Uniform magnetic chains of hollow cobalt mesospheres from one-pot synthesis and their assembly in solution

Magnetic chains up to 10 mu m in length formed of hollow cobalt mesospheres (480-850 nm) with a 60 nm thick shell are synthesized by a new soft-assembly protocol. The obtained chains show a saturation magnetization of 37.5 emu g(-1), a remnant magnetization of 1.55 emu g(-1), and a coercivity of ca. 66 Oe at 300 K. A possible mechanism for the formation of the chainlike hollow structures is proposed

One-step solution fabrication of magnetic chains consisting of jingle-bell-shaped cobalt mesospheres

Using a one-step solution phase approach, the authors have synthesized uniform jingle bell-shaped cobalt mesopheres (550-750 nm) and assembled the mesospheres into long magnetic chains (20-30 mu m). All of the cobalt spheres are hollow with similar to 40 nm thick shells but each contains an similar to 200 nm diameter solid ball. The nano- to mesoscale structures were realized via reaction of CoCl2 center dot 6H(2)O and N2H4 center dot H2O in the presence of polyvinylpyrrolidone (PVP) in an ethylene glycol solution. Magnetic measurements show a coercivity of about 75 Oe with a remnance of 9.6 emu/g at 300 K. We propose a possible mechanism for the formation of the nanoto mesoscale structures. (c) 2006 American Institute of Physics