Solvothermal Synthesis of Magnetic Chains Self-Assembled by Flowerlike Cobalt Submicrospheres

Abstract

Cobalt chains with lengths of up to 4-20 µm, self-assembled by flowerlike cobalt submicrospheres, have been synthesized at 200°C for 4 h by a solvothermal method with the surfactant poly(vinyl pyrrolidone) (PVP). The average diameter of individual flowerlike submicrospheres is 700-900 nm, which are composed of compact nanosheets with an average thickness of about 50 nm. The products were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). The effects of synthetic conditions, such as reaction temperature and the amount of reducing agent, on the morphology and size of the chains were investigated. The growth mechanism of the chains was proposed, based on the evolution of the structure and the morphology with increasing the reaction time. The magnetic hysteresis loops at 5 and 295 K of the chains show ferromagnetic characteristics with coercivities of 347 and 90 Oe, respectively. Our work may shed light on the design fabrication of one-dimensional chainlike structures self-assembled by complex three-dimensional architectures of materials.

The hierarchical three-dimensional cobalt superstructure: Controllable synthesis, electromagnetic properties and microwave absorption

“…The coercivity H c was larger than that of bulk cobalt (10 Oe), resulting from particles size, magnetocrystalline and shape anisotropy. Compared to cobalt hierarchical nanostructured microspheres (M s = 134.98 emu/g, H c = 95.45 Oe) [25] and flowerlike cobalt submicrospheres (M s = 139.4 emu/g, H c = 90 Oe) [26], the as-synthesized cobalt superstructure exhibits decreased saturation magnetization and enhanced coercivity, ascribed to their novel structure assembled by nanoflakes. Fig.…”

Influence of variation in the concentration of ammonium hydroxide on the size of ZnO crystal obtained by Microwave Chemical Bath Deposition

“…The increase of OH -ions inhibits growth in the plane direction (0001) and induces the growth in the family of planes [1010], [12,13]. Atomic Force Microscopy (AFM) was used for to obtain the topography of the deposits (Figure 4).…”

Solvothermal synthesis and characterization of cobalt microcrystals with hierarchical radial structure

“…Among magnetic metal nanoparticles, cobalt particles possess more outstanding magnetic properties and have potential applications in many areas including ferrofluids, biomedical systems, catalysts, optical and mechanic devices, high-density magnetic recording media [14][15][16][17][18][19][20][21][22][23]. The synthesis of cobalt particles with various morphologies has been reported including nanowires [24,25], nanorods [26], epitaxial film [27], platelets [28], rings [29], flowers [30] and chain-like structures [31,32]. For example, it has been reported recently that magnetic cobalt nanoparticles can selfassemble into rings through dipolar interactions, when dispersed under appropriate conditions, and show bistable flux closure states at ambient temperature [29].…”