High Magnetization Value Research Articles

MHD Mass Transfer Flow in Presence of Chemical Reaction, Thermal Radiation, and Thermal Diffusion Effect

ABSTRACTThe present work is interested in investigating the impacts of chemical reaction, magnetic field, thermal radiation, heat sink, and thermal diffusion on a steady two‐dimensional MHD convection‐free heat and mass transfer flow past a semi‐infinite upright porous plate. The dimensionless domain equations are solved analytically using the perturbation technique for two distinct scenarios: (a) small suction and (b) large suction. The effects of various crucial parameters on velocity, temperature, concentration, as well as on the skin friction, Nusselt number, and Sherwood number are graphically illustrated, and the subsequent discussion is rooted on the derived outcomes. Graphical representations were created utilizing MATLAB software. The results suggest that an increase in the Soret effect elevates both the momentum and concentration boundary layers while reducing the mass transfer rate, regardless of the suction intensity. Our research also identified a captivating result where fluid velocity escalates with higher magnetic values in the scenario of large suction, while it demonstrates contrasting behavior under small suction condition. The present investigation holds significant relevance across various industrial sectors, including uranium enrichment, petrology, petroleum reservoirs, polymer fractionation, among others.

Synergetic effect of edge states and point defects to tune ferromagnetism in CVD-grown vertical nanostructured MoS2: A correlation between electronic structure and theoretical study

Room-temperature ferromagnetism (RTFM) exhibited by nanostructured two-dimensional semiconductors for spintronics applications is a fascinating area of research. The present work reports on the correlation between the electronic structure and magnetic properties of defect-engineered nanostructured MoS2 thin films. Low-energy light and heavy-mass ion irradiation have been performed to create defects and tune the magnetic properties of MoS2. Vertical nanosheets with edge termination in the pristine sample have been examined by field emission scanning electron microscopy (FESEM). Deterioration of vertical nanosheets is observed in low-energy Ar+ and Xe+ irradiated samples. High-resolution transmission electron microscopy (HR-TEM) analysis confirmed the sample’s crystallinity and the (002) plane formation. An appreciably high magnetization value of 1.7emu/g was observed for edge-oriented nanostructured pristine MoS2 thin films, and it decreased after ion irradiation. From X-ray photoelectron spectroscopy (XPS) data, it is evident that, due to oxygen incorporation in the sulfur vacancy sites, Mo 5+ and 6+ states increase after ion irradiation. The density functional theory (DFT) calculations suggest that the edge-oriented spins of the prismatic edges of the vertical nanosheets are primarily responsible for the high magnetic moment in the pristine film, and the edge degradation and reduction in sulfur vacancies by the incorporation of oxygen upon irradiation result in a decrease in the magnetic moment.

Holocene paleoenvironment of the Nihewan Basin, China, inferred from high-resolution luminescence dating and a multiproxy analysis of gully sediments

As a pivotal region for studying early human occupation in East Asia, the Nihewan Basin has witnessed numerous studies on Paleolithic sites and associated paleoenvironmental records. However, little attention has been given to the Holocene period, despite the basin being a crossroads for the exchange of NE China Neolithic cultures. In the central part of the Nihewan Basin, we found a gully sediment section with a thickness of ∼9 m, which exhibits clear parallel bedding throughout. The section is composed of ten sediment layers (Layers 10–1 from bottom to top), from which three distinct dark-colored soil layers (Layers 8, 4 and 2) and two erosion surfaces (between Layers 10 and 9, and Layers 2 and 1) were identified. Forty-four sediment samples from the section were optically dated, and the obtained ages were refined using Bayesian statistical modeling. The age-depth relationship and sedimentary characteristics suggest that the sedimentation process of Layers 9–2 was continuous. To reconstruct the paleoenvironment, the grain-size distribution, magnetic susceptibility, and pollen content of the sediments were analyzed. The three soil layers exhibit high magnetic susceptibility values. Based on these climatic proxies, five climate stages were recognized. From ∼12.7 to ∼6.8 ka, the climate in the basin region was cold and dry. The period between ∼6.8 and ∼5.4 ka was marked by optimal climate conditions that led to soil formation. Subsequently, the climate was colder and drier during the period of ∼5.4 – ∼4.0 ka, and transitioned to warm and wet conditions again from ∼4.0 to ∼2.7 ka. Another stage of soil formation occurred between ∼2.7 and ∼1.7 ka, during which the climate was predominantly warm and humid, albeit punctuated by a brief interval of colder and drier conditions. These climate variations coincided with cultural evolution stages within the basin, highlighting a close relationship between environmental change and human adaptation.

