Magnetochemistry

13 pages, 1570 KB

Open AccessArticle

Refrigeration in Adiabatically Confined Anisotropic Transition Metal Complexes Induced by Sudden Magnetic Field Quenching

by Andrew Palii, Valeria Belonovich and Boris Tsukerblat

Magnetochemistry 2025, 11(8), 69; https://doi.org/10.3390/magnetochemistry11080069 - 15 Aug 2025

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Abstract

The article is devoted to the theoretical development of the mechanisms of molecular refrigeration, the area combining molecular magnetism and material science with promise for low-temperature physics and quantum computing, where conventional principles of refrigeration become inefficient. Given this general trend, we propose [...] Read more.

The article is devoted to the theoretical development of the mechanisms of molecular refrigeration, the area combining molecular magnetism and material science with promise for low-temperature physics and quantum computing, where conventional principles of refrigeration become inefficient. Given this general trend, we propose the concept of the magnetothermal effect in magnetically anisotropic complexes of 3d metal ions, caused by fast magnetic field quenching. Within this concept, the most topical case of an axially magnetically anisotropic system isolated from the environment by adiabatic envelope is analyzed. We evaluate the temperature change as a function of the initial temperature and magnetic field and also its dependence on the sign and the magnitude of the axial zero-field splitting parameter and the Debye temperature. Correlations are revealed between the sign of the magnetic anisotropy (dictated by the sign of the axial zero field splitting parameter) and the sign of the thermal effect (heating versus cooling) caused by field quenching. The temperature change is shown to be negative (cooling) in the case of complexes exhibiting easy-axis-type magnetic anisotropy, while for the case of easy-plane-type anisotropy, it proves to be positive (heating). The thermal effects are shown to have an efficient control by varying the initially applied field. These findings allow us to propose complexes exhibiting easy-axis-type magnetic anisotropy as candidates for achieving a low-temperature refrigeration effect caused by fast field quenching and also to employ the established magnetothermal correlations to the analysis of magnetic anisotropy. Full article

(This article belongs to the Special Issue Stimuli-Responsive Magnetic Molecular Materials—2nd Edition)

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15 pages, 2189 KB

Open AccessArticle

Synthesis, Crystal Structures and Magnetic Properties of Lanthanide Complexes with Rhodamine Benzoyl Hydrazone Ligands

by Lin Miao, Dong-Mei Zhu, Cai-Ming Liu, Yi-Quan Zhang and Hui-Zhong Kou

Magnetochemistry 2025, 11(8), 68; https://doi.org/10.3390/magnetochemistry11080068 - 7 Aug 2025

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Abstract

Given the outstanding magnetic characteristics of lanthanide ions, the development of mononuclear or multinuclear lanthanide complexes becomes imperative. Previous research showed that a series of mononuclear Dy(III) complexes of rhodamine benzoyl hydrazone Schiff base ligands exhibit remarkable single-molecule magnetic properties and fluorescence. In [...] Read more.

Given the outstanding magnetic characteristics of lanthanide ions, the development of mononuclear or multinuclear lanthanide complexes becomes imperative. Previous research showed that a series of mononuclear Dy(III) complexes of rhodamine benzoyl hydrazone Schiff base ligands exhibit remarkable single-molecule magnetic properties and fluorescence. In this study, we used analogous ligands to synthesize lanthanide complexes [Dy(HL¹-o)(NO₃)₂(CH₃OH)₂]NO₃·CH₃OH (complex 1·MeOH) and tetranuclear complexes [Ln₄(L¹-c)₂(L²)₂(μ₃-OH)₂(NO₃)₂(CH₃OH)₄](NO₃)₂·2CH₃CN·5CH₃OH·2H₂O (Ln = Dy, complex 2; Ln = Gd, complex 3). Magnetic susceptibility measurements show that 1·2H₂O is a single-molecule magnet, 2 shows slow magnetic relaxation and 3 is a magnetic cooling material with the magnetic entropy change of 9.81 J kg⁻¹ K⁻¹ at 2 K and 5 T. The theoretical calculations on 1·MeOH indicate that it shows good magnetic anisotropy with the calculated energy barrier of 194.6 cm⁻¹. Full article

