Study Of The Synthesis And Properties Of Lanthanide Hydroxycarbonats

Due to the unique physical and chemical properties of rare earth elements, rare earth compounds have been widely applied in many fields, such as optics, information, permanent magnet, superconducting, energy, catalysis, medicine, biology and other fields. Preparing different rare earth compounds have caused great interest for scientific researchers. In this dissertation, several lanthanide hydroxycarbonats have been synthesized via hydrothermal method without any surface active agent and complex agent. Their formation mechanisms and luminescent properties were studied. Detail results are summarized as follows:1. The NdOHCO3 dodecahedron microcrystals have been synthesized via a hydrothermal method by using neodymium nitrate and urea as the reactants. The phase, morphology and composition of the product were analyzed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and infrared spectroscopy. Experimental parameters, such as the reacting temperature, the reacting time, and the molar ratio of the starting reagents were examined. The results show that the reacting temperature is the key factor to prepare NdOHCO3 dodecahedron microcrystals. The possible growth process of NdOHCO3 dodecahedral microcrystals was discussed.2. EuCO3OH microspheres have been successfully prepared via a facile hydrothermal approach by using urea as the precipitant without the assistance of any surfactants or templates. The Eu2O3 microspheres have been prepared by thermal conversion of EuCO3OH microspheres. The as-obtained products were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, thermogravimetry–differential thermal analysis. Several experimental parameters were examined, such as the reaction temperature, the reaction time, and the molar ratios of the starting reagents. The results show that the temperature exerts a key influence on the formation of EuCO3OH microspheres and that the reaction time and molar ratio mainly affect the surface structure of the microspheres. Meanwhile, the photoluminescence properties of EuCO3OH and Eu2O3 microspheres were studied.3. GdOHCO3 diamond microcrystals have been successfully prepared by a facile hydrothermal method. The as-obtained product was characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and infrared spectroscopy. Systematic studies of their reaction temperature, reaction time and the molar ratios of the starting reagents have been carried out to investigate the influence on the formation of GdOHCO3 diamond microcrystals. In addition, the photoluminescence properties of GdOHCO3 diamond microcrystals were discussed.