One-Dimensional Magnetite Chains of Nanoparticles Synthesis by Self-Assembly in Magnetic Field

Abstract

Magnetite chains of spheres with different radii and lengths were prepared by aging ferrous hydroxide gel with 0.2M KNO3 under different external magnetic fields which induced the ultra-fine magnetite particles to combine into chain structure. The magnetite particle size and the chain length could be adjusted by varying the field intensity. The chains could be deposited on silicon substrates to form aligned structure in magnetic field. The hysteresis loops were measured in different directions by a vibrating sample magnetometer (VSM). The structure and magnetic properties were discussed.

Physical Properties of Elongated Magnetic Particles: Magnetization and Friction Coefficient Anisotropies

“…Although the packing fraction may also be an unknown in this technique, particles can be oriented along their easy axis by applying a field during the drying process. [50,51] This allows for measurements of the magnetization with the field applied at different angles relative to the easy magnetization axis. Use of the Langmuir-Blodgett technique may provide additional control over the formation of particle monolayers.…”

“…[103] In 2005, Zhang et al [51] synthesized magnetite chains of spheres with different radii and lengths by controlled aging of iron(II) hydroxide with nitrate under magnetic fields. This method was further improved in 2007 by Vereda et al (see Figure 9), who produced micron-sized rodlike magnetite [68] and non-stoichiometric Ni and Co ferrite [104] particles by magnetic-field-induced self-assembly for magnetorheological applications.…”

Influence of a Magnetic Field on the Formation of Magnetite Particles via Two Precipitation Methods

“…It should be mentioned that the magnetic field was not uniform within the volume occupied by the reactants since it was provided by permanent magnets placed under the reaction flask. Finally, Zhang et al used a process based on that of Sugimoto and Matijević for the synthesis of magnetite, with the particularity that the particles were subjected during growth to fields as high as 350 mT. When that maximum field was applied, they obtained “chains of spheres” with lengths of 4−8 μm and cross sections of approximately 310 nm.…”