Tuning the Shape Anisotropy and Electromagnetic Screening Ability of Ultrahigh Magnetic Polymer and Surfactant-Capped FeCo Nanorods and Nanocubes in Soft Conducting Composites.
Herein, we demonstrate that very high electromagnetic (EM) shielding efficiency can be achieved by dispersing nanoengineered FeCo anisometric nanostructures in a poly(vinylidene difluoride) matrix in the presence of conductive nanofillers (multiwall carbon nanotubes, MWCNTs). The FeCo nanorods (∼800 nm) and nanocubes (∼100 nm) were fabricated by a facile surfactant and polymer-assisted one-pot borohydride reduction method. The growth mechanism depicted a two-directional growth for cubes, whereas for nanorods, a unidirectional growth pattern across the (110) plane was evident. A total shielding effectiveness (SET) of -44 dB at 18 GHz was achieved for a particular combination of FeCo nanorods and MWCNT, and for nanocube-based composites, it was found to be -39 dB at 18 GHz. It was observed from zero field cooled-field cooled curves that the samples displayed room temperature ferromagnetism. An excellent correlation between high aspect ratio FeCo nanorod and superior EM absorption (89%) was explored, pertaining to the fact that nanorods possessed higher magnetic saturation (177.1 emu/g) and coercivity (550 Oe) in contrast to the nanocubes with similar composition. Furthermore, theoretical insight into the mechanism revealed a high degree of interface scattering between conductive MWCNT and magnetic loss components, giving rise to an excellent synergy between magnetic and dielectric parts.
Department of Materials Engineering, Indian Institute of Science , Bangalore, India 560012.
Injamamul
I
Arief
Department of Materials Engineering, Indian Institute of Science , Bangalore, India 560012.
Sourav
S
Biswas
Department of Materials Engineering, Indian Institute of Science , Bangalore, India 560012.
Suryasarathi
S
Bose
EMI shielding; FeCo; MWCNT; electrical conductivity; magnetic properties; polymer nanocomposite