Nanomaterials

Research

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9 pages, 7530 KiB

Open AccessArticle

Simulated Guidance in Interpreting Nano-Patterned Co₇₀Fe₃₀ Film Imaging with Differential Phase Contrast

by Björn Büker, Daniela Ramermann, Pierre-M. Piel, Judith Bünte, Inga Ennen and Andreas Hütten

Nanomaterials 2024, 14(1), 116; https://doi.org/10.3390/nano14010116 - 3 Jan 2024

Viewed by 885

Abstract

Our paper introduces a simulation-based framework designed to interpret differential phase contrast (DPC) magnetic imaging within the transmission electron microscope (TEM). We investigate patterned magnetic membranes, particularly focusing on nano-patterned Co₇₀Fe₃₀ thin-film membranes fabricated via focused ion beam (FIB) milling. [...] Read more.

Our paper introduces a simulation-based framework designed to interpret differential phase contrast (DPC) magnetic imaging within the transmission electron microscope (TEM). We investigate patterned magnetic membranes, particularly focusing on nano-patterned Co₇₀Fe₃₀ thin-film membranes fabricated via focused ion beam (FIB) milling. Our direct magnetic imaging reveals regular magnetic domain patterns in these carefully prepared systems. Notably, the observed magnetic structure aligns precisely with micromagnetic simulations based on the dimensions of the underlying nanostructures. This agreement emphasizes the usefulness of micromagnetic simulations, not only for the interpretation of DPC data, but also for the prediction of possible microstructures in magnetic sensor systems with nano-patterns. Full article

(This article belongs to the Special Issue Functionalized Magnetite Nanomaterials — Synthesis, Properties, and Applications)

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23 pages, 6668 KiB

Open AccessArticle

Direct Polyphenol Attachment on the Surfaces of Magnetite Nanoparticles, Using Vitis vinifera, Vaccinium corymbosum, or Punica granatum

by Ana E. Matías-Reyes, Margarita L. Alvarado-Noguez, Mario Pérez-González, Mauricio D. Carbajal-Tinoco, Elizabeth Estrada-Muñiz, Jesús A. Fuentes-García, Libia Vega-Loyo, Sergio A. Tomás, Gerardo F. Goya and Jaime Santoyo-Salazar

Nanomaterials 2023, 13(17), 2450; https://doi.org/10.3390/nano13172450 - 30 Aug 2023

Viewed by 1487

Abstract

This study presents an alternative approach to directly synthesizing magnetite nanoparticles (MNPs) in the presence of Vitis vinifera, Vaccinium corymbosum, and Punica granatum derived from natural sources (grapes, blueberries, and pomegranates, respectively). A modified co-precipitation method that combines phytochemical techniques was [...] Read more.

This study presents an alternative approach to directly synthesizing magnetite nanoparticles (MNPs) in the presence of Vitis vinifera, Vaccinium corymbosum, and Punica granatum derived from natural sources (grapes, blueberries, and pomegranates, respectively). A modified co-precipitation method that combines phytochemical techniques was developed to produce semispherical MNPs that range in size from 7.7 to 8.8 nm and are coated with a ~1.5 nm thick layer of polyphenols. The observed structure, composition, and surface properties of the MNPs@polyphenols demonstrated the dual functionality of the phenolic groups as both reducing agents and capping molecules that are bonding with Fe ions on the surfaces of the MNPs via –OH groups. Magnetic force microscopy images revealed the uniaxial orientation of single magnetic domains (SMDs) associated with the inverse spinel structure of the magnetite (Fe₃O₄). The samples’ inductive heating (H₀ = 28.9 kA/m, f = 764 kHz), measured via the specific loss power (SLP) of the samples, yielded values of up to 187.2 W/g and showed the influence of the average particle size. A cell viability assessment was conducted via the MTT and NRu tests to estimate the metabolic and lysosomal activities of the MNPs@polyphenols in K562 (chronic myelogenous leukemia, ATCC) cells. Full article

(This article belongs to the Special Issue Functionalized Magnetite Nanomaterials — Synthesis, Properties, and Applications)

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15 pages, 6166 KiB

Open AccessArticle

An Ethyl-Thioglycolate-Functionalized Fe₃O₄@ZnS Magnetic Fluorescent Nanoprobe for the Detection of Ag⁺ and Its Applications in Real Water Solutions

by Xin Chen, Jie Chen, Mingshuo Ma, Shihua Yu, Zhigang Liu and Xiaodan Zeng

Nanomaterials 2023, 13(13), 1992; https://doi.org/10.3390/nano13131992 - 1 Jul 2023

Cited by 3 | Viewed by 1127

Abstract

Ethyl-thioglycolate-modified Fe₃O₄@ZnS nanoparticles (Fe₃O₄@ZnS-SH) were successfully prepared using a simple chemical precipitation method. The introduction of ethyl thioglycolate better regulated the surface distribution of ZnS, which can act as a recognition group and can cause [...] Read more.

