Articles
Hosseini, S.,
Landrani, A.,
Moghadam, M.,
Sun, Y.,
Tangestaninejad, S.,
Mirkhani, V.,
Mohammadpoor-baltok, I.,
Karimi-maleh, H.,
Mozaffari, M. Energy and Fuels (08870624)39(24)pp. 11782-11792
Plasma catalysis for CO2 utilization technology shows considerable promise for advancement, with enhancing the synergistic relationship between plasma and catalysts being a key area of research challenge. However, current research focuses on the design of efficient catalyst formulations, but studies on metal-organic framework (MOF) screening and cold plasma methods have received less attention. Therefore, in this study, the hydrogenation of CO2 at ambient temperature and pressure was investigated using single-metal and bimetallic ZIF-67 as a MOF catalyst with the assistance of a dielectric barrier discharge (DBD) plasma reactor. The Co ZIF-67 and Ni Co ZIF-67 were synthesized and characterized by different analytical techniques. The synergistic effects between DBD plasma and these mono- and bimetal MOFs were investigated for the transformation protocol of CO2 to methanol. The flow rate of gas and input voltage as main parameters were screened. In this procedure, monometallic and bimetallic ZIF-67 showed 69.6 and 90.3% conversion with 84.1 and 98.1% selectivity of CH3OH production and 2.7 and 4.8 (mmol/kJ) energy efficiency under optimized conditions (flow rate: 60 mL/min; input voltage: 10 kV). Besides, the specific input energy of the transformation as a kinetic parameter was measured and showed linear behavior. The two catalysts can be reused up to six times without significant loss of their catalytic activities. © 2025 American Chemical Society.
Scientific Reports (20452322)14(1)
In this study, entanglement of composition, additive and/or sintering conditions and their effects on magnetic properties of soft ferrites, nickel zinc spinel ferrites (Ni1−xZnxFe2O4, x = 0.65 and 0.70) which were prepared via conventional solid-state reaction method investigated. Also an equiponderant calcined mixture of Bi2O3, CaO, CeO2, SiO2, Al2O3, Y2O3 and nanotitania was mixed thoroughly and used as a multi-compound calcined additive (MCCA). Calcined ferrite powders were crushed, dry and wet milled, dried, mixed with different amounts of MCCA (0.0, 0.5, 1.0, 1.5 and 2.0 wt%), formed in toroidal shapes and finally sintered at different temperatures, from 1150 up to 1360 °C for 3 h. X-ray diffraction assessment confirmed formation of the single phase cubic spinel structures. Initial permeability and Q-factor spectra of the toroids were obtained from 0.1 to 1000 kHz, using an LCR meter. The results show that initial permeability of each sample has a maximum and addition of MCCA to the ferrites leads to a marvelous increase in permeabilities. Additionally, MCCA decreases the optimum sintering temperature too. The optimum amounts of additive were 1.0 and 0.5 wt% for the x = 0.65 (μ′ = 492, Ts = 1280 °C) and x = 0.70 (μ′ = 478, Ts = 1320 °C), respectively. Permeability spectra illustrate that utility zone of the Ni0.35Zn0.65Fe2O4 and Ni0.3Zn0.7Fe2O4 are both less than 100 and 10 kHz, respectively. The results represent that there is a strong entanglement between composition, additive and/or sintering conditions. It can be concluded the MCCA added Ni0.35Zn0.65Fe2O4, is suitable for application in the switching power supplies. © The Author(s) 2024.
Asgarian, S.M.,
Mahjour-shafiei, M.,
Mozaffari, M.,
Shatooti s., S. Journal of Alloys and Compounds (09258388)986
Single phase Zn2+-substituted magnetite nanocrystallites are synthesized via co-precipitation method and used as lithium-ion battery electrodes. The structural properties and vacancy distribution of nanoparticles are evaluated by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and positron annihilation lifetime spectroscopy (PALS). The Rietveld refinement of the X-ray diffraction patterns shows that the lattice constant increases with Zn2+ content from 8.392 Å for magnetite to 8.448 Å for Zn0.2Fe2.8O4. The XPS measurements show that cation vacancies increase with Zn content on the surface of nanoparticles. Positron annihilation lifetime spectra suggest more concentration of monovacancies and larger size of vacancy clusters in the Zn0.1Fe2.9O4 sample compared with the other two samples, Fe3O4 and Zn0.2Fe2.8O4. Electrochemical measurements show better reversibility, higher initial discharge capacity, and lower electrochemical impedance for the Zn0.1Fe2.9O4 electrode, which are attributed to the higher concentration of vacancy defects in its nanocrystallites. The electrochemical impedance spectroscopy (EIS) shows that the Li+ diffusion coefficient (DLi+) increases with Zn2+ doping from 1.51 × 10–15 cm2s–1 for Fe3O4 to 3.25 × 10–13 cm2s–1 for Zn0.1Fe2.9O4, and 1.43 × 10–13 cm2s–1 for Zn0.2Fe2.8O4. The initial discharge capacities of the samples found to be about 1345.04 mAh g−1 for Fe3O4, 1435.82 mAh g−1 for Zn0.1Fe2.9O4, and 1063.72 mAh g−1 for Zn0.2Fe2.8O4 electrodes, respectively. During first few cycles, the discharge capacity decline faster as Zn content increases. The discharge capacity of the Zn0.2Fe2.8O4 electrode is stable at 410 mAhg−1 from the 60th to the 200th cycle, which is higher than the Fe3O4 electrode (150 mAhg−1) and the Zn0.1Fe2.9O4 electrode (270 mAhg−1). This variance is explained by the cation vacancy concentration and the lattice constant of the samples. The impedance of the electrodes is also affected by the vacancy defects formed during the sample preparation. © 2024 Elsevier B.V.
