Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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13 pages, 13711 KiB  
Article
High-Strength Copper/Silver Alloys Processed by Cold Spraying for DC and Pulsed High Magnetic Fields
by Simon Tardieu, Hanane Idrir, Christophe Verdy, Olivier Jay, Nelson Ferreira, François Debray, Anne Joulain, Christophe Tromas, Ludovic Thilly and Florence Lecouturier-Dupouy
Magnetochemistry 2024, 10(3), 15; https://doi.org/10.3390/magnetochemistry10030015 - 21 Feb 2024
Viewed by 928
Abstract
High-strength, high-conductivity copper/silver-alloyed materials were prepared by cold-spray (CS) manufacturing. For DC high-field application at room temperature, bulk Cu/Ag (5% vol. Ag) alloys with high mechanical properties and high electrical conductivity can be obtained by CS and post-heat treatments. For pulsed-field application at [...] Read more.
High-strength, high-conductivity copper/silver-alloyed materials were prepared by cold-spray (CS) manufacturing. For DC high-field application at room temperature, bulk Cu/Ag (5% vol. Ag) alloys with high mechanical properties and high electrical conductivity can be obtained by CS and post-heat treatments. For pulsed-field application at liquid nitrogen temperature, bulk Cu/Ag (5% vol. Ag) alloys serve as precursors for room-temperature wire drawing. The Cu/Ag-alloyed bulk CS deposit presents a high yield strength of about 510 MPa with a corresponding electrical resistivity of 1.92 µΩ·cm (at 293 K). The Cu/Ag-alloyed wires show a very high ultimate tensile strength (1660 MPa at 77 K or 1370 MPa at 293 K) and low electrical resistivity (1.05 µΩ·cm at 77 K or 2.56 µΩ·cm at 293 K). Microstructural studies via STEM allow us to understand this very high level of mechanical strength. The results evidence that materials developed by CS exhibit very high mechanical properties compared to materials prepared by other routes, due to the high velocity of the deposited particles, which leads to high initial deformation rates and specific microstructural features. Full article
(This article belongs to the Special Issue Feature Papers in Materials for High Field Resistive Magnets)
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24 pages, 16841 KiB  
Article
On the Magnetization and Entanglement Plateaus in One-Dimensional Confined Molecular Magnets
by Javier I. Norambuena Leiva, Emilio A. Cortés Estay, Eric Suarez Morell and Juan M. Florez
Magnetochemistry 2024, 10(2), 10; https://doi.org/10.3390/magnetochemistry10020010 - 01 Feb 2024
Viewed by 1169
Abstract
One-dimensional (1D) magnetic systems offer rich phenomena in the quantum limit, proving more chemically accessible than zero-dimensional or higher-dimensional frameworks. Single-walled carbon nanotubes (SWCNT) have recently been used to encapsulate trimetric nickel(II) acetylacetonate [Nanoscale, 2019, 11, 10615–10621]. Here, we investigate the magnetization on [...] Read more.
One-dimensional (1D) magnetic systems offer rich phenomena in the quantum limit, proving more chemically accessible than zero-dimensional or higher-dimensional frameworks. Single-walled carbon nanotubes (SWCNT) have recently been used to encapsulate trimetric nickel(II) acetylacetonate [Nanoscale, 2019, 11, 10615–10621]. Here, we investigate the magnetization on spin chains based on nickel trimers by Matrix Product State (MPS) simulations. Our findings reveal plateaus in the exchange/magnetic-field phase diagram for three coupling configurations, showcasing effective dimeric and trimeric spin-ordering with similar or staggered entanglement across chains. These ordered states allow the qubit-like tuning of specific local magnetic moments, exhibiting disengagement or uniform coupling in entanglement plateaus. This behavior is consistent with the experimental transition from frustrated (3D) to non-frustrated (1D) molecules, corresponding to large and smaller SWCNT diameters. Our study offers insights into the potential of 1D-confined trimers for quantum computation, extending beyond the confinement of trimetric nickel-based molecules in one dimension. Full article
(This article belongs to the Special Issue Advances in Functional Materials with Tunable Magnetic Properties)
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12 pages, 2587 KiB  
Article
The Influence of Viscosity on Heat Dissipation under Conditions of the High-Frequency Oscillating Magnetic Field
by Matus Molcan, Andrzej Skumiel, Jana Tothova, Katarina Paulovicova, Peter Kopcansky and Milan Timko
Magnetochemistry 2024, 10(1), 2; https://doi.org/10.3390/magnetochemistry10010002 - 24 Dec 2023
Viewed by 1247
Abstract
High-frequency components such as microprocessors, transistors, antennas, voltage-controlled oscillators, and many others generate a large amount of heat. In the absence of satisfactory cooling, these components may suffer damage or even destruction. Therefore, it is important to find effective ways to cool these [...] Read more.
High-frequency components such as microprocessors, transistors, antennas, voltage-controlled oscillators, and many others generate a large amount of heat. In the absence of satisfactory cooling, these components may suffer damage or even destruction. Therefore, it is important to find effective ways to cool these components. A possible solution is to use oil-based magnetic fluids. Magnetic fluids contain magnetic particles dispersed in oil, and their properties, including viscosity, affect their cooling capabilities. Viscosity can be changed by adding various additives or by adjusting the concentration of magnetic particles. The advantage of using oil-based magnetic fluids for cooling is that they allow for precise dosing and control of the amount of fluid applied to the component, reducing thermal losses and increasing cooling efficiency. In addition, oil-based magnetic fluids can also act as a dielectric, reducing electrical noise and increasing electromagnetic compatibility with the components. Analyzing the heating rate of magnetic fluids consisting of mineral oils in an alternating magnetic field with a frequency of 500 kHz, we have shown the capability of controlling thermal losses by adjusting the viscosity of the carrier liquid. Full article
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13 pages, 4474 KiB  
Article
Effect of Electrode–Normal Magnetic Field on the Motion of Hydrogen Bubbles
by Yen-Ju Chen, Yan-Hom Li and Ching-Yao Chen
Magnetochemistry 2023, 9(12), 233; https://doi.org/10.3390/magnetochemistry9120233 - 18 Dec 2023
Viewed by 1538
Abstract
In comparison to alternative methods for hydrogen production, water electrolysis stands out as the optimal means for obtaining ultra-pure hydrogen. However, its widespread adoption is significantly hampered by its low energy efficiency. It has been established that the introduction of an external magnetic [...] Read more.
In comparison to alternative methods for hydrogen production, water electrolysis stands out as the optimal means for obtaining ultra-pure hydrogen. However, its widespread adoption is significantly hampered by its low energy efficiency. It has been established that the introduction of an external magnetic field can mitigate energy consumption, consequently enhancing electrolysis efficiency. While much of the research has revealed that an electrode–parallel magnetic field plays a crucial role in enhancing the bubble detachment process, there has been limited exploration of the effect of electrode–normal magnetic fields. In this work, we compare the water electrolysis efficiency of a circular electrode subjected to electrode–normal magnetic field resulting in a magnet edge effect and electrode edge effect by varying the sizes of the magnet and electrode. The findings indicate that a rotational flow caused by the Lorentz force facilitates the detachment of the hydrogen from the electrode surface. However, the rotation direction of hydrogen gas bubbles generated by the magnet edge effect is opposite to that of electrode edge effect. Furthermore, the magnet edge effect has more significant influence on the hydrogen bubbles’ locomotion than the electrode edge effect. With an electrode gap of 30 mm, employing the magnet edge effect generated by a single magnet leads to an average of 4.9% increase in current density. On the other hand, the multiple magnet effects created by multiple small magnets under the electrode can further result in an average 6.6% increase in current density. Nevertheless, at an electrode spacing of 50 mm, neither the magnet edge effect nor the electrode edge effect demonstrates a notable enhancement in conductivity. In reality, the electrode edge effect even leads to a reduction in conductivity. Full article
(This article belongs to the Special Issue Advances in Electrochemical Properties of Magnetic Materials)
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50 pages, 40339 KiB  
Review
Spin Symmetry in Polynuclear Exchange-Coupled Clusters
by Roman Boča, Cyril Rajnák and Ján Titiš
Magnetochemistry 2023, 9(11), 226; https://doi.org/10.3390/magnetochemistry9110226 - 06 Nov 2023
Viewed by 1284
Abstract
The involvement of spin symmetry in the evaluation of zero-field energy levels in polynuclear transition metal and lanthanide complexes facilitates the division of the large-scale Hamiltonian matrix referring to isotropic exchange. This method is based on the use of an irreducible tensor approach. [...] Read more.