(This article belongs to the Special Issue Molecular Magnetism: A Themed Issue in Honor of Professor Dai-Zheng Liao on the Occasion of His 85th Birthday)

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10 pages, 2101 KB

Open AccessArticle

Structural and Ferromagnetic Response of B2-Type Al₄₅Mn_41.8X_13.2 (X = Fe, Co, Ni) Alloys

by Esmat Dastanpour, Haireguli Aihemaiti, Shuo Huang, Valter Ström, Lajos Károly Varga and Levente Vitos

Magnetochemistry 2025, 11(8), 67; https://doi.org/10.3390/magnetochemistry11080067 - 6 Aug 2025

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Abstract

To our knowledge, no magnetic B2 phase in the Al–Mn system of near-equiatomic compositions has been reported so far. Here, we investigate the structural and magnetic characteristics of Al₄₅Mn_41.8X_13.2 (X = Fe, Co or Ni) alloys. We demonstrate [...] Read more.

To our knowledge, no magnetic B2 phase in the Al–Mn system of near-equiatomic compositions has been reported so far. Here, we investigate the structural and magnetic characteristics of Al₄₅Mn_41.8X_13.2 (X = Fe, Co or Ni) alloys. We demonstrate that adding 13.2 atomic percent magnetic 3d metal to AlMn stabilizes a ferromagnetic B2 structure, where Al and X occupy different sublattices. We employ density functional theory calculations and experimental characterizations to underscore the role of the late 3d metals for the phase stability of the quasi-ordered ternary systems. We show that these alloys possess large local magnetic moments primarily due to Mn atoms partitioned to the Al-free sublattice. The revealed magneto-chemical effect opens alternative routes for tailoring the magnetic properties of B2 intermetallic compounds for various magnetic applications. Full article

(This article belongs to the Special Issue Advances in Functional Materials with Tunable Magnetic Properties)

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4 pages, 140 KB

Open AccessEditorial

Computational Chemistry in Nuclear Magnetic Resonance

by Irina L. Rusakova and Yuriy Yu. Rusakov

Magnetochemistry 2025, 11(8), 66; https://doi.org/10.3390/magnetochemistry11080066 - 4 Aug 2025

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Abstract

Determining molecular structure via nuclear magnetic resonance (NMR) spectral analysis has become an integral part of physical–chemical research in organic and inorganic chemistry [...] Full article

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

21 pages, 5366 KB

Open AccessArticle

Multifaceted Analysis of Pr₂Fe_16.75Ni_0.25 Intermetallic Compound: Crystallographic Insights, Critical Phenomena, and Thermomagnetic Behavior near Room Temperature

by Jihed Horcheni, Hamdi Jaballah, Sirine Gharbi, Essebti Dhahri and Lotfi Bessais

Magnetochemistry 2025, 11(8), 65; https://doi.org/10.3390/magnetochemistry11080065 - 31 Jul 2025

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Abstract

The alloy Pr₂Fe_16.75Ni_0.25 has been examined to investigate its structural properties, critical behavior, and magnetocaloric effects. Rietveld’s refinement of X-ray diffraction patterns has revealed a rhombohedral structure with an

R \bar{3} m

space group. Pr₂Fe [...] Read more.

The alloy Pr₂Fe_16.75Ni_0.25 has been examined to investigate its structural properties, critical behavior, and magnetocaloric effects. Rietveld’s refinement of X-ray diffraction patterns has revealed a rhombohedral structure with an

R \bar{3} m

space group. Pr₂Fe_16.9Ni_0.25 also demonstrates a direct magnetocaloric effect near room temperature, accompanied by a moderate magnetic entropy change (

- Δ S_{M}^{\max}

= 5.5 J kg⁻¹ K⁻¹ at

μ_{0} Δ H = 5

T) and a broad working temperature range. Furthermore, the Relative Cooling Power (RCP) is approximately 89% of the widely recognized gadolinium (Gd) for

μ_{0} Δ H = 2

T. This compound exhibits a commendable magnetocaloric response, on par with or even surpassing that of numerous other intermetallic alloys. Critical behavior was analyzed using thermo-magnetic measurements, employing methods such as the modified Arrott plot, critical isotherm analysis, and Kouvel-Fisher techniques. The obtained critical exponents (

