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Magnetochemistry, Volume 7, Issue 5 (May 2021) – 18 articles

Cover Story (view full-size image): Three new 1D cyanido-bridged 3d-4f coordination polymers were assembled following the building-block approach (L = pentadentate bis-semicarbazone ligand resulting from the condensation reaction between 2,6-diacetyl-pyridine and semicarbazide). The crystal structures consist of crenel-like LnIII-MIII alternate chains, with the LnIII ions connected by the hexacyanido metalloligands through two cis cyanido groups. The magnetic properties of the three complexes have been investigated. Field-induced slow relaxation of the magnetization was observed for compounds 2DyFe and 3DyCo. Compound 3DyCo is a new example of chain of Single Ion Magnets. View this paper
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Article
Two-Dimensional Nitronyl Nitroxide–Cu Networks Based on Multi-Dentate Nitronyl Nitroxides: Structures and Magnetic Properties
Magnetochemistry 2021, 7(5), 73; https://0-doi-org.brum.beds.ac.uk/10.3390/magnetochemistry7050073 - 20 May 2021
Viewed by 370
Abstract
Two multi-dentate nitronyl nitroxide radicals, namely, bisNITPhPy ([5-(4-pyridyl)-1,3-bis(1′-oxyl-3′-oxido-4′,4′,5′,5′-tetramethyl-4,5-hydro-1H-imidazol-2-yl)]benzene) and NIT-3Py-5-4Py (2-{3-[5-(4-pyridyl)]pyridyl}-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), were assembled with CuII ions to obtain two-dimensional heterospin 2p–3d coordination polymers [Cu7(hfac)14(bisNITPhPy)2]n (1) and [Cu2(hfac)4(NIT-3Py-5-4Py)] [...] Read more.
Two multi-dentate nitronyl nitroxide radicals, namely, bisNITPhPy ([5-(4-pyridyl)-1,3-bis(1′-oxyl-3′-oxido-4′,4′,5′,5′-tetramethyl-4,5-hydro-1H-imidazol-2-yl)]benzene) and NIT-3Py-5-4Py (2-{3-[5-(4-pyridyl)]pyridyl}-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), were assembled with CuII ions to obtain two-dimensional heterospin 2p–3d coordination polymers [Cu7(hfac)14(bisNITPhPy)2]n (1) and [Cu2(hfac)4(NIT-3Py-5-4Py)]n (2) (hfac: hexafluoroacetylacetonate). In both compounds, the bisNITPhPy and NIT-3Py-5-3Py radicals acted as pentadentate and tetradentate ligands, respectively, to connect with CuII ions, generating a 2D layer structure. The analysis of the magnetic behavior indicated that strong antiferromagnetic coupling and ferromagnetic interaction (J = 17.1 cm−1) coexisted in 1. For 2, there were ferromagnetic couplings between the CuII ion and NO group, as well as the CuII ion and radical via the pyridine ring with J1 = 32.8 and J2 = 2.2 cm−1, respectively. Full article
(This article belongs to the Special Issue Magnetic Coordination Polymers)
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Article
New Spin-Crossover Compounds Containing the [Ni(mnt)] Anion (mnt = Maleonitriledithiolate)
Magnetochemistry 2021, 7(5), 72; https://0-doi-org.brum.beds.ac.uk/10.3390/magnetochemistry7050072 - 19 May 2021
Viewed by 456
Abstract
Two novel salts containing the anion [Ni(mnt)2] (mnt = maleonitriledithiolate) have been synthesized. The counter-ions, [Fe(II)(L1 or L2)2], are cationic complexes where L1 and L2 are methylated derivatives of 2,6-bis(pyazolyl)pyridine or pyrazine, [...] Read more.