The involvement of spin symmetry in the evaluation of zero-field energy levels in polynuclear transition metal and lanthanide complexes facilitates the division of the large-scale Hamiltonian matrix referring to isotropic exchange. This method is based on the use of an irreducible tensor approach. This allows for the fitting of the experimental data of magnetic susceptibility and magnetization in a reasonable time for relatively large clusters for any coupling path. Several examples represented by catena-[AN} and cyclo-[AN] systems were modeled. Magnetic data for 20 actually existing endohedral clusters were analyzed and interpreted. Full article
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25 pages, 731 KiB  
Article
Jahn–Teller Magnets
by Alexander Moskvin
Magnetochemistry 2023, 9(11), 224; https://doi.org/10.3390/magnetochemistry9110224 - 02 Nov 2023
Viewed by 1423
Abstract
A wide class of materials with different crystal and electronic structures including quasi-2D unconventional superconductors, such as cuprates, nickelates, ferropnictides/chalcogenides, ruthenate Sr2RuO4, and 3D systems, such as manganites RMnO3, ferrates (CaSr)FeO3, nickelates RNiO3, [...] Read more.
A wide class of materials with different crystal and electronic structures including quasi-2D unconventional superconductors, such as cuprates, nickelates, ferropnictides/chalcogenides, ruthenate Sr2RuO4, and 3D systems, such as manganites RMnO3, ferrates (CaSr)FeO3, nickelates RNiO3, silver oxide AgO, are based on Jahn–Teller 3d and 4d ions. These unusual materials, called Jahn–Teller (JT) magnets, are characterized by an extremely rich variety of phase states, spanning from non-magnetic and magnetic insulators to unusual metallic and superconducting states. The unconventional properties of JT magnets can be attributed to the instability of their highly symmetric Jahn–Teller “progenitors” with the ground orbital E-state with repect to charge transfer, anti-Jahn–Teller d-d disproportionation, and the formation of a system of effective local composite spin–singlet or spin–triplet, electronic, or hole S-type bosons moving in a non-magnetic or magnetic lattice. We consider specific features of the anti-JT-disproportionation reaction, properties of the electron–hole dimers, possible phase states and effective Hamiltonians for single- and two-band JT magnets, concluding with a short overview of physical properties for actual JT magnets. Full article
(This article belongs to the Section Magnetic Materials)
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14 pages, 2988 KiB  
Review
Variability of the Conductance Changes Associated with the Change in the Spin State in Molecular Spin Crossover Complexes
by M. Zaid Zaz, Thilini K. Ekanayaka, Ruihua Cheng and Peter A. Dowben
Magnetochemistry 2023, 9(11), 223; https://doi.org/10.3390/magnetochemistry9110223 - 29 Oct 2023
Viewed by 1281
Abstract
Here, we examine the conductance changes associated with the change in spin state in a variety of different structures, using the example of the spin crossover complex [Fe(H2B(pz)2)2(bipy)] (pz = (pyrazol-1-yl)-borate and bipy = 2,2′-bipyridine) and [Fe(Htrz) [...] Read more.
Here, we examine the conductance changes associated with the change in spin state in a variety of different structures, using the example of the spin crossover complex [Fe(H2B(pz)2)2(bipy)] (pz = (pyrazol-1-yl)-borate and bipy = 2,2′-bipyridine) and [Fe(Htrz)2(trz)](BF4)] (Htrz = 1H-1,2,4-triazole) thin films. This conductance change is highly variable depending on the mechanism driving the change in spin state, the substrate, and the device geometry. Simply stated, the choice of spin crossover complex used to build a device is not the only factor in determining the change in conductance with the change in spin state. Full article
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17 pages, 25998 KiB  
Article
Polymer-Assisted Synthesis, Structure and Magnetic Properties of Bimetallic FeCo- and FeNi/N-Doped Carbon Nanocomposites
by Gulsara D. Kugabaeva, Kamila A. Kydralieva, Lyubov S. Bondarenko, Rose K. Baimuratova, Dmitry Yu. Karpenkov, Ekaterina A. Golovkova, Pavel N. Degtyarenko, Nina D. Golubeva, Igor E. Uflyand and Gulzhian I. Dzhardimalieva
Magnetochemistry 2023, 9(10), 213; https://doi.org/10.3390/magnetochemistry9100213 - 27 Sep 2023
Cited by 1 | Viewed by 1174
Abstract
Bimetallic FeCo and FeNi nanoparticles attract much attention due to their promising magnetic properties and a wide range of practical applications as recording and storage media, catalytic systems in fuel cells, supercapacitors, lithium batteries, etc. In this paper, we propose an original approach [...] Read more.
Bimetallic FeCo and FeNi nanoparticles attract much attention due to their promising magnetic properties and a wide range of practical applications as recording and storage media, catalytic systems in fuel cells, supercapacitors, lithium batteries, etc. In this paper, we propose an original approach to the preparation of FeCo- and FeNi/N-doped carbon nanocomposites by means of a coupled process of frontal polymerization and thermolysis of molecular co-crystallized acrylamide complexes. The phase composition, structure, and microstructure of the resulting nanocomposites are studied using XRD, IR spectroscopy, elemental and thermal analysis, and electron microscopy data. The main magnetic characteristics of the synthesized nanocomposites, including the field dependences and the ZFC-FC curves peculiarities, are studied. It is shown that the obtained FeCo/N-C nanocomposites exhibit exchange bias behavior at low temperatures. In turn, FeNi/N-C nanocomposites are ferromagnetically ordered. Full article
(This article belongs to the Section Magnetic Nanospecies)
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14 pages, 3303 KiB  
Article
Influence of the Particle Size on the Electrical, Magnetic and Biological Properties of the Bioglass® Containing Iron Oxide
by Joana Soares Regadas, Sílvia Rodrigues Gavinho, Sílvia Soreto Teixeira, Juliana Vieira de Jesus, Ana Sofia Pádua, Jorge Carvalho Silva, Susana Devesa and Manuel Pedro Fernandes Graça
Magnetochemistry 2023, 9(9), 209; https://doi.org/10.3390/magnetochemistry9090209 - 12 Sep 2023
Viewed by 1238
Abstract
Bioglasses have been used throughout the past century as a biomaterial in the bone regeneration field. However, recent studies have attempted to use them as a therapeutic material as well, mainly in the treatment of osteosarcomas. The most widely recognized bioglass is the [...] Read more.
Bioglasses have been used throughout the past century as a biomaterial in the bone regeneration field. However, recent studies have attempted to use them as a therapeutic material as well, mainly in the treatment of osteosarcomas. The most widely recognized bioglass is the 45S5 Bioglass, invented by Larry Hench et al., which presents higher bioactivity. A possible application of this bioglass in the treatment of osteosarcomas can be accomplished by adding specific ions, such as iron, that will allow the use of magnetic hyperthermia and Fenton reaction as therapeutic mechanisms. In this study, a 45S5 Bioglass containing 10%mol of Fe2O3 was produced using the melt-quenching method. A group of samples was prepared by changing the overall ball milling time, from 1 h up to 48 h, to analyze the effects of iron in the bioactive glass matrix and evaluate the influence of particle size on their physical and biological properties. The studied bioglasses showed no evidence of changes in the amorphous structural nature compared to the 45S5 Bioglass. The data of the impedance spectroscopy study revealed that the addition of Fe2O3 can increase the standard rate constant of the Electro-Fenton reaction, with the sample milled for 12 h showing the most promising results. The reduction in the particle size influenced the cytotoxicity and the bioactivity. The samples with lower particle sizes showed a higher level of cytotoxicity. Full article
(This article belongs to the Special Issue Advances in Functional Materials with Tunable Magnetic Properties)
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21 pages, 8924 KiB  
Article
The Influence of Magnetic Fields on Electrophoretic Processes in Magnetic Colloids with Different Stabilization Mechanisms
by Yurii I. Dikansky, Andrey S. Drozdov, Inna V. Eskova and Elena S. Beketova
Magnetochemistry 2023, 9(9), 207; https://doi.org/10.3390/magnetochemistry9090207 - 30 Aug 2023
Viewed by 1215
Abstract
Electrophoretic nanostructuring is a promising approach for the creation of functional surfaces and active layers. The potency of this approach may be further enhanced by additional factors of various natures, such as magnetic fields. In this work, we have studied the process of [...] Read more.
