Magnetochemistry

11 pages, 4913 KiB

Open AccessPerspective

MRI Quantitative Evaluation of Muscle Fatty Infiltration

by Vito Chianca, Bottino Vincenzo, Renato Cuocolo, Marcello Zappia, Salvatore Guarino, Francesco Di Pietto and Filippo Del Grande

Magnetochemistry 2023, 9(4), 111; https://doi.org/10.3390/magnetochemistry9040111 - 21 Apr 2023

Cited by 3 | Viewed by 3222

Abstract

Magnetic resonance imaging (MRI) is the gold-standard technique for evaluating muscle fatty infiltration and muscle atrophy due to its high contrast resolution. It can differentiate muscular from adipose tissue accurately. MRI can also quantify the adipose content within muscle bellies with several sequences [...] Read more.

Magnetic resonance imaging (MRI) is the gold-standard technique for evaluating muscle fatty infiltration and muscle atrophy due to its high contrast resolution. It can differentiate muscular from adipose tissue accurately. MRI can also quantify the adipose content within muscle bellies with several sequences such as T₁-mapping, T₂-mapping, spectroscopy, Dixon, intra-voxel incoherent motion, and diffusion tensor imaging. The main fields of interest in musculoskeletal radiology for a quantitative MRI evaluation of muscular fatty infiltration include neuro-muscular disorders such as myopathies, and dystrophies. Sarcopenia is another important field in which the evaluation of the degree of muscular fat infiltration or muscular hypotrophy is required for a correct diagnosis. This review highlights several MRI techniques and sequences focusing on quantitative methods of assessing adipose tissue and muscle atrophy. Full article

(This article belongs to the Special Issue Advanced Applications of Magnetic Resonance)

► Show Figures

Figure 1

32 pages, 10211 KiB

Open AccessReview

Recent Advances of Magnetite (Fe₃O₄)-Based Magnetic Materials in Catalytic Applications

by Mingyue Liu, Yuyuan Ye, Jiamin Ye, Ting Gao, Dehua Wang, Gang Chen and Zhenjun Song

Magnetochemistry 2023, 9(4), 110; https://doi.org/10.3390/magnetochemistry9040110 - 20 Apr 2023

Cited by 23 | Viewed by 4127

Abstract

Catalysts play a critical role in producing most industrial chemicals and are essential to environmental remediation. Under the demands of sustainable development, environment protection, and cost-related factors, it has been suggested that catalysts are sufficiently separable and conveniently recyclable in the catalysis process. [...] Read more.

Catalysts play a critical role in producing most industrial chemicals and are essential to environmental remediation. Under the demands of sustainable development, environment protection, and cost-related factors, it has been suggested that catalysts are sufficiently separable and conveniently recyclable in the catalysis process. Magnetite (Fe₃O₄) nanomaterials provide a possible way to achieve this goal, due to their magnetism, chemical stability, low toxicity, economic viability, etc. Therefore, Fe₃O₄-based materials are emerging as an important solid support to load heterogeneous catalysts and immobilize homogeneous catalysts. Moreover, the addition of magnetic character to catalysts will not only make their recovery much easier but also possibly endow catalysts with desirable properties, such as magnetothermal conversion, Lewis acid, mimetic enzyme activity, and Fenton activity. The following review comprises a short survey of the most recent reports in the catalytic applications of Fe₃O₄-based magnetic materials. It contains seven sections, an introduction into the theme, applications of Fe₃O₄-based magnetic materials in environmental remediation, electrocatalysis, organic synthesis, catalytic synthesis of biodiesel, and cancer treatment, and conclusions about the reported research with perspectives for future developments. Elucidation of the functions and mechanisms of Fe₃O₄ nanoparticles (NPs) in these applications may benefit the acquisition of robust and affordable protocols, leading to catalysts with good catalytic activity and enhanced recoverability. Full article

(This article belongs to the Special Issue New Advances in Magnetic Functional Materials)

► Show Figures

Figure 1

10 pages, 2367 KiB

Open AccessFeature PaperArticle

Magnetic Properties of the Fe₂B Alloy Doped with Transition Metal Elements

by Diana Benea and Viorel Pop

Magnetochemistry 2023, 9(4), 109; https://doi.org/10.3390/magnetochemistry9040109 - 20 Apr 2023

Cited by 2 | Viewed by 1183

Abstract

The intrinsic magnetic properties (magnetic moments, magneto-crystalline anisotropy, Curie temperatures) of the (Fe_1−xM_x)₂B alloys have been calculated using the spin-polarized relativistic Korringa–Kohn–Rostoker (SPR-KKR) band structure method. The transition metal elements M (M = Co, Ni, Mo, Ta, [...] Read more.

The intrinsic magnetic properties (magnetic moments, magneto-crystalline anisotropy, Curie temperatures) of the (Fe_1−xM_x)₂B alloys have been calculated using the spin-polarized relativistic Korringa–Kohn–Rostoker (SPR-KKR) band structure method. The transition metal elements M (M = Co, Ni, Mo, Ta, W and Re) considered in the present study are reported to form stable M₂B or FeMB alloys with a tetragonal Cu₂Al structure type. The experimental studies show that the Fe₂B alloy has a large magnetization (173 Am²/kg), a large Curie temperature (1017 K) and a relatively large anisotropy constant K₁ (−0.80 MJ/m³), but the alloy is inappropriate for permanent magnet applications due to in-plane easy magnetization axis (EMD). The present investigations show the magnetocrystalline anisotropy behaviour by doping with selected d-elements aiming to find an appropriate dopant which is able to switch the EMD from planar to axial and to enhance the magnetocrystalline anisotropy energy (MAE) value without a major decrease of magnetization and Curie temperature. Full article

(This article belongs to the Special Issue Soft and Hard Magnetic Materials: Latest Advances and Prospects)

► Show Figures

Figure 1

14 pages, 3020 KiB

Open AccessArticle

Structural, Elastic, Electronic, and Magnetic Properties of Full-Heusler Alloys Sc₂TiAl and Sc₂TiSi Using the FP-LAPW Method

by Khadejah M. Al-Masri, Mohammed S. Abu-Jafar, Mahmoud Farout, Diana Dahliah, Ahmad A. Mousa, Said M. Azar and Rabah Khenata

Magnetochemistry 2023, 9(4), 108; https://doi.org/10.3390/magnetochemistry9040108 - 16 Apr 2023

Cited by 2 | Viewed by 1738

Abstract

In this article, the structural, elastic, electronic, and magnetic characteristics of both regular and inverse Heusler alloys, Sc₂TiAl and Sc₂TiSi, were investigated using a full-potential, linearized augmented plane-wave (FP-LAPW) method, within the density functional theory. The optimized structural parameters [...] Read more.

