Magnetochemistry

15 pages, 3940 KiB

Open AccessArticle

Effect of Composition on the Phase Structure and Magnetic Properties of Ball-Milled LaFe_11.71-xMn_xSi_1.29H_1.6 Magnetocaloric Powders

by Jamieson Brechtl, Michael R. Koehler, Michael S. Kesler, Hunter B. Henderson, Alexander A. Baker, Kai Li, James Kiggans, Kashif Nawaz, Orlando Rios and Ayyoub M. Momen

Magnetochemistry 2021, 7(9), 132; https://doi.org/10.3390/magnetochemistry7090132 - 21 Sep 2021

Cited by 2 | Viewed by 1981

Abstract

Magnetocaloric alloys are an important class of materials that enable non-vapor compression cycles. One promising candidate for magnetocaloric systems is LaFeMnSi, thanks to a combination of factors including low-cost constituents and a useful curie temperature, although control of the constituents’ phase distribution can [...] Read more.

Magnetocaloric alloys are an important class of materials that enable non-vapor compression cycles. One promising candidate for magnetocaloric systems is LaFeMnSi, thanks to a combination of factors including low-cost constituents and a useful curie temperature, although control of the constituents’ phase distribution can be challenging. In this paper, the effects of composition and high energy ball milling on the particle morphology and phase stability of LaFe_11.71-xMn_xSi_1.29H_1.6 magnetocaloric powders were investigated. The powders were characterized with optical microscopy, dynamic light scattering, X-ray diffraction (XRD), and differential scanning calorimetry (DSC). It was found that the powders retained most of their original magnetocaloric phase during milling, although milling reduced the degree of crystallinity in the powder. Furthermore, some oxide phases (<1 weight percent) were present in the as-received and milled powders, which indicates that no significant contamination of the powders occurred during milling. Finally, the results indicated that the Curie temperature drops as Fe content decreases (Mn content increases). In all of the powders, milling led to an increase in the Curie temperature of ~3–6 °C. Full article

(This article belongs to the Special Issue Advanced Materials for Magnetic Cooling)

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13 pages, 1088 KiB

Open AccessArticle

Electronic Structure of Tyrosyl D Radical of Photosystem II, as Revealed by 2D-Hyperfine Sublevel Correlation Spectroscopy

by Maria Chrysina, Georgia Zahariou, Nikolaos Ioannidis, Yiannis Sanakis and George Mitrikas

Magnetochemistry 2021, 7(9), 131; https://doi.org/10.3390/magnetochemistry7090131 - 21 Sep 2021

Cited by 1 | Viewed by 1867

Abstract

The biological water oxidation takes place in Photosystem II (PSII), a multi-subunit protein located in thylakoid membranes of higher plant chloroplasts and cyanobacteria. The catalytic site of PSII is a Mn

_{4}

Ca cluster and is known as the oxygen evolving complex (OEC) [...] Read more.

The biological water oxidation takes place in Photosystem II (PSII), a multi-subunit protein located in thylakoid membranes of higher plant chloroplasts and cyanobacteria. The catalytic site of PSII is a Mn

_{4}

Ca cluster and is known as the oxygen evolving complex (OEC) of PSII. Two tyrosine residues D1-Tyr161 (Y

_{Z}

) and D2-Tyr160 (Y

_{D}

) are symmetrically placed in the two core subunits D1 and D2 and participate in proton coupled electron transfer reactions. Y

_{Z}

of PSII is near the OEC and mediates electron coupled proton transfer from Mn

_{4}

Ca to the photooxidizable chlorophyll species P

_{680}^{+}

. Y

_{D}

does not directly interact with OEC, but is crucial for modulating the various S oxidation states of the OEC. In PSII from higher plants the environment of Y

_{D}

^{•}

radical has been extensively characterized only in spinach (Spinacia oleracea) Mn-depleted non functional PSII membranes. Here, we present a 2D-HYSCORE investigation in functional PSII of spinach to determine the electronic structure of Y

_{D}

^{•}

radical. The hyperfine couplings of the protons that interact with the Y

_{D}

^{•}

radical are determined and the relevant assignment is provided. A discussion on the similarities and differences between the present results and the results from studies performed in non functional PSII membranes from higher plants and PSII preparations from other organisms is given. Full article

