Inorganics

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20 pages, 6295 KiB

Open AccessArticle

Influence of the Magnetization of Thermally Expandable Particles on the Thermal and Debonding Properties of Bonding Joints

by Juana Abenojar, Sara López de Armentia, Juan-Carlos del Real and Miguel-Angel Martínez

Inorganics 2024, 12(5), 129; https://doi.org/10.3390/inorganics12050129 - 28 Apr 2024

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Abstract

This study addresses the challenge of recycling adhesive bonds, as their disassembly is irreversible and damages the substrates. It explores the use of thermally expandable particles (TEPs), which, when heated, expand and weaken the bond. The magnetization of TEPs allows us to control [...] Read more.

This study addresses the challenge of recycling adhesive bonds, as their disassembly is irreversible and damages the substrates. It explores the use of thermally expandable particles (TEPs), which, when heated, expand and weaken the bond. The magnetization of TEPs allows us to control their distribution using a magnetic field. The work aims to obtain magnetized TEPs, study their influence on resin curing, mechanical performance, and durability, test their mobility in graded bonds, and analyze the temperature-induced debonding process. TEPs are characterized using various techniques, including differential scanning calorimetry, nuclear magnetic resonance, and scanning electron microscopy. Additionally, the impact of 25 wt.% TEPs on epoxy resin curing is examined using the Kamal model. Adhesion and disassembly assessments were conducted through tensile shear tests using single-lap-joint specimens, while the bond durability was determined via wedge testing. It was found that magnetization reduces the debonding time, though it decreases shear strength while increasing bond durability. The crack formation energy is higher with magnetic TEPs, and total crack length is lower in long-term wedge tests. Once debonded, the substrates are sanded and reused as raw material. Full article

(This article belongs to the Special Issue Magnetic Materials and Their Applications)

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23 pages, 10993 KiB

Open AccessArticle

Fe₃O₄-ZnO:V Nanocomposites with Modulable Properties as Magnetic Recoverable Photocatalysts

by Ana Varadi, Cristian Leostean, Maria Stefan, Adriana Popa, Dana Toloman, Stela Pruneanu, Septimiu Tripon and Sergiu Macavei

Inorganics 2024, 12(4), 119; https://doi.org/10.3390/inorganics12040119 - 17 Apr 2024

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Abstract

Since semiconductor-based photocatalysis uses solar energy as a free and sustainable energy source and inoffensive photocatalysts, it has been found to be a promising green approach to eliminating dyes, antibiotics, and other pharmaceuticals from water that has been contaminated. In this study, a [...] Read more.

Since semiconductor-based photocatalysis uses solar energy as a free and sustainable energy source and inoffensive photocatalysts, it has been found to be a promising green approach to eliminating dyes, antibiotics, and other pharmaceuticals from water that has been contaminated. In this study, a distinctive magnetic separable Fe₃O₄-ZnO:V photocatalyst is reported. ZnO:V semiconductors have been produced by seed-assisted growth over preformed magnetite to develop Fe₃O₄-ZnO:V nanocomposites. The results indicated nanocomposites with the structure of Fe₃O₄, ZnO:V, according to the findings of the XRD, XPS, and HRTEM investigations. Additionally, magnetic studies revealed at room temperature, the nanocomposite exhibited superparamagnetic properties. Electrochemical Impedance Spectroscopy (EIS) was employed to characterize the ability of the Fe₃O₄-ZnO:V nanocomposites to transfer electrons. Furthermore, the impact of dopant on optical characteristics was evaluated. When exposed to rhodamine B (RhB), all the samples exhibited photocatalytic activity. Through the use of an ESR experiment and the spin-trapping technique, the existence of reactive oxygen species (ROS) at the solid–liquid interface was demonstrated, and their impact on the samples’ photocatalytic activity was highlighted. After recycling, XRD, XPS, and SEM were performed to illustrate the stability of the material. The impact of V doping on the morphologic, structural, and compositional properties of magnetically separable Fe₃O₄-ZnO:V composite nanoparticles for photocatalytic applications is the innovative aspect of our work. Full article