Electrophoretic nanostructuring is a promising approach for the creation of functional surfaces and active layers. The potency of this approach may be further enhanced by additional factors of various natures, such as magnetic fields. In this work, we have studied the process of electrophoresis in thin layers of water- and kerosene-based magnetic liquids and the effect of additional magnetic fields on the occurring processes. It was found that the electrophoresis process can be significantly affected by inhomogeneous magnetic fields. The possibility of compensating electrophoresis processes in such systems by means of inhomogeneous magnetic field influence was shown. Structural changes in magnetic colloids on hydrocarbon bases under the influence of an electric field have been studied. The role of electrohydrodynamic flows arising in this process is considered, and the influence of the magnetic field on the configuration of the formed labyrinth structure is studied. The dependence of the threshold value of the electric field strength corresponding to the emergence of the structure on the temperature and additionally applied magnetic field has been established. The obtained results could contribute to the development of an original method for determining the charge and magnetic moment of a single nanoparticle. Full article
(This article belongs to the Section Magnetic Materials)
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27 pages, 6092 KiB  
Review
Recent Research Developments of 4D Printing Technology for Magnetically Controlled Smart Materials: A Review
by Hujun Wang, Jinqiu Zhao, Zhuo Luo and Zhenkun Li
Magnetochemistry 2023, 9(8), 204; https://doi.org/10.3390/magnetochemistry9080204 - 14 Aug 2023
Cited by 2 | Viewed by 2360
Abstract
Traditional printed products have to some extent affected the development of smart structures and their application in multiple fields, especially in harsh environments, due to their complex mechanisms and control principles. The 4D printing technology based on magnetically controlled smart materials exploits the [...] Read more.
Traditional printed products have to some extent affected the development of smart structures and their application in multiple fields, especially in harsh environments, due to their complex mechanisms and control principles. The 4D printing technology based on magnetically controlled smart materials exploits the advantages of magnetically controlled smart materials with good operability and security, and its printed smart structures can be obtained under magnetic field drive for unfettered remote manipulation and wireless motion control, which expands the application of printed products in complex environments, such as sealed and narrow, and has broad development prospects. At present, magnetically controlled smart material 4D printing technology is still in its infancy, and its theory and application need further in–depth study. To this end, this paper introduces the current status of research on magnetically controlled smart material 4D printing, discusses the printing process, and provides an outlook on its application prospects. Full article
(This article belongs to the Special Issue Sustainable Development Based on Magnetochemistry)
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22 pages, 12620 KiB  
Article
Green Magnetic Nanoparticles CoFe2O4@Nb5O2 Applied in Paracetamol Removal
by Jessica R. P. Oliveira, Laura S. Ribas, Jose S. Napoli, Eduardo Abreu, Jose L. Diaz de Tuesta, Helder T. Gomes, Angelo M. Tusset and Giane G. Lenzi
Magnetochemistry 2023, 9(8), 200; https://doi.org/10.3390/magnetochemistry9080200 - 05 Aug 2023
Cited by 5 | Viewed by 1933
Abstract
This study describes the synthesis of an innovative nanomaterial (patent application number BR 1020210000317) composed of cobalt ferrite functionalized in niobium pentoxide CoFe2O4@Nb5O2 (CFNb), synthesized via green synthesis using tangerine peel extract. The material emphasizes the [...] Read more.
This study describes the synthesis of an innovative nanomaterial (patent application number BR 1020210000317) composed of cobalt ferrite functionalized in niobium pentoxide CoFe2O4@Nb5O2 (CFNb), synthesized via green synthesis using tangerine peel extract. The material emphasizes the combination of a magnetic material (which allows for easy recovery after application) with niobium pentoxide (a metal which is abundant in Brazil). CFNb was applied as a catalyst for the paracetamol (PCT) degradation by photocatalysis. The new materials were characterized through surface and pore analysis (SBET, SEXT, Smic, Vmic, and VTOTAL), photoacoustic spectroscopy (PAS), zero charge point (pHPZC, scanning electron microscopy (SEM/EDS), and X-ray diffraction (XRD). The reaction parameters studied included pH and catalyst concentration. The results indicated that the CFNb nanocatalysts were efficient in the paracetamol degradation, presenting better results in conditions of low pH (close to 2) and low catalyst concentration under irradiation of the 250 W mercury vapor lamp (greater than 28 mW·cm−2) at 60 min of reaction. Full article
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16 pages, 5854 KiB  
Article
Preparation of Magnetic Molecularly Imprinted Polymer for Methylene Blue Capture
by Anastasia Sedelnikova, Yuliya Poletaeva, Victor Golyshev, Alexey Chubarov and Elena Dmitrienko
Magnetochemistry 2023, 9(8), 196; https://doi.org/10.3390/magnetochemistry9080196 - 31 Jul 2023
Cited by 1 | Viewed by 1549
Abstract
Hybrid magnetic molecularly imprinted polymers (MMIPs) have the advantages of the technology of molecularly imprinted material and magnetic nanoparticles. The magnetic properties of MMIPs allow easy magnetic separation of various pollutants and analytes. A convenient and simple approach has been developed for the [...] Read more.
Hybrid magnetic molecularly imprinted polymers (MMIPs) have the advantages of the technology of molecularly imprinted material and magnetic nanoparticles. The magnetic properties of MMIPs allow easy magnetic separation of various pollutants and analytes. A convenient and simple approach has been developed for the preparation of MMIPs based on polyamide (nylon-6) and magnetic nanoparticles. The polymer matrix was formed during the transition of nylon-6 from a dissolved state to a solid state in the presence of template molecules and Fe3O4 nanoparticles in the initial solution. Methylene blue (MB) was used as a model imprinted template molecule. The MMIPs exhibited a maximum adsorption amount of MB reached 110 µmol/g. The selectivity coefficients toward MB structural analogs were estimated to be 6.1 ± 0.6 and 2.1 ± 0.3 for 15 μM hydroxyethylphenazine and toluidine blue, which shows high MMIP selectivity. To prove the MMIPs’ specificity in MB recognition, magnetic nonimprinted polymers (MNIPs) were synthesized without the presence of a template molecule. MMIPs exhibited much higher specificity in comparison to MNIPs. To show the remarkable reusability of the MMIP sorbent, more than four MB absorption and release cycles were carried out, demonstrating almost the same extraction capacity step by step. We believe that the proposed molecular imprinting technology, shown in the MB magnetic separation example, will bring new advances in the area of MMIPs for various applications. Full article
(This article belongs to the Section Magnetic Nanospecies)
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39 pages, 4449 KiB  
Review
Ferromagnetic Resonance in Magnetic Oxide Nanoparticules: A Short Review of Theory and Experiment
by Ibtissem Benguettat-El Mokhtari and David S. Schmool
Magnetochemistry 2023, 9(8), 191; https://doi.org/10.3390/magnetochemistry9080191 - 25 Jul 2023
Cited by 2 | Viewed by 1621
Abstract
This review article aims to provide a comprehensive overview of recent FMR studies on magnetic oxide nanoparticles and their potential applications. The use of the FMR technique is a powerful tool to study the magnetic properties of magnetic nanoparticles and can provide valuable [...] Read more.
This review article aims to provide a comprehensive overview of recent FMR studies on magnetic oxide nanoparticles and their potential applications. The use of the FMR technique is a powerful tool to study the magnetic properties of magnetic nanoparticles and can provide valuable information on their behavior. For this, we will start by discussing the purpose of these magnetic nanoparticles and their application in various fields, including biomedical applications, energy storage, and environmental remediation. We will then discuss the methods used to prepare magnetic nanoparticles and the theory behind FMR including the superparamagnetic effect. Additionally, we will present the most recent studies on FMR for magnetic oxide nanoparticles by highlighting the effect of temperature and doping on the magnetic properties of these nanoparticles. Full article
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17 pages, 6147 KiB  
Perspective
Lanthanide-Based Metal–Organic Frameworks with Single-Molecule Magnet Properties
by Fabio Manna, Mariangela Oggianu, Narcis Avarvari and Maria Laura Mercuri
Magnetochemistry 2023, 9(7), 190; https://doi.org/10.3390/magnetochemistry9070190 - 22 Jul 2023
Cited by 2 | Viewed by 1560
Abstract
Lanthanide metal–organic frameworks (Ln-MOFs) showing single-molecule magnet (SMM) properties are an ever-growing family of materials where the magnetic properties can be tuned by various interrelated parameters, such as the coordinated solvent, temperature, organic linkers, lanthanide ions and their coordination environment. An overview of [...] Read more.
Lanthanide metal–organic frameworks (Ln-MOFs) showing single-molecule magnet (SMM) properties are an ever-growing family of materials where the magnetic properties can be tuned by various interrelated parameters, such as the coordinated solvent, temperature, organic linkers, lanthanide ions and their coordination environment. An overview of the general synthetic methodologies to access MOFs/Ln-MOFs and the peculiarities and parameters to control and/or fine-tune their SMM behavior is herein presented. Additionally, diverse challenging strategies for inducing SMM/SIM behavior in an Ln-MOF are discussed, involving redox activity and chirality. Furthermore, intriguing physical phenomena such as the CISS effect and CPL are also highlighted. Full article
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13 pages, 2569 KiB  
Article
Towards Resonantly Enhanced Acoustic Phonon-Exchange Magnon Interactions at THz Frequencies
by Tudor-Gabriel Mocioi, Antonia Ghita and Vasily V. Temnov
Magnetochemistry 2023, 9(7), 184; https://doi.org/10.3390/magnetochemistry9070184 - 17 Jul 2023
Cited by 3 | Viewed by 1161
Abstract
Using valid experimental parameters, we quantify the magnitude of resonantly phonon-driven precession of exchange magnons in freestanding ferromagnetic nickel thin films on their thickness L. Analytical solutions of acoustically driven equations for magnon oscillators display a nonmonotonous dependence of the peak magnetization [...] Read more.
