Nanomaterials

10 pages, 2582 KB

Open AccessArticle

High-Field Nonlinear Terahertz Conductivities of Iron Ultrathin Films

by Lewen Zhu, Zhiqiang Lan, Yingyu Guo, Danni Li, Lin Xi, Huiping Zhang and Zuanming Jin

Nanomaterials 2025, 15(18), 1386; https://doi.org/10.3390/nano15181386 - 9 Sep 2025

The electronic transport behavior in ferromagnetic thin films critically dictates the functionality and efficiency of devices in spintronics and modern materials science. This work characterizes terahertz (THz) responses and nonlinear conductivities of Fe ultrathin films under high-field THz excitation. We demonstrated that different nonlinearities are present for two different thickness samples. For a 2 nm thick Fe film, as the peak THz electric field was increased to 369 kV/cm, the THz transmittance of Fe films generally decreased. However, for the 4 nm thick Fe film, the THz transmittance is almost field strength independent. This result is correlated with the conductivity variations induced by carrier transport processes. The real part of the complex conductivity for the 2 nm thick film increased significantly with the THz electric field, while the 4 nm thick film showed negligible dependence. In addition, we extracted the frequency-domain complex conductivity of the Fe thin films and used the Drude or Drude–Smith model to explain the distinct behaviors between the two thickness samples under intense THz fields, mainly associated with the surface morphology. This work aims to elucidate the transport properties of Fe films in the THz frequency range. Our findings lay a crucial foundation for the design and development of future high-performance THz spintronic functional devices. Full article

(This article belongs to the Special Issue Nanomaterials and Nanostructures for Spintronic Terahertz Devices)

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11 pages, 2022 KB

Open AccessArticle

Thickness Influences on Structural and Optical Properties of Thermally Annealed (GaIn)₂O₃ Films

by Shiyang Zhang, Fabi Zhang, Tangyou Sun, Zanhui Chen, Xingpeng Liu, Haiou Li, Shifeng Xie, Wanli Yang and Yue Li

Nanomaterials 2025, 15(18), 1385; https://doi.org/10.3390/nano15181385 - 9 Sep 2025

Abstract

This work explores the relationship between the thickness and the structural, morphological, and optical features of thermally annealed (GaIn)₂O₃ thin films grown by pulsed laser deposition at room temperature. The thickness of the (GaIn)₂O₃ films varied from 20 to 391 nm with an increase in deposition time. The film with a thickness of about 105 nm showed largest grain size as well as the strongest XRD peak intensity, as measured by atomic force microscopy and X-ray diffraction. The studies on the optical properties show that the bandgap value decreased from 5.14 to 4.55 eV with the change in the film thickness from 20 to 391 nm. The film thickness had a significant impact on the structure, morphology, and optical properties of (GaIn)₂O₃, and the PLD growth mode notably influenced the film quality. The results suggest that optimizing the film thickness is essential for improving the film quality and achieving the target bandgap. Full article

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16 pages, 1541 KB

Open AccessArticle

Carbyne-Enriched Carbon Coatings on Silicon Chips as Biosensing Surfaces with Stable-over-Time Biomolecule Binding Capacity

by Dimitra Tsounidi, Panagiota Petrou, Mariya Aleksandrova, Tsvetozar Tsanev, Angeliki Tserepi, Evangelos Gogolides, Andrzej Bernasik, Kamil Awsiuk, Natalia Janiszewska, Andrzej Budkowski and Ioannis Raptis

Nanomaterials 2025, 15(18), 1384; https://doi.org/10.3390/nano15181384 - 9 Sep 2025

Abstract

Carbyne-containing materials offer significant potential for biosensor applications due to their unique chemical and mechanical properties. In this study, carbyne-enriched carbon coatings deposited on SiO₂/Si chips using ion-assisted pulse-plasma deposition were evaluated for the first time as substrates for optical biosensing. At first, the carbyne-enriched coatings were characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, Atomic Force Microscopy, and the sessile drop method to assess their composition, structure, and wettability. After that, chips with carbyne-enriched coatings were modified with biomolecules through physical absorption or covalent bonding, and the respective biomolecular interactions were monitored in real-time by White Light Reflectance Spectroscopy (WLRS). In both cases, SiO₂/Si chips modified with an aminosilane were used as reference substrates. Physical adsorption was tested through immobilization of an antibody against C-reactive protein (CRP) to enable its immunochemical detection, whereas covalent bonding was tested through coupling of biotin and monitoring its reaction with streptavidin. It was found that the carbyne-enriched carbon-coated chips retained both their antibody adsorption capability and their covalent bonding ability for over 18 months, while the modified with aminosilane SiO₂/Si chips lost 90% of their antibody adsorption capacity and covalent bonding ability after two months of storage. These findings highlight the strong potential of carbyne-enriched carbon-coated chips as robust biosensing substrates, with applications extending beyond WLRS. Full article

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11 pages, 3833 KB

Open AccessArticle

Preparation of Ag-Decorated TiO₂ Composite Materials and Study on Photocatalytic Performance

by Hongfei Dou, Jie Wang, Yan Zhao, Junjie Liu and Yannan Li

Nanomaterials 2025, 15(18), 1383; https://doi.org/10.3390/nano15181383 - 9 Sep 2025

Abstract

Aiming at the insufficient broad-spectrum absorption and high carrier complexation rate in the photocatalytic antimicrobial application of TiO₂, Ag/TiO₂ composite materials were prepared by co-precipitation method in this study. The material characterization showed that Ag was uniformly dispersed on the TiO₂ surface in the form of nanoparticles, and the specific surface area of Ag/TiO₂ composite materials was enhanced by 59.6% compared with that of pure TiO₂, and the mesoporous structure was significantly optimized. Visible photocatalytic tests showed that the degradation rate of Ag/TiO₂ composite materials for Rh B and M O was more than two times higher than that of pure TiO₂. Under dark conditions, the material showed a minimum inhibitory concentration (MIC) of 62.5 μg/mL against Escherichia coli and Staphylococcus aureus, with an antimicrobial rate of 99.8% for 8 h, confirming its non-light-dependent antimicrobial activity. Mechanistic studies revealed that photogenerated electrons were efficiently captured by Ag nanoparticles, which inhibited e-h⁺ complexation; meanwhile, the photothermal effect (ΔT > 15 °C) promoted the sustained release of Ag⁺, which realized the triple synergistic antimicrobial activity by disrupting the bacterial membrane and interfering with metabolism. This study provides a new strategy for the development of efficient solar-powered water treatment materials. Full article

(This article belongs to the Special Issue Green Nanoparticles and Nanocomposites for Water Remediation: Synthesis and Current Applications)

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Nanomaterials, Volume 15, Issue 18 (September-2 2025) – 4 articles

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