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Magnetochemistry
Volume 8
Issue 7
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Magnetochemistry, Volume 8, Issue 7 (July 2022) – 9 articles

Cover Story (view full-size image): Micro- and nano-structured metal layers are attractive for numerous applications including microelectronics, microcopies and electrocatalysis. Using pulse-reverse electroplating on a planar but magnetically patterned electrode, tall copper structures of about 2 μm height are obtained. A new numerical approach is presented which allows better agreement with the experimental results. A detailed discussion of the magnetic forces and the buoyancy force involved allows us to clarify the growth mechanism of the micro-structures during the alternating pulses and to give an explanation of why the maximum height of the structures is limited to a few microns. View this paper
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11 pages, 5734 KiB  
Article
ESR Investigations of the Submicron LiFe1−xMnxPO4 Systems
by Tatiana Gavrilova, Adilya Yagfarova, Sergey Khantimerov, Dinar Abdullin, Nina Kosova and Nail Suleimanov
Magnetochemistry 2022, 8(7), 74; https://doi.org/10.3390/magnetochemistry8070074 - 21 Jul 2022
Viewed by 1568
Abstract
Magnetic properties of the submicron carbon-coated LiFe1−xMnxPO4 (x = 0, 0.01, 0.1) systems were investigated using the electron spin resonance (ESR) method. The observed ESR signal consisted of two broad resonance lines with a Lorentzian line shape for [...] Read more.
Magnetic properties of the submicron carbon-coated LiFe1−xMnxPO4 (x = 0, 0.01, 0.1) systems were investigated using the electron spin resonance (ESR) method. The observed ESR signal consisted of two broad resonance lines with a Lorentzian line shape for all samples. The temperature dependence character of the integral intensity of these lines changed significantly with increasing manganese concentration, indicating a change in the nature of the magnetic interactions between the manganese and iron ions. We suggest that the noticeable capacity loss observed in the LiFe1−xMnxPO4 systems with increasing Mn content can be explained by the random distribution of Mn ions and changes to the type of magnetic ordering in these systems, despite the attractiveness of the electrochemical Mn2+/Mn3+ pair compared with Fe+2/Fe+3. Full article
(This article belongs to the Section Magnetic Materials)
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13 pages, 3909 KiB  
Article
Terbium (III) Oxide (Tb2O3) Transparent Ceramics by Two-Step Sintering from Precipitated Powder
by Dianjun Hu, Xiaoying Li, Lixuan Zhang, Ilya Snetkov, Penghui Chen, Zhengfa Dai, Stanislav Balabanov, Oleg Palashov and Jiang Li
Magnetochemistry 2022, 8(7), 73; https://doi.org/10.3390/magnetochemistry8070073 - 12 Jul 2022
Cited by 14 | Viewed by 3072
Abstract
As a result of preliminary air calcination and subsequent reduction in a flowing NH3 atmosphere of the precursor from the liquid precipitation method for the first time, pure-phase Tb2O3 powder with an average particle size of 135 nm was [...] Read more.
As a result of preliminary air calcination and subsequent reduction in a flowing NH3 atmosphere of the precursor from the liquid precipitation method for the first time, pure-phase Tb2O3 powder with an average particle size of 135 nm was prepared. The Tb2O3 magneto-optical transparent ceramics with the average grain size of 1.3 μm were successfully fabricated by vacuum pre-sintering and hot isostatic pressing post-treatment from the as-synthesized Tb2O3 powder. In-line transmittance values of Tb2O3 ceramics reach 70.3% at 633 nm, 78.1% at 1064 nm, and 79.4% at 1400 nm, respectively. Thanks to the high intrinsic concentration of Tb3+, Tb2O3 ceramics present high Verdet constants of −427.3 and −123.7 rad·T−1·m−1 at 633 and 1064 nm, which are about 3.1 and 3.4 times higher than those of commercial Tb3Ga5O12 crystals, respectively. Due to the excellent magneto-optical properties, Tb2O3 ceramics are promising candidates for the development of Faraday isolator toward compaction used in visible and near-infrared bands. Full article
(This article belongs to the Special Issue New Trends in Magneto-Optical Ceramics)
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16 pages, 1580 KiB  
Article
Magnetic and Luminescence Properties of 8-Coordinated Pyridyl Adducts of Samarium(III) Complexes Containing 4,4,4-Trifluoro-1-(naphthalen-2-yl)-1,3-butanedionate
by Franz A. Mautner, Florian Bierbaumer, Ramon Vicente, Saskia Speed, Ánnia Tubau, Roland C. Fischer and Salah S. Massoud
Magnetochemistry 2022, 8(7), 72; https://doi.org/10.3390/magnetochemistry8070072 - 11 Jul 2022
Cited by 5 | Viewed by 2046
Abstract
A novel series of polypyridyl adducts, [Sm(ntfa)3(NN)] (2–4), with ntfa = 4,4,4-trifluoro-1-(naphthalen-2-yl)-1,3-butanedionate, NN = 2,2′-bipyridine (bipy), 4,4′-dimethyl-2,2′-bipyridine (4,4′-Me2bipy), and 5,5′-dimethyl-2,2′-bipyridine (5,5′-Me2bipy) were synthesized from the precursor complex [Sm(ntfa)3(MeOH)2] ( [...] Read more.