In this article, the structural, elastic, electronic, and magnetic characteristics of both regular and inverse Heusler alloys, Sc₂TiAl and Sc₂TiSi, were investigated using a full-potential, linearized augmented plane-wave (FP-LAPW) method, within the density functional theory. The optimized structural parameters were determined from the minimization of the total energy versus the volume of the unit cell. The band structure and DOS calculations were performed within the generalized gradient approximation (GGA) and modified Becke–Johnson approaches (mBJ-GGA), employed in the Wien2K code. The density of states (DOS) and band structure (BS) indicate the metallic nature of the regular structure of the two compounds. The total spin magnetic moments for the two compounds were consistent with the previous theoretical results. We calculated the elastic properties: bulk moduli,

B

, Poisson’s ratio,

ν

, shear modulus, S, Young’s modulus (Y), and the B/s ratio. Additionally, we used Blackman’s diagram and Every’s diagram to compare the elastic properties of the studied compounds, whereas Pugh’s and Poisson’s ratios were used in the analysis of the relationship between interatomic bonding type and physical properties. Mechanically, we found that the regular and inverse full-Heusler compounds Sc₂TiAl and Sc₂TiSi were stable. The results agree with previous studies, providing a road map for possible uses in electronic devices. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: Magnetic and Magnetoelectric Materials)

► Show Figures

Figure 1

13 pages, 3968 KiB

Open AccessArticle

Study of the Effects of Er Doping on the Physical Properties of CdSe Thin Films

by Yuliana de Jesús Acosta-Silva, Luis A. Godínez, Manuel Toledano-Ayala, Rosendo Lozada-Morales, Orlando Zelaya-Angel and Arturo Méndez-López

Magnetochemistry 2023, 9(4), 107; https://doi.org/10.3390/magnetochemistry9040107 - 14 Apr 2023

Cited by 2 | Viewed by 1450

Abstract

Erbium-doped cadmium selenide thin films grown on 7059 Corning glass by means of a chemical bath at 80 °C were prepared. Doping was performed by adding an aqueous Er(NO3)₃3·H₂O dilution to the CdSe growth solution. The volume of Er [...] Read more.

Erbium-doped cadmium selenide thin films grown on 7059 Corning glass by means of a chemical bath at 80 °C were prepared. Doping was performed by adding an aqueous Er(NO3)₃3·H₂O dilution to the CdSe growth solution. The volume of Er doping solution was varied to obtain different Er concentration (x at%). Thus, in the Cd_1−xEr_xSe samples, the x values obtained were in the 0.0–7.8 at% interval. The set of the CdSe:Er thin films synthesized in the hexagonal wurtzite (WZ) crystalline phase are characterized by lattice parameters (a and c) that increase until x = 2.4% and that subsequently decrease as the concentration of x increases. Therefore, in the primitive unit cell volume (UC), the same effect was observed. Physical parameters such as nanocrystal size, direct band gap (E_g), and optical longitudinal vibrational phonon on the other hand, shift in an opposite way to that of UC as a function of x. All the samples exhibit photoluminescence (PL) emission which consists of a single broad band in the 1.3 ≤ hν ≤ 2.5 eV range (954 ≥ λ ≥ 496 nm), where the maximum of the PL-band shift depends on x in the same way as the former parameters. The PL band intensity shows a singular behavior since it increases as x augments but exhibits a strong decreasing trend in the intermediate region of the x range. Dark d.c. conductivity experiences a high increase with the lower x value, however, it gradually decreases as x increases, which suggests that the Er³⁺ ions are not only located in Cd²⁺ sites, but also in interstitial sites and at the surface. Different physical properties are correlated among them and discussed considering information from similar reports in the literature. Full article

(This article belongs to the Special Issue Magnetic Materials, Thin Films and Nanostructures)

► Show Figures

Figure 1

16 pages, 12177 KiB

Open AccessEditor’s ChoiceArticle

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 2115

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)

► Show Figures

Figure 1

11 pages, 3292 KiB

Open AccessArticle

Zero-Field Slow Magnetic Relaxation in Binuclear Dy Acetylacetonate Complex with Pyridine-N-Oxide

by Valeriya P. Shtefanets, Gennady V. Shilov, Denis V. Korchagin, Elena A. Yureva, Alexei I. Dmitriev, Mikhail V. Zhidkov, Roman B. Morgunov, Nataliya A. Sanina and Sergey M. Aldoshin

Magnetochemistry 2023, 9(4), 105; https://doi.org/10.3390/magnetochemistry9040105 - 12 Apr 2023

Viewed by 1410

Abstract

A new complex [Dy(C₅H₇O₂)₃(C₅H₅NO)]₂·2CHCl₃ (1) has been synthesized by the reaction of pyridine-N-oxide with dysprosium (III) acetylacetonate in an n-heptane/chloroform mixture (1/20). X-ray data show that [...] Read more.

