Search

Cu2+‐ion‐doped cobalt ferrites with the chemical formula Co1–xCuxFe2O4 (0 < x ≤ 0.20) are prepared using the citrate–nitrate autocombustion method. The structural properties of the synthesized samples are examined by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. The XRD studies reveal the formation of a single‐phase spinel cubic structure. A slight variation in the peak position is observed with the addition of Cu2+ ions. The proposed cation distribution is supported by X‐ray relative intensity calculations. FTIR and Raman spectroscopy studies also confirm the formation of a single‐phase cubic structure. Field‐emission scanning electron microscopy (FESEM) is used to measure the surface properties of the samples. The FESEM images reveal nearly uniform‐sized grains with the addition of Cu2+ ions. The DC electrical resistivity is determined using the conventional two‐probe technique and is typically found within the range of 106 Ω cm−1. Dielectric measurements are performed using an impedance analyzer with 100 Hz–10 MHz frequency range and the variations in the dielectric properties are discussed. The magnetic properties are measured using a vibrating sample magnetometer conducted the magnetic measurements. The uneven variations in the magnetic properties are explained based on Neel's two‐sublattice model. [ABSTRACT FROM AUTHOR]

Manganese magnesium ferrite (Mg 0.5 Mn 0.5 Fe 2 O 4) and Gd doped Mg 0.5 Mn 0.5 Fe 2 O 4 (Mg 0.5 Mn 0.5 Fe 2-x Gd x O 4 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) were synthesized using the solid-state method. The structural study was performed using the powder X-ray diffraction (XRD) technique. The XRD plot confirms the presence of a spinel cubic structure for pure MgMn ferrite and the existence of a secondary GdFeO 3 phase in addition to the cubic spinel phase for Gd-doped MgMn ferrite. The average crystallite size estimated from the Williamson-Hall plot decreases from 42.75 nm to 18.97 nm with the increase in Gd content. The microstructural study confirms the clear grains with well-defined grain boundaries. The Fourier Transform Infrared (FTIR) spectra of the samples show the vibrational bands at 3440 cm−1, 1636 cm−1, 1385 cm−1, 1100 cm−1, and 560 cm−1 assigned to tetrahedral and octahedral sites. The improvement in dielectric property has been observed for Gd-doped samples. The saturation magnetization and remnant magnetization decrease from 0.7 to 0.3 emu and 0.035 to 0.0273 emu respectively. The coercivity increases from 31 to 75 Oe with the increase in Gd content. The fabricated spinel ferrites have significant electrical and magnetic properties which may be promising candidates for microwave devices. [ABSTRACT FROM AUTHOR]

Recently, there has been a significant focus on developing various energy harvesting technologies to power remote electronic sensors, data loggers, and communication devices for smart grid systems. Among these technologies, magnetic energy harvesting stands out as one straightforward method to extract substantial power from current-carrying overhead lines. Due to the relatively small size of the harvester, the high currents in the distribution system quickly saturate its magnetic core. Consequently, the magnetic harvester operates in a highly nonlinear manner. The nonlinear nature of the downstream AC to DC converters further complicates the process, making precise analytical modeling a challenging task. In this paper, a clamped type overhead line magnetic energy harvester with a controlled active rectifier generating significant DC output power is investigated. A piecewise nonlinear analytical model of the magnetic harvester is derived and reported. The modeling approach is based on the application of the Froelich equation. The chosen approximation method allowed for a complete piecewise nonlinear analytical treatise of the harvester's behavior. The main findings of this study include a closed-form solution that accounts for both the core and rectifiers' nonlinearities and provides an accurate quantitative prediction of the harvester's key parameters such as the transfer window width, optimal pulse location, average DC output current, and average output power. To facilitate the study, a nonlinear model of the core was developed in simulation software, based on parameters extracted from core experimental data. Furthermore, theoretical predictions were verified through comparison with a computer simulation and experimental results of a laboratory prototype harvester. Good agreement between the theoretical, simulation, and experimental results was found. [ABSTRACT FROM AUTHOR]

The current study focuses on synthesizing and characterizing the Gd and Ni co-doped Ba1-xGdxFe12-yNiyO19 nanoparticles (NPs) via emulsion method. The as-fabricated NPs were characterized using X-ray diffraction (XRD) analysis , Fourier transform infrared (FTIR) analysis, Raman spectroscopy, Scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM) analysis. The synthesis of single-phase Ba-hexaferrites with hexagonal geometry was successfully formed, with co-doping of Gd at tetrahedral and Ni at octahedral sites. SEM analysis revealed tubular particles with rounded spherical geometry, with an increased surface area increase in particle size from 25 to 35 nm upon doping. The magnetic investigation showed increased magnetization (45.7–70.2 emu/g) with co-doping. The doped materials showed excellent photocatalytic activities, degrading almost 90.2% of methyl green (MG) dye in 60 min of sunlight illumination in comparison with 32.26% of their counterpart. The reusability test showed excellent stability and recoverability, with only 1% loss in degradation activity after 5 runs. The results suggest that Gd- and Ni-doped Ba1-xGdxFe12-yNiyO19 NPs have superior photocatalytic activities, more magnetization, an exposed surface area, and excellent reusability, making them suitable for potential applications. [ABSTRACT FROM AUTHOR]

The present study reveals the synthesis of Iron oxide nanoparticles (IONPs) by varying the molar ratio of ferric (Fe3+) to ferrous (Fe2+) ions via chemical coprecipitation method for the study of cationic distribution of Fe‐ions and its potential application for magnetic hyperthermia therapy (MHT). X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and X‐ray photoelectron spectroscopy (XPS), were used to characterize the physicochemical properties. Several structural parameters were estimated using the Rietveld refinement, resulting in structural modelling verified by magnetic characteristics. A vibrating sample magnetometer (VSM) assessed the magnetic hysteresis loop at room temperature in a field range of ±15 kOe, revealing superparamagnetic behavior for the ratio Fe2+/Fe3+ 1:2. The saturation magnetization (Ms) of IONPs increased with the increasing Fe2+ concentration and attained a maximum value of 60.21 emu g−1 at a molar ratio of 2:1. The potential of the inductive heating capability of IONPs in an alternating current magnetic field (AMF) was studied to treat localized MHT. The changes in magnetic properties and inductive heating properties of IONPs are associated with the cationic distribution of Fe2+ at the tetrahedral (A) and octahedral (B) sites of crystal structure. The variation in cationic properties at the A and B sites may result in varying/tuneable magnetic properties, affecting the overall heating profiles of hyperthermia. [ABSTRACT FROM AUTHOR]

