Magnetochemistry

22 pages, 1515 KB

Open AccessArticle

Numerical Simulation of Low-Frequency Magnetic Fields and Gradients for Magnetomechanical Applications

by Nikolaos Maniotis and Antonios Makridis

Magnetochemistry 2025, 11(12), 111; https://doi.org/10.3390/magnetochemistry11120111 - 13 Dec 2025

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This study aims to identify optimal parameters for the clinical implementation of magnetic fields in therapeutic contexts, with a particular focus on in vitro magneto-mechanical actuation in biological systems. This approach relies on the transduction of magnetic energy into mechanical stress at low [...] Read more.

This study aims to identify optimal parameters for the clinical implementation of magnetic fields in therapeutic contexts, with a particular focus on in vitro magneto-mechanical actuation in biological systems. This approach relies on the transduction of magnetic energy into mechanical stress at low frequencies (<<100 Hz). Accordingly, the investigation centers on evaluating the magnetic field gradients responsible for initiating the motion of intracellular magnetic nanoparticles and the resulting mechanical forces acting upon them. To achieve this, a novel, custom-built, and highly adaptable three-dimensional turntable system was designed, calibrated, and implemented. This apparatus allows the generation of magnetic fields with precisely tunable amplitude and frequency, enabling controlled activation of magneto-mechanical mechanisms. In vitro experiments using this device facilitated the exposure of cancer cells to well-characterized magnetic fields, thereby inducing mechanical stimulation in the presence of nanoparticles distributed within intracellular or extracellular environments. Quantitative measurements of magnetic field intensities were performed, providing estimations of the forces exerted by magnetic nanoparticles with diverse physical characteristics (phase, size, and shape) under varying magnetic field gradients. Full article

(This article belongs to the Special Issue Advances in Multifunctional Magnetic Nanomaterial)

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22 pages, 4954 KB

Open AccessArticle

Effect of Magnetic Excitation Intensity on Stress Recognition and Quantitative Evaluation in Ferromagnetic Pipelines

by Jiawen Zhang, Ning Luo, Long Chao, Nan Liu, Zheng Lian, Bin Liu and Lijian Yang

Magnetochemistry 2025, 11(12), 110; https://doi.org/10.3390/magnetochemistry11120110 - 12 Dec 2025

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Abstract

Stress detection is an effective way to prevent pipeline failure, but stress recognition alone can hardly meet the safety and maintenance requirements of pipelines. Rather, improving the accuracy of stress detection and quantification has long been a top priority in the engineering sector. [...] Read more.

Stress detection is an effective way to prevent pipeline failure, but stress recognition alone can hardly meet the safety and maintenance requirements of pipelines. Rather, improving the accuracy of stress detection and quantification has long been a top priority in the engineering sector. In the present study, stress detection models for pipelines were developed under varying magnetic excitation intensities, and the influence of a changing magnetic excitation field on stress recognition capacity was investigated. The variation law of the accuracy of stress detection under different excitation intensities was determined and validated experimentally. The results showed that at an excitation intensity of 2.5 of kA/m, the polarity of weak magnetic signals flipped when used to detect stress below 40 MPa, making the stress quantification difficult. The stress recognition capacity was the greatest under an excitation intensity of 7.5 kA/m for the stress below 40 MPa and the greatest under an excitation intensity of 5 kA/m for the stress of 40–160 MPa. Our research findings offer theoretical clues for choosing an appropriate excitation intensity for stress detection. The findings provide technical support for pipeline integrity assessment and risk warning, playing an important role in ensuring the safe operation of oil and gas transportation systems. Full article

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15 pages, 6557 KB

Open AccessArticle

Study on Influence Law and Mechanism of Rheological Properties of High-Viscosity Fluoroether Oil-Based Ferrofluids

by Fang Chen, Yuchen Liu, Qinkui Guo, Yangjie Xiao, Yuan Dong, Sihan Yue, Yichao Huang and Zhenggui Li

Magnetochemistry 2025, 11(12), 109; https://doi.org/10.3390/magnetochemistry11120109 - 8 Dec 2025

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Abstract

A series of high-viscosity ferrofluids with variations in particle concentration and carrier liquid molecular weight were synthesized in a fluoroether oil base by the chemical coprecipitation method. The microstructure, surface coating, and magnetic properties of the nanoparticles were characterized, and the rheological properties [...] Read more.