Ethyl-thioglycolate-modified Fe₃O₄@ZnS nanoparticles (Fe₃O₄@ZnS-SH) were successfully prepared using a simple chemical precipitation method. The introduction of ethyl thioglycolate better regulated the surface distribution of ZnS, which can act as a recognition group and can cause a considerable quenching of the fluorescence intensity of the magnetic fluorescent nanoprobe, Fe₃O₄@ZnS-SH. Benefiting from stable fluorescence emission, the magnetic fluorescent nanoprobe showed a highly selective fluorescent response to Ag+ in the range of 0–400 μM, with a low detection limit of 0.20 μM. The magnetic fluorescent nanoprobe was used to determine the content of Ag⁺ in real samples. A simple and environmentally friendly approach was proposed to simultaneously achieve the enrichment, detection, and separation of Ag⁺ and the magnetic fluorescent nanoprobe from an aqueous solution. These results may lead to a wider range of application prospects of Fe₃O₄ nanomaterials as base materials for fluorescence detection in the environment. Full article

(This article belongs to the Special Issue Functionalized Magnetite Nanomaterials — Synthesis, Properties, and Applications)

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11 pages, 3157 KiB

Open AccessArticle

The Role of Ferromagnetic Layer Thickness and Substrate Material in Spintronic Emitters

by Arseniy Buryakov, Pavel Avdeev, Dinar Khusyainov, Nikita Bezvikonnyy, Andreas Coclet, Alexey Klimov, Nicolas Tiercelin, Sergey Lavrov and Vladimir Preobrazhensky

Nanomaterials 2023, 13(11), 1710; https://doi.org/10.3390/nano13111710 - 23 May 2023

Cited by 1 | Viewed by 1424

Abstract

In this article, we investigate optically induced terahertz radiation in ferromagnetic FeCo layers of varying thickness on Si and SiO₂ substrates. Efforts have been made to account for the influence of the substrate on the parameters of the THz radiation generated by [...] Read more.

In this article, we investigate optically induced terahertz radiation in ferromagnetic FeCo layers of varying thickness on Si and SiO₂ substrates. Efforts have been made to account for the influence of the substrate on the parameters of the THz radiation generated by the ferromagnetic FeCo film. The study reveals that the thickness of the ferromagnetic layer and the material of the substrate significantly affect the generation efficiency and spectral characteristics of the THz radiation. Our results also emphasize the importance of accounting for the reflection and transmission coefficients of the THz radiation when analyzing the generation process. The observed radiation features correlate with the magneto-dipole mechanism, triggered by the ultrafast demagnetization of the ferromagnetic material. This research contributes to a better understanding of THz radiation generation mechanisms in ferromagnetic films and may be useful for the further development of THz technology applications in the field of spintronics and other related areas. A key discovery of our study is the identification of a nonmonotonic relationship between the radiation amplitude and pump intensity for thin films on semiconductor substrates. This finding is particularly significant considering that thin films are predominantly used in spintronic emitters due to the characteristic absorption of THz radiation in metals. Full article

(This article belongs to the Special Issue Functionalized Magnetite Nanomaterials — Synthesis, Properties, and Applications)

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11 pages, 3924 KiB

Open AccessArticle

Remote Sensing of the Nano-Rheological Properties of Soft Materials Using Magnetic Nanoparticles and Magnetic AC Susceptometry

by Sobhan Sepehri, Johanna Andersson, Vincent Schaller, Cordula Grüttner, Mats Stading and Christer Johansson

Nanomaterials 2023, 13(1), 67; https://doi.org/10.3390/nano13010067 - 23 Dec 2022

Viewed by 1340

Abstract

We have developed a nano-rheological characterization tool to extract the frequency- and scale-dependent rheological properties of soft materials during oral processing. Taking advantage of AC susceptometry, the dynamic magnetization of magnetic nanoparticles blended in the matrix material is measured. The magnetic AC susceptibility [...] Read more.