This study investigates the magnetic response of Ho3+ doped Ni 0.4 Cu 0.6 Ho y Fe 2-y O 4 (y = 0.0, 0.02, 0.04, 0.06, and 0.08) spinel ferrites (SFs) and their correlation with crystallite size. The synthesis was achieved using a sol-gel auto-combustion (SGAC) route and performed different characterizations, including X-ray diffraction (XRD), Scanning electron microscope (SEM), Energy dispersive x-ray (EDX), Inductively coupled plasma atomic emission spectroscopy (ICP-AES), and vibrating sample magnetometer (VSM) analysis. The cubic spinel phase was verified via XRD in pure NCF and Ho3+ doped NCF samples. The lattice constant (a) was improved from 8.344 Å to 8.378 Å. The substitution of Ho3+ ions led to a decrease in porosity from 42.22 % to 39.54 %. The introduction of Ho3+ ions also reduced the crystallite size (D) from 37.05 nm to 27.72 nm. The specific surface area (S) was increased from 27.44 g/cm2 to 36.14 g/cm2 with the doping of Ho3+. The average particle size (D S) was decreased from 54 nm to 35 nm. The EDX and ICP-AES analyses confirmed the good agreement with the theoretical composition. The VSM measurements provided insights into their magnetic properties. Furthermore, the doping of Ho3+ ions enhanced coercivity (H C), while reducing saturation magnetization (M S) from 64.35 emu/g to 16.22 emu/g. The decrease in crystalline anisotropy (K) observed at higher concentrations of Ho3+ may result from the increase in coercivity, potentially attributable to the smaller crystallite size of the single-domain SFs particles. The single-phase matrix and their magnetic behaviour showed that the Ho3+ doped Ni–Cu SFs samples are suitable for high-frequency applications. [Display omitted] • Ni 0.4 Cu 0.6 Ho y Fe 2-y O 4 was prepared via the sol-gel auto-combustion technique. • The crystallite size was the minimum (27.72 nm) for the y = 0.08 (NCHF4) sample. • The sample has y = 0.08 (NCHF4) and contains maximum coercivity (1031.44 Oe). • The sample has y = 0.08 (NCHF4) and is best-suitable for high-frequency applications. [ABSTRACT FROM AUTHOR]

Multiferroic materials can realize the mutual coupling between force, electricity, magnetism and other physical fields, and have important application prospects in the field of small size, fast response and low power consumption of magnetoelectric devices. GaFeO3 is a highly promising multiferroic material featuring high spontaneous magnetization and polarization beyond room temperature. In this study, Ferroelectric Mgx Ga1 - x FeO3 (x = 0. 02, 0. 05, 0. 07 and 0. 10) single crystals with a diameter of about 7 mm were grown by light floating zone method. The effect of Mg2 + on the saturation magnetization and magnetic transition temperature of GaFeO3 (GFO) crystals were studied. The structure and phase of the crystal were analyzed through XRD, the results show that all the prepared samples correspond to the diffraction characteristics of the standard crystal card library GFO (PDF#76-1005), and no other heterophase appears. The XRD refinement results indicate that, the crystal structure is orthogonal and its space group is Pna21. As the concentration of Mg2 + rises, the lattice constant and cell volume initially increase and subsequently decrease. Additionlly, the magnetic properties of the crystal were studied through a comprehensive physical property measurement system, the magnetic transition temperature and saturation magnetization of the grown crytals also increase firstly and then decrease with the increase of Mg2 + doping content. When the Mg2 + doping amount is 0. 07, the magnetic transition temperature and saturation magnetization reach the maximum values of 187. 82 K and 8. 75 emu/g, respectively, which achieves the purpose of doping modification. [ABSTRACT FROM AUTHOR]

Featured Application: Magnetic energy harvesting of an overhead line. Recently, much attention has been given to the development of various energy harvesting technologies to power remote electronic sensors, data loggers, and communicators that can be installed on smart grid systems. Magnetic energy harvesting is, perhaps, the most straightforward way to capture a significant amount of power from a current-carrying overhead line. Since the harvester is expected to have a small size, the high currents of the distribution system easily saturate its magnetic core. As a result, the operation of the magnetic harvester is highly nonlinear and makes precise analytical modeling difficult. The operation of an overhead line magnetic energy harvester (OLMEH) generating significant DC power output into a constant voltage load was investigated in this paper. The analysis method was based on the Froelich equation to analytically model the nonlinearity of the core's BH characteristic. The main findings of this piecewise nonlinear analysis include a closed-form solution that accounts for both the core and rectifiers' nonlinearities and provides an accurate prediction of OLMEH transfer window length, output current, and harvested power. Continuous and discontinuous operational modes are identified and the mode transition boundary is obtained quantitatively. The theoretical investigation was concluded by comparison with a computer simulation and also verified by the experimental results of a laboratory prototype harvester. A good agreement was found. [ABSTRACT FROM AUTHOR]

Holmium (Ho)‐doped bismuth ferrite (BiFeO3) nanoparticles are synthesized using the citrate‐gel autocombustion method to investigate their structural, dielectric, ferroelectric, and magnetic properties. X‐Ray diffraction analysis confirms the formation of a rhombohedral perovskite structure, with crystalline size decreasing from ≈14 to 7 nm as doping levels increase. Fourier‐transform infrared spectroscopy further validates the perovskite phase, while field emission scanning electron microscopy and energy‐dispersive X‐Ray spectroscopy confirm the nanocrystalline nature and composition of the samples. X‐Ray photoelectron spectroscopy verifies the successful incorporation of Ho3+ ions into the BiFeO3 matrix. The dielectric properties show high permittivity and low dielectric losses, while magnetic hysteresis loops reveal enhanced magnetic properties, including increased saturation magnetization, remanence, coercivity, squareness ratio, Bohr magneton, and magnetocrystalline anisotropy. These findings indicate that Ho‐doped BiFeO3 nanoparticles exhibit significantly improved electric and magnetic performance, positioning them as promising candidates for applications in magnetic storage devices and sensors. [ABSTRACT FROM AUTHOR]

