Synthesis and characterization of metallic co with different hierarchical structures prepared by a simple solvothermal method

摘要

Magnetic metallic cobalt with different hierarchical structures, such as dendritic particles, flowery particles, and flocky spheres, has been successfully prepared, by using a simple solvothermal process in which the relative amounts of H_2C_2O_4 and N _2H_4-H_2O in the reaction system were rationally adjusted. The Co crystals with hierarchical structure had a hexagonal-close- packed (hep) structure. The dendritic Co crystal, comprises several 1-5 um long dendrites, and. the hierarchical assemblies radiate from the center. The flowerlike Co submicrocrystals are composed of petal-like crystals around 1.5 μm in diameter and 100-200 nm thick. Interestingly, an intergrade from single-crystal to polycrystalline structures for flowerlike Co submicrocrystals is observed. The flocky spheres, about 600 nm in diameter, consist of 5 nm thick nanosheets. In addition, a growth mechanism is proposed which is based on the evolution of the structure and morphology with increasing reaction time. Further magnetic measurements for the Co crystals with different hierarchical structures indicated that the morphology of the Co crystals had an obvious influence on their magnetic properties.