Magnetic Field‐Induced Synthesis of One‐Dimensional Nickel Nanowires for Enhanced Microwave Absorption

Abstract

One‐dimensional magnetic nanowires have become one of the ideal candidates for microwave absorption (MA) due to their excellent mechanical properties, large aspect ratio, and excellent electron transport properties. Here, we introduce the synthesis of polyvinylpyrrolidone (PVP)‐directed nickel nanowires (PNNWs) by an externally magnetically induced solvothermal method, and the morphology and properties of PNNWs exhibit a magnetic field‐strength‐dependent relationship. The 9T‐PNNW synthesized at 9 T magnetic field has the characteristics of high aspect ratio, large specific surface area, and good magnetic properties, which endow it with excellent MA performance. The minimum reflection loss (RL) reaches −29.82 dB at 4.08 GHz with the thickness of 4.5 mm and the effective absorption bandwidth (fe) can over 3.6 GHz from 14.4 GHz to 18.0 GHz with a thickness of 1.5 mm. Multiple electromagnetic loss mechanisms are induced to attenuate the electromagnetic wave (EW), in which the dielectric loss dominates, and the magnetic loss, current loss, and resonance effect only play an auxiliary role. This work opens up a new avenue for rational design and preparation of nickel nanowires, and more importantly, the regulation of the magnetic field on the performance of absorbers has reference significance.

Tuning Structure and Properties of a Ferromagnetic Organic Semiconductor via a Magnetic Field-Modified Reduction Process

“…Therefore, the triplet/singlet ratio of the radicals, produced in the reduction process, might be modified remarkably [34], which could negatively influence the amount and stability of the resultant dianions and thus be correlated to deteriorated magnetic properties of the PDI magnets. The situation is different from the cases of the synthesis of the nanomaterials under HML [25,26], in which the formation of the product phases with a higher magnetic order is facilitated due to the lowering of magnetic energy upon the generation of these products under the magnetic field. On the other hand, the assembly and growth of the radical PDI aggregates could also be modulated via the solution cast of the dianion solution under HMF to study the MFE on the structure and magnetic properties of the PDI magnets.…”

“…They found that the formation of the metallic 1T-MoS 2 phase is facilitated under a high magnetic field (HMF) due to the higher magnetic susceptibility of 1T-MoS 2 than diamagnetic 2H-MoS 2 [25]. Qian et al have synthesized the PVP-directed nickel nanowires via a magnetically assisted hydrothermal method, which also exhibited enhanced magnetization and excellent microwave absorption performance [26]. Furthermore, our group has achieved a large area highly oriented film structure of several semiconducting polymers by solution-phase deposition under a field of 9T [27,28].…”

Self-Assembled Ni0.85Se/NiSe@MoSe2 Network with Tubular and Core–Sheath Structures toward Adjustable Electromagnetic Wave Absorption Properties

“…However, the existing EWA studies related to Ni nanowires seldom show superior properties due to the inferior impedance matching, which originates from the high conductivity caused by the easy escaping of electrons and the linear structure. As reported, − the current methods for fabrication of Ni nanowires are magnetic field-induced, electrodeposition, template-assisted, and solvothermal reactions. Among them, the solvothermal reaction has various advantages, such as cost-free, moderate reaction conditions, even size, and a large length-to-diameter ratio, prompting the development of Ni nanowire-related absorbing materials.…”