Using melt spinning technology, we successfully synthesized a series of Fe-rich Fe–P–C amorphous alloys exhibiting high saturation magnetization (B s), low coercivity (H c), and excellent bending ductility. These alloys exhibit low H c values ranging from 4.1 to 7.2 A/m, and high B s values ranging from 1.58 to 1.68 ​T. Particularly, after annealing at 588 ​K for 900 ​s, the Fe 83 P 11 C 6 amorphous alloy showed extraordinary soft magnetic properties: B s up to 1.68 ​T, H c only 4.7 A/m, and the core loss at approximately 1.5 ​W/kg under the condition of 0.5 ​T and 50 ​Hz, all of which surpass the reported Fe–P–C ternary amorphous and nanocrystalline alloys. These Fe-rich Fe–P–C alloy ribbon samples exhibit favorable bending ductility in both the as-spun and annealed states. Their simple alloy composition, outstanding soft magnetic properties, and excellent flexibility collectively make these soft magnetic alloys highly promising candidate materials for industrial applications. [Display omitted] • The prepared Fe-P-C alloys achieved B s > 1.65 T and H c < 5 A/m, outperforming reported ternary Fe-P-C alloys. • The paper investigates Fe-P-C amorphous alloys with Fe content surpassing 80 at.%, addressing an unexplored area. • The Fe-P-C alloy ribbons developed in this study exhibit good bending ductility, beneficial for production stability. • Fe-P-C alloys in this paper are low-cost, with excellent magnetic properties and bending ductility, ideal for industry. [ABSTRACT FROM AUTHOR]

A mixture of soft–hard (S–H) ferrites with the general chemical formula (1‐x) Ni0.5Cu0.25Zn0.25Fe2O4 (NCZFO) + (x) SrFe11Y1O19 (SFYO) is developed via sol‐gel auto‐combustion and their physical mixing. X‐ray diffraction (XRD), Fourier transform infrared spectroscopy, field emission scanning electron microscopy (SEM) coupled with energy dispersive X‐ray spectroscopy, high‐resolution transmission electron microscopy (HRTEM), vibrating sample magnetometry (VSM) and two‐probe technique are used to examine the resultant materials. Rietveld refinement of XRD data confirms the co‐existence of both soft and hard phases in the composites. The HRTEM and FESEM results confirm the nanocrystalline nature of the synthesized particles. Williamson‐Hall method is employed to reveal the strain nature in soft and hard phases. VSM analysis shows considerable changes in the magnetic characteristics for the different composition of NCZFO and SFYO. The exchange‐spring mechanism is discussed in the manuscript. [ABSTRACT FROM AUTHOR]

In this paper, we report a systematic study on effect of film thickness and substrate temperature on structural and magnetic behaviour of Fe-Ga films with Cu buffer layer, deposited on Si and Si/SiO2 substrates at room and high substrate temperatures. Grazing incidence X-ray diffraction studies reveal that all the films are crystalline with disordered alpha-Fe phase, which is BCC A2 phase. At 300 °C of substrate temperature, films deposited on Si/SiO2 substrate found to nucleate L12 phase from matrix of A2 phase, which is not seen in Si based films. Irrespective of substrate material, Fe-Ga films found to exist in dual phases at 500 °C substrate temperature. Lattice strains of the films were calculated from X-ray diffraction patterns, using Williamson-Hall method. From X- ray reflectivity analysis of all the films, film density, thickness and roughness of Fe-Ga layer and buffer layer were obtained after fitting the reflectivity data. Presence of an oxide layer is also evident from reflectivity fitting analysis. From magnetization studies it is clear that, all the films exhibited strong in-plane anisotropy. Saturation magnetization of films was found to vary with change in film density and oxide layer thickness of films. Saturation magnetization of films deposited on Si substrates found to decrease with decrease in film density. Coercivity of films found to vary with change in crystallite size, interface roughness and lattice strain of films. Films deposited on Si substrates are sensitive to strain with change in film thickness and films deposited on Si/SiO2 substrates are sensitive to strain with change in deposition temperature. Coercivity in films found to decrease with decrease in film roughness, increase in crystallite size and lowering the tensile lattice strain. [ABSTRACT FROM AUTHOR]

High-performance microwave-absorbing composites have attracted considerable attention in the field of electronic technology and telecommunications. These materials utilize stoichiometric combinations of components to enhance the magnetic parameters and reduce dielectric losses. In this work, microwave emulsion was used to synthesize magnetic nanocomposites with different concentrations of MgFe2O4 nanoparticles in polystyrene (PST). Samples of pure ferrite and PST were mixed in various amounts to form a ferrite polymer (FP-1, FP-2, FP-3, and FP-4, with 25%, 50%, 75%, and 100% ferrite, respectively). These composites were characterized using x-ray diffraction (XRD), dielectric characteristics, and vibrating-sample magnetometry (VSM). The XRD results showed that MgFe2O4 particles were evenly dispersed throughout single-phase PST. The crystallite size increased from 2 nm to 44 nm by mixing ferrites in PST. The dielectric properties were reduced as the percentage was decreased. The VSM tests indicated that all nanocomposites showed narrow loops and ferromagnetic behavior. The magnetic parameters decreased by adding the PST in magnesium ferrite components. The saturation magnetization decreased from 70 emu/g to 18 emu/g, remanence magnetization decreased from 21 emu/g to 5 emu/g, and coercivity decreased from 38 Oe to 8 Oe. All the above parameter results suggest that due to the high dielectric loss at high frequencies, magnesium spinel ferrites may be suitable for microwave absorption applications. [ABSTRACT FROM AUTHOR]

Mechanical alloying was employed to synthesize a nanostructured alloy with the chemical formula of (Fe80Ni20)1-xCrx (x= 0, 4). The microstructural and magnetic properties of the samples were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and a vibrating sample magnetometer (VSM). Additionally, theoretical calculations were performed using density functional theory (DFT) under the generalized gradient approximation (GGA). Simulations have demonstrated that an appropriate quantity of chromium (Cr) can dissolve within the BCC-Fe (Ni) structure, resulting in a favorable enhancement of the magnetic moment of the lattice. The XRD results indicated that after 96 hours of milling, Fe (Ni) and Fe (Ni, Cr) with a body-centered cubic (BCC) structure were formed. With increasing milling time, the grain size decreased while the microstrain increased. The saturation magnetization (Ms) of Fe80Ni20 composition increased up to 32 hours of milling, but further milling (up to 96 h) resulted in a decrease in the saturation magnetization However, for the (Fe80Ni20)96Cr4 powders, milling up to 64 h caused a reduction in Ms. The coercivity (Hc) trend was different and increased with longer milling times (up to 96 h) for both compositions.

Abstract An exciting prospect in the field of magnetic fluid hyperthermia (MFH) has been the integration of noble rare earth elements (Eu) with biopolymers (chitosan/dextran) that have optimum structures to tune specific effects on magnetic nanoparticles (NPs). However, the heating efficiency of MNPs is primarily influenced by their magnetization, size distribution, magnetic anisotropy, dipolar interaction, amplitude, and frequency of the applied field, the MNPs with high heating efficiency are still challenging. In this study, a comprehensive experimental analysis has been conducted on single-domain magnetic nanoparticles (SDMNPs) for evaluating effective anisotropy, assessing the impact of particle-intrinsic factors and experimental conditions on self-heating efficiency in both noninteracting and interacting systems, with a particular focus on the dipolar interaction effect. The study successfully reconciles conflicting findings on the interaction effects in the agglomeration and less agglomerated arrangements for MFH applications. The results suggest that effective control of dipolar interactions can be achieved by encapsulating Chitosan/Dextran in the synthesized MNPs. The lower dipolar interactions successfully tune the self-heating efficiency and hold promise as potential candidates for MFH applications.