(This article belongs to the Special Issue EPR Spectroscopy in Chemistry and Biology)

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14 pages, 2517 KiB

Open AccessArticle

by Carmine Stefano Clemente, Daniele Davino, Pavel Krejčí and Vincenzo Paolo Loschiavo

Magnetochemistry 2021, 7(9), 130; https://doi.org/10.3390/magnetochemistry7090130 - 17 Sep 2021

Cited by 1 | Viewed by 1597

Abstract

Magnetostrictive behavior is characterized by a complex coupling between magnetic and mechanical quantities. While this behavior can be quite easily exploited for both actuation and sensing or energy conversion purposes, the complex hysteresis interaction between magnetization and magnetic field and mechanical stress and [...] Read more.

Magnetostrictive behavior is characterized by a complex coupling between magnetic and mechanical quantities. While this behavior can be quite easily exploited for both actuation and sensing or energy conversion purposes, the complex hysteresis interaction between magnetization and magnetic field and mechanical stress and strain is hard to model. Nevertheless, magnetic and magnetostrictive experimental curves are quite self-similar, assuming stress as self-similarity parameter. The quantification of this concept would help modeling. Here, this concept is quantified and experimentally confirmed over different types of magnetostrictive samples. Full article

(This article belongs to the Special Issue Magnetoelastic Effects)

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13 pages, 3263 KiB

Open AccessArticle

Structure and Magnetic Properties of Fe-B-La-Al Alloy

by Sabina Lesz, Piotr Kwapuliński, Małgorzata Karolus, Klaudiusz Gołombek, Bartłomiej Hrapkowicz, Adam Zarychta, Rafał Babilas, Julia Popis and Patrycja Janiak

Magnetochemistry 2021, 7(9), 129; https://doi.org/10.3390/magnetochemistry7090129 - 17 Sep 2021

Viewed by 1512

Abstract

Nanocrystalline magnetic materials are of great interest in order to meet the needs of electronics and electrical engineering. There are many possibilities to modify the synthesis parameters and chemical composition in order to obtain the most desirable magnetic properties and microstructure. The paper [...] Read more.

Nanocrystalline magnetic materials are of great interest in order to meet the needs of electronics and electrical engineering. There are many possibilities to modify the synthesis parameters and chemical composition in order to obtain the most desirable magnetic properties and microstructure. The paper discusses an iron-based alloy with the addition of boron lanthanum and aluminium. The alloy was obtained by induction melting and casting with a melt-spinner. The main purpose of the work was to analyze the structure and properties of both the starting alloys in the form of ingots and the obtained tapes. X-ray diffraction (XRD), scanning electron microscopy (SEM), vibration magnetometry (VSM) and microhardness measurements using the Vickers method were carried out. Full article

(This article belongs to the Special Issue Advances in Amorphous and Nanocrystalline Magnetic Materials)

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12 pages, 1348 KiB

Open AccessArticle

The Effect of pH and Buffer on Oligonucleotide Affinity for Iron Oxide Nanoparticles

by Ekaterina Bobrikova, Alexey Chubarov and Elena Dmitrienko

Magnetochemistry 2021, 7(9), 128; https://doi.org/10.3390/magnetochemistry7090128 - 14 Sep 2021

Cited by 8 | Viewed by 2305

Abstract

Magnetic Fe₃O₄ nanoparticles (MNPs) have great potential in the nucleic acid delivery approach for therapeutic applications. Herein, the formation of a stable complex of iron oxide nanoparticles with oligonucleotides was investigated. Several factors, such as pH, buffer components, and oligonucleotides [...] Read more.

Magnetic Fe₃O₄ nanoparticles (MNPs) have great potential in the nucleic acid delivery approach for therapeutic applications. Herein, the formation of a stable complex of iron oxide nanoparticles with oligonucleotides was investigated. Several factors, such as pH, buffer components, and oligonucleotides sequences, were chosen for binding efficiency studies and oligonucleotide binding constant calculation. Standard characterization techniques, such as dynamic light scattering, zeta potential, and transmission electron microscopy, provide MNPs coating and stability. The toxicity experiments were performed using lung adenocarcinoma A549 cell line and high reactive oxygen species formation with methylene blue assay. Fe₃O₄ MNPs complexes with oligonucleotides show high stability and excellent biocompatibility. Full article

