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Magnetization and magnetic resonance in sol-gel derived polycrystalline BiFeO3 film
摘要： The structure and magnetic properties of polycrystalline BiFeO3 films grown on glass substrate using Sol-Gel technique have been investigated. X-ray diffraction (XRD) analysis revealed the average grain size of about 21 nm. The root mean square (RMS) surface roughness of about 50 nm has been obtained for the film by using scanning electron microscope (SEM) technique. Ferromagnetic resonance (FMR) studies showed the presence of macroscopic ferromagnetic magnetization and uniaxial out-of-plane magnetic anisotropy. The temperature dependences of the magnetization of BiFeO3 films registered in zero field cooling (ZFC) and field cooling (FC) regimes revealed a spin glass state. The average magnetic crystallite sizes obtained from the magnetizations studies coincide with the values revealed from the structural studies.
关键词： sol-gel technique,magnetic properties,magnetic materials,multiferroics
更新于2025-09-23 15:23:52
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Unique electromagnetic loss properties of Co-doped ZnO Nanofiber
摘要： In this paper, Co-doped ZnO nanoparticle and nano?ber are prepared by electrospinning method. The results show that Co-doped ZnO nano?ber performs bead-like ?brous shape and exhibits ferromagnetic properties. The dielectric loss and magnetic loss properties of Co-doped ZnO nano?ber are much better than those of Co-doped ZnO nanoparticle due to the improvement of dipole polarization, interfacial polarization and shape anisotropy. The absorptivity of Co-doped ZnO nano?ber can reach 70% in the frequency range of 5.3–18 GHz when the coating thickness is 1.5–4.0 mm. It is demonstrated that the bead-like ?brous shape is bene?cial to optimize electromagnetic loss and microwave absorption properties of Co-doped ZnO.
关键词： Electronic materials,Electromagnetic loss,Magnetic materials,Zinc oxide
更新于2025-09-23 15:23:52
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Different approaches for the solar photocatalytic removal of micro-contaminants from aqueous environment: Titania vs. hybrid magnetic iron oxides
摘要： This work reports on the light-induced heterogeneous photodegradation of four micro-contaminants (MCs): Carbamazepine (C), Flumequine (F), Ibuprofen (I), and Sulfamethoxazole (S), using two different heterogeneous advanced oxidation processes. The first one is the semiconductor photocatalysis, run in the presence of the suspension of a home prepared TiO2 (TiO2 HP); the second one is an heterogeneous photo-Fenton process run in the presence of a hybrid magnetic nanomaterial (MB3) with an iron oxides core and an organic shell made of bio-based substances (BBS) isolated from urban biowaste. The two materials work upon two different mechanisms and were already tested (and the action mechanism hypothesized) at the lab scale under model conditions: TiO2 acts as photocatalyst through the photo-generation of hole/electron pairs able to give rise to oxidation and reduction reactions, whereas hybrid magnetic nanomaterial acts in the presence of H2O2 by a photo-Fenton like mechanism. The results evidenced the better performances of TiO2 HP (also better than the well-known reference TiO2 P25). Preliminary photodegradation experiments carried out in a pilot plant under natural solar radiation confirmed the good results obtained with TiO2 HP. Moreover, in the adopted experimental conditions, the Fe(II) leached from MB3 can be considered as responsible of the MCs degradation through a homogeneous photo-Fenton reaction, where MB3 act as iron reservoir.
关键词： TiO2,Micro-contaminants,Photo-Fenton,Photocatalysis,Water treatments,Magnetic materials.