Yttrium Iron Garnet (YIG) ferrites, characterized by their superior magnetic and dielectric attributes, are instrumental in advancing the development of microwave devices, particularly in enhancing high-frequency performance, integration, and miniaturization. This paper synthesizes YIG ferrite materials with the composition Bi 0.6 Y 1.4-x Ca 1+x Fe 4.5-x V 0.5 Ge x O 12 (x = 0.10 to 0.50, incrementing by 0.10) through the solid-state sintering method. It delves deeply into the mechanism by which Ca2+-Ge4+ ions substitution regulates the magnetic properties of BiV-YIG. The microstructural and magnetic properties of the samples were systematically tested and analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), vibrating sample magnetometry (VSM), and TE106 perturbation method. At a substitution content of x = 0.50, the substitution of Ge4+ ions for the Fe3+ ions at the d-site transforms the material from ferrimagnetic to paramagnetic, and the saturation magnetization of the sample drops to 132.74 G. By calculating the ferromagnetic resonance (FMR) linewidth using the law of approach to saturation, the study elucidates the negative impact of low saturation magnetization on FMR linewidth. The mechanisms proposed in this paper provide theoretical and experimental bases for reducing the FMR linewidth of high dielectric constant Bi-substituted YIG, paving the way for developing high-dielectric, low-loss YIG ferrite materials for microwave devices. [ABSTRACT FROM AUTHOR]

Mechanical alloying was employed to synthesize a nanostructured alloy with the chemical formula of (Fe80Ni20)1-xCrx(x= 0, 4). The microstructural and magnetic properties of the samples were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), energy -dispersive X-ray spectroscopy (EDS), and a vibrating sample magnetometer (VSM). Additionally, theoretical calculations were performed using density functional theory (DFT) under the generalized gradient approximation (GGA). Simulations have demonstrated that an appropriate quantity of chromium (Cr) can dissolve within the BCC -Fe (Ni) structure, resulting in a favorable enhancement of the magnetic moment of the lattice. The XRD results indicated that after 96 hours of milling, Fe (Ni) and Fe (Ni, Cr) with a body -centered cubic (BCC) structure were formed. With increasing milling time, the grain size decreased while the microstrain increased. The saturation magnetization (Ms) of Fe80Ni20 composition increased up to 32 hours of milling, but further milling (up to 96 h) resulted in a decrease in the saturation magnetization However, for the (Fe80Ni20)96Cr4 powders, milling up to 64 h caused a reduction in Ms. The coercivity (Hc) trend was different and increased with longer milling times (up to 96 h) for both compositions. [ABSTRACT FROM AUTHOR]

Iron oxide nanoparticles (IONs) with good water dispersibility were prepared by the thermal decomposition of iron acetylacetonate (Fe(acac)3) in the high-boiling organic solvent polyethylene glycol (PEG) using polyethyleneimine (PEI) as a modifier. The nucleation and growth processes of the crystals were separated during the reaction process by batch additions of the reaction material, which could inhibit the nucleation but maintain the crystal growth, and products with larger particle sizes and high saturation magnetization were obtained. The method of batch addition of the reactant prepared IONs with the largest particle size and the highest saturation magnetization compared with IONs reported using PEG as the reaction solvent. The IONs prepared by this method also retained good water dispersibility. Therefore, these IONs are potentially suitable for the magnetic separation of cells, proteins, or nucleic acids when large magnetic responses are needed. [ABSTRACT FROM AUTHOR]

Hexaferrites, with their exceptional crystalline anisotropy, substantial coercivity, tuneable cations, and high magnetic hardness, are crucial as permanent magnets in applications such as information storage, sensors, high-frequency and microwave-absorbing devices. In this study, the focus was on synthesizing copper and cadmium-substituted strontium W-type hexagonal ferrites (SrCu 2-x Cd x Fe 16 O 27) with varying x values of 0.00, 0.01, 0.02, 0.03, and 0.04. To comprehensively investigate their structural, morphological and optical characteristics, several analytical techniques were employed, including XRD, SEM, FT-IR spectroscopy and UV–Vis spectroscopy along with dielectric and magnetic techniques. The XRD analysis showed a minimum crystallite size of 13 nm for x = 0.0 and a maximum of 21 nm for x = 0.04. The morphology was examined through SEM, affirming the characteristic structure of W-type hexaferrites. FT-IR spectra exhibited two prominent peaks at 491 cm−1 and 890 cm−1, further validating the creation of W-type hexaferrites. Notably, the UV–Vis spectroscopy demonstrated a reduction in the optical band gap from 2.41 to 2.11 eV with increasing concentrations. In terms of dielectric properties, a peak dielectric constant of 71 was observed at frequencies above 2.5 GHz. Furthermore, the AC conductivity displayed a linear trend at lower frequencies, reaching a maximum value of 0.35 [ohm cm]−1 at higher frequencies. The magnetic measurements indicated that the substitution of x = 0.04 exhibited the highest saturation magnetization, Ms value of 1.7 emu/g, but the lowest coercivity, Hc value of 75 Oe was observed. [ABSTRACT FROM AUTHOR]

In this context, we report the acoustic shock wave processing on amorphous Carbon quantum dots (a-CQD) such that its degree of graphitization and magnetic properties are analyzed. Analytical techniques such as the Raman spectrometer, high resonation–transmission electron microscopy (HR-TEM) and vibrating sample magnetometer (VSM) are utilized to understand the structural, morphological and magnetic properties changes under shocked conditions. The Raman spectroscopic data reveal that the I D /I G ratio is slightly reduced under shocked conditions and the observed values are 0.78, 0.77 and 0.75 for the respective 0, 150 and 300 shocked conditions. The formation of ultra-short-range graphitic nanostructures is confirmed by HR-TEM results at the 300-shocked condition. The most convincing and supporting results for the enhancement of the degree of graphitization are found by the outcome of the magnetic properties such that the saturation magnetization (Ms) is found to be linearly reduced with respect to the number of shock pulses and the observed values are 0.869, 0.757 and 0.710 emu/g for the 0, 150 and 300 shocked conditions, respectively. The electrical resistance of the a-CQD is found to be linearly reduced with respect to the number of shock pulses due to the reduction of sp3 carbon networks. The formation of crystalline graphitic nanostructures in amorphous CQD is explained on the basis of the hot-spot nucleation mechanism. Based on the obtained Raman, HR-TEM and VSM results, during the shocked conditions, slight enhancement of the graphitization is observed; however, from the structural stability point of view, the Carbon dots have high shock resistance than that of the amorphous carbon nanoparticles, multi-wall carbon nanotubes, and reduced graphene oxide nanoparticles. Hence, the title quantum dots can be strongly considered for the applications of device fabrication. [ABSTRACT FROM AUTHOR]