A series of high-viscosity ferrofluids with variations in particle concentration and carrier liquid molecular weight were synthesized in a fluoroether oil base by the chemical coprecipitation method. The microstructure, surface coating, and magnetic properties of the nanoparticles were characterized, and the rheological properties of the corresponding ferrofluids were systematically investigated to elucidate their governing mechanisms and underlying mechanisms. The results indicate that the synthesized zinc-doped ferrite particles are spherical with a size of less than 50 nm and are chemically coated with a fluoroether acid. Moreover, the saturation magnetization of the ferrofluids increases with rising particle concentration. With the increase in particle concentration, the zero-field viscosity and shear stress of the ferrofluids increase significantly. The zero-field viscosity and shear yield stress of the ferrofluid increase significantly with the molecular weight of the carrier liquid, due to the strengthened entanglement of its molecular chains. At a carrier liquid molecular weight of 4600 g/mol, the 50 wt.% ferrofluid displayed a liquid character, in contrast to the gel-like character displayed by the 60 and 70 wt.% samples. The 60 wt.%-7480 g/mol sample demonstrated superior elasticity to its 60 wt.%-4600 g/mol counterpart. Furthermore, the application of a 100 mT magnetic field induced a transition from a liquid to a gel state in the 50 wt.%-4600 g/mol sample. This transition, driven by the formation of magnetic field-induced chain-like structures, significantly enhanced the magnetoviscous effect. This study provides the theoretical basis and experimental support for the development of high-viscosity ferrofluid sealing materials suitable for high-pressure, liquid environments and corrosive working conditions. Full article

(This article belongs to the Special Issue Ferrofluids: Electromagnetic Properties and Applications)

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15 pages, 2498 KB

Open AccessArticle

A Hybrid CMOS-MTJ Polymorphic Logic for Secure and Versatile IC Design

by Rajat Kumar, Yogesh Sharma and Amit Kumar Goyal

Magnetochemistry 2025, 11(12), 108; https://doi.org/10.3390/magnetochemistry11120108 - 8 Dec 2025

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Abstract

Recent advancements in nanotechnology have intensified research efforts to address security concerns like hardware trojans and intellectual property (IP) piracy, particularly by exploring novel alternatives to traditional MOSFET devices. Spin-based devices, known for their low power consumption, non-volatility, and seamless integration with silicon [...] Read more.

Recent advancements in nanotechnology have intensified research efforts to address security concerns like hardware trojans and intellectual property (IP) piracy, particularly by exploring novel alternatives to traditional MOSFET devices. Spin-based devices, known for their low power consumption, non-volatility, and seamless integration with silicon substrates, have emerged as promising candidates. This research proposes a novel approach to enhance the security of integrated circuits using spin-based devices known as magnetic tunnel junctions (MTJs). A Non-volatile Polymorphic Logic (NPL) is optimized and designed to perform multiple operations, effectively concealing its true functionality. The analytical studies conducted on the Cadence Virtuoso platform using TSMC 65 nm MOS technology demonstrate the feasibility and efficacy of the proposed approach. The proposed NPL circuit enables polymorphism by allowing the circuit to perform all one- and two-input Boolean logic operations, including NOT, AND/NAND, OR/NOR, and XOR/XNOR, through adjustments of applied keys. This dynamic functionality makes it challenging for attackers to determine the circuit’s true operation. The proposed design exhibits similar timing characteristics for different logic operations, which further complicates the tampering attempts. Additionally, the circuit’s layout is designed to be symmetric, ensuring the execution of all possible operations by the same physical layout. This provides post-manufacturing security from reverse engineering and finds its applications in securing custom IC designs against the evolving landscape of hardware-based threats. Full article

(This article belongs to the Special Issue Design and Application of Spintronic Devices)

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15 pages, 1802 KB

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Mössbauer Study of Weathering Products in Meteorites from the Atacama Desert

by Andrew Pyataev, Dilyara Kuzina, Jérôme Gattacceca, Carine Sadaka and Razilia Muftakhetdinova

Magnetochemistry 2025, 11(12), 107; https://doi.org/10.3390/magnetochemistry11120107 - 4 Dec 2025

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Abstract

During their stay at the surface of the Earth, meteorites undergo terrestrial weathering. In particular, the iron-nickel alloys and iron sulfides that are abundant in many types of meteorites transform into oxides and oxihydroxides (magnetite, maghemite, akaganeite, etc.). Mössbauer spectroscopy is a powerful [...] Read more.