Using valid experimental parameters, we quantify the magnitude of resonantly phonon-driven precession of exchange magnons in freestanding ferromagnetic nickel thin films on their thickness L. Analytical solutions of acoustically driven equations for magnon oscillators display a nonmonotonous dependence of the peak magnetization precession on the film thickness. It is explained by different L-dependence of multiple prefactors entering in the expression for the total magnetization dynamics. Depending on the ratio of acoustic and magnetic (Gilbert) damping constants, the magnetization precession is shown to be amplified by a Q-factor of either the phonon or the magnon resonance. The increase in the phonon mode amplitude for thinner membranes is also found to be significant. Focusing on the magnetization dynamics excited by the two first acoustic eigenmodes with p=1 and p=2, we predict the optimum thicknesses of nickel membranes to achieve large amplitude magnetization precession at multi 100 GHz frequencies at reasonably low values of an external magnetic field. By extending the study to the case of Ni-Si bilayers, we show that these resonances are achievable at even higher frequencies, approaching the THz range. Full article
(This article belongs to the Special Issue State-of-the-Art Research in Magnetism in France)
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16 pages, 1086 KiB  
Article
On the Size of Superconducting Islands on the Density-Wave Background in Organic Metals
by Vladislav D. Kochev, Seidali S. Seidov and Pavel D. Grigoriev
Magnetochemistry 2023, 9(7), 173; https://doi.org/10.3390/magnetochemistry9070173 - 04 Jul 2023
Cited by 2 | Viewed by 911
Abstract
Most high-Tc superconductors are spatially inhomogeneous. Usually, this heterogeneity originates from the interplay of various types of electronic ordering. It affects various superconducting properties, such as the transition temperature, the magnetic upper critical field, the critical current, etc. In this paper, [...] Read more.
Most high-Tc superconductors are spatially inhomogeneous. Usually, this heterogeneity originates from the interplay of various types of electronic ordering. It affects various superconducting properties, such as the transition temperature, the magnetic upper critical field, the critical current, etc. In this paper, we analyze the parameters of spatial phase segregation during the first-order transition between superconductivity (SC) and a charge- or spin-density wave state in quasi-one-dimensional metals with imperfect nesting, typical of organic superconductors. An external pressure or another driving parameter increases the transfer integrals in electron dispersion, which only slightly affects SC but violates the Fermi surface nesting and suppresses the density wave (DW). At a critical pressure Pc, the transition from a DW to SC occurs. We estimate the characteristic size of superconducting islands during this phase transition in organic metals in two ways. Using the Ginzburg–Landau expansion, we analytically obtain a lower bound for the size of SC domains. To estimate a more specific interval of the possible size of the superconducting islands in (TMTSF)2PF6 samples, we perform numerical calculations of the percolation probability via SC domains and compare the results with experimental resistivity data. This helps to develop a consistent microscopic description of SC spatial heterogeneity in various organic superconductors. Full article
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24 pages, 11538 KiB  
Article
Interplay of Magnetic Interaction and Electronic Structure in New Structure RE-12442 Type Hybrid Fe-Based Superconductors
by Amit Pokhriyal, Abyay Ghosh, Smritijit Sen and Haranath Ghosh
Magnetochemistry 2023, 9(7), 164; https://doi.org/10.3390/magnetochemistry9070164 - 26 Jun 2023
Cited by 1 | Viewed by 1068
Abstract
We present detailed first-principles density functional theory-based studies on RbRE2Fe4As4O2 (RE = Sm, Tb, Dy, Ho) hybrid 12442-type iron-based superconducting compounds with particular emphasis on competing magnetic interactions and their effect on possible magneto-structural coupling and [...] Read more.
We present detailed first-principles density functional theory-based studies on RbRE2Fe4As4O2 (RE = Sm, Tb, Dy, Ho) hybrid 12442-type iron-based superconducting compounds with particular emphasis on competing magnetic interactions and their effect on possible magneto-structural coupling and electronic structure. The stripe antiferromagnetic (sAFM) pattern across the xy plane emerges as the most favorable spin configuration for all the four compounds, with close competition among the different magnetic orders along the z-axis. The structural parameters, including arsenic heights, Fe-As-Fe angle, and other relevant factors that influence superconducting Tc and properties, closely match the experimental values in stripe antiferromagnetic arrangement of Fe spins. Geometry optimization with inclusion of explicit magnetic ordering predicts a spin–lattice coupling for all the four compounds, where a weak magneto–structural transition, a tetragonal-to-orthorhombic structural transition, takes place in the relaxed stripe antiferromagnetic spin configuration. Absence of any experimental evidence of such structural transition is possibly an indication of nematic transition in RE-12442 compounds. As a result of structural distortion, the lattice contracts (expands) along the direction with parallel (anti-parallel) alignment of Fe spins. Introduction of stripe antiferromagnetic order in Fe sub-lattice reconstructs the low-energy band structure, which results in significantly reduced number of bands crossing the Fermi level. Moreover, the dispersion of bands and their orbital characteristics also are severely modified in the stripe antiferromagnetic phase similar to BaFe2As2. Calculations of exchange parameters were performed for all the four compounds. Exchange coupling along the anti-parallel alignment of Fe spins J1a is larger than that for the parallel aligned spins J1b. A crossover between the super-exchange-driven in-plane next-nearest-neighbor exchange coupling J2 and in-plane exchange coupling J1a due to lanthanide substitution was found. A large super-exchange-driven next-nearest-neighbor exchange interaction is justified using the construction of 32 maximally localized Wannier functions, where the nearest-neighbor Fe-As hopping amplitudes were found to be larger than the nearest- and the next-nearest-neighbor Fe-Fe hopping amplitudes. We compare the hopping parameters in the stripe antiferromagnetic pattern with non-magnetic configuration, and increased hopping amplitude was found along the anti-parallel spin alignment with more majority-spin electrons in Fe dxz and dxy but not in Fe dyz. On the other hand, the hopping amplitudes are increased in stripe antiferromagnetic phase along the parallel spin alignment with more majority-spin electrons in only Fe dyz. This difference in hopping amplitudes in the stripe antiferromagnetic order enables more isotropic hopping. Full article
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14 pages, 3008 KiB  
Article
Reduction of Oxidizable Pollutants in Waste Water from the Wadi El Bey River Basin Using Magnetic Nanoparticles as Removal Agents
by Hajer Tlili, Anis Elaoud, Nedra Asses, Karima Horchani-Naifer, Mounir Ferhi, Gerardo F. Goya and Jesús Antonio Fuentes-García
Magnetochemistry 2023, 9(6), 157; https://doi.org/10.3390/magnetochemistry9060157 - 14 Jun 2023
Cited by 3 | Viewed by 1763
Abstract
Many of the current strategies for removing pollutants from water are based on nanomaterials and nanotechnology. Lower values of Biological Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD) in water results in reduction in the amount of oxidizable pollutants. We present [...] Read more.
Many of the current strategies for removing pollutants from water are based on nanomaterials and nanotechnology. Lower values of Biological Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD) in water results in reduction in the amount of oxidizable pollutants. We present a study on the reduction of COD and BOD5 in water from Wadi El Bey River (Tunisia), using magnetite nanoparticles (MNPs) and magnetic fields. The COD and BOD5 removal reached values higher than 50% after 60 min, with optimum efficiency at pH values of ≈8 and for MNPs concentrations of 1 g/L. The use of a permanent magnetic field (0.33 T) showed an increase of COD and BOD5 removal from 61% to 76% and from 63% to 78%, respectively. This enhancement is discussed in terms of the MNPs coagulation induced by the magnetic field and the adsorption of ionic species onto the MNPs surface due to Fe3O4 affinity. Full article
(This article belongs to the Section Magnetic Nanospecies)
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16 pages, 2583 KiB  
Article
Spin Frustrated Pyrazolato Triangular CuII Complex: Structure and Magnetic Properties, an Overview
by Walter Cañón-Mancisidor, Patricio Hermosilla-Ibáñez, Evgenia Spodine, Verónica Paredes-García, Carlos J. Gómez-García and Diego Venegas-Yazigi
Magnetochemistry 2023, 9(6), 155; https://doi.org/10.3390/magnetochemistry9060155 - 11 Jun 2023
Viewed by 1369
Abstract
The synthesis and structural characterization of a new triangular Cu3–μ3OH pyrazolato complex of formula, [Cu33−OH)(pz)3(Hpz)3][BF4]2 (1−Cu3), Hpz = pyrazole, is presented. The triangular unit forms [...] Read more.