A new complex [Dy(C₅H₇O₂)₃(C₅H₅NO)]₂·2CHCl₃ (1) has been synthesized by the reaction of pyridine-N-oxide with dysprosium (III) acetylacetonate in an n-heptane/chloroform mixture (1/20). X-ray data show that each dysprosium atom is chelate-like coordinated by three acetylacetonate ligands and the oxygen atom from two bridging molecules of pyridine-N-oxide, which unite the dysprosium atoms into a binuclear complex. Static (constant current) and dynamic (alternating current) investigations and ab initio calculations of the magnetic properties of complex 1 were performed. The complex was shown to exhibit a frequency maximum under alternating current. At temperatures above 10 K, the maximum shifts to a higher frequency, which is characteristic of SMM behavior. It is established that the dependence of ln(τ) on 1/T for the relaxation process is nonlinear, which indicates the presence of Raman relaxation mechanisms, along with the Orbach mechanism. Full article

(This article belongs to the Special Issue Magnetic Relaxation in Metal Complexes)

► Show Figures

Graphical abstract

8 pages, 1853 KiB

Open AccessCommunication

An Optical Spectroscopic Study of Air-Degradation of van der Waals Magnetic Semiconductor Cr₂Ge₂Te₆

by Woye Pei, Zhiren Xiong, Yingjia Liu, Xingguang Wu, Zheng Vitto Han, Siwen Zhao and Tongyao Zhang

Magnetochemistry 2023, 9(4), 104; https://doi.org/10.3390/magnetochemistry9040104 - 10 Apr 2023

Viewed by 1221

Abstract

Two-dimensional (2D) magnetic semiconductors exhibit unique combination of electronic and magnetic properties, holding great promise in potential applications such as spintronics and magneto-optics. However, many of them are air-sensitive, and their properties can be significantly altered upon exposure to air. Here, we showed [...] Read more.

Two-dimensional (2D) magnetic semiconductors exhibit unique combination of electronic and magnetic properties, holding great promise in potential applications such as spintronics and magneto-optics. However, many of them are air-sensitive, and their properties can be significantly altered upon exposure to air. Here, we showed an optical spectroscopic investigation of the effects of air-degradation on few-layered van der Waals (vdW) magnetic semiconductor Cr₂Ge₂Te₆. It was found that although the partially degraded few-layered Cr₂Ge₂Te₆ showed a significant Raman redshift and a split of E_g peak at room temperature, the magneto-optic Kerr hysteresis loop can remain largely unchanged below the Curie temperature. Temperature-dependent Raman measurements further revealed characteristic blueshifts of phonon energy, which were associated with the ferromagnetic phase transition in partially degraded Cr₂Ge₂Te₆, in agreement with Kerr measurements. Our results provide an optical spectroscopic insight into the air-instability of 2D magnetic semiconductors, and contribute to a better understanding of the relationship between phonon modes and long-range spin order at the presence of defects in ultra-thin vdW magnetic semiconductors. Full article

(This article belongs to the Special Issue Advances in Magnetic Two Dimensional Materials)

► Show Figures

Figure 1

14 pages, 2229 KiB

Open AccessArticle

Investigation of Microstructure and Magnetic Properties of CH₄ Heat Treated Sr-Hexaferrite Powders during Re-Calcination Process

by Ramin Dehghan, Seyyed Ali Seyyed Ebrahimi, Zahra Lalegani and Bejan Hamawandi

Magnetochemistry 2023, 9(4), 103; https://doi.org/10.3390/magnetochemistry9040103 - 08 Apr 2023

Cited by 1 | Viewed by 1213

Abstract

The microstructure and magnetic properties of methane (CH₄) heat-treated Sr-hexaferrite powders during the re-calcination process were investigated and compared with the magnetic properties of conventionally synthesized Sr-hexaferrite powder. Gradual changes in the magnetic behavior of the produced powder in each re-calcination [...] Read more.

The microstructure and magnetic properties of methane (CH₄) heat-treated Sr-hexaferrite powders during the re-calcination process were investigated and compared with the magnetic properties of conventionally synthesized Sr-hexaferrite powder. Gradual changes in the magnetic behavior of the produced powder in each re-calcination stage were investigated using magnetization curves obtained from the vibration sample magnetometry (VSM) technique. First, the initial Sr-hexaferrite powder was prepared by the conventional route. Then the powder was heat treated in a dynamic CH₄ atmosphere in previously optimized conditions (temperature: 950 °C, gas flow rate:15 cc min⁻¹ and time: 30 min), and finally, re-calcined in various temperatures from 200 to 1200 °C. By investigating the hysteresis loops, we found the transition temperature of soft to hard magnetic behavior to be 700 °C. The maximum ratio M_r/M_s was obtained at temperatures of 800–1100 °C. At 1100 °C, and despite the Sr-hexaferrite single phase, the magnetic behavior showed a multiphase behavior that was demonstrated by a kink in the hysteresis loop. Uniform magnetic behavior was observed only at 900 °C and 1000 °C. Although the ratio M_r/M_s was almost the same at these temperatures, the values of M_r and M_s at 1000 °C were almost double of 900 °C. At 1000 °C, the second quadrant of hysteresis curve had the maximum area. Therefore, 1000 °C was the optimum temperature for re-calcination after CH₄ gas heat treatment in the optimized conditions. Due to the presence of a small amount of hematite soft phase at 1000 °C, the most probable reason for the exclusive properties of the optimized product may be the exchange coupling phenomenon between the hard Sr-hexaferrite phase and the impurity of the soft hematite phase. Full article

(This article belongs to the Section Applications of Magnetism and Magnetic Materials)

► Show Figures

Figure 1

14 pages, 2740 KiB

Open AccessFeature PaperArticle

The Importance of Solvent Effects in Calculations of NMR Coupling Constants at the Doubles Corrected Higher Random-Phase Approximation

by Louise Møller Jessen, Peter Reinholdt, Jacob Kongsted and Stephan P. A. Sauer

Magnetochemistry 2023, 9(4), 102; https://doi.org/10.3390/magnetochemistry9040102 - 06 Apr 2023

Cited by 3 | Viewed by 1846

Abstract

In this work, 242 NMR spin–spin coupling constants (SSCC) in 20 molecules are calculated, either with correlated wave function methods, SOPPA and HRPA(D), or with density functional theory based on the B3LYP, BHandH, or PBE0 functionals. The calculations were carried out with and [...] Read more.