During their stay at the surface of the Earth, meteorites undergo terrestrial weathering. In particular, the iron-nickel alloys and iron sulfides that are abundant in many types of meteorites transform into oxides and oxihydroxides (magnetite, maghemite, akaganeite, etc.). Mössbauer spectroscopy is a powerful tool to identify these weathering products. However, distinguishing signals from different phases summed up in the Fe³⁺ paramagnetic doublets in the central part of the spectrum remains challenging. This study focuses on a detailed investigation of meteorite weathering products to separate signals from different secondary minerals formed on Earth in a series of weathered meteorites. We carried out a room-temperature Mössbauer spectroscopy study on seventy ordinary chondrites collected in the Atacama Desert, Chile, in order to make a comparative qualitative analysis of the mineralogy of their terrestrial weathering products. Based on these results, three samples showing a variety of weathering products (Catalina 146, Catalina 535, and El Médano 070) were selected for a detailed study and two of them for low-temperature Mössbauer study. We found that, above 200 K, most meteorites exhibit superparamagnetic magnetization dynamics attributable to strong dispersed maghemite–magnetite phase formed as a weathering product. On the other hand, other iron-bearing weathering products (goethite, akaganeite, hematite) demonstrate line shapes of the corresponding partial components that are close to the shapes of the bulk samples. Only two of the 70 measured meteorites showed no superparamagnetic behavior at room temperature. Full article

(This article belongs to the Section Magnetic Materials)

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9 pages, 1802 KB

Open AccessArticle

Magnetocaloric Response of an Eutectic Er₆₉Ni₃₁ Amorphous Alloy

by Tian-Ge Zhai, Jia-Meng Yuan, Zhan-Bo Li, Ding Ding and Lei Xia

Magnetochemistry 2025, 11(12), 106; https://doi.org/10.3390/magnetochemistry11120106 - 1 Dec 2025

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Abstract

The magnetocaloric response of an amorphous Er₆₉Ni₃₁ alloy was studied in the present work. The eutectic Er₆₉Ni₃₁ alloy was successfully melt-spun into an amorphous ribbon. The formability and magnetocaloric performance of the Er₆₉Ni₃₁ amorphous [...] Read more.

The magnetocaloric response of an amorphous Er₆₉Ni₃₁ alloy was studied in the present work. The eutectic Er₆₉Ni₃₁ alloy was successfully melt-spun into an amorphous ribbon. The formability and magnetocaloric performance of the Er₆₉Ni₃₁ amorphous alloy were studied. The amorphous sample exhibits good glass formability and a remarkable magnetocaloric effect with a magnetic entropy change peak of ~16.65 J/(kg × K) near 10 K under 5 Tesla. The magnetization and magnetocaloric behaviors were investigated to reveal the effect of spin-glass-like behaviors on the magnetocaloric response of the binary amorphous sample. Full article

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24 pages, 8644 KB

Open AccessArticle

Analytical Modeling of Demagnetization Effects on Magnetic Flux Leakage Signals in Ferromagnetic Pipelines

by Jiawen Zhang, Nan Liu, Zheng Lian, Guangwen Sun, Bin Liu and Lijian Yang

Magnetochemistry 2025, 11(12), 105; https://doi.org/10.3390/magnetochemistry11120105 - 29 Nov 2025

Cited by 1 | Viewed by 1517

Abstract

Magnetic flux leakage (MFL) testing is a widely used non-destructive method for detecting defects in ferromagnetic pipelines. However, demagnetizing fields in ferromagnetic materials can distort MFL signals, reducing detection accuracy. This study integrates demagnetizing components into the classical magnetic charge model using magnetic [...] Read more.