The synthesis and structural characterization of a new triangular Cu3–μ3OH pyrazolato complex of formula, [Cu33−OH)(pz)3(Hpz)3][BF4]2 (1−Cu3), Hpz = pyrazole, is presented. The triangular unit forms a quasi-isosceles triangle with Cu–Cu distances of 3.3739(9), 3.3571(9), and 3.370(1) Å. This complex is isostructural to the hexanuclear complex [Cu33−OH)(pz)3(Hpz)3](ClO4)2]2 (QOPJIP). A comparative structural analysis with other reported triangular Cu3–μ3OH pyrazolato complexes has been carried out, showing that, depending on the pyrazolato derivative, an auxiliary ligand or counter-anion can affect the nuclearity and/or the dimensionality of the system. The magnetic properties of 1−Cu3 are analyzed using experimental data and DFT calculation. A detailed analysis was performed on the magnetic properties, comparing experimental and theoretical data of other molecular triangular Cu3–μ3OH complexes, showing that the displacement of the μ3−OH from the Cu3 plane, together with the type of organic ligands, influences the nature of the magnetic exchange interaction between the spin-carrier centers, since it affects the overlap of the magnetic orbitals involved in the exchange pathways. Finally, a detailed comparison of the magnetic properties of 1−Cu3 and QOPJIP was carried out, which allowed us to understand the differences in their magnetic properties. Full article
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18 pages, 3251 KiB  
Article
Band Structure Evolution during Reversible Interconversion between Dirac and Standard Fermions in Organic Charge-Transfer Salts
by Ryuhei Oka, Keishi Ohara, Kensuke Konishi, Ichiro Yamane, Toshihiro Shimada and Toshio Naito
Magnetochemistry 2023, 9(6), 153; https://doi.org/10.3390/magnetochemistry9060153 - 09 Jun 2023
Cited by 3 | Viewed by 1807
Abstract
Materials containing Dirac fermions (DFs) have been actively researched because they often alter electrical and magnetic properties in an unprecedented manner. Although many studies have suggested the transformation between standard fermions (SFs) and DFs, the non-availability of appropriate samples has prevented the observation [...] Read more.
Materials containing Dirac fermions (DFs) have been actively researched because they often alter electrical and magnetic properties in an unprecedented manner. Although many studies have suggested the transformation between standard fermions (SFs) and DFs, the non-availability of appropriate samples has prevented the observation of the transformation process. We observed the interconversion process of DFs and SFs using organic charge-transfer (CT) salts. The samples are unique in that the constituents (the donor D and acceptor A species) are particularly close to each other in energy, leading to the temperature- and D-A-combination-sensitive CT interactions in the solid states. The three-dimensional weak D–A CT interactions in low-symmetry crystals induced the continuous reshaping of flat-bottomed bands into Dirac cones with decreasing temperature; this is a characteristic shape of bands that converts the behavior of SFs into that of DFs. Based on the first-principles band structures supported by the observed electronic properties, round-apex-Dirac-cone-like features appear and disappear with temperature variation. These band-structure snapshots are expected to add further detailed understanding to the related research fields. Full article
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16 pages, 715 KiB  
Review
Nuclear Dipole Moments and Shielding Constants of Light Nuclei Measured in Magnetic Fields
by Włodzimierz Makulski, Mateusz A. Słowiński and Piotr Garbacz
Magnetochemistry 2023, 9(6), 148; https://doi.org/10.3390/magnetochemistry9060148 - 02 Jun 2023
Cited by 1 | Viewed by 1290
Abstract
Nuclear magnetic resonance (NMR) is a branch of spectroscopy commonly used for identifying the chemical structure of various materials. One of the areas in which NMR provides accurate data is the determination of nuclear magnetic moments. This work reviews NMR experiments with the [...] Read more.
Nuclear magnetic resonance (NMR) is a branch of spectroscopy commonly used for identifying the chemical structure of various materials. One of the areas in which NMR provides accurate data is the determination of nuclear magnetic moments. This work reviews NMR experiments with the nuclei of light elements in simple molecules. Since nuclear shielding constants from up-to-date quantum calculations are now available, very accurate dipole moments of many nuclei can be determined. Recent experimental measurements of 1H, 2H, 3H, 3He, 6Li, 7Li, 9Be, 10B, and 11B nuclear magnetic moments and the appropriate theoretical predictions are presented and commented upon. Several achievements in this field using different methodologies, such as NMR spectroscopy, molecular beam experiments, and the Penning trap method are reported. Full article
(This article belongs to the Section Magnetic Resonances)
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12 pages, 7794 KiB  
Article
Research on the Surfactant-Assisted Synthesis of MnZn Ferrite Precursor Powders
by Zhanyuan Xu, Wei Zhao, Jiefu Liu and Jinglian Fan
Magnetochemistry 2023, 9(6), 146; https://doi.org/10.3390/magnetochemistry9060146 - 30 May 2023
Viewed by 1125
Abstract
MnZn ferrite precursor powders were prepared by the nano in situ composite method. Three surfactants, which include polyethylene glycol 400 (PEG-400), cetyltrimethyl ammonium bromide (CTAB), and sodium dodecyl sulfate (SDS), were usedM and the impact of the surfactants on the precursor sol solutions [...] Read more.
MnZn ferrite precursor powders were prepared by the nano in situ composite method. Three surfactants, which include polyethylene glycol 400 (PEG-400), cetyltrimethyl ammonium bromide (CTAB), and sodium dodecyl sulfate (SDS), were usedM and the impact of the surfactants on the precursor sol solutions and precursor powders was studied. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, a field emission scanning electron microscope (FE-SEM), a transmission electron microscope (TEM), a Zeta potential meter, a BET surface analyzer, and a vibrational sample magnetometer (VSM) were used to characterize the precursor sol solutions and the precursor powders. The results showed that these surfactants can improve the dispersion state and Zeta potentials of sol particles and increase the specific surface areas of the precursor powders. Moreover, the precursor powders were composed of MnZn ferrite, and some were amorphous. CTAB was the optimum surfactant and the zeta potential of the sol particles and the specific surface area of the precursor powders named P-0.1CTAB are 10.7 mV and 129.07 m2/g, respectively. In addition, the nano-particles that were made up of the P-0.1CTAB precursor powders had smaller sizes and more uniform particle distributions than the others. The magnetic properties’ improvement was attributed to the addition of surfactants, and CTAB is the optimal type. In addition, the novel nano in situ composite method will inspire fresh thinking and investigation into the research of ferrite. Full article
(This article belongs to the Special Issue Advances in Soft Magnetic Materials)
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6 pages, 226 KiB  
Editorial
Magnetic Materials, Thin Films and Nanostructures
by Catalin-Daniel Constantinescu and Lucian-Gabriel Petrescu
Magnetochemistry 2023, 9(5), 133; https://doi.org/10.3390/magnetochemistry9050133 - 19 May 2023
Viewed by 2024
Abstract
In this first volume, we cover relevant aspects of chemical and physical processes of the production and characterization of magnetic materials in bulk, thin films, nanostructures, and/or nanocomposites, as well as modeling aspects involving such structures. Accordingly, this volume presents eleven original research [...] Read more.
In this first volume, we cover relevant aspects of chemical and physical processes of the production and characterization of magnetic materials in bulk, thin films, nanostructures, and/or nanocomposites, as well as modeling aspects involving such structures. Accordingly, this volume presents eleven original research and review works on the challenges and trends covering fundamental and experimental work, with a special focus on the design, synthesis, and characterization of various types of magnetic materials, and the study of their structure–property relationships. State-of-the-art results on the development of new experimental concepts, leading to the transfer, chemical transformation, and high-resolution patterning of advanced thin films and nanomaterials, and to the design and fabrication of devices, are also presented and discussed. Full article
(This article belongs to the Special Issue Magnetic Materials, Thin Films and Nanostructures)
14 pages, 6095 KiB  
Article
Influence of High Viscosity and Magnetoviscous Effect on the Washout Resistance of Magnetic Fluid
by Zixian Li, Decai Li, Yanwen Li and Shuntao Han
Magnetochemistry 2023, 9(5), 134; https://doi.org/10.3390/magnetochemistry9050134 - 19 May 2023
Viewed by 1177
Abstract
Magnetic fluid seals have long been thought to be a successful sealing form while sealing liquids are always a challenge. The instability of the liquid–liquid interface under the washout has become the key technical problem that hinders the realization of sealing liquid. This [...] Read more.