In order to mitigate the rapid grain growth, a sintered ferrite magnet exhibiting stable characteristics was successfully synthesized. M-type strontium ferrite Sr 1- x Sm x Fe 12- x Co x O 19 (x = 0.00, 0.01, 0.02, 0.03, 0.04, 0.05 and 0.10) was synthesized via a low-temperature co-firing method, incorporating an appropriate quantity of Bi 2 O 3 and CuO as additives within the solid-phase reaction process. The magnetic and electrical properties of the resulting composites were meticulously examined, and X-ray diffraction (XRD) analysis was performed for structural characterization. The findings reveal that a pure hexagonal strontium phase is achieved consistently when the substitution level, x , remains below 0.5. With an increase in the substitution level, a heterogeneous phase α-Fe 2 O 3 becomes apparent within the phase structure. Upon introducing doping elements, the subtle incorporation of SmCo (x ≤ 0.02) enhances the saturation magnetization, remanent magnetization, and coercivity of the composite material. Moreover, the resistances of grain and grain boundary (Rg, Rgb) have been downscaled from 1.856 × 106Ω and 3.61 × 106Ω to 3.182 × 104Ω and 4.37 × 105Ω respectively. Consequently, the Sr 1- x Sm x Fe 12- x Co x O 19 ferrite sintered under low-temperature conditions demonstrates outstanding electromagnetic characteristics, presenting a viable option for materials in microwave device applications. [ABSTRACT FROM AUTHOR]

Copyright of Erzincan University Journal of Science & Technology is the property of Erzincan Binali Yildirim Universitesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An exciting prospect in the field of magnetic fluid hyperthermia (MFH) has been the integration of noble rare earth elements (Eu) with biopolymers (chitosan/dextran) that have optimum structures to tune specific effects on magnetic nanoparticles (NPs). However, the heating efficiency of MNPs is primarily influenced by their magnetization, size distribution, magnetic anisotropy, dipolar interaction, amplitude, and frequency of the applied field, the MNPs with high heating efficiency are still challenging. In this study, a comprehensive experimental analysis has been conducted on single-domain magnetic nanoparticles (SDMNPs) for evaluating effective anisotropy, assessing the impact of particle-intrinsic factors and experimental conditions on self-heating efficiency in both noninteracting and interacting systems, with a particular focus on the dipolar interaction effect. The study successfully reconciles conflicting findings on the interaction effects in the agglomeration and less agglomerated arrangements for MFH applications. The results suggest that effective control of dipolar interactions can be achieved by encapsulating Chitosan/Dextran in the synthesized MNPs. The lower dipolar interactions successfully tune the self-heating efficiency and hold promise as potential candidates for MFH applications. [ABSTRACT FROM AUTHOR]

The spinel ferrites (SFs) are renowned for their distinctive magnetic and electrical characteristics. Sol-gel route was used for the fabrication of Sr0.6 Zn0.4 Gdx Fe2-x O4 (0.00, 0.025, 0.050, 0.075, 0.100) ferrites. The structural, magnetic, microwave, and DC (direct current) properties of prepared Nps were found using of number characterization techniques. The X-ray diffraction (XRD) pattern of Sr0.6 Zn0.4 Gdx Fe2-x O4 SFs showed a single cubic phase. The magnetic behavior was determined by applying a field of 2 kOe. The various magnetic features, including those determined based on the M-H loop, and prepared spinel ferrites showed the soft nature of magnetic materials. When amount of gadolinium (Gd) is increased, then saturation magnetization, coercivity, remanence magnetization is decreased. The Ms values decreased from 69.36 to 32.18 emu/g, coercivity reduced from 220 to 14 emu/g, and remanence magnetization is decreased from 32 to 3 emu/g. The electrical parameters revealed that direct current resistivity and activation energy (Ea) increased (from 0.16 eV to 0.28eV) with the inclusion of the Gd. The activation energy was increased from 0.16 to 0.28 eV. The dielectric constant and loss of permittivity and permeability were determined by applying the frequency 5.5–9.5 GHz. From the above enhanced parameters, it can be concluded that fabricated SFs may be suitable for high-frequency devices. [ABSTRACT FROM AUTHOR]

A long pulse width solid-state Linear Transformer Driver (LTD) is designed by means of pulse superposition for high voltage, large current and wide range pulses required in biomedical applications of pulsed electromagnetic fields. To break through the pulse width range under the volt-second product limit of the pulse transformer, the LTD increases the output pulse width using parallel superposition. The reset circuit of the pulse transformer is designed to improve the output pulse duty cycle of LTD, so that the multi-pulse superposition of the minimum branch LTD can be achieved. A simulation circuit model is built on Pspice to verify the design principle and the effect. In the case of a single-turn pulse transformer with a volt-second product of 146 V · ms, a pulse output with a single-stage voltage of 300 V and a pulse width of 1.6 ms is realized, which is 3 times of its original volt-second product, and a wider range of pulse extension can be achieved by increasing the number of superimposed pulses. [ABSTRACT FROM AUTHOR]

A sample of Y2.85Ca0.15Sn0.08Ti0.05Mn0.07Fe4.8O12 doped with four different ions was prepared using the solid method and a subsequent procedure. X-ray diffraction (XRD), energy-dispersive X-ray (EDX), and scanning electron microscope (SEM) were used to analyze the sample's structural features, elemental distribution, and surface morphology. The study used the B-H magnetic characteristic analyzer and superconducting quantum interferometer magnetic performance measurement system to analyze the magnetic properties of Y2.85Ca0.15Sn0.08Ti0.05Mn0.07Fe4.8O12. The correlation becomes more surprising as the frequency increases, indicating a decrease in permeability when the magnetic field H reaches 200 A/m. Ion substitution leads to changes in magnetic crystal anisotropy, affecting permeability as the external magnetic field strength increases. We analyze the correlation between saturation magnetization and temperature in the 520–540 K range and explain the variation of saturation magnetization with temperature. The study shows that saturation magnetization decreases as temperature increases. This result suggests that saturation magnetization decreases as temperature increases. The increased super-exchange effect due to Ti and Mn occupying the (d) sites is much stronger than the reduced effect caused by Sn occupying the (a) sites. Therefore, the saturation magnetization of the Y2.85Ca0.15Sn0.08Ti0.05Mn0.07Fe4.8O12 sample is higher than that of the undoped sample. The Curie temperature (Tc) of the Y2.85Ca0.15Sn0.08Ti0.05Mn0.07Fe4.8O12 sample is lower than that of the undoped sample. [ABSTRACT FROM AUTHOR]

