Magnetochemistry

12 pages, 3540 KiB

Open AccessReview

Recent Advances in the Catalytic Applications of Lanthanide-Oxo Clusters

by Weiming Huang, Qingxin Liu, Wanmin Chen, Min Feng and Zhiping Zheng

Magnetochemistry 2021, 7(12), 161; https://doi.org/10.3390/magnetochemistry7120161 - 20 Dec 2021

Cited by 18 | Viewed by 4050

Lanthanide-oxo/hydroxo clusters (LOCs) in this mini-review refer to polynuclear complexes featuring a polyhedral metal-oxo/hydroxo cluster core of lanthanide ions exclusively or with coexisting 3d metal ions. We summarize herein the recent works using this unique family of cluster complexes for catalysis; this [...] Read more.

Lanthanide-oxo/hydroxo clusters (LOCs) in this mini-review refer to polynuclear complexes featuring a polyhedral metal-oxo/hydroxo cluster core of lanthanide ions exclusively or with coexisting 3d metal ions. We summarize herein the recent works using this unique family of cluster complexes for catalysis; this aspect of research stands in stark contrast to their extensively studied synthetic and structural chemistry as well as the much-researched magnetic properties. Following a brief introduction of the synthetic strategies for these clusters, pertinent results from available literature reports are surveyed and discussed according to the types of catalyzed reactions. Particular attention was paid to the selection of a cluster catalyst for a specific type of reactions as well as the corresponding reaction mechanism. To the end, the advantages and challenges in utilizing LOCs as multifunctional catalysts are summarized, and possible future research directions are proposed. Full article

(This article belongs to the Special Issue Advances in Lanthanide Coordination Chemistry)

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7 pages, 1244 KiB

Open AccessArticle

Microstructure and Magnetic Properties of Ce₁₄Fe₇₈Co₂B₆ Nanopowders Prepared by Ball Milling at Low Temperature

by Marian Grigoras, Mihaela Lostun, Firuta Borza, Marieta Porcescu, George Stoian and Nicoleta Lupu

Magnetochemistry 2021, 7(12), 160; https://doi.org/10.3390/magnetochemistry7120160 - 10 Dec 2021

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Abstract

Ce₁₄Fe₇₈Co₂B₆ nanopowders with hard-magnetic properties have been successfully prepared by ball milling at low temperatures in liquid nitrogen. The morphology, structure, and magnetic properties of Ce₁₄Fe₇₈Co₂B₆ powders have been [...] Read more.

Ce₁₄Fe₇₈Co₂B₆ nanopowders with hard-magnetic properties have been successfully prepared by ball milling at low temperatures in liquid nitrogen. The morphology, structure, and magnetic properties of Ce₁₄Fe₇₈Co₂B₆ powders have been investigated using scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometry, respectively. It was found that powder ball milling at low temperature in liquid nitrogen, has the advantage that the oxidation of powders is inhibited and the particles rapidly reach nanometric dimensions. In comparison to the Ce₁₄Fe₇₈Co₂B₆ powders prepared by ball milling at room temperature, the powders milled at low temperature present a more uniform particle size and no rare-earth oxides, which leads thus to remarkable magnetic properties. The nanocrystalline Ce₁₄Fe₇₈Co₂B₆ powders with optimum characteristics, prepared at low temperature, have the size of 153 nm or less, present a coercivity of 5.1 kOe, and a saturation magnetization of 113 emu/g after milling for 6 h at low temperature. Low temperature milling may become a promising technique for the fabrication of high performance powders used for permanent magnets preparation. Full article

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

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12 pages, 3900 KiB

Open AccessArticle

Structural, Electronic and Magnetic Properties of Mn₂Co_1-xV_xZ (Z = Ga, Al) Heusler Alloys: An Insight from DFT Study

by Fatima Abuova, Talgat Inerbaev, Aisulu Abuova, Nurpeis Merali, Nurgul Soltanbek, Gulbanu Kaptagay, Marina Seredina and Vladimir Khovaylo

Magnetochemistry 2021, 7(12), 159; https://doi.org/10.3390/magnetochemistry7120159 - 8 Dec 2021

Cited by 5 | Viewed by 3557

Abstract

Structural, electronic, and magnetic properties of Mn₂Co_1-xV_xZ (Z = Ga, Al, x = 0, 0.25, 0.5, 0.75, 1) Heusler alloys were theoretically investigated for the case of L2₁ (space group Fm

\bar{3}

m), [...] Read more.