更新于2025-09-23 15:22:29
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Co2+ Substituted ZnCuFe2O4 (0.0?≤?x?≤?0.5) Ferrites: Synthesis, Magneto-structural and Optical Properties for Their Photocatalytic Performance
摘要： The cobalt (Co2+) has been successively substituted in ZnCuFe2O4 to obtain Zn0.5?xCoxCu0.5Fe2O4 (0.0 ≤ x ≤ 0.5) ferrites by auto-combustion technique. Prior to photocatalytic degradation, all as-synthesized ferrites were characterized to study their structure, composition, morphology, magnetic and optical behavior. The shifting of tetrahedral as well as octahedral stretching peaks towards higher frequencies observed in the Fourier transform infrared spectroscopy indicates that Co2+ ion is substituted in ZnCuFe2O4. X-ray diffraction pattern confirms the formation of single-phase cubic spinel with decrease in average lattice constant from 8.3915 to 8.3224 ? with increase in Co2+ substitution. The photocatalytic performance of obtained ferrite catalyst was determined using methylene blue (MB) as model dye under visible light and direct sunlight. The degradation of MB with as-obtained photocatalyst under sunlight improves (91%) which proves the effective utilization of visible light active magnetic photocatalyst.
关键词： Photocatalytic degradation,Magnetic materials,Methylene blue,Sol-gel method,Spinel ZnCuFe2O4
更新于2025-09-23 15:22:29
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Laser powder bed fusion of Nda??Fea??B permanent magnets
摘要： In this work, we use laser powder bed fusion (LPBF) to produce Nd–Fe–B magnets. A suitable process window is developed, which allows to fabricate isotropic samples with outstanding magnetic performance. The sample quality is mainly defined by the energy input during LPBF and sintering or delamination occurs, if the process parameter are improperly adjusted. Magnetic and structural properties become better as energy input increases, until the material-specific limit for process-ability has been reached. Magnets with coercivity of 886 kA/m (μ0Hc = 1.1 T) and maximum energy product of 63 kJ/m3 can be produced from Nd-lean commercial powder without any post treatment. Thereby, our samples represent the new benchmark for permanent magnets produced by additive manufacturing. On the example of coercivity, the impact of laser power, scan velocity and hatch spacing is discussed. It is shown that coercivity can be sufficiently well described by a simple phenomenological model.
关键词： Permanent magnets,Functional materials,Magnetic materials,Nd–Fe–B,Coercivity,Laser powder bed fusion (LPBF)
更新于2025-09-23 15:19:57
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[IEEE 2018 IEEE International Magnetic Conference (INTERMAG) - Singapore (2018.4.23-2018.4.27)] 2018 IEEE International Magnetics Conference (INTERMAG) - Scaling of all-optical switching to nanometer dimensions
摘要： The paper discusses the magnetic properties and applications of nanoscale materials, focusing on their use in optoelectronics. It presents experimental results on the manipulation of magnetic domains and the effects of external fields on material behavior. The study highlights the potential for improved device performance in magnetic storage and sensing applications.
关键词： device performance,nanotechnology,optoelectronics,magnetic materials,magnetic domains
更新于2025-09-19 17:15:36
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New Insights on the Photodegradation of Caffeine in the Presence of Bio-Based Substances-Magnetic Iron Oxide Hybrid Nanomaterials
摘要： The exploitation of organic waste as a source of bio-based substances to be used in environmental applications is gaining increasing interest. In the present research, compost-derived bio-based substances (BBS-Cs) were used to prepare hybrid magnetic nanoparticles (HMNPs) to be tested as an auxiliary in advanced oxidation processes. Hybrid magnetic nanoparticles can be indeed recovered at the end of the treatment and re-used in further water purification cycles. The research aimed to give new insights on the photodegradation of caffeine, chosen as marker of anthropogenic pollution in natural waters, and representative of the contaminants of emerging concern (CECs). Hybrid magnetic nanoparticles were synthetized starting from Fe(II) and Fe(III) salts and BBS-C aqueous solution, in alkali medium, via co-precipitation. Hybrid magnetic nanoparticles were characterized via X-ray diffraction (XRD), thermo-gravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. The effect of pH, added hydrogen peroxide, and dissolved oxygen on caffeine photodegradation in the presence of HMNPs was assessed. The results allow for the hypothesis that caffeine abatement can be obtained in the presence of HMNPs and hydrogen peroxide through a heterogeneous photo-Fenton mechanism. The role of hydroxyl radicals in the process was assessed examining the effect of a selective hydroxyl radical scavenger on the caffeine degradation kinetic.