In this research, a nano-sized cobalt ferrite material doped with Yttrium has been successfully fabricated using the sol-gel method of automatic combustion with variations in low sintering temperatures of 200, 300 and 400 °C. The results of refinement of XRD data using the Rietveld method show that the Yttrium-doped cobalt ferrite compound with a Yttrium concentration molarity of 0.1 possess a cubic crystal system and Fd-3m space group. The increasing annealing temperatures also increase the crystallite size of Yttrium-doped cobalt ferrite with the highest magnitude of 16.05 nm. The FTIR results of the samples indicated the presence of Co-O bonds around wave number 385 cm-1 and Fe-O bonds around wave number 582 cm-1 which are characteristic of the presence of cobalt ferrite compounds. From the VSM measurement results, it can be seen that there is a decrease in magnetic saturation with an increase in annealing temperature. The presence of Yttrium substitution, which takes the place of Fe3+ in cobalt ferrite material, indicates lower saturation magnetization. Image from SEM results showed samples have nanoparticle crystallite size. Evaluation of potential photocatalyst applications using a UV-Visible Spectrophotometer (UV-Vis). For Yttrium doped cobalt ferrite at 200 °C, the best degradation efficiency of Congo Red findings showed a magnitude of 76.10 %; the results are confirmed by the occurrence of the smallest crystallite size (15.11 nm). [ABSTRACT FROM AUTHOR]

The saturation magnetization and core size distribution of magnetic nanoparticles (MNPs) play an important role in biomedical and biological applications. Fast and precise estimation of the saturation magnetization and core size distribution are critical. The core size distribution of MNPs can be determined from the static magnetization (M-H curve) obtained by a vibrating sample magnetometer (the M-H curve consists of a saturated region and an unsaturated region). However, the method is time-consuming, the number of sampling points and the field strength range have a large influence on the estimation result of the distribution, it is necessary to find the optimal number of sampling points and magnetic field strength range, and the saturation magnetization needs to be obtained from the saturated region before determining the distribution. We compared the two methods [geometric series sampling (GSS) and arithmetic series sampling (ASS)] for the M-H curve to reduce the field strength range and the number of sampling points, and the saturation magnetization and core size distribution can be estimated with the unsaturated region of M-H curve. The experimental results show that the saturation magnetization and the core size distribution of MNPs can be estimated more quickly and precisely using GSS in comparison to ASS.

Recently, there has been a significant focus on developing various energy harvesting technologies to power remote electronic sensors, data loggers, and communication devices for smart grid systems. Among these technologies, magnetic energy harvesting stands out as one straightforward method to extract substantial power from current-carrying overhead lines. Due to the relatively small size of the harvester, the high currents in the distribution system quickly saturate its magnetic core. Consequently, the magnetic harvester operates in a highly nonlinear manner. The nonlinear nature of the downstream AC to DC converters further complicates the process, making precise analytical modeling a challenging task. In this paper, a clamped type overhead line magnetic energy harvester with a controlled active rectifier generating significant DC output power is investigated. A piecewise nonlinear analytical model of the magnetic harvester is derived and reported. The modeling approach is based on the application of the Froelich equation. The chosen approximation method allowed for a complete piecewise nonlinear analytical treatise of the harvester’s behavior. The main findings of this study include a closed-form solution that accounts for both the core and rectifiers’ nonlinearities and provides an accurate quantitative prediction of the harvester’s key parameters such as the transfer window width, optimal pulse location, average DC output current, and average output power. To facilitate the study, a nonlinear model of the core was developed in simulation software, based on parameters extracted from core experimental data. Furthermore, theoretical predictions were verified through comparison with a computer simulation and experimental results of a laboratory prototype harvester. Good agreement between the theoretical, simulation, and experimental results was found.

Recently, much attention has been given to the development of various energy harvesting technologies to power remote electronic sensors, data loggers, and communicators that can be installed on smart grid systems. Magnetic energy harvesting is, perhaps, the most straightforward way to capture a significant amount of power from a current-carrying overhead line. Since the harvester is expected to have a small size, the high currents of the distribution system easily saturate its magnetic core. As a result, the operation of the magnetic harvester is highly nonlinear and makes precise analytical modeling difficult. The operation of an overhead line magnetic energy harvester (OLMEH) generating significant DC power output into a constant voltage load was investigated in this paper. The analysis method was based on the Froelich equation to analytically model the nonlinearity of the core’s BH characteristic. The main findings of this piecewise nonlinear analysis include a closed-form solution that accounts for both the core and rectifiers’ nonlinearities and provides an accurate prediction of OLMEH transfer window length, output current, and harvested power. Continuous and discontinuous operational modes are identified and the mode transition boundary is obtained quantitatively. The theoretical investigation was concluded by comparison with a computer simulation and also verified by the experimental results of a laboratory prototype harvester. A good agreement was found.

The study of europium-substituted Cu-Zn spinel ferrites (Cu0.6Zn0.4EuxFe2−xO4) is important for high-frequency applications as they can have a substantial effect on the magnetic and electrical residences of these materials. Single-phase nano-structured ferrites with varying amounts of Eu were synthesized using the sol–gel technique. The crystalline characteristics were identified using x-ray diffraction (XRD) testing, which demonstrated a rise in lattice parameters as the Eu concentration increased. The DC (direct current) resistivity measurements showed that the samples exhibit a semiconducting behavior, with a decrease in resistance at elevated temperatures. We found that the measured magnetic properties of magnetic saturation (Ms), remanence magnetization (Mr), and coercivity (Hc) were all impacted by the presence of Eu substitution. The saturation magnetization and remanence magnetization decreased while the coercivity increased, making the Eu-doped Cu-Zn spinel ferrites efficient magnetic semiconductors. The improved magnetic and electrical properties make these materials suitable for high-frequency applications. [ABSTRACT FROM AUTHOR]