(This article belongs to the Special Issue Magnetic Materials and Their Applications)

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13 pages, 5577 KiB

Open AccessArticle

Room-Temperature Entanglement of the Nickel-Radical Molecular Complex (Et₃NH)[Ni(hfac)₂L] Reinforced by the Magnetic Field

by Jozef Strečka and Elham Shahhosseini Shahrabadi

Inorganics 2024, 12(4), 102; https://doi.org/10.3390/inorganics12040102 - 31 Mar 2024

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Abstract

Bipartite entanglement is comprehensively investigated in the mononuclear molecular complex (Et₃NH)[Ni(hfac)₂L], where HL denotes 2-(2-hydroxy-3-methoxy-5-nitrophenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-3-oxide-1-oxyl and hfacH stands for hexafluoroacetylacetone. From the magnetic point of view, the molecular compound (Et₃NH)[Ni(hfac)₂L] consists of an exchange-coupled spin-1 [...] Read more.

Bipartite entanglement is comprehensively investigated in the mononuclear molecular complex (Et₃NH)[Ni(hfac)₂L], where HL denotes 2-(2-hydroxy-3-methoxy-5-nitrophenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-3-oxide-1-oxyl and hfacH stands for hexafluoroacetylacetone. From the magnetic point of view, the molecular compound (Et₃NH)[Ni(hfac)₂L] consists of an exchange-coupled spin-1 Ni²⁺ magnetic ion and a spin-

\frac{1}{2}

nitronyl-nitroxide radical substituted nitrophenol. The nickel-radical molecular complex affords an experimental realization of a mixed spin-(

\frac{1}{2}

, 1) Heisenberg dimer with a strong antiferromagnetic exchange coupling, J/

k_{B}

= 505 K, and two distinct g-factors, g_Rad = 2.005 and g_Ni = 2.275. By adopting this set of magnetic parameters, we demonstrate that the Zeeman splitting of a quantum ferrimagnetic ground-state doublet due to a weak magnetic field may substantially reinforce the strength of bipartite entanglement at low temperatures. The molecular compound (Et₃NH)[Ni(hfac)₂L] maintains sufficiently strong thermal entanglement, even at room temperature, vanishing only above 546 K. Specifically, the thermal entanglement in the nickel-radical molecular complex retains approximately 40% of the maximum value, corresponding to perfectly entangled Bell states at room temperature, which implies that this magnetic compound provides a suitable platform of a molecular qubit with potential implications for room-temperature quantum computation and quantum information processing. Full article

(This article belongs to the Special Issue Magnetic Materials and Their Applications)

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12 pages, 5263 KiB

Open AccessArticle

Production of Sm₂Fe₁₇N₃ Bulk Magnets

by Tetsuji Saito

Inorganics 2024, 12(4), 95; https://doi.org/10.3390/inorganics12040095 - 23 Mar 2024

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Abstract

Sm₂Fe₁₇N₃ powder exhibits excellent magnetic properties but is unstable and decomposes into α-Fe and SmN phases at high temperatures. Therefore, the key to producing Sm₂Fe₁₇N₃ bulk magnets is to reduce the deterioration of [...] Read more.

Sm₂Fe₁₇N₃ powder exhibits excellent magnetic properties but is unstable and decomposes into α-Fe and SmN phases at high temperatures. Therefore, the key to producing Sm₂Fe₁₇N₃ bulk magnets is to reduce the deterioration of Sm₂Fe₁₇N₃ powder during sintering. Herein, Sm₂Fe₁₇N₃ bulk magnets were made using the spark plasma sintering (SPS) method with the addition of zinc stearate powder and zinc powder. Adding small amounts of zinc stearate powder and zinc powder improved the magnetic anisotropy and the coercivity of the magnets, respectively. The magnets produced by the SPS method using zinc stearate powder and zinc powder exhibited enhanced magnetic properties almost comparable to those of Sm₂Fe₁₇N₃ powder. Full article