We have developed a nano-rheological characterization tool to extract the frequency- and scale-dependent rheological properties of soft materials during oral processing. Taking advantage of AC susceptometry, the dynamic magnetization of magnetic nanoparticles blended in the matrix material is measured. The magnetic AC susceptibility spectra of the particles are affected by the viscosity and mechanical modulus of the matrix material and provide the rheological properties of the matrix. Commercially available iron-oxide magnetic nanoparticles with 80 and 100 nm particle sizes are used as tracers in the frequency range of 1 Hz–10 kHz. The AC susceptibility is measured using two differentially connected coils, and the effects of the sample temperature and distance with respect to the detection coils are investigated. The developed measurement setup shows the feasibility of remote nano-rheological measurements up to 2 cm from the coil system, which can be used to, e.g., monitor the texture of matrix materials during oral processing. Full article

(This article belongs to the Special Issue Functionalized Magnetite Nanomaterials — Synthesis, Properties, and Applications)

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14 pages, 4902 KiB

Open AccessArticle

Structural and Superconducting Proximity Effect of SnPb Bimetallic Nanoalloys

by Ashish Chhaganlal Gandhi, Krishtappa Manjunatha, Ting-Shan Chan and Sheng Yun Wu

Nanomaterials 2022, 12(23), 4323; https://doi.org/10.3390/nano12234323 - 5 Dec 2022

Viewed by 1248

Abstract

We report the superconducting properties between a conventional strong-coupled Pb and weak-coupled Sn superconductor. A series of Sn_rPb_1-r nanoalloys with various compositions r were synthesized, and their superconducting properties were measured using superconducting quantum interference devices (SQUIDs) magnetometer. Our results [...] Read more.

We report the superconducting properties between a conventional strong-coupled Pb and weak-coupled Sn superconductor. A series of Sn_rPb_1-r nanoalloys with various compositions r were synthesized, and their superconducting properties were measured using superconducting quantum interference devices (SQUIDs) magnetometer. Our results reveal a superconducting proximity effect (SPE) between immiscible Sn and Pb granules in the range of r = 0.2~0.9, as a weak superconducting coupling can be established with the coexistence of phonon hardening and increased Ginzburg–Landau coherence length. Furthermore, our results provide new insights into improving the study of the superconducting proximity effect introduced by Sn doping. Full article

(This article belongs to the Special Issue Functionalized Magnetite Nanomaterials — Synthesis, Properties, and Applications)

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19 pages, 5947 KiB

Open AccessArticle

Synthesis and Characterization of MWCNT-COOH/Fe₃O₄ and CNT-COOH/Fe₃O₄/NiO Nanocomposites: Assessment of Adsorption and Photocatalytic Performance

by Adina Stegarescu, Humberto Cabrera, Hanna Budasheva, Maria-Loredana Soran, Ildiko Lung, Francesca Limosani, Dorota Korte, Matteo Amati, Gheorghe Borodi, Irina Kacso, Ocsana Opriş, Monica Dan and Stefano Bellucci

Nanomaterials 2022, 12(17), 3008; https://doi.org/10.3390/nano12173008 - 30 Aug 2022

Cited by 13 | Viewed by 2315

Abstract

In this study the adsorption and photodegradation capabilities of modified multi-walled carbon nanotubes (MWCNTs), using tartrazine as a model pollutant, is demonstrated. MWCNT-COOH/Fe₃O₄ and MWCNT-COOH/Fe₃O₄/NiO nanocomposites were prepared by precipitation of metal oxides in the presence [...] Read more.