In this study, lithium–zinc ferrite (LZF) ceramics were prepared by spark plasma sintering. Problem of carbon pollution was effectively resolved by annealing decarburization, formation of BN-coated carbon paper, and formation of protective layer of different metal foils (Ti, Mo, W, and Ta). The effects of carbon pollution and different protective layers on microstructure and dielectric and magnetic properties of LZF ceramics were studied comprehensively. Results reveal that annealing decarburization and BN-coated carbon paper could significantly improve resistance and saturation magnetization (M s) of LZF, while real part of dielectric constant (ε′) and dielectric loss (tanδ) were significantly reduced. X-ray diffraction patterns indicate that all selected protective layers can provide good spinel-phase LZF ceramics. The utilization of metallic foil as protective layer can effectively reduce carburization, improve the resistance of LZF ceramics, and reduce ε′ and tanδ values. X-ray photoemission spectroscopy and Raman spectroscopy results reveal that cations with the highest valence state replace Fe3+ at B-site. The use of metal foil protective layer leads to the infiltration of metal ions into LZF lattice, leading to the increase in the lattice constant and decrease in the M s value. This study deepens the understanding of carburization during SPS, providing a reference scheme for future applications. [ABSTRACT FROM AUTHOR]

In this investigation, BiFeO 3 (BFO) and 10% La-doped BiFeO 3 (BLFO) nanoceramics were synthesized by a sol–gel method for the photocatalytic degradation of colorless antibiotics ciprofloxacin and levofloxacin under the irradiation of 500 W Hg-Xe lamp. A good agreement between the structural transitions from rhombohedral to orthorhombic phase was observed by the X-ray diffraction and the vibrational modes in the Raman spectra, due to the substitution of Bi by La. Moreover, La doping resulted in a decrease in the particle size from ∼ 117 to 32 nm, reduction of oxygen vacancies, significant enhancement of magnetization, dramatic improvement of optical absorption, and reduction of band gap from 2.19 to 2.14 eV. The significantly enhanced magnetization might be associated with the suppression of the spiral spin cycloid of BFO due to the substitution of La and reduced size of the BLFO nanoceramics to ∼ 32 nm which was also confirmed by transmission electron microscopy imaging. The strong optical absorption of BLFO nanoceramics boosted their photo-generated charge carriers separation, produced more reactive species, and demonstrated ∼ 70% photocatalytic efficiency to degrade pharmaceutical pollutants from aqueous solution. The high saturation magnetization and strong optical absorption mostly in the visible region suggest the potentiality of BLFO nanoceramics as a promising photocatalyst with a superior recyclability to be magnetically extracted from the reaction medium. [ABSTRACT FROM AUTHOR]

The effects of La-Co co-substitution on the structural and magnetic properties of strontium M-type hexaferrites (SrM) were carefully investigated for the Sr1−xLaxFe12−xCoxO19 (0.0 ≤ x ≤ 0.3) polycrystalline samples prepared by solid-state reaction in air. Without the use of sintering additives, La-Co co-substituted SrM single phases could be obtained from polycrystalline bulk samples by employing proper processing conditions. The lattice parameter a initially increases with increasing x from 0.0 to 0.1 but gradually decreases with increasing x to 0.20, and then remains almost unaltered up to x = 0.3; the lattice parameter c monotonously decreases with increasing x from 0.0 to 0.25, but it turns to an increase when x = 0.3. The reduction in c/a ratios and Vcell values with increasing x up to x = 0.25 are obviously attributable to the decreasing size effect resulting from La3+ substitution at the Sr2+ site, which surpasses the increasing size effect due to Co2+ and Fe2+ occupancy at the Fe3+ site. Meanwhile, with increasing x from 0.0 to 0.3, while the saturation magnetization (MS) continuously decreases from 75.90 to 72.07 emu/g, the magnetic anisotropy field (Ha) increases from 20.1 to 24.7 kOe, leading to an increase in the intrinsic coercivity (Hci) from 2.68 to 3.99 kOe. The gradual increase in Ha with x, probably caused by a gradual decrease in the crystallographic symmetry, is inversely proportional to the variation in the c/a ratios up to x = 0.25 as usual except when x = 0.3, of which deviation needs further study. [ABSTRACT FROM AUTHOR]

Dysprosium (Dy3+)-substituted Ni–Co nanoparticles were synthesized by sol–gel technique. Structural and morphological analyses were accomplished by X-ray diffraction (XRD), scanning electron microscopy (SEM) and field emission transmission electron microscopy (FE-TEM). The crystallite size and lattice parameter followed a decreasing trend up on increase in Dy3+ substitution for the concentration x ≤ 0.15, which is due to the hindrance in crystallite growth and deposition of Dy3+ on grain boundaries, respectively. The lattice strain was increased from 5.027 to 8.814 × 10 - 3 with enhancement in Dy3+ content. The morphological studies showed uniform distribution of particles with slight agglomeration and the average particle size was calculated to be 22.17 nm, which is in good agreement with XRD results. The magnetic studies were executed by vibrating sample magnetometer (VSM) over a wide range of applied magnetic field. The soft ferrimagnetic nature of these ferrites was revealed by narrow (M–H) curve. The magnetic parameters exhibited decreasing behavior upon increasing amount of substitution. The coercivity (Hc) was recorded to be 1097 Oe for x = 0.00 and saturation magnetization (Ms) was calculated in the range 27.04–40.86 emu/g. The anisotropy constant and magneton number were found to be in the range of 9887–46,703 erg/cm3 and 1.21–1.71 µB, respectively. These properties of prepared ferrites point towards their applicability in magnetic recording instruments, memory, and high-density data storage devices. [ABSTRACT FROM AUTHOR]

In the field of materials science, spinel ferrites are like priceless pearls owing of their unique crystalline structure and magnetic characteristics. Cobalt-erbium-based CoEr0.05Fe1.95 O4 spinel ferrites and polypyrole composites with compositions (PF1:25%, PF2:50%, PF3:75%, and PF4:100%) were fabricated via a sol gel technique. The X-ray diffractogram pattern of prepared Er-doped cobalt ferrites showed a crystalline nature, while pure polypyrole has an amorphous nature. The dielectric characteristics of all these spinel ferrites in the X-band were determined by applying frequency (8–12 GHz). The temperature-dependent DC (direct current) electrical resistance of cobalt ferrite reduces with higher temperature. The magnetic behavior of prepared spinel ferrites was determined from the magnetic loop. There was a direct correlation between the quantity of RE ions and a rise in retentivity, coercivity, and saturation magnetization values. The saturation value is found at 41.98 emu/g, the remanence magnetization is found at 16 emu/g, and the activation energy is found at 0.14–0.25 eV. From all suggested parameters, prepared composites may be an ideal choice for high frequency utilizations. [ABSTRACT FROM AUTHOR]