In this work, 242 NMR spin–spin coupling constants (SSCC) in 20 molecules are calculated, either with correlated wave function methods, SOPPA and HRPA(D), or with density functional theory based on the B3LYP, BHandH, or PBE0 functionals. The calculations were carried out with and without treatment of solvation via a polarizable continuum model in both the geometry optimization step and/or the SSCC calculation, and thereby, four series of calculations were considered (the full-vacuum calculation, the full-solvent calculation, and the two cross combinations). The results were compared with experimental results measured in a solvent. With the goal of reproducing experimental values, we find that the performance of the PBE0 and BHandH SSCCs improves upon including solvation effects. On the other hand, the quality of the B3LYP SSCCs worsens with the inclusion of solvation. Solvation had almost no effect on the performance of the SOPPA and HRPA(D) calculations. We find that the PBE0-based calculations of the spin–spin coupling constants have the best agreement with the experimental data. Full article

(This article belongs to the Special Issue Computational Chemistry in Nuclear Magnetic Resonance)

► Show Figures

Figure 1

14 pages, 1831 KiB

Open AccessArticle

Robustness of the Skyrmion Phase in a Frustrated Heisenberg Antiferromagnetic Layer against Lattice Imperfections and Nanometric Domain Sizes

by Mariia Mohylna and Milan Žukovič

Magnetochemistry 2023, 9(4), 101; https://doi.org/10.3390/magnetochemistry9040101 - 06 Apr 2023

Viewed by 1386

Abstract

By employing GPU-implemented hybrid Monte Carlo simulations, we study the robustness of the skyrmion lattice phase (SkX) in a frustrated Heisenberg antiferromagnetic (AFM) layer on a triangular lattice with a Dzyaloshinskii–Moriya interaction in the external magnetic field against the presence of lattice imperfections [...] Read more.

By employing GPU-implemented hybrid Monte Carlo simulations, we study the robustness of the skyrmion lattice phase (SkX) in a frustrated Heisenberg antiferromagnetic (AFM) layer on a triangular lattice with a Dzyaloshinskii–Moriya interaction in the external magnetic field against the presence of lattice imperfections (nonmagnetic impurities) and lattice finiteness. Both features are typical of experimentally accessible magnetic materials and require theoretical investigation. In the pure model of infinite size, SkX is known to be stabilized in a quite wide temperature-field window. We first study the effects of such imperfections on the SkX stability and compare them with those in the nonfrustrated ferromagnetic counterpart. The partial results of this part appeared in the conference proceedings [M. Mohylnaand M. Žukovič, Proceedings of the 36th International ECMS International Conference on Modelling and Simulation, ECMS, 2022]. We further look into whether SkX can also persist in finite clusters, i.e., zero-dimensional systems of nanometric sizes. In general, both the presence of magnetic vacancies as well as the finiteness of the system tend to destabilize any ordering. We show that in the present model, SkX can survive, albeit in a somewhat distorted form, in the impure infinite system up to a fairly large concentration of impurities, and, in the pure finite systems, down to sizes comprising merely tens of particles. Distortion of the SkX phase due to the formation of bimerons, reported in the ferromagnetic model, was not observed in the present frustrated AFM case. Full article

(This article belongs to the Special Issue Phase Change Material and Magnetic Research)

► Show Figures

Figure 1

31 pages, 23603 KiB

Open AccessFeature PaperArticle

Zero-Field Splitting in Hexacoordinate Co(II) Complexes

by Roman Boča, Cyril Rajnák and Ján Titiš

Magnetochemistry 2023, 9(4), 100; https://doi.org/10.3390/magnetochemistry9040100 - 04 Apr 2023

Cited by 7 | Viewed by 1844

Abstract

A collection of 24 hexacoordinate Co(II) complexes was investigated by ab initio CASSCF + NEVPT2 + SOC calculations. In addition to the energies of spin–orbit multiplets (Kramers doublets, KD) their composition of the spins is also analyzed, along with the projection norm to [...] Read more.

A collection of 24 hexacoordinate Co(II) complexes was investigated by ab initio CASSCF + NEVPT2 + SOC calculations. In addition to the energies of spin–orbit multiplets (Kramers doublets, KD) their composition of the spins is also analyzed, along with the projection norm to the effective Hamiltonian. The latter served as the evaluation of the axial and rhombic zero-field splitting parameters and the g-tensor components. The fulfilment of spin-Hamiltonian (SH) formalism was assessed by critical indicators: the projection norm for the first Kramers doublet N(KD1) > 0.7, the lowest g-tensor component g₁ > 1.9, the composition of KDs from the spin states |±1/2> and |±3/2> with the dominating percentage p > 70%, and the first transition energy at the NEVPT2 level ⁴Δ₁. Just the latter quantity causes a possible divergence of the second-order perturbation theory and a failure of the spin Hamiltonian. The data set was enriched by the structural axiality D_str and rhombicity E_str, respectively, evaluated from the metal–ligand distances Co-O, Co-N and Co-Cl corrected to the mean values. The magnetic data (temperature dependence of the molar magnetic susceptibility, and the field dependence of the magnetization per formula unit) were fitted simultaneously, either to the Griffith–Figgis model working with 12 spin–orbit kets, or the SH-zero field splitting model that utilizes only four (fictitious) spin functions. The calculated data were analyzed using statistical methods such as Cluster Analysis and the Principal Component Analysis. Full article

(This article belongs to the Section Molecular Magnetism)

► Show Figures

Figure 1

22 pages, 6973 KiB

Open AccessArticle

Investigation of Cubic and Spherical IONPs’ Rheological Characteristics and Aggregation Patterns from the Perspective of Magnetic Targeting

by Maria-Cristina Ioncica, Sulalit Bandyopadhyay, Nesrine Bali, Vlad Socoliuc and Sandor I. Bernad

Magnetochemistry 2023, 9(4), 99; https://doi.org/10.3390/magnetochemistry9040099 - 02 Apr 2023

Viewed by 1792

Abstract

Based on our prior research, we synthesized iron-oxide nanoparticles (IONPs) in two shapes (spherical and cubic) and sized them for the current inquiry. This research examined the magnetic, rheological, and sedimentation properties of the suspensions containing PEG-coated IONPs, considering that both produced particles [...] Read more.