In this study the adsorption and photodegradation capabilities of modified multi-walled carbon nanotubes (MWCNTs), using tartrazine as a model pollutant, is demonstrated. MWCNT-COOH/Fe₃O₄ and MWCNT-COOH/Fe₃O₄/NiO nanocomposites were prepared by precipitation of metal oxides in the presence of MWCNTs. Their properties were examined by X-ray diffraction in powder (XRD), Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman spectroscopy, synchrotron-based Scanning PhotoElectron Microscopy (SPEM), and Brunauer-Emmett-Teller (BET) analysis. It was found that the optimal adsorption conditions were pH 4 for MWCNT-COOH/Fe₃O₄ and pH 3 for MWCNT-COOH/Fe₃O₄/NiO, temperature 25 °C, adsorbent dose 1 g L⁻¹, initial concentration of tartrazine 5 mg L⁻¹ for MWCNT-COOH/Fe₃O₄ and 10 mg L⁻¹ for MWCNT-COOH/Fe₃O₄/NiO and contact time 5 min for MWCNT-COOH/Fe₃O₄/NiO and 15 min for MWCNT-COOH/Fe₃O₄. Moreover, the predominant degradation process was elucidated simultaneously, with and without simulated sunlight irradiation, using thermal lens spectrometry (TLS) and UV–Vis absorption spectrophotometry. The results indicated the prevalence of the photodegradation mechanism over adsorption from the beginning of the degradation process. Full article

(This article belongs to the Special Issue Functionalized Magnetite Nanomaterials — Synthesis, Properties, and Applications)

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15 pages, 6565 KiB

Open AccessArticle

Effects of Rhenium Substitution of Co and Fe in Spinel CoFe₂O₄ Ferrite Nanomaterials

by Yuruo Zheng, Ghulam Hussain, Shuyi Li, Shanta Batool and Xiawa Wang

Nanomaterials 2022, 12(16), 2839; https://doi.org/10.3390/nano12162839 - 18 Aug 2022

Cited by 2 | Viewed by 1500

Abstract

In this work, nanoparticles of Co_1−xRe_xFe₂O₄ and CoFe_2−xRe_xO₄ (0 ≤ x ≤ 0.05) were synthesized by the sol-gel method. The Rietveld refinement analysis of XRD and Raman data revealed that all [...] Read more.

In this work, nanoparticles of Co_1−xRe_xFe₂O₄ and CoFe_2−xRe_xO₄ (0 ≤ x ≤ 0.05) were synthesized by the sol-gel method. The Rietveld refinement analysis of XRD and Raman data revealed that all of the prepared samples were single phase with a cubic spinel-type structure. With the substitution of Re, the lattice parameters were slightly increased, and Raman spectra peak positions corresponding to the movement of the tetrahedral sublattice shifted to a higher energy position. Furthermore, Raman spectra showed the splitting of T_2g mode into branches, indicating the presence of different cations at crystallographic A- and B-sites. The SEM micrograph confirms that surface Re exchange changes the coordination environment of metals and induces Fe-site structure distortion, thereby revealing more active sites for reactions and indicating the bulk sample’s porous and agglomerated morphology. The vibrating sample magnetometer (VSM) results demonstrated that the synthesized nanoparticles of all samples were ferromagnetic across the entire temperature range of 300–4 K. The estimated magnetic parameters, such as the saturation magnetization, remanent magnetization, coercivity, blocking temperature (T_B), and magnetic anisotropy, were found to reduce for the Co-site doping with the increasing doping ratio of Re, while in the Fe site, they enhanced with the increasing doping ratio. The ZFC-FC magnetization curve revealed the presence of spin-glass-like behavior due to the strong dipole–dipole interactions in these ferrite nanoparticles over the whole temperature range. Finally, the dielectric constant (ε_r′) and dielectric loss (tanδ) were sharply enhanced at low frequencies, while the AC conductivity increased at high frequencies. The sharp increases at high temperatures are explained by enhancing the barrier for charge mobility at grain boundaries, suggesting that samples were highly resistive. Interestingly, these parameters (ε_r′, tanδ) were found to be higher for the Fe-site doping with the increasing Re doping ratio compared with the Co site. Full article

(This article belongs to the Special Issue Functionalized Magnetite Nanomaterials — Synthesis, Properties, and Applications)

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9 pages, 2997 KiB

Open AccessArticle

Controlled Oxidation of Cobalt Nanoparticles to Obtain Co/CoO/Co₃O₄ Composites with Different Co Content

by Aleksandr S. Lozhkomoev, Alexander V. Pervikov, Sergey O. Kazantsev, Konstantin V. Suliz, Roman V. Veselovskiy, Andrey A. Miller and Marat I. Lerner

Nanomaterials 2022, 12(15), 2523; https://doi.org/10.3390/nano12152523 - 22 Jul 2022

Cited by 5 | Viewed by 1786

Abstract

The paper studies patterns of interaction of electroexplosive Co nanoparticles with air oxygen during heating. The characteristics of Co nanoparticles and composite Co/CoO/Co₃O₄ nanoparticles formed as a result of oxidation were studied using transmission electron microscopy, X-ray phase analysis, thermogravimetric [...] Read more.