Two novel salts containing the anion [Ni(mnt)2] (mnt = maleonitriledithiolate) have been synthesized. The counter-ions, [Fe(II)(L1 or L2)2], are cationic complexes where L1 and L2 are methylated derivatives of 2,6-bis(pyazolyl)pyridine or pyrazine, which are similar to ligands found in a series of spin-crossover (SCO) complexes. Both salts are characterized by variable temperature single crystal X-ray diffraction and bulk magnetization measurements. Compound 1, [Fe(II)(L1)2][Ni(mnt)2]2 displays an incomplete and gradual SCO up to 300 K, followed by a more rapid increase in the high-spin fraction between 300 and 350 K. Compound 2, [Fe(II)(L2)2][Ni(mnt)2]2.MeNO2, shows a gradual, but more complete SCO response centered at 250 K. For compound 2, the SCO is confirmed by variable temperature Mössbauer spectroscopy. In both cases, the anionic moieties are isolated from each other and so no electrical conductivity is observed. Full article
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Article
The Internal Field in a Ferromagnetic Crystal with Chiral Molecular Packing of Achiral Organic Radicals
Magnetochemistry 2021, 7(5), 71; https://0-doi-org.brum.beds.ac.uk/10.3390/magnetochemistry7050071 - 18 May 2021
Viewed by 343
Abstract
The achiral organic radical dinitrophenyl nitronyl nitroxide crystallizes in two enantiomorphs, both being chiral tetragonal space groups that are mirror images of each other. Muon-spin rotation experiments have been performed to study the magnetic properties of these crystals and demonstrate that long-range magnetic [...] Read more.
The achiral organic radical dinitrophenyl nitronyl nitroxide crystallizes in two enantiomorphs, both being chiral tetragonal space groups that are mirror images of each other. Muon-spin rotation experiments have been performed to study the magnetic properties of these crystals and demonstrate that long-range magnetic order is established below a temperature of 1.10(1) K. Two oscillatory components are detected in the muon data, which show two different temperature dependences. Full article
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Article
FMR Damping in Thin Films with Exchange Bias
Magnetochemistry 2021, 7(5), 70; https://0-doi-org.brum.beds.ac.uk/10.3390/magnetochemistry7050070 - 17 May 2021
Viewed by 371
Abstract
Ferromagnetic resonance (FMR) linewidth (LW) is a tool for studying the high frequency properties of magnetic materials for their application in high-speed devices. Here, we investigate different mechanisms which determine FMR damping in bilayer ferromagnetic/antiferromagnetic (F/AF and AF/F) exchange bias systems. Variations of [...] Read more.
Ferromagnetic resonance (FMR) linewidth (LW) is a tool for studying the high frequency properties of magnetic materials for their application in high-speed devices. Here, we investigate different mechanisms which determine FMR damping in bilayer ferromagnetic/antiferromagnetic (F/AF and AF/F) exchange bias systems. Variations of FMR LW with the thickness and deposition order of the F and AF layers were studied, as well as their correlation with the exchange bias field and roughness of the sample surface. We observed much larger LW in AF/F structures compared with F/AF samples. It was found that neither the exchange bias nor surface/interface roughness in the samples could explain the difference in LW for F/AF and AF/F samples. Instead, the different underlayer microstructure influenced the grainsize, leading to different angular dispersion of magnetization and different internal stray field in F-layers, promoting a different intensity of magnon scattering and FMR damping in F/AF and AF/F samples. Full article
(This article belongs to the Special Issue Advances in Magnetic Hysteresis)
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Article
Hexagonal-Shaped Spin Crossover Nanoparticles Studied by Ising-Like Model Solved by Local Mean Field Approximation
Magnetochemistry 2021, 7(5), 69; https://0-doi-org.brum.beds.ac.uk/10.3390/magnetochemistry7050069 - 17 May 2021
Viewed by 428
Abstract
The properties of spin crossover (SCO) nanoparticles were studied for five 2D hexagonal lattice structures of increasing sizes embedded in a matrix, thus affecting the thermal properties of the SCO region. These effects were modeled using the Ising-like model in the framework of [...] Read more.
The properties of spin crossover (SCO) nanoparticles were studied for five 2D hexagonal lattice structures of increasing sizes embedded in a matrix, thus affecting the thermal properties of the SCO region. These effects were modeled using the Ising-like model in the framework of local mean field approximation (LMFA). The systematic combined effect of the different types of couplings, consisting of (i) bulk short- and long-range interactions and (ii) edge and corner interactions at the surface mediated by the matrix environment, were investigated by using parameter values typical of SCO complexes. Gradual two and three hysteretic transition curves from the LS to HS states were obtained. The results were interpreted in terms of the competition between the structure-dependent order and disorder temperatures (TO.D.) of internal coupling origin and the ligand field-dependent equilibrium temperatures (Teq) of external origin. Full article
(This article belongs to the Special Issue Characterization of Spin Crossover Compounds)
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Article
Deciphering the Structural Characterization, Hirshfeld Surface Analysis, Raman Studies, and Temperature-Dependent Magnetodielectric Properties of BiMn2O5
Magnetochemistry 2021, 7(5), 68; https://0-doi-org.brum.beds.ac.uk/10.3390/magnetochemistry7050068 - 16 May 2021
Viewed by 444
Abstract
We investigate the structural, Hirshfeld surface, magnetic, and magnetodielectric properties of BiMn2O5. The sample can be indexed with an orthorhombic phase associated with space group Pbam, with crystallographic parameters a = 7.54946 Å, b = 8.54962 Å and [...] Read more.