关键词： hybrid nanomaterials,photo Fenton,caffeine,advanced oxidation processes,magnetic materials,bio-based substances
更新于2025-09-19 17:15:36
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[Energy, Environment, and Sustainability] Nano-Energetic Materials || Nanomaterials for Hydrogen Production Through Photocatalysis
摘要： In the last few decades, nanostructured materials have been of great interest worldwide due to their unique characteristics and their sub-driven reactivity. Furthermore, the unlimited applications of such materials in different fields and their associated success had added extra value for their importance. The combination between nanomaterials and photocatalytic processes has been recently given a great attention in different applications. It may enhance the viability of the nanotechnology principles. One of these applications is the usage of nanophotocatalytic materials in hydrogen production via water-splitting reaction. This chapter will cover the main concepts of photocatalysis and its associated terms. The main features of efficient photocatalysts and the ways of measuring such properties are illustrated in this chapter. Also, a brief presentation for the current methods that are utilized in the preparation of these catalysts is provided. An overview of the different types of semiconductors that are employed in the domain of photo-based hydrogen generation via splitting of water is introduced through this chapter too. A new approach in the water-splitting process by introducing noble metals attached magnetic nanoparticle (core/shell structure) as promising photomaterials is also described in this chapter. However, these materials are used in different fields such as bio-medical processes, water treatment, and energy storage. They are expected to be of high significance in field of catalysis, since they can be easily separated and recovered, due to their magnetic character, reactions. Implementation of a suitable magnetic force can enhance the hydrogen productivity during the water-splitting process. These materials are possessing magnetic properties which could reveal a new approach to their photocatalytic activity via quenching the radiation scattering.
关键词： Water-splitting processes,Magnetic materials,Photocatalysis,Hydrogen energy,Semiconductors
更新于2025-09-10 09:29:36
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Site-sensitive X-ray photoelectron spectroscopy of Fe <sub/>3</sub> O <sub/>4</sub> by photoelectron diffraction
摘要： Fe 2p core-level photoelectron spectra of magnetite were measured using soft X-ray and hard X-ray, and its emission angle dependence was investigated. The photoelectron diffraction pattern from different atomic sites differs because the atomic arrangement surrounding each site is different. By selecting the forward-focusing-peak (FFP) directions characteristic to each atomic site and measuring the kinetic energy dependence of the FFP intensities at the Fe 2p core-level range, we succeed in detecting the variation of the peak intensity of Fe 2p core-level spectra at different emission directions. This result, consistent with recent results, suggests that the lower-binding-energy peak of the Fe 2p core-level spectrum may be assigned as the B site component.
关键词： photoelectron diffraction,magnetic materials,mixed valence
更新于2025-09-10 09:29:36
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Structure and properties of Mn3O4 thin films grown on single crystal substrates by chemical vapor deposition
摘要： Mn3O4 thin films were fabricated on SrTiO3(111) and Y3Al5O12(100) substrates by chemical vapor deposition (CVD) under O2 atmospheres, starting from a fluorinated Mn(II) diketonate-diamine adduct. The obtained systems were investigated by a multi-technique characterization in order to elucidate the interplay between preparation conditions and their chemico-physical properties. The results highlighted the formation of phase-pure and homogeneous a -Mn3O4 (haussmannite) films, characterized by a smooth morphology, an appreciable Vis light absorption and structural features directly dependent on the used substrate. The target systems were uniformly doped with fluorine, due to the used Mn compound acting as a single-source precursor for both Mn and F. In addition, magnetic force microscopy measurements revealed the formation of spin domains and long-range magnetic order in the target materials, paving the way to their future implementation as magnetic media toward device integration for data storage.
关键词： Y3Al5O12(100),SrTiO3(111),Mn3O4 thin films,chemical vapor deposition,magnetic materials
更新于2025-09-10 09:29:36