Magnetic flux leakage (MFL) testing is a widely used non-destructive method for detecting defects in ferromagnetic pipelines. However, demagnetizing fields in ferromagnetic materials can distort MFL signals, reducing detection accuracy. This study integrates demagnetizing components into the classical magnetic charge model using magnetic charge and dipole theories to assess the impact of demagnetization on MFL signals. The behavior of MFL signals under demagnetization, particularly for rectangular defects, is analytically characterized. The generation mechanism of the demagnetizing field is examined, and explicit expressions for triaxial demagnetizing components in cylindrical pipelines are derived. The effects of geometric parameters, such as inner and outer diameters and pipeline length, on demagnetizing components are systematically studied. The influence of demagnetization on MFL signal transmission is also explored. MFL scanning experiments on rectangular defects of different sizes validate the theoretical model, revealing that demagnetization attenuates the axial and radial components while enhancing the circumferential component. The proposed model improves prediction accuracy, reducing errors in the axial and radial components by 14.9% and enhancing the circumferential signal by 15%. Experimental MFL waveforms align closely with the model, confirming its validity and effectiveness. Full article

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14 pages, 2038 KB

Open AccessArticle

Electronic Influence of Trifluoromethyl Substituents on Benzoate Ligands in Paddlewheel-Type Diruthenium(II,II) Naphthyridine Complexes

by Nozomi Tada, Natsumi Yano, Makoto Handa and Yusuke Kataoka

Magnetochemistry 2025, 11(12), 104; https://doi.org/10.3390/magnetochemistry11120104 - 27 Nov 2025

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Abstract

Two diruthenium(II,II) naphthyridine complexes coordinated with 4-trifluoromethylbenzoate (O₂CPh-4-CF₃) and 3,5-bis(trifluoromethyl)benzoate (O₂CPh-3,5-diCF₃) ligands, formulated as [Ru₂(npc)₂(O₂CPh-4-CF₃)₂] (4; npc = 1,8-naphthyridine-2-carboxylate) and [Ru₂(npc) [...] Read more.

Two diruthenium(II,II) naphthyridine complexes coordinated with 4-trifluoromethylbenzoate (O₂CPh-4-CF₃) and 3,5-bis(trifluoromethyl)benzoate (O₂CPh-3,5-diCF₃) ligands, formulated as [Ru₂(npc)₂(O₂CPh-4-CF₃)₂] (4; npc = 1,8-naphthyridine-2-carboxylate) and [Ru₂(npc)₂(O₂CPh-3,5-diCF₃)₂] (5), respectively, were synthesized and structurally characterized. Single-crystal X-ray diffraction analysis revealed that both 4 and 5 form a direct metal–metal bond between the two Ru ions (2.2893(8) and 2.2896(7) Å, respectively) and adopt a paddlewheel-type structure in which two npc and two trifluoromethyl-substituted benzoate ligands are coordinated to a Ru₂⁴⁺ core with a cis-2:2 arrangement. The temperature dependence of the magnetic susceptibility measurements of 4 and 5 exhibited very large zero-field splitting (D = 242 and 246 cm⁻¹, respectively) of the triplet ground state of the Ru₂⁴⁺ core, similar to that of [Ru₂(npc)₂(O₂CPh)₂] (3; D = 238 cm⁻¹). Owing to the effects of the trifluoromethyl substituents, compared with 3, 4 and 5 showed (i) a significant blue shift of the absorption bands in the visible region and (ii) a positive shift of the redox potentials, with both shifts becoming more pronounced as the number of trifluoromethyl substituents increased. These experimental results are in good agreement with the electronic structure results obtained from density functional theory calculations. Full article

(This article belongs to the Special Issue 10th Anniversary of Magnetochemistry: Past, Present and Future)

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25 pages, 2953 KB

Open AccessArticle

Superparamagnetism of Baked Clays Containing Polymorphs of Iron Oxides: Experimental Study and Theoretical Modeling

by Petr Kharitonskii, Andrei Krasilin, Nadezhda Belskaya, Svetlana Yanson, Nikita Bobrov, Andrey Ralin, Kamil Gareev, Nikita Zolotov, Dmitry Zaytsev and Elena Sergienko

Magnetochemistry 2025, 11(12), 103; https://doi.org/10.3390/magnetochemistry11120103 - 25 Nov 2025

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Abstract

A comprehensive study of the magnetic properties of baked clays containing ferrimagnetic particles in various magnetic states, including superparamagnetic, has been carried out in this work. The phase composition of the magnetic fraction of laboratory and industrial samples made from the same clay [...] Read more.

