Printable Hierarchical Nickel Nanowires for Soft Magnetic Applications

Hierarchical nickel nanowires (h-NiNWs) were synthesized by a simple reduction method and their electrical, magnetic, and electromagnetic characteristics were investigated. These nanowires possess a high magnetic saturation (<i>M</i><sub>s</sub>) of 51 emu/g and also a coercivity (<i>H</i><sub>c</sub>) of 34.5 Oe, which makes them suitable for soft magnetic sensor applications. Hall transport is being reported for the first time for h-NiNWs, and electrical conductivity at room temperature was studied to assess their applicability as a Hall sensor wherein the Hall coefficient <i>R</i><sub>H</sub> was found to be −1.39 × 10<sup>–12</sup> Ω cm/Oe. Electromagnetic characterization of synthesized h-NiNWs shows excellent microwave shielding effectiveness of above 24 dB for the Ku band (12.4–18 GHz) and a maximum value of 32 dB at 14 GHz for a sample with a thickness of about 1 mm. A room-temperature-curable screen-printable ink was formulated using the synthesized magnetic nanostructures and printed on different flexible substrates. Printed patterns show promising ferromagnetic properties, and they could be potential candidates for soft magnetic sensor applications.