Reducing the filling content of high-density ferromagnetic particles is a key prerequisite for obtaining lightweight absorbers. To this end, large iron nanowires (Fe NWs) with high length-diameters, uniform length of approximately 21 μ m and diameters of approximately 60 nm were synthesized through a facile magnetic field-induced in situ reduction method without templates and surfactants. The phase structures, and micromorphology of the high-aspect-ratio Fe NWs were analyzed, and the electromagnetic properties of Fe NWs-paraffin composites were measured with a vector network analyzer at 2–18 GHz. The Fe NWs-paraffin composite with a low filler loading also exhibited satisfactory microwave absorption performance, and the composites filled with 20 wt.% of as-prepared Fe NWs shows a minimum reflection loss (RL _min ) of −44.67 dB at 2.72 GHz and effective absorption bandwidth (EAB) with reflection loss below −10 dB reached 8.56 GHz at a layer thickness of 1.42 mm. At a thickness of 3 mm, the RL _min value and EAB (RL ⩽ −10 dB) reached −29.74 dB and 3.28 GHz (3.84–7.12 GHz), respectively. This study suggests that Fe NWs with high-aspect-ratios have promising microwave absorbing applications, and provides a good reference for the preparation of ferromagnetic metal-based lightweight electromagnetic wave-absorbing materials.

Transparent conductive oxide (TCO) films are crucial in optoelectronic devices, such as photodetectors, due to their unique blend of transparency and electrical conductivity. ZnO is a top choice for TCOs owing to its excellent properties, non-toxicity, and cost-effectiveness. In this work, we explore the potential of carbon doping to enhance the electrical properties of ZnO films for transparent conductive applications. Our findings reveal that C-doped ZnO (ZnO:C) films retain the pristine high quality and surface morphology despite an increase in defects with higher C doping. Notably, C doping does not compromise the visible light transmittance of ZnO films, while inducing a gradual increase in optical bandgap, indicative of the typical Burstein–Moss effect. As carbon doping increases, the ZnO:C films exhibit improved carrier concentration, lower resistivity, and sustained high mobility, achieving optimal performance with an electron concentration of 3.73 × 1019 cm−3, resistivity of 3.69 × 10−3 Ω cm, and mobility of 46.08 cm2 V−1 s−1. Finally, we utilized ZnO:C films as a transparent electrode material in ε-Ga2O3-based photodetector, achieving the development of transparent device and attaining high-performance solar-blind detection capabilities. This work provides a strategy for developing a transparent conductive oxide, with ZnO:C emerging as a promising rival to IIIA-doped ZnO for optoelectronic applications.

Customizing the frequency range of electromagnetic wave (EMW) absorbing materials, especially for low-frequency, is a key research focus for 5G/6G and stealth applications. However, achieving precise low-frequency tuning remains challenging due to unpredictable parameter variations in practical design. Here, a constant-permeability-based electromagnetic parameter inversion method predicts the required complex permittivity range for multilayer MXene’s effective microwave absorption in the target low-frequency band. Since traditional modulation methods are plagued by electromagnetic parameter fluctuations, this study regulated the dielectric response by adjusting the embedding amount of small-sized iron nanoparticles (Fe NPs) with stable permeability. Under this guidance, multilayer MXene/Fe NPs (MTF) are prepared by embedding small-sized Fe NPs on the MXene surface via electrostatic self-assembly and in-situ reduction. The introduction of Fe NPs increased charge carriers’ concentration and strengthened the interface effect, resulting in a significant increase in the real part of the complex permittivity (ε') compared with that of multi-layer MXene (7.13-8.89), reaching the predicted range of the real part of the low-frequency complex permittivity (13.12-15.16, 14.34-16.81, and 15.29-18.12). Experimental results show that the MTF has a small error in the frequency of the minimum reflection loss (RL_min) compared to the predicted value (error percentage of 4.69%), along with an in-situ enhancement of the effective absorption bandwidth (EAB) (325.00% growth). Thus, MTF exhibits enhanced low-frequency absorption, with MTF-2 achieving -46.3 dB RLmin at 4.64 GHz (4.35 mm) and 2.24 GHz EAB at 3.8 mm. This work offers a strategy for accurate prediction and regulation of absorption bands over a wide range.

N-doped p-type zinc oxide (ZnO) thin films were prepared by rapid thermal annealing (RTA) of nitrogen ion implanted high quality ZnO epitaxial layers. Annealing at 900 °C in a nitrogen atmosphere leads to the conversion of conductivity from n to p-type with a hole concentration of 9.60×10¹⁷ cm^-3, which is reflected in photoluminescence spectra. To reveal the thermal activation and doping mechanism of this film, the samples were also analyzed by Raman scattering and X-ray photoelectron spectroscopy. The results indicate that elimination of the Zn_i related shallow donors and the formation of shallow acceptor complex N_o-V_Zn account for the stable p-type conductivity of N-doped ZnO. The shallow acceptor state is calculated at 0.161 eV above the valence band edge.

High-performance iron nanowires have attracted wide attention from researchers due to their ‘controllable’ arrangement distribution by magnetic fields. In this paper, a simple magnetic field assisted in situ reduction method was proposed to synthesize Fe NWs with high aspect ratio, small-diameter, and good dispersion. A detailed parametric study determining the relationship among the final morphologies of the products and magnetic field, injection sequence of sodium borohydride that was injected into ferrous sulfate heptahydrate, reactant concentration, and injection rate is presented. The as-synthesized Fe NWs were analyzed by scanning electron microscopy, transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy and vibrating sample magnetometry. A plausible mechanism for the formation of high-aspect-ratio Fe NWs is proposed. The SEM images showed the dependence of the NWs morphology and aspect ratio on synthesis parameters. Magnetic field and injection sequence showed considerable influences on the synthesis of high-aspect-ratio Fe NWs. In the absence of magnetic field or with the changes in injection sequence, only the Fe flakes were obtained. The NWs diameter decreased, and the aspect ratio increased with the increase in injection rate. The FeSO ₄ ·7H ₂ O and NaBH ₄ concentration considerably influenced the aspect ratio of the product, which increased first, decreased, and then increased again with the increase in FeSO ₄ ·7H ₂ O concentration. Meanwhile, the product aspect ratio increased and then became saturated with the increase in NaBH ₄ concentration Thus, an optimum synthesis process was obtained, with the average aspect ratio of 350, and the average diameter of 60 nm. The results reported in this paper provide a basis for optimizing the growth of Fe NWs by magnetic field-assisted method.