In this study, the effect of addition of molybdenum as a ferrite phase stabilizer to Vicalloy I was investigated for enhancing its magnetic properties. Initially, an alloy with a composition of 45Fe-45Co-9V-1Mo was cast. The cast alloy was subjected to homogenization at a constant temperature of 1200 ºC for various times to examine the influence of homogenization time. The results indicated that a completely homogeneous structure with an average grain size of 306.48 μm was obtained after homogenization for 10 hours. Furthermore, homogenized samples were subjected to hot and cold rolling processes to produce ultrathin foils of this alloy, resulting in thickness reduction of 83% and 81.5%, respectively, and ultimately yielding foils with a thickness of 180 μm. Phase analysis revealed that while the hot and cold rolling processes did not induce phase changes, the magnetic properties was influenced. Specially, the saturation magnetization increased from 169.94 emu/g in the cast sample to 190.33 emu/g in the cold-rolled sample. Additionally, the coercive force increased by 10 Oe after homogenization due to the formation of a martensitic phase, but decreased again after cold rolling due to the changes in the texture components. [ABSTRACT FROM AUTHOR]

Ball-milled Fe-Si-Al soft magnetic powder cores with the particle compositions away from the classical Sendust point were prepared in this work. The influences of alloy composition on the metallographic structure, density, hardness, and resistivity of Fe-Si-Al alloy, as well as the frequency-dependent permeability, loss, and the anti-saturation performance of Fe-Si-Al powder cores, were investigated systematically. It was found that the hardness of Fe-Si-Al alloy increases with the Si mass ratio and the saturation magnetization (Ms) increases with the Fe mass ratio. The alloy hardness affects the particle size after the ball-milling process and, thus, influences the porosity of the powder core. Together with adjusting the demagnetization field by controlling the particle size and the core's porosity, changing the alloy composition to drive K and λ deviating from zero can effectively improve the anti-saturation performance of Fe-Si-Al powder cores at the expense of hysteresis loss, to some extent. In this work, good comprehensive magnetic properties were obtained in the Fe85.5-Si12-Al2.5 powder core. Its effective permeability percentage at 100 Oe and Ms were 59.12% and 132.23 emu/g, respectively, which are higher than those of the classical Sendust core. This work provides a feasible idea for optimizing the overall performance of the high-power magnetic device. [ABSTRACT FROM AUTHOR]

The paper proposes the use of contact low-temperature non-equilibrium plasma for the synthesis of cobalt ferrite. The influence of the pH of the reaction medium, temperature, and duration of treatment on magnetic properties, the intensity of X-ray diffraction peaks, the average size of crystallites, and the value of dislocation density were determined using the central composite rotary design of the experiment. The results of X-ray phase analysis, vibrational magnetometry, and electron microscopy were used to create the models. The results showed that the pH of the reaction medium is the parameter that has the greatest influence on the growth of cobalt ferrite powder crystallites and the magnetic properties of the samples. It was established that the largest size of crystallites (505-560 Å) was obtained at high temperatures and pH values. The smallest crystallite size (119-165 Å) was obtained at a temperature of 20 °C, a minimum processing time of 5 minutes, and a pH of 10. Based on the analysis of hysteresis curves, it is shown that high values of magnetization saturation (120-138 Emu/g) can be achieved at an elevated temperature of 40 °C and processing time. This is due to the formation of cobalt ferrite with high crystallinity and large crystallite sizes. Smaller values of saturation magnetization (8-14 Emu/g) are due to the formation of nonmagnetic impurity phases of iron oxides and oxyhydroxides. [ABSTRACT FROM AUTHOR]

The present study aims to improve the magnetic properties with tunable coercivity of SrM hexaferrite by substituted Co and Zn ions instead of Fe and to elucidate in detail the changes in their structural, morphological, and site occupancy characteristics. Sr Co x Zn x Fe 12 - 2 x O 19 (Co, Zn; x = 0.4, 0.8, 1.2, 1.6 and 2.0) powders were synthesized by the autocombustion sol–gel method. Substitution of Co–Zn ions caused the formation of magnetoplumbite and a secondary phase (CoFe2O4) in the structure. Increasing the Co–Zn content ratio led to a nonlinear increment in crystallite size ranging from 41.9 to 49.8 nm. SEM micrographs depicted platelet-shaped hexagonal particles that were nano-scale in thickness and micro-scale in diameter. Mössbauer spectra revealed that the substituent tends to occupy both spin-up sites 12k-2a-2b and spin-down sites 4f1 and 4f2 of crystal lattice from x = 0.4 to x = 2.0, which elucidate meagre change observed in magnetization, as per literature. The saturation magnetization (Ms) and remanent magnetization (Mr) were higher than the initial values of Ms = 75.26 emu/g and Mr = 26.95 emu/g. The highest coercivity and saturation magnetization was observed as, 4159 Oe and 80 emu/g, respectively, for x = 2.0. The squareness ratio (Mr/Ms) of x = 1.6 and x = 2.0 samples, was observed to be greater than 0.5, elucidating the existence of single-domain particles. The magnetic parameters Ms with tunable Hc, Mr/Ms, and magnetic susceptibility (dM/dH) results make the synthesized sample considerable for recording applications. [ABSTRACT FROM AUTHOR]

In this work, the transformation of waste iron cans to gamma iron oxide (γ-Fe2O3) nanoparticles following acid leaching precipitation method along with their structural, surface chemistry, and magnetic properties was studied. Highly magnetic iron-based nanomaterials, maghemite with high saturation magnetization have been synthesized through an acid leaching technique by carefully tuning of pH and calcination temperature. The phase composition and crystal structure, surface morphology, surface chemistry, and surface composition of the synthesized γ-Fe2O3 nanoparticles were explored by X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Energy-dispersive X-ray spectroscopy (EDS). The XRD results confirm the cubic spinel structure having crystallite size 26.90–52.15 nm. The XPS study reveals the presence of Fe, O element and the binding energy of Fe (710.31 and 724.48 eV) confirms the formation of γ-Fe2O3 as well. By dynamic light scattering (DLS) method and zeta potential analyzer, the particle size distribution and stability of the systems were investigated. The magnetic behavior of the synthesized γ-Fe2O3 nanoparticles were studied using a vibrating sample magnetometer (VSM) which confirmed the ferrimagnetic particles with saturation magnetization of 54.94 emu/g. The resultant maghemite nanoparticles will be used in photocatalysts and humidity sensing. The net impact of the work stated here is based on the principle of converting waste into useful nanomaterials. Finally, it was concluded that our results can give insights into the design of the synthesis procedure from the precursor to the high-quality gamma iron oxide nanoparticles with high saturation magnetization for different potential applications which are inexpensive and very simple.