Based on our prior research, we synthesized iron-oxide nanoparticles (IONPs) in two shapes (spherical and cubic) and sized them for the current inquiry. This research examined the magnetic, rheological, and sedimentation properties of the suspensions containing PEG-coated IONPs, considering that both produced particles are intended to be employed for magnetic targeting applications. The saturation magnetization of both IONPs was lower than the magnetite domain magnetization of 92 emu/g due to the surfactant and the dead surface magnetic layer. Under each investigated magnetic field (0, 34 and 183 mT), the shear viscosity behaviour of the MNP suspensions of both kinds was comparable. Shear thinning behaviour was seen for both particle suspensions in the low shear rate area (0.1 s⁻¹ to 1 s⁻¹). The rheological curves from this paper show that the suspensions present a higher viscosity at lower shear rates for spherical and cubic PEG-coated nanoparticles when a magnetic field is applied. The aggregation behaviour demonstrates that cubic-shaped IONPs are more stable throughout time, with hydrodynamic diameter measurements showing a relatively slow variation of the DLS size distribution from 250 nm to 210 nm in the first 600 s; contrarily, the hydrodynamic diameter of spherical IONPs fluctuated significantly, from 855 nm to 460 nm. Another key finding relates to the sedimentation profile, specifically that PEG-coated IONPs with spherical shapes have a stronger tendency to sediment than those with cubic forms, which are more stable. Full article

(This article belongs to the Special Issue Advances in Magnetic Nanocarrier for Biomedical Applications)

► Show Figures

Figure 1

10 pages, 2128 KiB

Open AccessArticle

An Effect of Fe³⁺ Ion Substitution for Cr³⁺ in the Octahedral Sites of FeCr₂O₄ Multiferroic Spinel: Mössbauer Spectroscopy Study

by Almaz L. Zinnatullin, Mikhail A. Cherosov, Ruslan G. Batulin, Farit G. Vagizov and Roman V. Yusupov

Magnetochemistry 2023, 9(4), 98; https://doi.org/10.3390/magnetochemistry9040098 - 02 Apr 2023

Viewed by 1128

Abstract

We present the results of a successful synthesis and investigation of polycrystalline Fe²⁺(Cr³⁺_, Fe³⁺)₂O₄ powder, where 1/8 part of the Cr³⁺ ions in the octahedral sites is substituted by the Fe³⁺ ones. [...] Read more.

We present the results of a successful synthesis and investigation of polycrystalline Fe²⁺(Cr³⁺_, Fe³⁺)₂O₄ powder, where 1/8 part of the Cr³⁺ ions in the octahedral sites is substituted by the Fe³⁺ ones. It is shown that under such doping, the material retains the cubic spinel structure characteristic of the parent FeCr₂O₄ compound. However, the values of the critical temperatures have changed. Both the orbital and magnetic orderings occur at about 120 K, and magnetic structure rearrangement associated with an onset of spiral modulation takes place at 26 K. Mössbauer studies in a wide temperature range make it possible to accurately control the content of iron ions, their valence and magnetic states, and local environment, therefore, allowing a deeper understanding of the features of the revealed transformations. Full article

(This article belongs to the Special Issue Phase Change Material and Magnetic Research)

► Show Figures

Graphical abstract

19 pages, 7038 KiB

Open AccessArticle

A Comparative Investigation on the Microstructure and Thermal Resistance of W-Film Sensor Using dc Magnetron Sputtering and High-Power Pulsed Magnetron Sputtering

by Jing Huan, Zhengtao Wu, Qimin Wang, Shihong Zhang and Se-Hun Kwon

Magnetochemistry 2023, 9(4), 97; https://doi.org/10.3390/magnetochemistry9040097 - 31 Mar 2023

Cited by 2 | Viewed by 1899

Abstract

Traditional dc magnetron sputtering has a low ionization rate when preparing metallic thin films. With the development of thin film science and the market demand for thin film material applications, it is necessary to improve the density of magnetron-sputtered films. High-power pulsed magnetron [...] Read more.

Traditional dc magnetron sputtering has a low ionization rate when preparing metallic thin films. With the development of thin film science and the market demand for thin film material applications, it is necessary to improve the density of magnetron-sputtered films. High-power pulsed magnetron sputtering (HiPIMS) technology is a physical vapor deposition technology with a high ionization rate and high energy. Therefore, in this work, HiPIMS was applied to prepare metallic tungsten films and compare the surface morphology and microstructure of metallic tungsten films deposited using HiPIMS and dc magnetron sputtering (dcMS) technology under different pulse lengths, as well as related thermal resistance performance, followed by annealing treatment for comparative analysis. We used AFM, SEM, XRD, and plasma characterization testing to comprehensively analyze the changes in the TCR value, stability, repeatability and other related performance of the metallic tungsten thin-film sensor deposited by the HiPIMS technology. It was determined that the thin film prepared by the HiPIMS method is denser, with fewer defects, and the film sensor was stable. The 400 °C annealed sample prepared using HiPIMS with a 100 μs pulse length reaches the largest recorded TCR values of 1.05 × 10⁻³ K⁻¹. In addition, it shows better stability in repeated tests. Full article

(This article belongs to the Special Issue Magnetron Sputtering Process)

► Show Figures

Figure 1

24 pages, 770 KiB

Open AccessArticle

Study of Solar Energetic Particle Events with Ulysses, ACE Observations and Numerical Simulations

by Lele Lian, Gang Qin, Yang Wang and Shuwang Cui

Magnetochemistry 2023, 9(4), 96; https://doi.org/10.3390/magnetochemistry9040096 - 30 Mar 2023

Viewed by 1225

Abstract

We study the latitudinal extent of the near-relativistic electron events of 10 June 2000 and 26 December 2001, observed by both Ulysses and ACE. From the observations it is shown that the intensity of ACE was quite different from that of Ulysses. Through [...] Read more.