A novel series of polypyridyl adducts, [Sm(ntfa)3(NN)] (2–4), with ntfa = 4,4,4-trifluoro-1-(naphthalen-2-yl)-1,3-butanedionate, NN = 2,2′-bipyridine (bipy), 4,4′-dimethyl-2,2′-bipyridine (4,4′-Me2bipy), and 5,5′-dimethyl-2,2′-bipyridine (5,5′-Me2bipy) were synthesized from the precursor complex [Sm(ntfa)3(MeOH)2] (1) and the corresponding pyridyl ligands. Single X-ray crystallography showed that the complexes displayed 8-coordinated geometry. The solid pyridyl adducts 2–4 exhibited emission of luminescence in the NIR and visible regions with close quantum yields (QY = 0.20–0.25%). The magnetic data of 1–4 showed larger values than those expected for magnetically noncoupled Sm(III) complexes in the 6H5/2 ground state, with no saturation on the applied high magnetic field static at a temperature of 2 K. Full article
(This article belongs to the Special Issue Characterization of Coordination Compounds)
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66 pages, 6727 KiB  
Article
Theory of Chiral Electrodeposition by Chiral Micro-Nano-Vortices under a Vertical Magnetic Field -1: 2D Nucleation by Micro-Vortices
by Ryoichi Morimoto, Miki Miura, Atsushi Sugiyama, Makoto Miura, Yoshinobu Oshikiri, Iwao Mogi, Yusuke Yamauchi, Satoshi Takagi and Ryoichi Aogaki
Magnetochemistry 2022, 8(7), 71; https://doi.org/10.3390/magnetochemistry8070071 - 6 Jul 2022
Cited by 3 | Viewed by 2308
Abstract
Remarkable chiral activity is donated to a copper deposit surface by magneto-electrodeposition, whose exact mechanism has been clarified by the three-generation model. In copper deposition under a vertical magnetic field, a macroscopic tornado-like rotation called the vertical magnetohydrodynamic (MHD) flow (VMHDF) emerges on [...] Read more.
Remarkable chiral activity is donated to a copper deposit surface by magneto-electrodeposition, whose exact mechanism has been clarified by the three-generation model. In copper deposition under a vertical magnetic field, a macroscopic tornado-like rotation called the vertical magnetohydrodynamic (MHD) flow (VMHDF) emerges on a disk electrode, inducing the precessional motions of various chiral microscopic MHD vortices: First, chiral two-dimensional (2D) nuclei develop on an electrode by micro-MHD vortices. Then, chiral three-dimensional (3D) nuclei grow on a chiral 2D nucleus by chiral nano-MHD vortices. Finally, chiral screw dislocations are created on a chiral 3D nucleus by chiral ultra-micro MHD vortices. These three processes constitute nesting boxes, leading to a limiting enantiomeric excess (ee) ratio of 0.125. This means that almost all chiral activity of copper electrodes made by this method cannot exceed 0.125. It also became obvious that chirality inversion by chloride additive arises from the change from unstable to stable nucleation by the specific adsorption of it. Full article
(This article belongs to the Special Issue Magnetohydrodynamic Effect in Electrochemical Processes: Magnetoelectrodeposition, Magnetoelectrocatalysis, and Related Studies)
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10 pages, 1595 KiB  
Article
Influence of a Constant Magnetic Field on the Mechanism of Adrenaline Oxidation
by Vyacheslav N. Kazin, Evgenii A. Guzov, Valentina A. Moshareva and Evgenii M. Pliss
Magnetochemistry 2022, 8(7), 70; https://doi.org/10.3390/magnetochemistry8070070 - 1 Jul 2022
Cited by 2 | Viewed by 1895
Abstract
In order to establish the role of the magnetic effect in the key stages of the autoxidation and initiated oxidation radical-chain reactions, the experimental data and kinetic analysis of the influence of a magnetic field on the oxidative transformations of adrenaline are presented [...] Read more.