We investigate the structural, Hirshfeld surface, magnetic, and magnetodielectric properties of BiMn2O5. The sample can be indexed with an orthorhombic phase associated with space group Pbam, with crystallographic parameters a = 7.54946 Å, b = 8.54962 Å and c = 5.753627 Å. The Hirshfeld surface analysis, associated with 2D fingerprint plots, was used to visualize and explore the significant intermolecular interactions in the crystal structure quantitatively. The Raman spectra, measured from 6 to 300 K in a frequency range between 250 and 750 cm−1, exhibit good agreement between the SHELL model calculations and the experimental measurement of the proximity of the phonon frequencies for our sample. Furthermore, magnetic measurements show that BiMn2O5 becomes antiferromagnetic below the Néel temperature (TN)—the temperature above which an antiferromagnetic material becomes paramagnetic (TN = 31 K). The relaxation at intermediate temperatures (200–300 K) can be attributed to the polar jump process at two charge transfer sites between the Mn3+ and Mn4+ ions, which, in combination with the special arrangement of the Mn3+/Mn4+ ions, is likely to produce the strong intrinsic magnetodielectric effect (MD) in the same temperature range. Full article
(This article belongs to the Special Issue Advanced Materials for Magnetic Cooling)
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Article
Numerical Optimization of a Single Bunch of NiTi Wires to Be Placed in an Elastocaloric Experimental Device: Preliminary Results
Magnetochemistry 2021, 7(5), 67; https://0-doi-org.brum.beds.ac.uk/10.3390/magnetochemistry7050067 - 15 May 2021
Viewed by 474
Abstract
Italy has not yet presented to the scientific community any elastocaloric prototype suitable for refrigeration/air conditioning. The SUSSTAINEBLE project was born from the idea to build a demonstrative elastocaloric prototype for environmental conditioning. The prototype is planned to be rotary and composed by [...] Read more.
Italy has not yet presented to the scientific community any elastocaloric prototype suitable for refrigeration/air conditioning. The SUSSTAINEBLE project was born from the idea to build a demonstrative elastocaloric prototype for environmental conditioning. The prototype is planned to be rotary and composed by a few bunches of elastocaloric wires crossed by air as heat transfer fluid. Many are the parameters to be investigated before the realization of the device. A numerical practical tool would help to easily optimize the prototype. In this paper a two-dimensional tool of a single bunch of elastocaloric wires based on finite-element method is introduced; it can reproduce step by step the velocity and the pressure field of fluid to predict more accurately the solid-to-fluid heat exchange. The results of a test campaign mostly focused on the optimization of the frequency of the cycle, fluid velocity and the distance between the elastocaloric wires are presented. The results reveal that: (i) 0.12 Hz as frequency; (ii) 7 m s−1 as velocity; (iii) 1.0 mm as optimal wire distance, would better satisfy the trade-off existing in the maximization of temperature span and cooling power per mass unit: 23.7 K and 311.97 W kg−1 are the values achieved, respectively. Full article
(This article belongs to the Special Issue Magnetocaloric and Caloric Materials for Solid-State Cooling)
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Article
In Quest of Molecular Materials for Quantum Cellular Automata: Exploration of the Double Exchange in the Two-Mode Vibronic Model of a Dimeric Mixed Valence Cell
Magnetochemistry 2021, 7(5), 66; https://0-doi-org.brum.beds.ac.uk/10.3390/magnetochemistry7050066 - 12 May 2021
Viewed by 464
Abstract
In this article, we apply the two-mode vibronic model to the study of the dimeric molecular mixed-valence cell for quantum cellular automata. As such, we consider a multielectron mixed valence binuclear d2d1–type cluster, in which the double exchange, as well as the Heisenberg-Dirac-Van Vleck exchange interactions are operative, and also the local (“breathing”) and intercenter vibrational modes are taken into account. The calculations of spin-vibronic energy spectra and the “cell-cell”-response function are carried out using quantum-mechanical two-mode vibronic approach based on the numerical solution of the dynamic vibronic problem. The obtained results demonstrate a possibility of combining the function of molecular QCA with that of spin switching in one electronic device and are expected to be useful from the point of view of the rational design of such multifunctional molecular electronic devices. Full article
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Article
Magnetic Switching in Vapochromic Oxalato-Bridged 2D Copper(II)-Pyrazole Compounds for Biogenic Amine Sensing
Magnetochemistry 2021, 7(5), 65; https://0-doi-org.brum.beds.ac.uk/10.3390/magnetochemistry7050065 - 12 May 2021
Viewed by 424
Abstract
A new two-dimensional (2D) coordination polymer of the formula {Cu(ox)(4-Hmpz)·1/3H2O}n (1) (ox = oxalate and 4-Hmpz = 4-methyl-1H-pyrazole) has been prepared, and its structure has been determined by single-crystal X-ray diffraction. It consists of corrugated oxalato-bridged [...] Read more.