(This article belongs to the Special Issue Magnetic Materials and Their Applications)

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11 pages, 1401 KiB

Open AccessArticle

Mechano-Synthesis, Structure, and Thermal and Magnetic Behaviors of the New Compound Mn_1.2Co_0.05Fe_0.7P_0.45Si_0.5B_0.05

by Nawel Khitouni, Maha M. Almoneef, Amira Mili, Mohamed Khitouni, Asma Wederni and Joan-Josep Suñol

Inorganics 2024, 12(3), 63; https://doi.org/10.3390/inorganics12030063 - 20 Feb 2024

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Abstract

The Mn_1.2Co_0.05Fe_0.7P_0.45Si_0.5B_0.05 compound has been systematically synthesized by mechanical alloying for 15 h, followed by annealing with two heating cycles at 1373 K for 2 h and 1073 K for 24 h. [...] Read more.

The Mn_1.2Co_0.05Fe_0.7P_0.45Si_0.5B_0.05 compound has been systematically synthesized by mechanical alloying for 15 h, followed by annealing with two heating cycles at 1373 K for 2 h and 1073 K for 24 h. The powder that was milled for 15 h revealed the main hexagonal-Mn₂P-type phase and the minor cubic-Mn₃Fe₂Si phase through X-ray diffraction examination. After annealing the same powder at 1373 K for 2 h and again at 1073 K for 24 h, the refined phase was the unique (Mn, Fe)₂(P, Si) type with a hexagonal structure. For the mechanically alloyed powder, the final crystallite size was approximately 20 nm, and it rose to 95 nm during the annealing process. Further, a large amount of lattice microstrain was achieved as a result of high-energy milling (about 0.75%). Over the whole temperature range of 373 to 923 K, the thermal analysis showed several overlapping exothermic peaks, which indicated the improvement of the microstructure after the structural relaxation and reordering process. Moreover, the Curie temperature of the alloy was retrieved at approximately 675 K. According to an analysis of the magnetic properties, the mechanically alloyed powder exhibited an exceptional soft ferromagnetic state after 15 h of milling, and the annealed alloy showed superparamagnetic characteristics. Full article

(This article belongs to the Special Issue Magnetic Materials and Their Applications)

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13 pages, 2828 KiB

Open AccessArticle

Hyperthermia and Photocatalytic Performance of Magnetic Polyvinyl Alcohol under External Magnetic Field

by Manal M. Khowdiary, Hind Alsnani and Mohamed S. A. Darwish

Inorganics 2024, 12(2), 47; https://doi.org/10.3390/inorganics12020047 - 30 Jan 2024

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Abstract

The promising physical and chemical properties of components of magnetic polymers could enable extending their intelligent behaviors to material applications. Indeed, investigation into magnetic nanofillers to ensure their uniform dispersion within the polymer matrix remains a great challenge at present. In this work, [...] Read more.

The promising physical and chemical properties of components of magnetic polymers could enable extending their intelligent behaviors to material applications. Indeed, investigation into magnetic nanofillers to ensure their uniform dispersion within the polymer matrix remains a great challenge at present. In this work, polyvinyl alcohol-stabilized iron oxide nanoparticles (PVA@IONPs) were prepared using ultrasonic-assisted coprecipitation at room temperature. It is possible to produce PVA@IONPs with desirable shapes and sizes, which would enable the control of their hyperthermia and photocatalytic performance under an external magnetic field. The saturation magnetization of PVA@IONPs (45.08 emu g⁻¹) was enhanced to the level of IONPs (41.93 emu g⁻¹). The PVA@IONPs showed good photocatalytic and outstanding self-heating behavior. The hydrogen yield was 60 mmole min⁻¹ g⁻¹ for photocatalyst PVA@IONPs under visible light with magnetic force. In addition, the PVA@IONPs exhibited a higher specific absorption rate (SAR) than IONPs under the same magnetic field conditions. The PVA@IONPs displayed superior self-heating and photocatalytic performances, rendering them appropriate materials for biomedical and environmental applications. Full article