In order to establish the role of the magnetic effect in the key stages of the autoxidation and initiated oxidation radical-chain reactions, the experimental data and kinetic analysis of the influence of a magnetic field on the oxidative transformations of adrenaline are presented in this work. In the case of autoxidation, the process is being controlled by the rate of adrenaline consumption in the gross process of quinoid oxidation. The analysis of the obtained results is estimative and is based on the assumption of the leading role of superoxide radical during the autoxidation. Superoxide radical concentration increases with the increase in the applied magnetic field strength, which leads to the decrease in the rate of initiation of the quinoid process. In the case of initiated oxidation, the results obtained are based on the known radical-chain mechanism, and they were interpreted using the theory of radical pairs. The observed magnetic effect is explained by the influence of a constant magnetic field on the mechanism of chain termination of radical-chain oxidation and/or initiation of the autoxidation process. Full article
(This article belongs to the Special Issue Magnetic Effects—a Tool for Studying the Mechanism of Chemical and Biochemical Processes)
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20 pages, 9469 KiB  
Article
Corrosion Behavior of ZnMn Coatings Magnetoelectrodeposited
by Lamia Allam, Florica S. Lazar and Jean-Paul Chopart
Magnetochemistry 2022, 8(7), 69; https://doi.org/10.3390/magnetochemistry8070069 - 26 Jun 2022
Viewed by 2198
Abstract
The zinc–manganese alloy coatings have been obtained without and with superimposition of a 0.3 T magnetic field in a parallel direction to the working surface electrode. The electrodeposition during 30 min, for two applied potentials (E = −1.6 V/SCE and E = −1.8 [...] Read more.
The zinc–manganese alloy coatings have been obtained without and with superimposition of a 0.3 T magnetic field in a parallel direction to the working surface electrode. The electrodeposition during 30 min, for two applied potentials (E = −1.6 V/SCE and E = −1.8 V/SCE) in an electrochemical bath with the (Zn2+)/(Mn2+) concentration ratio equal to 0.5. The structural, the morphological, and the chemical composition characteristics of the deposits have been studied. It has been found that the applied potentials modify the structural properties of the deposits, η phase-rich deposits elaborated for E = −1.6 V/SCE, and MnZn3-rich deposits elaborated for E = −1.8 V/SCE. The magnetohydrodynamic convection favors the manganese content of the deposit. The corrosion behavior of these coatings has been analyzed in 3.5% NaCl solution by free corrosion potential measurements and electrochemical impedance spectroscopy. The different results show that the corrosion resistance of these zinc–manganese alloy coatings is linked to their structure, to their composition, and to the magnetic field amplitude used during the electrodeposition process. Full article
(This article belongs to the Special Issue Magnetohydrodynamic Effect in Electrochemical Processes: Magnetoelectrodeposition, Magnetoelectrocatalysis, and Related Studies)
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8 pages, 1972 KiB  
Article
Microstructure and Magnetic Properties of M-Type Sr0.1Ca0.4La0.5Fe12O19 Ferrites: The Impact of Different Precursors
by Xiubin Zhao, Shuang Zhang, Jinsong Li, Ailin Xia and Yujie Yang
Magnetochemistry 2022, 8(7), 68; https://doi.org/10.3390/magnetochemistry8070068 - 25 Jun 2022
Cited by 2 | Viewed by 1782
Abstract
M-type Sr0.1Ca0.4La0.5Fe12O19 powder specimens doped with different precursors RFe2O4(R = Co, Ni, Cu, Zn, and Mg) were prepared via a traditional solid-state reaction method. The structural and magnetic properties of [...] Read more.