The paper studies patterns of interaction of electroexplosive Co nanoparticles with air oxygen during heating. The characteristics of Co nanoparticles and composite Co/CoO/Co₃O₄ nanoparticles formed as a result of oxidation were studied using transmission electron microscopy, X-ray phase analysis, thermogravimetric analysis, differential scanning calorimetry, and vibrating sample magnetometry. It was established that nanoparticles with similar morphology in the form of hollow spheres with different content of Co, CoO, and Co₃O₄ can be produced by varying oxidation temperatures. The influence of the composition of composite nanoparticles on their magnetic characteristics is shown. Full article

(This article belongs to the Special Issue Functionalized Magnetite Nanomaterials — Synthesis, Properties, and Applications)

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Review

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30 pages, 2118 KiB

Open AccessReview

Magnetic Fluids: The Interaction between the Microstructure, Macroscopic Properties, and Dynamics under Different Combinations of External Influences

by Petr Ryapolov, Anastasia Vasilyeva, Dariya Kalyuzhnaya, Alexander Churaev, Evgeniy Sokolov and Elena Shel’deshova

Nanomaterials 2024, 14(2), 222; https://doi.org/10.3390/nano14020222 - 19 Jan 2024

Cited by 1 | Viewed by 1360

Abstract

Magnetic fluids were historically the first active nano-dispersion material. Despite over half a century of research, interest in these nano-objects continues to grow every year. This is due to the impressive development of nanotechnology, the synthesis of nanoscale structures, and surface-active systems. The [...] Read more.

Magnetic fluids were historically the first active nano-dispersion material. Despite over half a century of research, interest in these nano-objects continues to grow every year. This is due to the impressive development of nanotechnology, the synthesis of nanoscale structures, and surface-active systems. The unique combination of fluidity and magnetic response allows magnetic fluids to be used in engineering devices and biomedical applications. In this review, experimental results and fundamental theoretical approaches are systematized to predict the micro- and macroscopic behavior of magnetic fluid systems under different external influences. The article serves as working material for both experienced scientists in the field of magnetic fluids and novice specialists who are just beginning to investigate this topic. Full article

(This article belongs to the Special Issue Functionalized Magnetite Nanomaterials — Synthesis, Properties, and Applications)

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27 pages, 10407 KiB

Open AccessReview

Radiolabeled Iron Oxide Nanoparticles as Dual Modality Contrast Agents in SPECT/MRI and PET/MRI

by Maria-Argyro Karageorgou, Penelope Bouziotis, Efstathios Stiliaris and Dimosthenis Stamopoulos

Nanomaterials 2023, 13(3), 503; https://doi.org/10.3390/nano13030503 - 27 Jan 2023

Cited by 6 | Viewed by 2032

Abstract

During the last decades, the utilization of imaging modalities such as single photon emission computed tomography (SPECT), positron emission tomography (PET), and magnetic resonance imaging (MRI) in every day clinical practice has enabled clinicians to diagnose diseases accurately at early stages. Radiolabeled iron [...] Read more.

During the last decades, the utilization of imaging modalities such as single photon emission computed tomography (SPECT), positron emission tomography (PET), and magnetic resonance imaging (MRI) in every day clinical practice has enabled clinicians to diagnose diseases accurately at early stages. Radiolabeled iron oxide nanoparticles (RIONs) combine their intrinsic magnetic behavior with the extrinsic character of the radionuclide additive, so that they constitute a platform of multifaceted physical properties. Thus, at a practical level, RIONs serve as the physical parent of the so-called dual-modality contrast agents (DMCAs) utilized in SPECT/MRI and PET/MRI applications due to their ability to combine, at real time, the high sensitivity of SPECT or PET together with the high spatial resolution of MRI. This review focuses on the synthesis and in vivo investigation of both biodistribution and imaging efficacy of RIONs as potential SPECT/MRI or PET/MRI DMCAs. Full article

(This article belongs to the Special Issue Functionalized Magnetite Nanomaterials — Synthesis, Properties, and Applications)

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