(This article belongs to the Special Issue Magnetic Nanospecies: Synthesis, Properties, Physical and Biomedical Applications)

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Graphical abstract

9 pages, 1954 KiB

Open AccessArticle

Growth and Characterisation of Antiferromagnetic Ni₂MnAl Heusler Alloy Films

by Teodor Huminiuc, Oliver Whear, Andrew J. Vick, David C. Lloyd, Gonzalo Vallejo-Fernandez, Kevin O’Grady and Atsufumi Hirohata

Magnetochemistry 2021, 7(9), 127; https://doi.org/10.3390/magnetochemistry7090127 - 13 Sep 2021

Cited by 4 | Viewed by 2198

Abstract

Recent rapid advancement in antiferromagnetic spintronics paves a new path for efficient computing with THz operation. To date, major studies have been performed with conventional metallic, e.g., Ir-Mn and Pt-Mn, and semiconducting, e.g., CuMnAs, antiferromagnets, which may suffer from their elemental criticality and [...] Read more.

Recent rapid advancement in antiferromagnetic spintronics paves a new path for efficient computing with THz operation. To date, major studies have been performed with conventional metallic, e.g., Ir-Mn and Pt-Mn, and semiconducting, e.g., CuMnAs, antiferromagnets, which may suffer from their elemental criticality and high resistivity. In order to resolve these obstacles, new antiferromagnetic films are under intense development for device operation above room temperature. Here, we report the structural and magnetic properties of an antiferromagnetic Ni₂MnAl Heusler alloy with and without Fe and Co doping in thin film form, which has significant potential for device applications. Full article

(This article belongs to the Special Issue Advances in Antiferromagnetic Spintronics)

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18 pages, 2674 KiB

Open AccessFeature PaperArticle

Ferromagnetic Resonance Studies in Magnetic Nanosystems

by David S. Schmool, Daniel Markó, Ko-Wei Lin, Aurelio Hierro-Rodríguez, Carlos Quirós, Javier Díaz, Luis Manuel Álvarez-Prado and Jong-Ching Wu

Magnetochemistry 2021, 7(9), 126; https://doi.org/10.3390/magnetochemistry7090126 - 12 Sep 2021

Cited by 3 | Viewed by 5053

Abstract

Ferromagnetic resonance is a powerful method for the study of all classes of magnetic materials. The experimental technique has been used for many decades and is based on the excitation of a magnetic spin system via a microwave (or rf) field. While earlier [...] Read more.

Ferromagnetic resonance is a powerful method for the study of all classes of magnetic materials. The experimental technique has been used for many decades and is based on the excitation of a magnetic spin system via a microwave (or rf) field. While earlier methods were based on the use of a microwave spectrometer, more recent developments have seen the widespread use of the vector network analyzer (VNA), which provides a more versatile measurement system at almost comparable sensitivity. While the former is based on a fixed frequency of excitation, the VNA enables frequency-dependent measurements, allowing more in-depth analysis. We have applied this technique to the study of nanostructured thin films or nanodots and coupled magnetic layer systems comprised of exchange-coupled ferromagnetic layers with in-plane and perpendicular magnetic anisotropies. In the first system, we have investigated the magnetization dynamics in Co/Ag bilayers and nanodots. In the second system, we have studied Permalloy (Ni

_{80}

Fe

_{20}

, hereafter Py) thin films coupled via an intervening Al layer of varying thickness to a NdCo film which has perpendicular magnetic anisotropy. Full article

(This article belongs to the Special Issue Recent Advances in Nanomagnetism)

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12 pages, 5136 KiB

Open AccessArticle

Low-Coordinate Dinuclear Dysprosium(III) Single Molecule Magnets Utilizing LiCl as Bridging Moieties and Tris(amido)amine as Blocking Ligands

by Maria Brzozowska, Gabriela Handzlik, Mikolaj Zychowicz and Dawid Pinkowicz

Magnetochemistry 2021, 7(9), 125; https://doi.org/10.3390/magnetochemistry7090125 - 11 Sep 2021

Cited by 4 | Viewed by 1860

Abstract

A low-coordinate dinuclear dysprosium complex {[Dy(N₃N)(THF)][LiCl(THF)]}₂ (Dy₂) with a double bridging ‘LiCl’ moiety and tris(amido)amine (N₃N)³⁻ anions as a blocking ligand is synthesized and characterized structurally and magnetically. Thanks to the use of the [...] Read more.