M-type Sr0.1Ca0.4La0.5Fe12O19 powder specimens doped with different precursors RFe2O4(R = Co, Ni, Cu, Zn, and Mg) were prepared via a traditional solid-state reaction method. The structural and magnetic properties of the specimens were studied. Only nthe single magnetoplumbite phase was found in all the specimens with uniformly distributed particles. The specimen with Zn-type precursor has the highest saturation (Ms), while the specimen with Co-type precursor has the highest remanent magnetism (Mr), coercivity (Hc), and the best comprehensive magnetic properties. Full article
(This article belongs to the Special Issue Hexagonal Ferrites: Synthesis, Structure and Properties)
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14 pages, 4824 KiB  
Review
Breaking of Odd Chirality in Magnetoelectrodeposition
by Iwao Mogi, Ryoichi Morimoto, Ryoichi Aogaki and Kohki Takahashi
Magnetochemistry 2022, 8(7), 67; https://doi.org/10.3390/magnetochemistry8070067 - 23 Jun 2022
Cited by 3 | Viewed by 1678
Abstract
Electrodeposition under magnetic fields (magnetoelectrodeposition; MED) can induce surface chirality on copper films. The chiral signs of MED films should depend on the magnetic field polarity; namely, the reversal of the magnetic field causes the opposite chiral sign. This represents odd chirality for [...] Read more.
Electrodeposition under magnetic fields (magnetoelectrodeposition; MED) can induce surface chirality on copper films. The chiral signs of MED films should depend on the magnetic field polarity; namely, the reversal of the magnetic field causes the opposite chiral sign. This represents odd chirality for the magnetic field polarity. However, odd chirality was broken in several MED conditions. This paper makes a survey of breaking of odd chirality in the MED conditions such as low magnetic fields, specific adsorption of chloride ions, micro-electrode, and cell rotation. These results indicate that the ordered fluctuation of magnetohydrodynamic micro-vortices induces the breaking of odd chirality and that the random fluctuation results in the disappearance of surface chirality. Full article
(This article belongs to the Special Issue Magnetohydrodynamic Effect in Electrochemical Processes: Magnetoelectrodeposition, Magnetoelectrocatalysis, and Related Studies)
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12 pages, 2059 KiB  
Article
Pulse Reverse Plating of Copper Micro-Structures in Magnetic Gradient Fields
by Mengyuan Huang, Margitta Uhlemann, Kerstin Eckert and Gerd Mutschke
Magnetochemistry 2022, 8(7), 66; https://doi.org/10.3390/magnetochemistry8070066 - 22 Jun 2022
Cited by 4 | Viewed by 2131
Abstract
Micro-structured copper layers are obtained from pulse-reverse electrodeposition on a planar gold electrode that is magnetically patterned by magnetized iron wires underneath. 3D numerical simulations of the electrodeposition based on an adapted reaction kinetics are able to nicely reproduce the micro-structure of the [...] Read more.
Micro-structured copper layers are obtained from pulse-reverse electrodeposition on a planar gold electrode that is magnetically patterned by magnetized iron wires underneath. 3D numerical simulations of the electrodeposition based on an adapted reaction kinetics are able to nicely reproduce the micro-structure of the deposit layer, despite the height values still remain underestimated. It is shown that the structuring is enabled by the magnetic gradient force, which generates a local flow that supports deposition and hinders dissolution in the regions of high magnetic gradients. The Lorentz force originating from radial magnetic field components near the rim of the electrode causes a circumferential cell flow. The resulting secondary flow, however, is superseded by the local flow driven by the magnetic gradient force in the vicinity of the wires. Finally, the role of solutal buoyancy effects is discussed to better understand the limitations of structured growth in different modes of deposition and cell geometries. Full article
(This article belongs to the Special Issue Magnetohydrodynamic Effect in Electrochemical Processes: Magnetoelectrodeposition, Magnetoelectrocatalysis, and Related Studies)
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