Magnetite submicrospheres with an average size range of 90–490 nm were obtained by a facile polyol process. The effects of reaction conditions on the morphology and static magnetism of magnetite submicrospheres were studied when the reaction time, the concentration of component, and the types of the solvent or surfactant changed. The average size of primary crystals was controlled by changing the concentration of surfactant thus the superparamagnetism was obtained, meanwhile the average size of secondary clusters was tuned by changing the concentration of ferrous precursor FeCl 3 ·6H 2 O. The ratio of ethylene glycol and diethylene glycol , the concentration of NaAC, and the reaction time all exhibited novel effects on the morphology of magnetite submicrospheres facilitating our understanding about the synthesis mechanism. The synthesized magnetite submicrospheres were successfully used for photonic crystal .
Pd-based nanostructures with stepped facets possess potential applications in many fields, particularly in catalysis. Generally, crystal growth often only allows the formation of nanostructures with energetically non-stepped facets, so it is desirable to develop methods that can be used to prepare Pd-based nanostructures bounded by stepped facets. Herein, penta-fold twinned (PFT) Au@Pd nanobipyramids (NBs) with stepped {100} facets were synthesized through growing Pd on Au decahedral nanoparticles (NPs) in polyol. During the growth of Au@Pd NBs, Br− was a critical factor, because it has appropriate affinity for the Pd atom and adjusted the growth rate ratio along 〈110〉 and 〈100〉, resulting in the formation of Au@Pd NBs with stepped {100} facets. The product shape and size could be tailored by controlling the reaction conditions. Transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS), high angle annular dark field (HAADF) imaging and scanning transmission electron microscopy EDS (STEM-EDS) were used to investigate the structure and growth of the Au@Pd NBs. A growth mechanism involving two stages was elucidated. In the first stage, the growth of Pd clearly occurred along both 〈110〉 and 〈100〉. In the second stage, the growth along 〈110〉 was faster than that along 〈100〉. Furthermore, we also demonstrated that the as-prepared Au@Pd NBs had high catalytic activity, compared with Pd nanocubes and Pd–Au–Pd segmental nanorods.
危险品化学品经营许可证（带存储）