A new two-dimensional (2D) coordination polymer of the formula {Cu(ox)(4-Hmpz)·1/3H2O}n (1) (ox = oxalate and 4-Hmpz = 4-methyl-1H-pyrazole) has been prepared, and its structure has been determined by single-crystal X-ray diffraction. It consists of corrugated oxalato-bridged copper(II) neutral layers featuring two alternating bridging modes of the oxalate group within each layer, the symmetric bis-bidentate (μ-κ2O1,O2:κ2O2′,O1′) and the asymmetric bis(bidentate/monodentate) (μ4-κO1:κ2O1,O2:κO2′:κ2O2′,O1′) coordination modes. The three crystallographically independent six-coordinate copper(II) ions that occur in 1 have tetragonally elongated surroundings with three oxygen atoms from two oxalate ligands, a methylpyrazole-nitrogen defining the equatorial plane, and two other oxalate-oxygen atoms occupying the axial positions. The monodentate 4-Hmpz ligands alternatively extrude above and below each oxalate-bridged copper(II) layer, and the water molecules of crystallization are located between the layers. Compound 1 exhibits a fast and selective adsorption of methylamine vapors to afford the adsorbate of formula {Cu(ox)(4-Hmpz)·3MeNH2·1/3H2O}n (2), which is accompanied by a concomitant color change from cyan to deep blue. Compound 2 transforms into {Cu(ox)(4-Hmpz)·MeNH2·1/3H2O}n (3) under vacuum for three hours. The cryomagnetic study of 13 revealed a unique switching from strong (1) to weak (2 and 3) antiferromagnetic interactions. The external control of the optical and magnetic properties along this series of compounds might make them suitable candidates for switching optical and magnetic devices for chemical sensing. Full article
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Article
Magnetic Properties of Li3V2(PO4)3/Li3PO4 Composite
Magnetochemistry 2021, 7(5), 64; https://0-doi-org.brum.beds.ac.uk/10.3390/magnetochemistry7050064 - 12 May 2021
Viewed by 398
Abstract
Here, we present the investigation of the magnetic properties of Li3V2(PO4)3/Li3PO4 composites, which can be potentially used as a cathode material in lithium-ion batteries. Li3V2(PO4)3 [...] Read more.
Here, we present the investigation of the magnetic properties of Li3V2(PO4)3/Li3PO4 composites, which can be potentially used as a cathode material in lithium-ion batteries. Li3V2(PO4)3/Li3PO4 was synthesized by the thermal hydrolysis method and has a granular mesoporous structure. Magnetic properties of the composite were investigated using magnetometry and electron spin resonance methods. Based on magnetization measurements, the simultaneous existence of the paramagnetic phase with antiferromagnetic interactions between spins of V3+ ions and magnetically correlated regions was suggested. Most probably, magnetically correlated regions were formed due to anti-site defects and the presence of V4+ ions that was directly confirmed by electron spin resonance measurements. Full article
(This article belongs to the Special Issue Recent Advances in Solid State Physics Devices)
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Article
Structure, Microstructure, and Magnetic Properties of Melt Spun Ni50Mn50−xInx Ribbons
Magnetochemistry 2021, 7(5), 63; https://0-doi-org.brum.beds.ac.uk/10.3390/magnetochemistry7050063 - 07 May 2021
Viewed by 481
Abstract
Structural, microstructural, and magnetic properties of Heusler Ni50Mn50−xInx (x = 5 and 10) ribbons have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS), differential scanning calorimetry (DSC), and vibrating [...] Read more.