Magnetic fluid seals have long been thought to be a successful sealing form while sealing liquids are always a challenge. The instability of the liquid–liquid interface under the washout has become the key technical problem that hinders the realization of sealing liquid. This work mainly presents an experimental study about the influence of high viscosity and magnetoviscous effects on washout resistance. Three engine oil-based magnetic fluids of different viscosities were prepared with two kinds of surfactants. The magnetoviscous effects of the prepared magnetic fluids under different working conditions were found through rheological experiments. The viscosity of the three samples decreased at most by about 100 times with the shear rate increasing. An experimental platform was designed and built for the washout tests. The entire process of magnetic fluids being washed away was obtained experimentally. The magnetic fluid of higher viscosity can remain stationary with lower magnetic force. The quantitative results show that the viscosity of the magnetic fluid has a significant influence on washout resistance under a magnetic field. Full article
(This article belongs to the Special Issue Advanced Applications of Magnetic Field-Responsive Fluid)
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13 pages, 3732 KiB  
Article
Novel Concentric Magnetic Continuum Robot with Multiple Stiffness Modes for Potential Delivery of Nanomedicine
by Na Li, Daojing Lin, Junfeng Wu, Quan Gan, Xingyue Hu and Niandong Jiao
Magnetochemistry 2023, 9(5), 129; https://doi.org/10.3390/magnetochemistry9050129 - 12 May 2023
Cited by 1 | Viewed by 1726
Abstract
The utilisation of miniature robots has become essential in the domain of minimally invasive surgery and long-distance delivery of nanomedicine. Among these, the miniature magnetic continuum robot (MCR) stands out because of its simple structure and dexterity, which allow it to penetrate small [...] Read more.
The utilisation of miniature robots has become essential in the domain of minimally invasive surgery and long-distance delivery of nanomedicine. Among these, the miniature magnetic continuum robot (MCR) stands out because of its simple structure and dexterity, which allow it to penetrate small cavities, transport specialised tools such as a laser, and deliver medications to support surgical treatment. Nevertheless, because of their soft bodies with a single stiffness, conventional MCRs have limited controllability when navigating through intricate cavities. To address this limitation, we propose a novel concentric magnetic continuum robot (C-MCR) comprising a concentric magnetic catheter with a guidewire having varying stiffness. The C-MCR allows substantial curvature bending owing to its difference in stiffness, and its detachable nature allows it to have four working modes to adapt to specific application requirements with improved stiffness controllability. Experiments demonstrate the ability of the C-MCR to navigate complex pathways and deliver nanomedicines over long distances to specific areas via its internal channels using a large homemade eight-coil electromagnetic system. The C-MCR offers promising application prospects for the long-distance delivery of tailored nanomedicines because of its simple operation, reduced risks, and larger attainable workspace. Full article
(This article belongs to the Section Magnetic Materials)
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36 pages, 6819 KiB  
Review
Nanocomposites of Ferrites with TiO2, SiO2 and Carbon Quantum Dots as Photocatalysts for Degradation of Organic Pollutants and Microbes
by Ajaypal Kaur, Manpreet Kaur, Vasundhara Singh and Pratibha Vyas
Magnetochemistry 2023, 9(5), 127; https://doi.org/10.3390/magnetochemistry9050127 - 09 May 2023
Cited by 5 | Viewed by 2701
Abstract
Ferrites are important magnetic materials used in electronic devices. Nanocomposites of ferrites with TiO2, SiO2 and carbon quantum dots have gained recent interest due to their unique advantages, such as high chemical stability, surface-active sites, high specific surface area, non-toxicity, [...] Read more.
Ferrites are important magnetic materials used in electronic devices. Nanocomposites of ferrites with TiO2, SiO2 and carbon quantum dots have gained recent interest due to their unique advantages, such as high chemical stability, surface-active sites, high specific surface area, non-toxicity, excellent optical properties, and tunable porosity. In the present review, general and adaptable coprecipitation, sol–gel, hydrothermal, solvothermal, and Stöber methods for the fabrication of nanocomposites are discussed. These materials offer the advantage of magnetic recovery and superior photocatalytic performance. The potential of nanocomposites to act as photocatalysts to eliminate organic pollutants and microbes from water is discussed. Mechanisms involved in these applications are also elaborated upon. The review provides a detailed study of recent applications and future perspectives of nanocomposites in sustainable water treatment. Full article
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10 pages, 2081 KiB  
Article
A Cu12 Metallacycle Assembled from Four C3-Symmetric Spin Frustrated Triangular Units
by Basharat Ali, Grégoire David, Frédéric Gendron, Xiao-Lei Li, Olivier Cador, Winfried Plass, Boris Le Guennic and Jinkui Tang
Magnetochemistry 2023, 9(5), 122; https://doi.org/10.3390/magnetochemistry9050122 - 06 May 2023
Viewed by 1350
Abstract
Assembling metallacycles with interesting topological arrangements is a critical task for chemists. We report here a novel dodecanuclear CuII compound, [{Cu3L(µ-N3)}4(Py)14]·2Py (Cu12) (where Py = pyridine and [H6L]Cl = [...] Read more.
Assembling metallacycles with interesting topological arrangements is a critical task for chemists. We report here a novel dodecanuclear CuII compound, [{Cu3L(µ-N3)}4(Py)14]·2Py (Cu12) (where Py = pyridine and [H6L]Cl = tris(2-hydroxybenzylidine)triaminoguanidinium chloride, respectively), with the topology of a cycle accomplished by four two-connecting approximately flat C3-symmetric guanidine-based ligands. Each ligand affords three tridentate metal-binding cavities and the four node-to-node connections through single azido bridges are provided by pairs of metal centers. A theoretical investigation using CASSCF in addition to DFT calculations showed strong antiferromagnetic coupling within the Cu3-triangles, resulting in spin-frustrated systems. However, these calculations were not able to properly reproduce the very weak antiferromagnetic couplings between the triangle units, highlighting the challenge of describing the magnetic behavior of this compound. Full article
(This article belongs to the Special Issue Advances in Molecular Magnetism)
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16 pages, 12177 KiB  
Article
Nylon-6-Coated Doxorubicin-Loaded Magnetic Nanoparticles and Nanocapsules for Cancer Treatment
by Ekaterina Kovrigina, Yuliya Poletaeva, Yanfang Zheng, Alexey Chubarov and Elena Dmitrienko
Magnetochemistry 2023, 9(4), 106; https://doi.org/10.3390/magnetochemistry9040106 - 12 Apr 2023
Cited by 8 | Viewed by 2120
Abstract
Nanoplatforms used for the loading of anticancer drugs constitute a promising approach to cancer treatment and reducing the side effects of these drugs. Among the cutting-edge systems used in this area are magnetic nanocomposites (MNCs) and nanocapsules (NCs). MNCs are considered to constitute [...] Read more.
Nanoplatforms used for the loading of anticancer drugs constitute a promising approach to cancer treatment and reducing the side effects of these drugs. Among the cutting-edge systems used in this area are magnetic nanocomposites (MNCs) and nanocapsules (NCs). MNCs are considered to constitute a smart tool for magnetic-field-guided targeted drug delivery, magnetic resonance imaging, and hyperthermia therapy. Nanocapsules offer great potential due to their ability to control drug-loading capacity, their release efficiency, their stability, and the ease with which their surfaces can be modified. This study proposes a method for the development of nylon-6-coated MNCs and nylon-6 polymeric membrane NCs. A biocompatible nylon-6 polymer was first used for NC synthesis. Oleic-acid-modified and non-modified Fe3O4 nanoparticles were synthesized for the production of nylon-coated MNCs. Dynamic light scattering (DLS), transmission electron microscopy (TEM), and ζ-potential measurements were used to perform size, morphology, and charge analyses. The above-mentioned two types of MNCs were considered templates for the manufacture of nylon nanocapsules, leading to NCs with different charges and structures. The developed oleic-acid-coated nylon-6 MNCs and NCs showed excellent loading values of the chemotherapy drug doxorubicin (DOX) of up to 732 and 943 µg/mg (DOX/MNC or NC), respectively. On the contrary, the capacity of the nano-construction that was not modified with oleic acid did not exceed 140 µg/mg. The DOX-loaded nanosystems displayed pH-sensitive drug release properties, for which the highest efficiency was observed at an acidic pH. The series of DOX-loaded MNCs and NCs inhibited A549 and HEK 293FT cell lines, with the lowest IC50 value of 0.31 µM observed for the nanocapsules, which is a 1.5-fold lower concentration than the free DOX. Therefore, the presented nanoscale systems offer great potential for cancer treatment. Full article
(This article belongs to the Section Magnetic Nanospecies)
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13 pages, 6238 KiB  
Article
Fine-Grained Tb3Al5O12 Transparent Ceramics Prepared by Co-Precipitation Synthesis and Two-Step Sintering
by Lixuan Zhang, Xiaoying Li, Dianjun Hu, Mariya Dobrotvorska, Roman Yavetskiy, Zhengfa Dai, Tengfei Xie, Qiang Yuan, Haohong Chen, Qiang Liu and Jiang Li
Magnetochemistry 2023, 9(2), 47; https://doi.org/10.3390/magnetochemistry9020047 - 01 Feb 2023
Cited by 4 | Viewed by 1539
Abstract
In recent years, transparent terbium aluminum garnet (TAG) ceramics have attracted much attention for use in high-power Faraday isolators. Fine-grained ceramics usually possess better mechanical properties and accordingly better service performance. In this work, transparent TAG ceramics with fine grains were prepared using [...] Read more.