A comprehensive study of the magnetic properties of baked clays containing ferrimagnetic particles in various magnetic states, including superparamagnetic, has been carried out in this work. The phase composition of the magnetic fraction of laboratory and industrial samples made from the same clay is mainly represented by iron (III) oxide polymorphs and possibly non-stoichiometric magnetite. Experimental methods included magnetic granulometry, Mössbauer spectroscopy, scanning electron microscopy, X-ray phase analysis, and pulsed electromagnetic measurements. A theoretical model of magnetostatically interacting particles with a lognormal volume distribution was used to interpret the experimental data, allowing the contribution of superparamagnetic grains to be taken into consideration. It is shown that the firing mode significantly affects the composition of iron oxide phases and their magnetic characteristics. Laboratory samples are characterized by approximately twice the proportion of superparamagnetic particles. At sufficiently low concentrations of ferrimagnet in samples <0.1%, the concentration of superparamagnetic particles is even two orders of magnitude lower. It is the use of pulse methods that provides a more reliable diagnosis of their presence. The complex application of experimental methods with theoretical modeling makes it possible to reveal and quantitatively describe the microheterogeneous nature of the magnetic state of baked clays, which is applicable to a wide range of magnetic materials, and to analyze more deeply the thermal and phase history of archaeological and geological objects. Full article

(This article belongs to the Section Magnetic Nanospecies)

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16 pages, 2212 KB

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Dysprosium Complexes Incorporating Halogen-Substituted Anthracene: Piezochromism and Single-Molecule Magnet Properties

by Ye-Hui Qin, Qian-Qian Su, Song-Song Bao and Li-Min Zheng

Magnetochemistry 2025, 11(12), 102; https://doi.org/10.3390/magnetochemistry11120102 - 21 Nov 2025

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Abstract

Lanthanide-based single-molecule magnets (Ln-SMMs) showing stimuli-responsive changes in photoluminescence (PL) and magnetic properties are attractive for their potential applications in information storage and molecular devices. In this work, we report two mononuclear complexes, namely, Dy(SCN)₂(NO₃)(Cl-depma)₂(4-hpy)₂ ( [...] Read more.

Lanthanide-based single-molecule magnets (Ln-SMMs) showing stimuli-responsive changes in photoluminescence (PL) and magnetic properties are attractive for their potential applications in information storage and molecular devices. In this work, we report two mononuclear complexes, namely, Dy(SCN)₂(NO₃)(Cl-depma)₂(4-hpy)₂ (Dy-Cl) and Dy(SCN)₂(NO₃)(Br-depma)₂(4-hpy)₂ (Dy-Br), where X-depma represents 10-X-9-diethylphosphinomethylanthracene (X = Cl, Br) and 4-hpy is 4-hydroxypyridine. Both contain face-to-face π-π-interacted anthracene rings and exhibit yellow-green excimer emission. Unlike the other related Dy–anthracene complexes without a halogen substituent, Dy-Cl and Dy-Br cannot undergo photocycloaddition reaction under UV-light irradiation. However, they exhibited remarkable grinding-induced changes in luminescence. Magnetic studies revealed that Dy-Cl and Dy-Br show SMM behavior under zero dc field with the effective energy barriers (U_eff/k_B) of 259 K and 264 K, respectively. We also investigated the effect of pressure on the magnetic properties of Dy-Br and observed a reduction in the magnetization value, narrowing of the butterfly-shaped hysteresis loop, and acceleration of the magnetic relaxation under 1.09 GPa. The results demonstrate that introducing a halogen substituent into an anthracene group may pose significant influences on the photophysical and photochemical properties of the complexes. In addition, pressure may be a promising external stimulus to modulate the PL and SMM behaviors of Dy–anthracene complexes. Full article

(This article belongs to the Special Issue Molecular Magnetism: A Themed Issue in Honor of Professor Dai-Zheng Liao on the Occasion of His 85th Birthday)

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Magnetochemistry, Volume 11, Issue 12 (December 2025) – 10 articles

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