Structural, electronic, and magnetic properties of Mn₂Co_1-xV_xZ (Z = Ga, Al, x = 0, 0.25, 0.5, 0.75, 1) Heusler alloys were theoretically investigated for the case of L2₁ (space group Fm

\bar{3}

m), L2_1b (L2₁ structure with partial disordering between Co and Mn atoms) and XA (space group F

\bar{4}

3m) structures. It was found that the XA structure is more stable at low V concentrations, while the L2₁ structure is energetically favorable at high V concentrations. A transition from L2₁ to XA ordering occurs near x = 0.5, which qualitatively agrees with the experimental results. Comparison of the energies of the L2_1b and XA structures leads to the fact that the phase transition between these structures occurs at x = 0.25, which is in excellent agreement with the experimental data. The lattice parameters linearly change as x grows. For the L2₁ structure, a slight decrease in the lattice constant a was observed, while for the XA structure, an increase in a was found. The experimentally observed nonlinear behavior of the lattice parameters with a change in the V content is most likely a manifestation of the presence of a mixture of phases. Almost complete compensation of the magnetic moment was achieved for the Mn₂Co_1-xV_xZ alloy (Z = Ga, Al) at x = 0.5 for XA ordering. In the case of the L2₁ ordering, it is necessary to consider a partial disorder of atoms in the Mn and Co sublattices in order to achieve compensation of the magnetic moment. Full article

(This article belongs to the Section Spin Crossover and Spintronics)

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18 pages, 2918 KiB

Open AccessReview

Polarized Neutron Diffraction: An Excellent Tool to Evidence the Magnetic Anisotropy—Structural Relationships in Molecules

by Dominique Luneau and Béatrice Gillon

Magnetochemistry 2021, 7(12), 158; https://doi.org/10.3390/magnetochemistry7120158 - 6 Dec 2021

Cited by 5 | Viewed by 3026

Abstract

This publication reviews recent advances in polarized neutron diffraction (PND) studies of magnetic anisotropy in coordination compounds comprising d or f elements and having different nuclearities. All these studies illustrate the extent to which PND can provide precise and direct information on the [...] Read more.

This publication reviews recent advances in polarized neutron diffraction (PND) studies of magnetic anisotropy in coordination compounds comprising d or f elements and having different nuclearities. All these studies illustrate the extent to which PND can provide precise and direct information on the relationship between molecular structure and the shape and axes of magnetic anisotropy of the individual metal sites. It makes this experimental technique (PND) an excellent tool to help in the design of molecular-based magnets and especially single-molecule magnets for which strong uniaxial magnetic anisotropy is required. Full article

(This article belongs to the Special Issue From Magnetic Anisotropy to Molecular Magnets: Theory and Experiments)

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15 pages, 5143 KiB

Open AccessArticle

Electrochemical, Electrocatalytic, and Magnetic Properties of Vanadium-Containing Polyoxometalates

by Joseph Dika Manga, Anne-Lucie Teillout, Eric Rivière, Pedro de Oliveira and Israël Martyr Mbomekallé

Magnetochemistry 2021, 7(12), 157; https://doi.org/10.3390/magnetochemistry7120157 - 3 Dec 2021

Cited by 2 | Viewed by 3104

Abstract

Mono-substituted vanadium-containing Dawson-type polyoxometalates having the general formula α₁-[V^IVW₁₇X₂O₆₂]⁸⁻ and α₂-[V^IVW₁₇X₂O₆₂]⁸⁻, with X = As or P, were synthesised and [...] Read more.