A low-coordinate dinuclear dysprosium complex {[Dy(N₃N)(THF)][LiCl(THF)]}₂ (Dy₂) with a double bridging ‘LiCl’ moiety and tris(amido)amine (N₃N)³⁻ anions as a blocking ligand is synthesized and characterized structurally and magnetically. Thanks to the use of the chelating blocking ligand (N₃N)³⁻ equipped with large steric –SiMe₃ groups, the coordination sphere of both Dy^III ions is restricted to only six donor atoms. The three amido nitrogen atoms determine the orientation of the easy magnetization axes of both Dy^III centers. Consequently, Dy₂ shows slow magnetic relaxation typical for single molecule magnets (SMMs). However, the effective energy barrier for magnetization reversal determined from the AC magnetic susceptibility measurements is much lower than the separation between the ground and the first excited Kramers doublet based on the CASSCF ab initio calculations. In order to better understand the possible influence of the anticipated intramolecular magnetic interactions in this dinuclear molecule, its Gd^III-analog {[Gd(N₃N)(THF)][LiCl(THF)]}₂ (Gd₂) is also synthesized and studied magnetically. Detailed magnetic measurements reveal very weak antiferromagnetic interactions in Gd₂. This in turn suggests similar antiferromagnetic interactions in Dy₂, which might be responsible for its peculiar SMM behavior and the absence of the magnetic hysteresis loop. Full article

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

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Graphical abstract

14 pages, 2024 KiB

Open AccessArticle

Field-Induced SMM and Vis/NIR Luminescence on Mononuclear Lanthanide Complexes with 9-Anthracenecarboxylate and 2,2′:6,2″-Terpyridine

by Berta Casanovas, Oriol Porcar, Saskia Speed, Ramon Vicente, Mercè Font-Bardía and Mohamed Salah El Fallah

Magnetochemistry 2021, 7(9), 124; https://doi.org/10.3390/magnetochemistry7090124 - 10 Sep 2021

Cited by 7 | Viewed by 2212

Abstract

Five new mononuclear lanthanide complexes are synthesized by adding the several lanthanide nitrate hexahydrate salts, which for lanthanide (Ln) are Eu, Tb, Dy, Er, and Yb, with 9-anthracenecarboxylic acid (9-Hanthc) and 2,2′:6,2″-terpyridine (TPY) in mixed solution of methanol and dimethylformamide (DMF). The general [...] Read more.

Five new mononuclear lanthanide complexes are synthesized by adding the several lanthanide nitrate hexahydrate salts, which for lanthanide (Ln) are Eu, Tb, Dy, Er, and Yb, with 9-anthracenecarboxylic acid (9-Hanthc) and 2,2′:6,2″-terpyridine (TPY) in mixed solution of methanol and dimethylformamide (DMF). The general formula is [Eu(9-anthc)₃(TPY)(DMF)]·H₂O (1Eu) where Eu(III) is ennea-coordinated or [Ln(9-anthc)₃(TPY)(H₂O)]·H₂O·DMF (Ln = Tb (2Tb), Dy (3Dy), Er (4Er), and Yb (5Yb)) where Ln(III) is octa-coordinated. For compounds 3Dy, 4Er, and 5Yb, the dynamic ac magnetic study indicated field-induced single molecule magnet (SMM) behavior. The photoluminescence studies in the solid state of these complexes show the sensitization of 4f-4f transitions for 4Er and 5Yb in the NIR region. Full article

(This article belongs to the Special Issue Reviews on Slow-Relaxation Molecules)

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25 pages, 5391 KiB

Open AccessReview

Review of Magnetic Shape Memory Polymers and Magnetic Soft Materials

by Sanne J. M. van Vilsteren, Hooman Yarmand and Sepideh Ghodrat

Magnetochemistry 2021, 7(9), 123; https://doi.org/10.3390/magnetochemistry7090123 - 9 Sep 2021

Cited by 16 | Viewed by 4982

Abstract

Magnetic soft materials (MSMs) and magnetic shape memory polymers (MSMPs) have been some of the most intensely investigated newly developed material types in the last decade, thanks to the great and versatile potential of their innovative characteristic behaviors such as remote and nearly [...] Read more.