In recent years, transparent terbium aluminum garnet (TAG) ceramics have attracted much attention for use in high-power Faraday isolators. Fine-grained ceramics usually possess better mechanical properties and accordingly better service performance. In this work, transparent TAG ceramics with fine grains were prepared using a two-step sintering procedure based on the low-temperature sintering process to suppress grain growth. The composition of TAG precursor and powders calcined at different temperatures was studied in detail. The microstructure and relative density of air pre-sintered TAG ceramics were studied to meet the requirements of hot isostatic pressing (HIP) post-treatment. Driven by the low pre-sintering temperature in air, the average grain sizes of the obtained TAG ceramics after HIP treatment are about 2.9–5.3 μm. The TAG ceramics (1.2 mm thick) pre-sintered at 1450 °C with HIP post-treatment at 1550 °C for 3 h under a 176 MPa Ar atmosphere possess the highest in-line transmittance of 80.3% at 1064 nm. The Verdet constant of the TAG ceramics at 632.8 nm is −180.5 rad·T−1·m−1 at room temperature, which is about 1.3 times larger than that of the commercial Tb3Ga5O12 single crystals. Full article
(This article belongs to the Special Issue New Trends in Magneto-Optical Ceramics)
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12 pages, 1767 KiB  
Review
Characteristics and Recent Development of Fluoride Magneto-Optical Crystals
by Zhonghan Zhang, Zhen Wu, Zhen Zhang, Liangbi Su, Anhua Wu, Yang Li and Jianghe Lan
Magnetochemistry 2023, 9(2), 41; https://doi.org/10.3390/magnetochemistry9020041 - 27 Jan 2023
Cited by 7 | Viewed by 1876
Abstract
Magneto-optical materials are the fundamental component of Faraday isolators; therefore, they are significantly important for solid-state laser systems. Fluoride magneto-optical crystals such as CeF3, KTb3F10 and LiTbF4 exhibit advantages of wide transmittance range, high optical homogeneity, smaller [...] Read more.
Magneto-optical materials are the fundamental component of Faraday isolators; therefore, they are significantly important for solid-state laser systems. Fluoride magneto-optical crystals such as CeF3, KTb3F10 and LiTbF4 exhibit advantages of wide transmittance range, high optical homogeneity, smaller thermal lensing and weaker thermal induced depolarization effect, and thus are promising candidates for Faraday isolators in high-power solid-state lasers. Recent progress in crystal growth and characterizations of these fluoride magneto-optical crystals are introduced. Possible applications of Faraday isolators based on various fluoride crystals are discussed, especially for solid-state lasers in the ultraviolet (UV) or infrared (IR) spectral region. Full article
(This article belongs to the Special Issue New Trends in Magneto-Optical Ceramics)
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55 pages, 8990 KiB  
Review
Relativistic Effects from Heavy Main Group p-Elements on the NMR Chemical Shifts of Light Atoms: From Pioneering Studies to Recent Advances
by Irina L. Rusakova and Yuriy Yu. Rusakov
Magnetochemistry 2023, 9(1), 24; https://doi.org/10.3390/magnetochemistry9010024 - 07 Jan 2023
Cited by 9 | Viewed by 2025
Abstract
This review represents a compendium of computational studies of relativistic effects on the NMR chemical shifts of light nuclei caused by the presence of heavy main group p-block elements in molecules. The narration starts from a brief discussion of the relativistic theories and [...] Read more.
This review represents a compendium of computational studies of relativistic effects on the NMR chemical shifts of light nuclei caused by the presence of heavy main group p-block elements in molecules. The narration starts from a brief discussion of the relativistic theories and quantum chemical methods for the calculation of NMR chemical shifts at the relativistic level of the electronic theory. The main part of the review contains a survey on the relativistic calculations of NMR shielding constants of the most popular NMR-active light nuclei such as 1H, 13C, 19F, 29Si, 15N, and 31P of compounds containing heavy p-elements. A special focus is placed on the relativistic effects initiated by the 16th and 17th group elements. Different factors governing the behavior of the relativistic effects on the chemical shifts of light atoms are discussed. In particular, the stereochemistry of the relativistic “heavy atom on the light atom” effect and the influence of the spin–orbit relativistic effects on the vibrational contributions to the shielding constants of light nuclei are considered. Full article
(This article belongs to the Special Issue Computational Chemistry in Nuclear Magnetic Resonance)
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15 pages, 22709 KiB  
Article
Magnetizable Membranes Based on Cotton Microfibers, Honey, Carbonyl Iron, and Silver Nanoparticles: Effects of Static Magnetic Fields and Medium-Frequency Electric Fields on Electrical Properties
by Ioan Bica, Eugen Mircea Anitas and Paula Sfirloaga
Magnetochemistry 2023, 9(1), 19; https://doi.org/10.3390/magnetochemistry9010019 - 03 Jan 2023
Cited by 2 | Viewed by 1235
Abstract
In this work, we present the manufacturing process of magnetizable membranes based on cotton microfibers, honey, carbonyl iron, and three different concentrations of silver microparticles. Each membrane is used as a dielectric material for the fabrication of electrical devices. By using the plane [...] Read more.
In this work, we present the manufacturing process of magnetizable membranes based on cotton microfibers, honey, carbonyl iron, and three different concentrations of silver microparticles. Each membrane is used as a dielectric material for the fabrication of electrical devices. By using the plane capacitor method, the electrical capacitance and dielectric loss tangent are measured in a medium-frequency alternating field superimposed on a static magnetic field. From the obtained data, the time constants of the devices, the components of complex dielectric permittivity, and the electrical conductivity of the membranes as a function of the electric field frequency and magnetic flux density can be extracted. The results show that the obtained membranes can be useful for the fabrication of low-cost and environmentally friendly magneto-active membranes that are required for various technical and biomedical applications. Full article
(This article belongs to the Section Magnetic Field)
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26 pages, 4088 KiB  
Review
Magnetic Nanocomposites and Imprinted Polymers for Biomedical Applications of Nucleic Acids
by Victoriya Popova, Elena Dmitrienko and Alexey Chubarov
Magnetochemistry 2023, 9(1), 12; https://doi.org/10.3390/magnetochemistry9010012 - 30 Dec 2022
Cited by 14 | Viewed by 2840
Abstract
Magnetic nanocomposites (MNCs) combine the features of magnetic nanoparticles and a second material, which provide distinct physical, chemical, and biological properties. The magnetic core for nanocomposite synthesis is extensively used due to its high saturation magnetization, chemical stability, large surface area, and easy [...] Read more.
Magnetic nanocomposites (MNCs) combine the features of magnetic nanoparticles and a second material, which provide distinct physical, chemical, and biological properties. The magnetic core for nanocomposite synthesis is extensively used due to its high saturation magnetization, chemical stability, large surface area, and easy functionalization. Moreover, magnetic nanoparticles (MNPs) have great potential for magnetic resonance imaging (MRI), magnetic particle imaging (MPI), hyperthermia, and targeted drug and gene delivery by an external magnetic field. Numerous composing units exist, which leads to the outstanding application of composites. This review focuses on nucleic acid-based bioapplications of MNCs with polymeric, organic, inorganic, biomolecules, and bioinspared surface coating. In addition, different forms, such as core–shell, doping, multilayer, yolk–shell, and Janus-shaped hybrids, are discussed, and their unique properties are highlighted. The unique types of nanocomposites as magnetic molecularly imprinted polymer (MMIP) properties are presented. This review presents only the synthesis of MNCs using ready-made magnetic cores. These restrictions are associated with many materials, the quantitative and qualitative magnetic core composition, and synthesis procedures. This review aims to discuss the features of nucleic acid-based MNC information available to researchers in this field and guide them through some problems in the area, structure variation, and surface functionalization possibilities. The most recent advancements of MNCs and imprinted polymers in nucleic acid-based therapy, diagnostics, theranostics, magnetic separation, biocatalytic, and biosensing are introduced. Full article
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30 pages, 13276 KiB  
Review
Application of the Heptacyanidorhenate(IV) as a Metalloligand in the Design of Molecular Magnets
by Kira E. Vostrikova
Magnetochemistry 2022, 8(12), 189; https://doi.org/10.3390/magnetochemistry8120189 - 14 Dec 2022
Cited by 2 | Viewed by 1207
Abstract
This review is devoted to an analysis of currently known heterometallic molecular magnets based on an orbitally degenerate 5d metalloligand, [ReIV(CN)7]3−. Heptacyanidometallates with a pentagonal bipyramidal structure of the coordination site and degenerate ground spin state [...] Read more.