Mono-substituted vanadium-containing Dawson-type polyoxometalates having the general formula α₁-[V^IVW₁₇X₂O₆₂]⁸⁻ and α₂-[V^IVW₁₇X₂O₆₂]⁸⁻, with X = As or P, were synthesised and subject to a comprehensive electrochemical study comprising the pH dependency. These POMs exhibit an electrocatalytic behaviour towards the oxidation of thiols (namely cysteine), rendering them interesting species for mimicking oxidative stress situations, at physiological pH values. The efficiency of the electro-oxidation was assessed with thiols of different nature, and the substrate that responded best was used to compare the electrocatalytic capabilities of the POM series. The magnetic behaviour of these POMs was also evaluated and compared to their analogues, α₁- and α₂-[V^VW₁₇X₂O₆₂]⁷⁻ (X = As or P), at low temperatures and showed, as expected, a paramagnetic behaviour of V^IV based compounds. Full article

(This article belongs to the Special Issue Paramagnetic Metal Ion-Containing Polyoxometalates)

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8 pages, 1759 KiB

Open AccessArticle

Ferromagnetic Resonance of a [GeTe/Sb₂Te₃]₆/Py Superlattice

by Satoshi Sumi, Yuichiro Hirano, Hiroyuki Awano and Junji Tominaga

Magnetochemistry 2021, 7(12), 156; https://doi.org/10.3390/magnetochemistry7120156 - 26 Nov 2021

Cited by 2 | Viewed by 2725

Abstract

A [GeTe/Sb₂Te₃] superlattice is known as a topological insulator. It shows magnetic responses such as magneto-optical effect, magneto resistance, magneto capacitance, and so on. We have reported that [GeTe/Sb₂Te₃] superlattice film has a large spin–orbit [...] Read more.

A [GeTe/Sb₂Te₃] superlattice is known as a topological insulator. It shows magnetic responses such as magneto-optical effect, magneto resistance, magneto capacitance, and so on. We have reported that [GeTe/Sb₂Te₃] superlattice film has a large spin–orbit interaction using a spin pumping method of a [GeTe/Sb₂Te₃]/Py superlattice. In this paper, we demonstrate a ST-FMR (spin transfer torque ferromagnetic resonance) of the [GeTe/Sb₂Te₃]₆/Py superlattice, compared with a W/Py bilayer. The superlattice film showed a large resonance signal with a symmetric component. The ratio of symmetric components (S) to anti-symmetric (A) components (S/A) was 1.4, which suggests that the superlattice exhibits a large spin Hall angle. The [GeTe/Sb₂Te₃] superlattice will be suitable as a hetero-interface material required for high performance spintronics devices in future. Full article

(This article belongs to the Section Spin Crossover and Spintronics)

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9 pages, 1223 KiB

Open AccessArticle

Magnonic Crystal with Strips of Magnetic Nanoparticles: Modeling and Experimental Realization via a Dip-Coating Technique

by Zorayda Lazcano-Ortiz, Cesar L. Ordóñez-Romero, Jorge Luis Domínguez-Juárez, Guillermo Monsivais, Rafael Quintero-Torres, Daniel Matatagui, José Roberto Fragoso-Mora, Naser Qureshi and Oleg Kolokoltsev

Magnetochemistry 2021, 7(12), 155; https://doi.org/10.3390/magnetochemistry7120155 - 26 Nov 2021

Cited by 4 | Viewed by 2955

Abstract

In this article, we describe a magnonic crystal formed by magnetite nanoparticles. The periodic strip-like structure of the nanoparticles was fabricated on the surface of thin yttrium iron garnet single-crystal film grown on a gallium–gadolinium garnet substrate via dip-coating techniques. It was shown [...] Read more.

