earth elements phosphates are with monoclinic structure, while heavy rare earth elements phosphates are with tetragonal structure.