We study the latitudinal extent of the near-relativistic electron events of 10 June 2000 and 26 December 2001, observed by both Ulysses and ACE. From the observations it is shown that the intensity of ACE was quite different from that of Ulysses. Through the numerical simulations, we obtain the SEPs time-intensity profiles, which generally fit well to the observations. To compare the observations we obtained the best fit parameters for the simulations. We suggest that the transport effects, especially the perpendicular diffusion effect, can cause the difference between the intensity profiles of ACE and Ulysses, which is dominated by particle transport at a large radial distance and high-latitude when a spacecraft has poor magnetic connection to the particle source. Furthermore, we present the particle source from the best fit parameters to show that the start and peak times of the particle sources are between the onset and max times of a flare in all the energy channels. Moreover, we propose models for the peak intensity and half width of the particle source, and the time interval from the flare onset to the particle source peak time. We show that the models generally agree with the best fit parameters. Full article

(This article belongs to the Special Issue Magnetodynamics of Space Plasmas)

► Show Figures

Figure 1

15 pages, 3187 KiB

Open AccessFeature PaperArticle

Nonreciprocity of Optical Absorption in the Magnetoelectric Antiferromagnet CuB₂O₄

by Kirill N. Boldyrev, Anastasiia D. Molchanova, Alexey R. Nurmukhametov, Mikhail V. Eremin, Roman V. Pisarev and Marina N. Popova

Magnetochemistry 2023, 9(4), 95; https://doi.org/10.3390/magnetochemistry9040095 - 30 Mar 2023

Cited by 1 | Viewed by 1201

Abstract

The change in the absorption spectra due to reversal of the direction of light propagation (nonreciprocity of absorption) is a consequence of a simultaneous violation of both time-reversal and spatial-inversion symmetries. Here, we report on a high-resolution spectroscopic study of absorption nonreciprocity in [...] Read more.

The change in the absorption spectra due to reversal of the direction of light propagation (nonreciprocity of absorption) is a consequence of a simultaneous violation of both time-reversal and spatial-inversion symmetries. Here, we report on a high-resolution spectroscopic study of absorption nonreciprocity in the noncentrosymmetric multiferroic CuB₂O₄ below the antiferromagnetic transition temperature T_N = 21 K in the commensurate phase in magnetic fields up to 0.5 T. The study was performed in a broad spectral region covering several exciton transitions, which all are followed by an anomalously rich structure due to the multiple exciton-magnon-phonon satellites. Two components were resolved for the spectral line near 1.4 eV corresponding to the exciton transition between the ground and the first excited state. A quantitative theory of the optical absorption and nonreciprocity at this line was developed. The theory takes into account the interference between the electric and magnetic dipole contributions to the absorption and gives an adequate explanation of the relevant effects. Full article

(This article belongs to the Special Issue Spectroscopy of Multiferroic Materials)

► Show Figures

Figure 1

8 pages, 2386 KiB

Open AccessCommunication

Magnetoelectric Properties of Ni-PZT-Ni Heterostructures Obtained by Electrochemical Deposition of Nickel in an External Magnetic Field

by Natalia Poddubnaya, Dmitry Filippov, Vladimir Laletin, Aliaksei Aplevich and Kazimir Yanushkevich

Magnetochemistry 2023, 9(4), 94; https://doi.org/10.3390/magnetochemistry9040094 - 30 Mar 2023

Cited by 2 | Viewed by 1131

Abstract

This paper studied the influence of external electric and magnetic fields on the magnetoelectric properties of layered structures of metal-piezoelectric-metal. The structures under study had the shape of a square 4 mm wide and were obtained in two steps: first, by the chemical [...] Read more.

This paper studied the influence of external electric and magnetic fields on the magnetoelectric properties of layered structures of metal-piezoelectric-metal. The structures under study had the shape of a square 4 mm wide and were obtained in two steps: first, by the chemical deposition of nickel with a thickness of 0.5 μm, and then by the electrochemical deposition of nickel with a thickness of 50 μm on each side onto a lead zirconate–lead titanate substrate. Electrochemical deposition was carried out without a magnetic field on both non-polarized and polarized ceramics. Electrochemical deposition was also carried out in a magnetic field on a non-polarized and polarized PZT ceramic substrate. A magnetic field of 500 Oe at electrochemical deposition was applied in all cases in the direction of structure polarization. The maximum ME voltage coefficient 300 mV/(cmOe) was obtained at transverse orientation at bias magnetic field near 20 Oe. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: Magnetic and Magnetoelectric Materials)

► Show Figures

Graphical abstract

18 pages, 9906 KiB

Open AccessArticle

PTA-Welded Coatings with Saturation Magnetization above 1.3 T Using FeCrBSi Powders with Chemical Composition Similar to AISI 430 Ferrite Stainless Steel

by Yingqing Fu, Haiming Wang, Wenhao Huang, Zhoujian Pan, Changhao Liu, Lei Zhao, Chao Li, Liangyu Zhu and Naibao Huang

Magnetochemistry 2023, 9(4), 93; https://doi.org/10.3390/magnetochemistry9040093 - 29 Mar 2023

Viewed by 1016

Abstract

Fe-Cr-based soft magnetic alloy (SMA) monolayer coatings with high saturation magnetization (Ms) above 1.3 T were deposited onto AISI 1010 substrate by co-axial powder feeding plasma transferred arc (PTA) welding, using FeCrBSi self-fluxing powders Fe313, which have a similar chemical composition to AISI [...] Read more.

