Rare Earth Compounds Nanomaterials: Synthesis And Property Investigation

Rare earth compounds nanomaterials have intensive potential in various fields, such as catalysis, optics, biology analysis, and so on. Developing synthetic routes for rare earth compounds nanomaterials, exploring the formation mechanisms and investigating the relationship among the crystal structure, morphology and properties of nanomaterials have great significance. This dissertation explored new solution-based synthetic strategies for rare earth nanomaterials, emphasizing the relationship between structure and shape/properties manipulation of nanomaterials, and new strategies based on glycol systems for preparation of functional rare earth compounds and composites nanocrystals and hollow structures.NaYF4 nanocrystals with various morphologies and crystal structures have been synthesized via a hydrothermal approach assisted with oleic acid. Synthesis approaches have been developed for multi-armed NaYF4 nanocrystals and NH4Ln2F7 hollow spheres. By taking complex rare earth fluorides as an ideal system, we have carried out careful investigations on the influences of reaction parameters on the morphologies and phases of nanocrystals, explored the influence of lanthanide contraction on crystals structures, shape/properties of complex rare earth fluorides, discussed and summed up the underlying rules of the nucleation, growth and phase transition process of nanocrystals.Designing and developing a new surfactant free solvothermal synthetic strategy for monodisperse rare earth orthovanadate nanocrystals, with the use of glycol and water as mixed solvent.The glycol solvothermal method has been extended from rare earth orthovanadate to the system of ceria and related composite oxides. Series of CeO2 nanomaterials with controllable morphologies (spheres, polyhedrons, mesoporous spheres and hollow spheres) have been fabricated by introducing short-chain organic acids. By taking CeO2 as precursors, we constructed Ce1-xZrxO2 and Ce1-xTixO2 solid-solution hollow spheres. The formation mechanism based on kirkendall effect was proposed and verified. Ceria and related composite oxides are important catalytic promoters. As-prepared CeO2-based nanomaterials have high surface area and good thermal stability, which would have promising application potentials in the field of catalysis.For a further step, the application fields of this glycol-based solvothermal method were stretched from rare earth compound nanocrystals to functional rare earth composite nanomaterials. A one-step synthesis strategy for functional rare earth organic/inorganic hybrid capsules has been developed by using the reaction between strong oxidizing acid (HNO3) and glycol ethylene. The hybrid capsules have functional surface. And some distinctive optical and magnetic characteristics were found on the capsules, which would be of promising potentials in the fields such as biology analysis and drug deliver. Associating the reaction of Ag+ ions in glycol with this method, series of Ag and rare earth composites nanostructures have been constructed. By taking it as precursor, a new synthetic method for Ag and rare earth oxides composites hollow spheres have been developed.