Physics of Metals and Metallography (0031918X)125(Suppl 1)
Abstract: A unique intermetallic alloy composed of Fe (81–85 wt %), Si (7–13 wt %), and Al (4–7 wt %) which is named Sendust, is typically synthesized by conventional methods, such as crushing and/or atomizing. Various techniques have been described for obtaining Sendust nanostructures in recent decades. This paper reviews the synthesis, crystal structure, magnetic properties, and old and new applications of Sendust. Formation of its ordered and/or disordered phases through different methods such as mechanical alloying, atomizing, and/or melting is possible. Its special magnetic properties, including high permeability, low hysteresis loss, zero magnetostriction, and nearly zero first constant of magnetic anisotropy, make it suitable for a wide range of electronic applications. Various applications of Sendust from magnetic cores in power supplies, its role in magnetic recording devices, the excellent magnetic permeability of its nanostructures in the GHz frequency range, reduced power losses for suppressing microwave absorption, and electromagnetic interference shielding are reviewed. © Pleiades Publishing, Ltd. 2024.
Saeidi, H.,
Mozaffari, M.,
Ilbey, S.,
Dutz s., S.,
Zahn d., D.,
Azimi gandomani, G.,
Bock, M. Nanomaterials (20794991)13(2)
Magnetic nanoparticles (MNPs) have been widely applied as magnetic resonance imaging (MRI) contrast agents. MNPs offer significant contrast improvements in MRI through their tunable relaxivities, but to apply them as clinical contrast agents effectively, they should exhibit a high saturation magnetization, good colloidal stability and sufficient biocompatibility. In this work, we present a detailed description of the synthesis and the characterizations of europium-substituted Mn-Zn ferrite (Mn0.6Zn0.4EuxFe2-xO4, x = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10, and 0.15, herein named MZF for x = 0.00 and EuMZF for others). MNPs were synthesized by the coprecipitation method and subsequent hydrothermal treatment, coated with citric acid (CA) or pluronic F127 (PF-127) and finally characterized by X-ray Diffraction (XRD), Inductively Coupled Plasma (ICP), Vibrating Sample Magnetometry (VSM), Fourier-Transform Infrared (FTIR), Dynamic Light Scattering (DLS) and MRI Relaxometry at 3T methods. The XRD studies revealed that all main diffraction peaks are matched with the spinel structure very well, so they are nearly single phase. Furthermore, XRD study showed that, although there are no significant changes in lattice constants, crystallite sizes are affected by europium substitution significantly. Room-temperature magnetometry showed that, in addition to coercivity, both saturation and remnant magnetizations decrease with increasing europium substitution and coating with pluronic F127. FTIR study confirmed the presence of citric acid and poloxamer (pluronic F127) coatings on the surface of the nanoparticles. Relaxometry measurements illustrated that, although the europium-free sample is an excellent negative contrast agent with a high r(2) relaxivity, it does not show a positive contrast enhancement as the concentration of nanoparticles increases. By increasing the europium to x = 0.15, r(1) relaxivity increased significantly. On the contrary, europium substitution decreased r(2) relaxivity due to a reduction in saturation magnetization. The ratio of r(2)/r(1) decreased from 152 for the europium-free sample to 11.2 for x = 0.15, which indicates that Mn0.6Zn0.4Eu0.15Fe1.85O4 is a suitable candidate for dual-mode MRI contrast agent potentially. The samples with citric acid coating had higher r(1) and lower r(2) relaxivities than those of pluronic F127-coated samples.