Magnetic soft materials (MSMs) and magnetic shape memory polymers (MSMPs) have been some of the most intensely investigated newly developed material types in the last decade, thanks to the great and versatile potential of their innovative characteristic behaviors such as remote and nearly heatless shape transformation in the case of MSMs. With regard to a number of properties such as shape recovery ratio, manufacturability, cost or programming potential, MSMs and MSMPs may exceed conventional shape memory materials such as shape memory alloys or shape memory polymers. Nevertheless, MSMs and MSMPs have not yet fully touched their scientific-industrial potential, basically due to the lack of detailed knowledge on various aspects of their constitutive response. Therefore, MSMs and MSMPs have been developed slowly but their importance will undoubtedly increase in the near future. This review emphasizes the development of MSMs and MSMPs with a specific focus on the role of the magnetic particles which affect the shape memory recovery and programming behavior of these materials. In addition, the synthesis and application of these materials are addressed. Full article

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

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10 pages, 924 KiB

Open AccessFeature PaperArticle

AC Susceptibility Studies of Magnetic Relaxation in Mn₁₂-Stearate SMMs on the Spherical Silica Surface

by Oleksandr Pastukh, Piotr Konieczny, Magdalena Laskowska and Łukasz Laskowski

Magnetochemistry 2021, 7(9), 122; https://doi.org/10.3390/magnetochemistry7090122 - 8 Sep 2021

Cited by 3 | Viewed by 1919

Abstract

The study of magnetic relaxations in Mn

_{12}

-stearate single-molecule magnets deposited on the surface of spherical silica nanoparticles was performed. For such a purpose, the investigation of AC magnetic susceptibility dependence on the frequency and temperature was performed. Based on the Argand [...] Read more.

The study of magnetic relaxations in Mn

_{12}

-stearate single-molecule magnets deposited on the surface of spherical silica nanoparticles was performed. For such a purpose, the investigation of AC magnetic susceptibility dependence on the frequency and temperature was performed. Based on the Argand plots obtained for different temperatures and temperature dependencies of susceptibility, obtained for different frequencies of AC field, the corresponding relaxation times were derived. Fitting to the Arrhenius law revealed the values of an effective energy barrier and a mean relaxation time, which were consistent for both measuring techniques (

U_{e f f} / k_{B} \sim

50 K and

τ_{0} \sim

10

^{- 7}

s) and similar to the corresponding values for the analogous bulk compounds. Additionally, the obtained relaxation parameters for the Mn

_{12}

-stearate molecules on the spherical silica surface were compared with corresponding values for the Mn

_{12}

-based single-molecule magnets deposited upon other types of nanostructured silica surface. Full article

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

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26 pages, 5216 KiB

Open AccessFeature PaperReview

Recent Applications of Benchtop Nuclear Magnetic Resonance Spectroscopy

by Hyo-Yeon Yu, Sangki Myoung and Sangdoo Ahn

Magnetochemistry 2021, 7(9), 121; https://doi.org/10.3390/magnetochemistry7090121 - 1 Sep 2021

Cited by 16 | Viewed by 8781

Abstract

Benchtop nuclear magnetic resonance (NMR) spectroscopy uses small permanent magnets to generate magnetic fields and therefore offers the advantages of operational simplicity and reasonable cost, presenting a viable alternative to high-field NMR spectroscopy. In particular, the use of benchtop NMR spectroscopy for rapid [...] Read more.

Benchtop nuclear magnetic resonance (NMR) spectroscopy uses small permanent magnets to generate magnetic fields and therefore offers the advantages of operational simplicity and reasonable cost, presenting a viable alternative to high-field NMR spectroscopy. In particular, the use of benchtop NMR spectroscopy for rapid in-field analysis, e.g., for quality control or forensic science purposes, has attracted considerable attention. As benchtop NMR spectrometers are sufficiently compact to be operated in a fume hood, they can be efficiently used for real-time reaction and process monitoring. This review introduces the recent applications of benchtop NMR spectroscopy in diverse fields, including food science, pharmaceuticals, process and reaction monitoring, metabolomics, and polymer materials. Full article

(This article belongs to the Section Magnetic Resonances)

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Magnetochemistry, Volume 7, Issue 9 (September 2021) – 12 articles

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