Structural, microstructural, and magnetic properties of Heusler Ni50Mn50−xInx (x = 5 and 10) ribbons have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS), differential scanning calorimetry (DSC), and vibrating sample magnetometry (VSM). The as quenched Ni50Mn45In5 ribbons exhibit a mixture of monoclinic 14M (a = 4.329(3) Å, b = 5.530(3) Å, and c = 28.916(3) Å), and tetragonal L10 (a = b = 3.533(3) Å, and c = 7.522(3) Å) martensite structures, while Ni50Mn40In10 ribbons display a single monoclinic 14M phase (a = 4.262(3) Å, b = 5.692(3) Å, and c = 29.276(3) Å). After three heating/cooling cycles, in the temperature range of 303–873 K, the Rietveld refinement of the XRD patterns revealed the presence of a single 14M martensite for Ni50Mn45In5 ribbons, and a mixture of cubic L21 (31%) and 14M (69%) phases for Ni50Mn40In10 ribbons. The characteristic temperatures of the martensitic transition (Astart, Afinish, Mstart, and Mfinish), the thermal hysteresis temperature width, and the equilibrium temperature decreased with increasing indium content and heating cycles. The samples show a paramagnetic like behavior in the as quenched state, and a ferromagnetic like behavior after the third heating/cooling cycle. Full article
(This article belongs to the Special Issue Magnetocaloric Effect: Theory, Materials and Applications)
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Article
Magnetic and Structural Properties of Organic Radicals Based on Thienyl- and Furyl-Substituted Nitronyl Nitroxide
Magnetochemistry 2021, 7(5), 62; https://0-doi-org.brum.beds.ac.uk/10.3390/magnetochemistry7050062 - 06 May 2021
Viewed by 333
Abstract
Magnetic properties of organic radicals based on thienyl- and furyl-substituted nitronyl nitroxide (NN) and iminonitroxide (IN) were investigated by measuring the temperature dependence of the magnetization. The magnetic behavior of 2-benzo[b]thienyl NN (2-BTHNN) is interpreted in terms of the two-magnetic-dimer model, [...] Read more.
Magnetic properties of organic radicals based on thienyl- and furyl-substituted nitronyl nitroxide (NN) and iminonitroxide (IN) were investigated by measuring the temperature dependence of the magnetization. The magnetic behavior of 2-benzo[b]thienyl NN (2-BTHNN) is interpreted in terms of the two-magnetic-dimer model, in which one dimer exhibits ferromagnetic (FM) intermolecular interaction and the other dimer shows antiferromagnetic (AFM) interaction. The existence of two dimers in 2-BTHNN is supported by crystal structure analysis. The magnetic behaviors of 2-bithienyl NN, 4-(2′-thienyl)phenyl NN (2-THPNN), 2- and 3-furyl NN, 2-benzo[b]furyl NN, and 3-benzo[b]thienyl IN are also reported. The one-dimensional alternating AFM nature observed in 2-THPNN is consistent with its crystal structure. Full article
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Article
Magnetic Properties Study of Iron Oxide Nanoparticles-Loaded Poly(ε-caprolactone) Nanofibres
Magnetochemistry 2021, 7(5), 61; https://0-doi-org.brum.beds.ac.uk/10.3390/magnetochemistry7050061 - 05 May 2021
Viewed by 484
Abstract
Magnetic nanofibres have attracted more and more attention recently due to their possible applications e.g., in spintronics and neuromorphic computing. This work presents the synthesis and physicochemical characterization of the electrospun nanofibres of poly(ε-caprolactone) (PCL) doped by iron oxide nanoparticles with diameters of [...] Read more.
