Magnetic nanowire synthesis: A chemical engineering approach

Abstract

Bimetallic one-dimensional cobalt-nickel magnetic nanowires capped on both sides with conical heads were synthesized using the polyol process. Then, the process was scaled up to produce magnetic nanowires in sample aliquots of approximately 20 g. The scale-up strategy involved improving the mixing reagents using either axial or radial mixing configurations and was experimentally validated by comparing the structural and magnetic properties of the resulting nanowires. The results indicated a connection between the flow patterns and the size and shape of the nanowires. When a Rushton turbine was used, shorter nanowires with unconventional small heads were obtained. Because the demagnetizing field is strongly localized near or inside these heads, the coercive field was enhanced nearly twofold. These results were confirmed by micromagnetic simulations using isolated nanowires. In addition, the development of flow patterns at the small and pilot scales was predicted and compared using three-dimensional turbulent computational fluid dynamics simulations.

Enhanced magnetic performance of aligned wires assembled from nanoparticles: from nanoscale to macroscale

“…The template-based method associates with its high cost and timeconsuming nature, this method still cannot be adopted for large-scale production [1,30]. Although chemical process method is relatively low-cost and simple, some reaction parameters, including temperature and pH, as well as an external magnetic field (EMF), must be strictly controlled [8,18,[31][32][33].…”

Size-Controlled Synthesis of Carboxyl-Functionalized Magnetite Particles: Effects of Molecular Weight of the Polymer and Aging

“…Similar results of decreased relative XRD peak intensities with increased PAA concentration were also found in PAA-magnetic nanoparticles synthesized by a coprecipitation method, indicating that PAA is able to alter the crystallinity of Fe 3 O 4 crystalline . Other polymers [cellulose, poly­(ethylene oxide), and poly­(propylene oxide)] were also reported slowing the nucleation rate of nanocrystals. , …”

“…24 Other polymers [cellulose, poly(ethylene oxide), and poly(propylene oxide)] were also reported slowing the nucleation rate of nanocrystals. 29,30 2.1.3. Characterization of Coatings on One-Step Hydrothermally Synthesized MPs.…”

“…The crystallite size of the Fe 3 O 4 particles is calculated using the Scherrer equation where L is the average crystallite size (nm), λ is the X-ray wavelength (∼1.5418 Å), β is the peak breadth measured at half the maximum intensity (radians), and θ is the Bragg’s angle (degrees) . Whereas the absolute crystallite size of one sample determined by Scherrer equation is roughly accurate, the difference in relative sizes between the two samples is more meaningful (refs and ).…”

Synthesis of Nickel Nanowires with Tunable Characteristics

“…Diverse types of morphologies and sizes of Ni nanomaterials have been synthesized, including chains [ 10 ], belts [ 11 ], tubules [ 12 ], rods [ 13 ], triangular plates [ 14 ], hexagonal hierarchy [ 9 ], hollow spheres [ 15 ], particles, and flowers [ 16 ]. Among these members, nickel nanowire (NiNW) is a prominent example for having different properties from bulk metal due to the one-dimensional (1D) geometry and large shape anisotropy, which can enhance the coercivity and prevent it from becoming superparamagnetic [ 17 , 18 ]. Based on the special properties of NiNWs, numerous promising applications have been achieved, such as optical sensing, plasmonic resonance sensors, perpendicular magnetic storage, functional devices, negative permeability, biological separation, wire-grid type micro polarizer, trenches, and capacitors [ 19 , 20 ].…”