Fe-Cr-based soft magnetic alloy (SMA) monolayer coatings with high saturation magnetization (Ms) above 1.3 T were deposited onto AISI 1010 substrate by co-axial powder feeding plasma transferred arc (PTA) welding, using FeCrBSi self-fluxing powders Fe313, which have a similar chemical composition to AISI 430 ferritic stainless steel (FSS). The effect of welding parameters on the phase assemblage, microstructure, hardness and magnetic performance of the coatings was investigated. The results show that the coating’s maximum width and the welding surplus height increased with the rise in welding heat input and powder distribution density, respectively. The coating’s Ms increased sharply, but its coercivity (Hc) decreased with the growth in the substrate dilution ratio. The coating’s Hc increased whereas its Ms decreased with the increment in welding heat input. The as-welded coating C3 with optimum magnetic performance had a dendrites–eutectics composite structure, where the columnar or equiaxed sorbitic pearlite dendritic cores surrounded by network-like eutectics α(Fe,Cr) + (Fe_1−xCr_x)₂B were the main contents. Moreover, (Fe,Cr)₇C₃ and CrB had also been detected, and they were mainly distributed in the interdendritic regions. The body-centered cubic (b.c.c.) α(Fe,Cr) multi-element solid solution contributes to a high Ms of 1.61 T, and the borides (Fe_1−xCr_x)₂B and CrB as well as (Fe,Cr)₇C₃ and other carbides cause a high Hc of 58.6 Oe and hardness HV_0.3 of 4.90 ± 0.06 GPa, much higher than that of AISI 430 FSS (HV < 1.8 GPa). The current work verifies the feasibility of fabricating Ni- and Co-free FeCrBSi SMA coatings with high Ms and high hardness via PTA welding, and since the feedstock powders have chemical composition similar to AISI 430 FSS, the work may bring about novel applications for AISI 430 FSS in particular cases where the considerable wear-resistant performance as well as superior soft magnetic and anti-corrosive properties are required. Full article

(This article belongs to the Special Issue Recent Research on Ferromagnetic Materials)

► Show Figures

Figure 1

16 pages, 4483 KiB

Open AccessArticle

Synthesis and Characterization of Magnetic Molecularly Imprinted Polymer for the Monitoring of Amoxicillin in Real Samples Using the Chromatographic Method

by Rosario López, Sabir Khan, Sergio Espinoza Torres, Ademar Wong, Maria D. P. T. Sotomayor and Gino Picasso

Magnetochemistry 2023, 9(4), 92; https://doi.org/10.3390/magnetochemistry9040092 - 29 Mar 2023

Cited by 5 | Viewed by 1864

Abstract

Amoxicillin (AMX) is an antibiotic frequently used for the treatment of bacterial disorders and respiratory problems in both humans and animals. This work aims to synthesize a molecularly imprinted superparamagnetic polymer (SP-MIP) with a core-shell structure for the selective detection of AMX in [...] Read more.

Amoxicillin (AMX) is an antibiotic frequently used for the treatment of bacterial disorders and respiratory problems in both humans and animals. This work aims to synthesize a molecularly imprinted superparamagnetic polymer (SP-MIP) with a core-shell structure for the selective detection of AMX in real samples. Magnetite superparamagnetic nanoparticles (SNP) were prepared by the polyol method, coated with silica, and functionalized with silane groups. The polymerization process was executed using the free-radical precipitation method. Thermogravimetric analysis (TGA) was used to evaluate the thermal stability of the synthesized materials. The results obtained from N₂ adsorption and desorption analyses showed that the surface area of SP-MIP (19.8 m²/g) was higher than that of the non-molecularly imprinted superparamagnetic polymer (SP-NIP—9.24 m²/g). The optimized adsorption analysis showed that both SP-MIP and SP-NIP followed SIP-type behavior, with adsorption constant K_S 0.01176, 1/n 1.73. The selectivity tests showed that SP-MIP is highly selective for AMX in the presence of other molecules. Finally, for the recovery analysis, the application of SP-MIP for determining AMX in samples of tap water, river water, and drugs using HPLC yielded a mean recovery value of 94.3%. Full article

(This article belongs to the Special Issue Surface Modification of Magnetic Nanoparticles and Their Applications)

► Show Figures

Figure 1

17 pages, 767 KiB

Open AccessArticle

Modeling of the Magnetic Turbulence Level and Source Function of Particle Injection from Multiple SEP Events

by Lele Lian, Gang Qin, Shuangshuang Wu, Yang Wang and Shuwang Cui

Magnetochemistry 2023, 9(4), 91; https://doi.org/10.3390/magnetochemistry9040091 - 27 Mar 2023

Cited by 1 | Viewed by 1092

Abstract

Solar energetic particles (SEPs) are produced by solar eruptions and are harmful to spacecraft and astronauts. The four source function parameters of particle injection for SEP events and the magnetic turbulence level can be collectively referred to as key parameters. We reproduce the [...] Read more.

Solar energetic particles (SEPs) are produced by solar eruptions and are harmful to spacecraft and astronauts. The four source function parameters of particle injection for SEP events and the magnetic turbulence level can be collectively referred to as key parameters. We reproduce the electron intensity-time profiles with simulations for five SEP events observed by multispacecraft such as ACE, STEREO-A, and STEREO-B, so we can obtain the five fitted key parameters for each of the events. We analyze the relationship among the five fitted key parameters, and also the relationship between these parameters and the observed event features. Thus, the model of key parameters are established. Next, we simulate another 12 SEP events with the key parameters model. Though the predicted electron intensity-time profiles do not fit the observed ones well, the peak flux and event-integrated fluence can be predicted accurately. Therefore, the model can be used to estimate the radiation hazards. Full article

(This article belongs to the Special Issue Magnetodynamics of Space Plasmas)

► Show Figures

Figure 1

26 pages, 9997 KiB

Open AccessReview

Recent Structural Developments and Applications of Magnetorheological Dampers (MRD): A Review

by Yanjuan Zhang, Jiaxuan Guo, Jianwei Yang and Xin Li

Magnetochemistry 2023, 9(4), 90; https://doi.org/10.3390/magnetochemistry9040090 - 27 Mar 2023

Cited by 3 | Viewed by 2541

Abstract

Magnetorheological dampers (MRDs) use the controlled rheological properties of MRF with the action of an applied magnetic field to achieve lower current regulation and control larger damping. MRD technology is applied to the defense industry, vehicle engineering, civil engineering, traffic engineering, aerospace, and [...] Read more.