Magnetic nanofibres have attracted more and more attention recently due to their possible applications e.g., in spintronics and neuromorphic computing. This work presents the synthesis and physicochemical characterization of the electrospun nanofibres of poly(ε-caprolactone) (PCL) doped by iron oxide nanoparticles with diameters of 5 nm. PCL is a semi-crystalline, hydrophilic polymer showing controllable biodegradation rates, biocompatibility, and flexible mechanical properties. In the composite material, two different concentrations of magnetic nanoparticles were used: 2 and 6 wt.%. PCL-based composites were investigated using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetry (TGA). Although in the literature one can find many studies on magnetic polymeric composites, the investigation of their magnetic properties is usually limited to measuring the magnetization curve. Detailed analysis of dynamic magnetic susceptibility is rather rare. In this report, special attention was paid to the detailed analysis of magnetic properties, where we followed the evolution of changes in the magnetic behavior of the material depending on the concentration of magnetic nanoparticles. Full article
(This article belongs to the Special Issue Modern Magnetic Systems: Theory and Experiment in Concert)
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Article
Reversibility of the Magnetocaloric Effect in the Bean-Rodbell Model
Magnetochemistry 2021, 7(5), 60; https://0-doi-org.brum.beds.ac.uk/10.3390/magnetochemistry7050060 - 05 May 2021
Viewed by 483
Abstract
The applicability of magnetocaloric materials is limited by irreversibility. In this work, we evaluate the reversible magnetocaloric response associated with magnetoelastic transitions in the framework of the Bean-Rodbell model. This model allows the description of both second- and first-order magnetoelastic transitions by the [...] Read more.
The applicability of magnetocaloric materials is limited by irreversibility. In this work, we evaluate the reversible magnetocaloric response associated with magnetoelastic transitions in the framework of the Bean-Rodbell model. This model allows the description of both second- and first-order magnetoelastic transitions by the modification of the η parameter (η<1 for second-order and η>1 for first-order ones). The response is quantified via the Temperature-averaged Entropy Change (TEC), which has been shown to be an easy and effective figure of merit for magnetocaloric materials. A strong magnetic field dependence of TEC is found for first-order transitions, having a significant increase when the magnetic field is large enough to overcome the thermal hysteresis of the material observed at zero field. This field value, as well as the magnetic field evolution of the transition temperature, strongly depend on the atomic magnetic moment of the material. For a moderate magnetic field change of 2 T, first-order transitions with η1.31.8 have better TEC than those corresponding to stronger first-order transitions and even second-order ones. Full article
(This article belongs to the Special Issue Magnetocaloric Effect: Theory, Materials and Applications)
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Article
Unexpected Light-Induced Thermal Hysteresis in Matrix Embedded Low Cooperative Spin Crossover Microparticles
Magnetochemistry 2021, 7(5), 59; https://0-doi-org.brum.beds.ac.uk/10.3390/magnetochemistry7050059 - 29 Apr 2021
Viewed by 475
Abstract
The embedding of spin-crossover micro- or nanocrystals in various surroundings dramatically changes their functionalities based on first-order spin transitions. The dampening of their internal cooperativity, together with introducing a new kind of interactions occurring at interfaces between spin-crossover particles and their environment, results [...] Read more.
The embedding of spin-crossover micro- or nanocrystals in various surroundings dramatically changes their functionalities based on first-order spin transitions. The dampening of their internal cooperativity, together with introducing a new kind of interactions occurring at interfaces between spin-crossover particles and their environment, results in spectacular effects, as an enhanced hysteresis with non-cooperative transitions. In this work, we deal with the influence of the embedding matrix on the light-induced thermal hysteresis (LITH) in the case of spin-crossover microparticles of Fe(phen)2(NCS)2. Despite the low cooperativity of this compound, the competition between the continuous photoexcitation towards the metastable high spin state and the relaxation down to low spin ground state leads to a light-induced thermal hysteresis, with a quasi-static width of around 10 K. This unexpected hysteresis is explained by considering a switch-on/cutoff mechanism of the particle–matrix interactions in the framework of a mean-field approach based on negative external pressures, with Gaussian distributed variations and of an Ising-like model with various interactions with the environment. Additional first-order reversal curves measurements and corresponding calculated distributions are in line with relaxations under light and confirm the existence of a non-kinetic LITH. Full article
(This article belongs to the Special Issue Molecular Magnetism 2021: Paradigmatic Landmarks and Horizons)
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Article
Preparation of CD3 Antibody-Conjugated, Graphene Oxide Coated Iron Nitride Magnetic Beads and Its Preliminary Application in T Cell Separation
Magnetochemistry 2021, 7(5), 58; https://0-doi-org.brum.beds.ac.uk/10.3390/magnetochemistry7050058 - 29 Apr 2021
Viewed by 387
Abstract
Immunomagnetic beads (IMBs) for cell sorting are universally used in medical and biological fields. At present, the IMBs on the market are ferrite coated with a silicon shell. Based on a new type of magnetic material, the graphene coated iron nitride magnetic particle [...] Read more.
Immunomagnetic beads (IMBs) for cell sorting are universally used in medical and biological fields. At present, the IMBs on the market are ferrite coated with a silicon shell. Based on a new type of magnetic material, the graphene coated iron nitride magnetic particle ([email protected]), which we previously reported, we prepared a novel IMB, a graphene oxide coated iron nitride immune magnetic bead ([email protected]), and explored its feasibility for cell sorting. First, the surface of the [email protected] was oxidized to produce oxygen-containing groups as carboxyl, etc. by the optimized Hummers’ method, followed by a homogenization procedure to make the particles uniform in size and dispersive. The carboxy groups generated were then condensed and coupled with anti-CD3 antibodies by the carbodiimide method to produce an [email protected] after the coupling efficacy was proved by bovine serum albumin (BSA) and labeled antibodies. Finally, the [email protected] were incubated with a cell mixture containing human T cells. With the aid of a magnetic stand, the T cells were successfully isolated from the cell mixture. The isolated T cells turned out to be intact and could proliferate with the activation of the IMBs. The results show that the [email protected] can be modified for IMB preparation, and the [email protected] we prepared can potentially separate T cells. Full article
(This article belongs to the Special Issue Biomedical Application of Magnetic Nanoparticles in 2021)
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Article
New Cyanido-Bridged Heterometallic 3d-4f 1D Coordination Polymers: Synthesis, Crystal Structures and Magnetic Properties
Magnetochemistry 2021, 7(5), 57; https://0-doi-org.brum.beds.ac.uk/10.3390/magnetochemistry7050057 - 28 Apr 2021
Viewed by 588
Abstract
Three new 1D cyanido-bridged 3d-4f coordination polymers, {[Gd(L)(H2O)2Fe(CN)6]·H2O}n (1GdFe), {[Dy(L)(H2O)2Fe(CN)6]·3H2O}n (2DyFe), and {[Dy(L)(H2O)2Co(CN)6]·H [...] Read more.
Three new 1D cyanido-bridged 3d-4f coordination polymers, {[Gd(L)(H2O)2Fe(CN)6]·H2O}n (1GdFe), {[Dy(L)(H2O)2Fe(CN)6]·3H2O}n (2DyFe), and {[Dy(L)(H2O)2Co(CN)6]·H2O}n (3DyCo), were assembled following the building-block approach (L = pentadentate bis-semicarbazone ligand resulting from the condensation reaction between 2,6-diacetyl-pyridine and semicarbazide). The crystal structures consist of crenel-like LnIII-MIII alternate chains, with the LnIII ions connected by the hexacyanido metalloligands through two cis cyanido groups. The magnetic properties of the three complexes have been investigated. Field-induced slow relaxation of the magnetization was observed for compounds 2DyFe and 3DyCo. Compound 3DyCo is a new example of chain of Single Ion Magnets. Full article
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Article
Pressureless Sintering of YIG Ceramics from Coprecipitated Nanopowders
Magnetochemistry 2021, 7(5), 56; https://0-doi-org.brum.beds.ac.uk/10.3390/magnetochemistry7050056 - 25 Apr 2021
Viewed by 432
Abstract
Nanoparticles prepared by the coprecipitation method were used as raw materials to fabricate Y3Fe5O12 (YIG) ceramics by air pressureless sintering. The synthesized YIG precursor was calcinated at 900–1100 °C for 4 h in air. The influences of the [...] Read more.
Nanoparticles prepared by the coprecipitation method were used as raw materials to fabricate Y3Fe5O12 (YIG) ceramics by air pressureless sintering. The synthesized YIG precursor was calcinated at 900–1100 °C for 4 h in air. The influences of the calcination temperature on the phase and morphology of the nanopowders were investigated in detail. The powders calcined at 1000–1100 °C retained the pure YIG phase. YIG ceramics were fabricated by sintering at 1200–1400 °C for 10 h, and its densification behavior was studied. YIG ceramics prepared by air sintering at 1250 °C from powders calcinated at 1000 °C have the highest in-line transmittance in the range of 1000-3000 nm. When the sintering temperature exceeds 1300 °C, the secondary phase appears in the YIG ceramics, which may be due to the loss of oxygen during the high-temperature sintering process, resulting in the conversion of Fe3+ into Fe2+. Full article
(This article belongs to the Special Issue Magneto-Optical Ceramics)
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