Controlled Synthesis, Characterization And Luminescent Properties Of Several Yttrium Compounds Micro-and Nanostructures

Yttrium compound (such as yttria, yttrium fluoride, etc.) is an important class of rare-earth compounds which has potential applications in optical, opto-electronic, biolabeling, catalytic fields due to their excellent physical and chemical properties. As is well known, the performance of materials depends not only on the composition of them, but also on their structure, dimension, size and morphology and so on. In recent years, synthesis of micron- and nano-structured rare earth materials with controllable morphology and size has drawn intensive research attention. In this study, several novel structures and morphologies of the yttrium compound at micro- and nanoscale have been prepared via various preparation methods by selectively controlling the synthesis conditions. The properties of the products have been investigated and their applications have been explored, which provide experimental methods and data for their application. The mechanisms of the synthesis is studied and summarized, which would provide synthetic pathways and experimental data for the synthesis of other rare earth micro- and nanomaterials. Therefore, this study is of importance of theoretical research and practical application, which is a very worthwhile research. The main content of this thesis is as following:1. Synthesis and characterization of Y(OH)3 micro- and nanostructures.In this part, both inorganic strong alkali and organic alkali were selected as the base source. Firstly, Y(OH)3 microtubes have been prepared for the first time through a crystal transformation process in the absence of morphology modifier. Secondly, novel structured Y(OH)3 microspindles attached with small rods in middle part were obtained by solvothermal method employing absolute ethanol as solvent. Thirdly, yttrium hydroxide bundle constructed with parallel nanorods have been prepared with Na2H2EDTA as the morphology modifier. Fourthly, when sodium citrate was employed, sphere-like, hexagonal tube-like, hexagonal prism-like yttrium hydroxide were obtained by varying the reaction conditions. Fifthly, yttrium hydroxide microspindles and microprisms have been prepared via a fast microwave heating method in short time when Na2H2EDTA and sodium citrate were used, respectively.Organic strong alkali, triethylenetetramine (H2N(C2H4NH2)2C2H4NH2), was also used as base when the reactions carried out in a mixed solvent of ethanol and deionized water, and the results were compared with the results obtained with ammonia as base. Results demonstrated that triprism-like and trident triprism-like Y(OH)3 microstructures can be achieved when triethylenetetramine and ammonia were selected as the base source.2. Synthesis, characterization and photoluminescence properties of yttrium oxide and Eu3+ ions doped yttrium oxideBy finely controlling the thermal treatment conditions of above as-obtained yttrium hydroxide, yttrium oxide with similar morphologies can be obtained. Eu3+ ions doped yttrium oxide with similar morphology was also prepared and their photoluminescence properties were investigated. Results show that their photoluminescence properties depend greatly on their morphology.3. Synthesis of yttrium fluoride and Eu3+ ions doped yttrium fluorideDisk-like yttrium fluoride superstructures have been fabricated for the first time through a mixed solvothermal method with the assistance in the mixed solvent of water and ethanol. Water-soluble yttrium fluoride was prepared for the first time thorough a solvothermal method employing KF·2H2O as the fluoride source and ethanol as the solvent. Rare earth ions doped yttrium fluoride disk-like superstructures and water-soluble nanoparticles were also prepard and their photoluminescence properties have been studied.