(This article belongs to the Special Issue Magnetic Materials and Their Applications)

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14 pages, 2870 KiB

Open AccessArticle

The Effect of the Linking Unit on the Electronic and Magnetic Interactions in Copper(II) Porphyrin Dimers Linked by Metal Ions

by Jordan L. Appleton, Nolwenn Le Breton, Sylvie Choua and Romain Ruppert

Inorganics 2024, 12(2), 44; https://doi.org/10.3390/inorganics12020044 - 27 Jan 2024

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Abstract

The syntheses of a series of copper(II) porphyrins and their dimers linked by palladium(II) or platinum(II) are reported. Their electronic properties and their magnetic properties were studied. In particular, the effect of the linking unit on these properties was evaluated. It was discovered [...] Read more.

The syntheses of a series of copper(II) porphyrins and their dimers linked by palladium(II) or platinum(II) are reported. Their electronic properties and their magnetic properties were studied. In particular, the effect of the linking unit on these properties was evaluated. It was discovered that three factors influence the electronic and magnetic interactions between the two metalloporphyrins: the nature of the linking metal ion, the nature of the external coordination site of the porphyrin, and also the nature of the metal ion present in the central core of the aromatic macrocycle. Full article

(This article belongs to the Special Issue Magnetic Materials and Their Applications)

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11 pages, 2569 KiB

Open AccessArticle

Magnetic Anisotropy Tailoring by 5d-Doping in (Fe,Co)₅SiB₂ Alloys

by Diana Benea

Inorganics 2024, 12(1), 6; https://doi.org/10.3390/inorganics12010006 - 22 Dec 2023

Viewed by 1104

Abstract

Band-structure calculations were performed using the spin-polarized relativistic Korringa–Kohn–Rostoker (SPR-KKR) band-structure method, determining intrinsic magnetic properties, such as magnetic moments, magnetocrystalline anisotropy energy (MAE), and Curie temperatures, of Fe_5−x−yCo_xM_ySiB₂ (M = Re, W) alloys. The general [...] Read more.

Band-structure calculations were performed using the spin-polarized relativistic Korringa–Kohn–Rostoker (SPR-KKR) band-structure method, determining intrinsic magnetic properties, such as magnetic moments, magnetocrystalline anisotropy energy (MAE), and Curie temperatures, of Fe_5−x−yCo_xM_ySiB₂ (M = Re, W) alloys. The general gradient approximation (GGA) for the exchange–correlation potential and the atomic sphere approximation (ASA) were used in the calculations. Previous studies have shown that for Fe₅SiB₂, the easy magnetization direction is in-plane, but it turns axial for Co-doping in the range 1 < x ≤ 2.5 (y = 0). Furthermore, studies have shown that 5d-doping enhances the MAE by enabling the strong spin–orbit coupling of Fe–3d and M–5d states. The aim of the present theoretical calculations was to find the dependence of the anisotropy constant K₁ for combined Co- and M-doping, building a two-dimensional (2D) map of K₁ for 0 ≤ x ≤ 2 and 0 ≤ y ≤ 1. Similar theoretical 2D maps for magnetization and Curie temperature vs. Co and M content (M = W and Re) were built, allowing for the selection of alloy compositions with enhanced values of uniaxial anisotropy, magnetization, and Curie temperature. The magnetic properties of the Fe_4.1W_0.9SiB₂ alloy that meet the selection criteria for axial anisotropy K₁ > 0.2 meV/f.u., Curie temperature T_c > 800 K determined by the mean-field approach, and magnetization µ₀M_s > 1 T are discussed. Full article

(This article belongs to the Special Issue Magnetic Materials and Their Applications)

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