Magnetorheological dampers (MRDs) use the controlled rheological properties of MRF with the action of an applied magnetic field to achieve lower current regulation and control larger damping. MRD technology is applied to the defense industry, vehicle engineering, civil engineering, traffic engineering, aerospace, and other equipment. In this paper, the structural design and latest engineering applications of three types of MRDs including internal, bypass, and hybrid are investigated in terms of the number of coils, piston structure, damping channels, and operating modes to obtain the latest developments of MRDs and analyze potential applications. This study is essential for understanding and developing magnetorheological damping technology and applications. Full article

(This article belongs to the Section Applications of Magnetism and Magnetic Materials)

► Show Figures

Figure 1

12 pages, 4311 KiB

Open AccessArticle

Improving the Path to Obtain Spectroscopic Parameters for the PI3K—(Platinum Complex) System: Theoretical Evidences for Using ¹⁹⁵Pt NMR as a Probe

by Taináh M. R. Santos, Gustavo A. Andolpho, Camila A. Tavares, Mateus A. Gonçalves and Teodorico C. Ramalho

Magnetochemistry 2023, 9(4), 89; https://doi.org/10.3390/magnetochemistry9040089 - 26 Mar 2023

Cited by 3 | Viewed by 1210

Abstract

The absence of adequate force field (FF) parameters to describe certain metallic complexes makes new and deeper analyses impossible. In this context, after a group of researchers developed and validated an AMBER FF for a platinum complex (PC) conjugated with AHBT, new possibilities [...] Read more.

The absence of adequate force field (FF) parameters to describe certain metallic complexes makes new and deeper analyses impossible. In this context, after a group of researchers developed and validated an AMBER FF for a platinum complex (PC) conjugated with AHBT, new possibilities emerged. Thus, in this work, we propose an improved path to obtain NMR spectroscopic parameters, starting from a specific FF for PC, allowing to obtain more reliable information and a longer simulation time. Initially, a docking study was carried out between a PC and PI3K enzyme, aiming to find the most favorable orientation and, from this pose, to carry out a simulation of classical molecular dynamics (MD) with an explicit solvent and simulation time of 50 ns. To explore a new PC environment, a second MD simulation was performed only between the complex and water molecules, under the same conditions as the first MD. After the results of the two MDs, we proposed strategies to select the best amino acid residues (first MD) and water molecules (second MD) through the analyses of hydrogen bonds and minimum distance distribution functions (MDDFs), respectively. In addition, we also selected the best frames from the two MDs through the OWSCA algorithm. From these resources, it was possible to reduce the amount and computational cost of subsequent quantum calculations. Thus, we performed NMR calculations in two chemical environments, enzymatic and aqueous, with theory level GIAO–PBEPBE/NMR-DKH. So, from a strategic path, we were able to obtain more reliable chemical shifts and, therefore, propose safer spectroscopic probes, showing a large difference between the values of chemical shifts in the enzymatic and aqueous environments. Full article

(This article belongs to the Special Issue NMR Spectroscopy in Transition Metal Complexes)

► Show Figures

Figure 1

11 pages, 2218 KiB

Open AccessArticle

The Relationship between Solar Wind Charge Exchange Soft X-ray Emission and the Tangent Direction of Magnetopause in an XMM–Newton Event

by Yingjie Zhang, Tianran Sun, Jennifer A. Carter, Wenhao Liu, Steve Sembay, Li Ji and Chi Wang

Magnetochemistry 2023, 9(4), 88; https://doi.org/10.3390/magnetochemistry9040088 - 24 Mar 2023

Cited by 2 | Viewed by 1164

Abstract

With the advent of soft X-ray imaging enabling global magnetopause detection, it is critical to use reconstruction techniques to derive the 3-dimensional magnetopause location from 2-dimensional X-ray images. One of the important assumptions adopted by most techniques is that the direction with maximum [...] Read more.

With the advent of soft X-ray imaging enabling global magnetopause detection, it is critical to use reconstruction techniques to derive the 3-dimensional magnetopause location from 2-dimensional X-ray images. One of the important assumptions adopted by most techniques is that the direction with maximum soft X-ray emission is the tangent direction of the magnetopause, which has not been validated in observation so far. This paper analyzes a magnetospheric solar wind charge exchange (SWCX) soft X-ray event detected by XMM–Newton during relatively stable solar wind and geomagnetic conditions. The tangent direction of the magnetopause is determined by an empirical magnetopause model. Observation results show that the maximum SWCX soft X-ray intensity gradient tends to be the tangent of the magnetopause’s inner boundary, while the maximum SWCX soft X-ray intensity tends to be the tangent of the magnetopause’s outer boundary. Therefore, it is credible to use the assumption that the tangent direction of the magnetopause is the maximum SWCX soft X-ray intensity or its gradient when reconstructing the 3-dimensional magnetopause location. In addition, since these two maxima tend to be the inner and outer boundaries of the magnetopause, the thickness of magnetopause can also be revealed by soft X-ray imaging. Full article

(This article belongs to the Special Issue Magnetodynamics of Space Plasmas)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Magnetochemistry, Volume 9, Issue 4 (April 2023) – 24 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI