Low-Dimension Lanthanum Hydroxide:Synthesis, Characterization And Magntic Property

The shape-controlled and size-tunable synthesis of rare earth nanomaterials has recently drawn intensive interests. Rare earth nanomaterials have been proposed for a wide range of applications in hydrogen storage materials, superconductors, catalysts, up-conversion phosphors, optical coatings, exhaust-gas convectors, time-resolved fluorescence labels for biological detection and so on, due to their excellent catalytic, optoelectronic and magnetic properties which results from their4f orbital electrons shells. In this thesis, low dimensional lanthanum hydroxide (La(OH)3) nanomaterials with tunable diameter and length have been systematically prepared, and their chemistry, crystal structure and magnetic property characterized at the nanoscale. The main achievements are as follows:1. Ethanol-water mixture solvent method was developed to synthesize size-and shape-controlled lanthanum hydroxide (La(OH)3) nanomaterials. The influence of solvent concentrations, temperature, pH value, reaction time on the morphologies of La(OH)3nanomaterials were investigated. And their chemical stability, magnetic properties and optical properties were further characterized by using TEM, SEM, XRD, TGA, DTA and FTIR techniques. The experimental results showed that the reaction time and solvent selection have significant impact on the morphology of lanthanum hydroxide nanowires.2. A simple and convenient low temperature precipitation method using ammonia as precipitant, lanthanum hydroxide nanotubes were developed to prepare lanthanum hydroxide nanotubes. Their morphology and structure were analyzed and characterized by using TEM, SEM and XRD techniques. The data showed that individual lanthanum hydroxide nanotubes have a uniform diameter, smooth surface and uneven length ranging from100nm to500nm. The magnetic measurement showed that the lanthanum hydroxide nanotubes appear a room-temperature ferromagnetic behavior.3. Lanthanum hydroxide nanoparticles were prepared by a simple hydrothermal method, which adopted citric acid as a nucleating agent. The morphological characterization showed that individual nanoparticles have a uniform size with a smooth surface. The crystal structure of individual La(OH)3were detected to be single crystal with a hcp structure. Similar with above La(OH)3nanowires and nanotubes, the La(OH)3nanoparticles shows ferromagnetic.