This review is devoted to an analysis of currently known heterometallic molecular magnets based on an orbitally degenerate 5d metalloligand, [ReIV(CN)7]3−. Heptacyanidometallates with a pentagonal bipyramidal structure of the coordination site and degenerate ground spin state are the source of anisotropic magnetic exchange interactions upon the formation of cyanide-bonded assemblies involving the paramagnetic complexes of the first transition series. Therefore, the development of methods for chemical design using such molecular magnetic modules is extremely important. If for the 4d congener, isoelectronic [MoIII(CN)7]3−, a family of approximately 40 heterometallic compounds, was obtained, whereas for heptacyanorhenate(IV), no more than 20 are known. However, as a result of recent studies, heterobimetallic magnetic assemblies of all dimensionalities have been synthesized, from 0D to 1D, demonstrating slow magnetization relaxation, to 2D networks and 3D frameworks possessing large magnetic hysteresis. The most anisotropic is a 2D network, PPN[{MnIII(acacen)}2ReIV(CN)7]·Solv, with a critical temperature of 20 K and magnetic hysteresis with a record coercivity for cyanide-bridged molecular materials. Full article
(This article belongs to the Special Issue Reviews on Molecular Magnetism)
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28 pages, 9713 KiB  
Article
Stability Analysis of Buoyancy Magneto Flow of Hybrid Nanofluid through a Stretchable/Shrinkable Vertical Sheet Induced by a Micropolar Fluid Subject to Nonlinear Heat Sink/Source
by Umair Khan, Aurang Zaib, Anuar Ishak, Abeer M. Alotaibi, Sayed M. Eldin, Nevzat Akkurt, Iskandar Waini and Javali Kotresh Madhukesh
Magnetochemistry 2022, 8(12), 188; https://doi.org/10.3390/magnetochemistry8120188 - 14 Dec 2022
Cited by 12 | Viewed by 1678
Abstract
The utilization of hybrid nanofluids (HNs) to boost heat transfer is a promising area of study, and thus, numerous scientists, researchers, and academics have voiced their admiration and interest in this area. One of the main functions of nanofluids is their dynamic role [...] Read more.
The utilization of hybrid nanofluids (HNs) to boost heat transfer is a promising area of study, and thus, numerous scientists, researchers, and academics have voiced their admiration and interest in this area. One of the main functions of nanofluids is their dynamic role in cooling small electrical devices such as microchips and associated gadgets. The major goal of this study is to perform an analysis of the buoyancy flow of a shrinking/stretching sheet, whilst considering the fascinating and practical uses of hybrid nanofluids. The influence of a nonlinear heat source/sink induced by a micropolar fluid is also inspected. Water-based alumina and copper nanoparticles are utilized to calculate the fine points of the fluid flow and the features of heat transfer. The governing equations are framed with acceptable assumptions and the required similarity transformations are used to turn the set of partial differential equations into ordinary differential equations. The bvp4c technique is used to solve the simplified equations. Dual solutions are presented for certain values of stretching/shrinking parameters as well as the mixed convective parameter. In addition, the shear stress coefficient in the first-branch solution (FBS) escalates and decelerates for the second-branch solution (SBS) with the superior impact of the magnetic parameter, the mass transpiration parameter, and the solid nanoparticles volume fraction, while the contrary behavior is seen in both (FB and SB) solutions for the larger values of the material parameter. Full article
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26 pages, 4898 KiB  
Review
Magnetic Semiconductors as Materials for Spintronics
by Andrei Telegin and Yurii Sukhorukov
Magnetochemistry 2022, 8(12), 173; https://doi.org/10.3390/magnetochemistry8120173 - 29 Nov 2022
Cited by 7 | Viewed by 3253
Abstract
From the various aspects of spintronics the review highlights the area devoted to the creation of new functional materials based on magnetic semiconductors and demonstrates both the main physical phenomena involved and the technical possibilities of creating various devices: maser, p-n diode with [...] Read more.
From the various aspects of spintronics the review highlights the area devoted to the creation of new functional materials based on magnetic semiconductors and demonstrates both the main physical phenomena involved and the technical possibilities of creating various devices: maser, p-n diode with colossal magnetoresistance, spin valve, magnetic lens, optical modulators, spin wave amplifier, etc. Particular attention is paid to promising research directions such as ultrafast spin transport and THz spectroscopy of magnetic semiconductors. Special care has been taken to include a brief theoretical background and experimental results for the new spintronics approach employing magnetostrictive semiconductors—strain-magnetooptics. Finally, it presents top-down approaches for magnetic semiconductors. The mechano-physical methods of obtaining and features of the physical properties of high-density nanoceramics based on complex magnetic oxides are considered. The potential possibility of using these nanoceramics as an absorber of solar energy, as well as in modulators of electromagnetic radiation, is shown. Full article
(This article belongs to the Special Issue Spintronics, Magnetic Semiconductors and Devices)
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20 pages, 13102 KiB  
Review
Two-Dimensional Doped Materials
by Junchi Liu, Bo Li and Qiuqiu Li
Magnetochemistry 2022, 8(12), 172; https://doi.org/10.3390/magnetochemistry8120172 - 29 Nov 2022
Cited by 7 | Viewed by 2419
Abstract
The recently intensified research in atomically thick two-dimensional (2D) materials has been motivated by their unique properties and the possibility of updating the future electronic and optoelectronic technologies. Doping can change the band structure of a semiconductor and regulate its physical and chemical [...] Read more.
The recently intensified research in atomically thick two-dimensional (2D) materials has been motivated by their unique properties and the possibility of updating the future electronic and optoelectronic technologies. Doping can change the band structure of a semiconductor and regulate its physical and chemical properties. Doping has a significant effect on the electronic structure of 2D materials due to their atomic thickness. Here, we present a tutorial review of 2D doped materials (except graphene), including various doping types and theoretical calculations, the preparation and characterization methods, and its multifunctional application. Finally, we will summarize by stating the current challenges and future opportunities in the development of 2D doped materials. Full article
(This article belongs to the Special Issue Advances in Magnetic Two Dimensional Materials)
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19 pages, 4178 KiB  
Article
Amorphous Carbon Films with Embedded Well-Dispersed Nanodiamonds: Plasmon-Enhanced Analysis and Possible Antimicrobial Applications
by Oleg Streletskiy, Elena Perevedentseva, Ilya Zavidovskiy, Artashes Karmenyan, Vladimir Sychev, Vera Sadykova, Anastasia Kuvarina and Chia-Liang Cheng
Magnetochemistry 2022, 8(12), 171; https://doi.org/10.3390/magnetochemistry8120171 - 26 Nov 2022
Cited by 6 | Viewed by 2311
Abstract
An amorphous carbon film with embedded detonation nanodiamond (DND) particles (a-C:ND) was produced by magnetron sputtering of nanodiamond powder. An Ag film was deposited on the carbon structure by radiofrequency magnetron sputtering. The silver film was irradiated with a 150 eV Ar+ [...] Read more.
An amorphous carbon film with embedded detonation nanodiamond (DND) particles (a-C:ND) was produced by magnetron sputtering of nanodiamond powder. An Ag film was deposited on the carbon structure by radiofrequency magnetron sputtering. The silver film was irradiated with a 150 eV Ar+ to form plasmonic-active nanoparticles (NP) on the surface of the a-C:ND. The structure of the obtained a-C:ND and a-C:ND/Ag structures were studied by scanning and transmission electron microscopy, electron energy-loss spectroscopy, UV–Visible absorption spectroscopy, Raman spectroscopy, and fluorescence lifetime imaging at two-photon excitation. The analysis revealed 76% of sp3-carbon and a good dispersion of diamond nanoparticles in the a-C. Surface-enhanced Raman scattering (SERS) was applied to investigate the a-C:ND/Ag structure, allowing for the observation of SERS from the sp2-carbon species and the absence of significant a-C:ND damage after Ar+ irradiation of the Ag overlayer. A plasmonic-metal-enhanced luminescence was observed at one- and two-photon excitations, revealing a two- to five-fold intensity increase. The activity of the used DNDs was tested using the agar diffusion method and observed against the bacteria of Bacillus subtilis, Staphylococcus aureus, and Escherichia coli and the fungi of Aspergillus niger, Aspergillus fumigatus, and the yeast of Candida albicans, showing DND activity against all the test strains of fungi. Full article
(This article belongs to the Special Issue Magnetron Sputtering Process)
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