A novel chemical reduction route towards the synthesis of crystalline nickel nanoflowers from a mixed source

A novel chemical reduction route was designed for the synthesis of nickel nanocrystals with distinct flowery shapes by using a mixture of two complexes of Ni(N2H4)(3)(2+) and Ni(dmg)(2) (nickel dimethylglyoximate) as the nickel source. Formation of these flowers, comprising spherical centers and swordlike petals, was related to the varying stability and structural properties of the two precursors as well as the reaction conditions. Investigations of the time-dependent shape-evolution process indicated that spherical particles were formed first as flower centers, and then swordlike petals grew radially from the particle surfaces. A rational mechanism of formation was proposed on the basis of a range of contrasting experiments. Compared with bulk nickel, these nanoflowers exhibited an enhanced coercivity (H-c) and a decreased saturation magnetization (M-s); this fact is attributed to their peculiar morphology. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).