In this article, we describe a magnonic crystal formed by magnetite nanoparticles. The periodic strip-like structure of the nanoparticles was fabricated on the surface of thin yttrium iron garnet single-crystal film grown on a gallium–gadolinium garnet substrate via dip-coating techniques. It was shown that such periodic structure induces the formation of the bandgaps in the transmission spectra of magnetostatic surface spin-waves (MSSW). The structure was simulated by the transfer matrix method. Spin-wave detection has been carried out by using a pair of microwave antennas and a vector network analyzer. Full article

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7 pages, 1065 KiB

Open AccessCommunication

Solid-State Heating Using the Multicaloric Effect in Multiferroics

by Melvin M. Vopson, Yuri K. Fetisov and Ian Hepburn

Magnetochemistry 2021, 7(12), 154; https://doi.org/10.3390/magnetochemistry7120154 - 24 Nov 2021

Cited by 2 | Viewed by 3280

Abstract

The multicaloric effect is defined as the adiabatic reversible temperature change in multiferroic materials induced by the application of an external electric or magnetic field, and it was first theoretically proposed in 2012. The multicaloric effects in multiferroics, as well as other similar [...] Read more.

The multicaloric effect is defined as the adiabatic reversible temperature change in multiferroic materials induced by the application of an external electric or magnetic field, and it was first theoretically proposed in 2012. The multicaloric effects in multiferroics, as well as other similar caloric effects in single ferroics, such as magnetocaloric, elastocaloric, barocaloric, and electrocaloric, have been the focus of much research due to their potential commercialization in solid-state refrigeration. In this short communication article, we examine the thermodynamics of the multicaloric effect for solid-state heating applications. A possible thermodynamic multicaloric heating cycle is proposed and then implemented to estimate the solid-state heating effect for a known electrocaloric system. This work offers a path to implementing caloric and multicaloric effects to efficient heating systems, and we offer a theoretical estimate of the upper limit of the temperature change achievable in a multicaloric cooling or heating effect. Full article

(This article belongs to the Special Issue Multiferroic Materials 2021)

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11 pages, 3107 KiB

Open AccessFeature PaperArticle

Syntheses, Structures and Magnetic Properties of M₂ (M = Fe, Co) Complexes with N₆ Coordination Environment: Field-Induced Slow Magnetic Relaxation in Co₂

by Qianqian Yang, Xiao-Lei Li and Jinkui Tang

Magnetochemistry 2021, 7(12), 153; https://doi.org/10.3390/magnetochemistry7120153 - 23 Nov 2021

Cited by 1 | Viewed by 2752

Abstract

Two dinuclear complexes [M₂(H₂L)₂](ClO₄)₄·2MeCN (M = Co for Co₂ and Fe for Fe₂) were synthesized using a symmetric hydrazone ligand with the metal ions in an N₆ coordination environment. [...] Read more.

Two dinuclear complexes [M₂(H₂L)₂](ClO₄)₄·2MeCN (M = Co for Co₂ and Fe for Fe₂) were synthesized using a symmetric hydrazone ligand with the metal ions in an N₆ coordination environment. The crystal structures and magnetic properties were determined by single-crystal X-ray diffraction and magnetic susceptibility measurements. The crystal structure study revealed that the spin centers were all in the high-spin state with a distorted octahedron (O_h) geometry. Dynamic magnetic properties measurements revealed that complex Co₂ exhibited field-induced single-molecule magnet properties with two-step relaxation in which the fast relaxation path was from QTM and the slow relaxation path from the thermal relaxation under an applied field. Full article

(This article belongs to the Special Issue Magnetic Properties of Metal Complexes)

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6 pages, 252 KiB

Open AccessEditorial

Perspectives on Molecular Materials—A Tribute to Professor Peter Day

by Lee Martin, Scott S. Turner, John D. Wallis, Hiroki Akutsu and Carlos J. Gómez-García

Magnetochemistry 2021, 7(12), 152; https://doi.org/10.3390/magnetochemistry7120152 - 23 Nov 2021

Viewed by 2230

Abstract

Professor Peter Day FRS was born on 20 August 1938 in Kent (UK) and attended Maidstone Grammar School [...] Full article

(This article belongs to the Special Issue Perspectives on Molecular Materials—A Tribute to Professor Peter Day)

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Magnetochemistry, Volume 7, Issue 12 (December 2021) – 10 articles

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