β

,

γ

, and

δ

) exhibit similarities to those of the 3D-Ising model, characterized explicitly by intermediate range interactions. Full article

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3 pages, 142 KB

Open AccessEditorial

Magnetism: Energy, Recycling, Novel Materials

by Joan-Josep Suñol

Magnetochemistry 2025, 11(8), 64; https://doi.org/10.3390/magnetochemistry11080064 - 31 Jul 2025

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Abstract

Magnetism is a field of physics that should be developed within this century in order to enhance its applicability [...] Full article

(This article belongs to the Special Issue Magnetism: Energy, Recycling, Novel Materials)

14 pages, 4243 KB

Open AccessArticle

Evaluation of the Effects of Food and Fasting on Signal Intensities from the Gut Region in Mice During Magnetic Particle Imaging (MPI)

by Saeed Shanehsazzadeh and Andre Bongers

Magnetochemistry 2025, 11(8), 63; https://doi.org/10.3390/magnetochemistry11080063 - 25 Jul 2025

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Abstract

Gastrointestinal signals present a major challenge in magnetic particle imaging (MPI) because of their strong background interference. This study aimed to evaluate and compare the gut MPI signal in mice fed six commercially available diets in Australia, including Gordon’s Specialty Stock Feeds (normal [...] Read more.

Gastrointestinal signals present a major challenge in magnetic particle imaging (MPI) because of their strong background interference. This study aimed to evaluate and compare the gut MPI signal in mice fed six commercially available diets in Australia, including Gordon’s Specialty Stock Feeds (normal and low iron), Specialty Feeds (normal and low iron), a Western diet, and Gubra-Amylin NASH (GAN diet). We also assessed the impact of 24 h fasting on gut signal reduction. Each diet group included three mice, and the gut signal intensity was monitored over seven days. The results indicated that the standard diet produced signal intensities approximately eight times greater than those of the low-iron diet from specialty feeds and over eleven times greater than those of the GAN or Western diets. Notably, switching to GAN or Western diets led to a tenfold reduction in the gut signal within 24 h, a decrease comparable to that achieved by fasting. These findings suggest that dietary modification—particularly the use of low-iron diets—can effectively minimize gastrointestinal signals in MPI, reducing background interference by up to 90%. This simple dietary adjustment offers a practical and noninvasive method for improving image clarity and experimental reliability in preclinical MPI studies. Full article

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37 pages, 3791 KB

Open AccessReview

The Advancing Understanding of Magnetorheological Fluids and Elastomers: A Comparative Review Analyzing Mechanical and Viscoelastic Properties

by Salah Rouabah, Fadila-Yasmina Didouche, Abdelmalek Khebli, Salah Aguib and Noureddine Chikh

Magnetochemistry 2025, 11(8), 62; https://doi.org/10.3390/magnetochemistry11080062 - 24 Jul 2025

Viewed by 908

Abstract

Magnetorheological fluids (MRFs) and elastomers (MREs) are two types of smart materials that exhibit modifiable rheological properties in response to an applied magnetic field. Although they share a similarity in their magnetorheological response, these two materials differ in their nature, structure, and mechanical [...] Read more.

Magnetorheological fluids (MRFs) and elastomers (MREs) are two types of smart materials that exhibit modifiable rheological properties in response to an applied magnetic field. Although they share a similarity in their magnetorheological response, these two materials differ in their nature, structure, and mechanical behavior when exposed to a magnetic field. They also have distinct application differences due to their specific rheological properties. These fundamental differences therefore influence their properties and applications in various industrial fields. This review provides a synthesis of the distinct characteristics of MRFs and MREs. The differences in their composition, rheological behavior, mechanical properties, and respective applications are summarized and highlighted. This analysis will enable a comprehensive understanding of these differences, thereby allowing for the appropriate selection of the material based on the specific requirements of a given application and fostering the development of new applications utilizing these MR materials. Full article

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

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Magnetochemistry, Volume 11, Issue 8 (August 2025) – 8 articles

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