Immobilization of aldo-keto reductase on dopamine/polyethyleneimine functionalized magnetic cellulose nanocrystals to enhance the detoxification of patulin in fresh pear juice

Patulin (PAT) is a highly toxic mycotoxin, which can contaminate fruits and their products and cause harm to human health. Cellulose nanocrystals (CNCs) were functionalized by magnetite nanoparticles, dopamine (DA) and polyethyleneimine (PEI) to form a multifunctional nanocarrier (DA/PEI@Fe3O4/CNCs) for immobilizing aldo-keto reductase (MgAKR) to degrade PAT. The MgAKR-DA/PEI@Fe3O4/CNCs were reusable and environmentally friendly due to its surface area, high magnetization value, and oxygen/amine function. The immobilization method significantly improved reusability, resistance to proteolysis, temperature stability and storage stability of MgAKR-DA/PEI@Fe3O4/CNCs. With NADPH as a coenzyme, the detoxification rate of MgAKR-DA/PEI@Fe3O4/CNCs on PAT reached 100 % in phosphate buffer and 98 % in fresh pear juice. The quality of fresh pear juice was unaffected by MgAKR-DA/PEI@Fe3O4/CNCs and could be quickly separated by magnet after detoxification, which was convenient for recycling. It has broad application prospects in the control of PAT contamination in beverage products containing fruit and vegetable ingredients.

Do phosphorus amendments enhance biodegradation activity in stalled petroleum hydrocarbon-contaminated soil?

Phosphorus (P) fertilizers promote soil petroleum-hydrocarbon (PHC) bioremediation by correcting carbon-to-P ratio imbalances. While these inputs create conditions favorable to microbial growth, areas of a site or an entire site with low degradation rates (i.e., "stalled") occur for unknown reasons. We hypothesized that soil conditions limit P bioavailability, leading to stalls in PHC bioremediation, and adding the correct P amendment restarts microbial activity. Soils were collected and characterized from four cold calcareous PHC-impacted sites in Saskatchewan, Canada, undergoing bioremediation. A generalized linear mixed model identified that regions with lower degradation rates possessed a neutral pH with high magnetic and salinity values. In a subsequent laboratory experiment, the proportion of benzene degraded at greater rates within active (i.e., higher degradation rates) than stalled soils, thereby following model predictions (p-value=0.19, Kruskal-Wallis). The PHC degradation efficiency of different P amendments was tested by doping stalled soils (n=3) with one of five treatments: 0 (control), 0 (autoclaved control), or 50mg phosphate kg-1 soil as sodium diphosphate, triethyl phosphate, or tripolyphosphate. Tripolyphosphate accelerated benzene degradation (75.5±5.4%) in one stalled soil (Outlook 323) and increased degradation non-significantly (43.9±9.4%) in another (Allan 917). Alternatively, the final sample (Davidson 421) possessed the greatest benzene removal with no amendments. This implies that soil P bioavailability may not be the sole cause of decreased microbial activity. Accordingly, combining model outputs with mineralogy and microbiology investigations could enhance PHC biodegradation rates in these cold calcareous soils.

Structural, magnetic and photoluminescence properties of Zn-Ni ferrites synthesized by hydrothermal method

Nanocrystalline ZnxNi1-xFe2O4 (0 ≤ x ≤ 1.0) ferrites were synthesized by hydrothermal method. XRD analysis showed that all compositions crystallize with a cubic spinel-type structure with an average crystallite size in the range of 17–27 nm which corresponded to particle sizes obtained from TEM. The lattice parameter increased from 8.289 to 8.432 Å with increasing Zn content. The ZnxNi1-xFe2O4 nanoferrites exhibit superparamagnetic behaviour at room temperature (RT). The saturation magnetization (Ms) varies considerably with Zn content to reach a maximum value for Zn0.5Ni0.25Fe2O4 composition, i.e. 41.893 emu/g. The high Ms and magnetic moment values are attributed to cation distribution change. The electron spin resonance (ESR) results demonstrated g-values ranging between 2.005 and 2.621 which indicated strong exchange interaction between nanoparticles, type of morphology, and crystalline nature of particles. These low g-values make ZnxCo1-xFe2O4 nanoferrites suitable for applications in low-frequency devices. The Mössbauer spectroscopy results revealed the transition from ferromagnetic to paramagnetic state, by showing collapse of sestet to quadrupole doublet. The optical properties of the nanoferrites were investigated photoluminescence (PL) spectra. The broad visible emission band at 427 nm (2.90 eV), 471 nm (2.60 eV) and 520 nm (2.38 eV) were observed in all PL spectra. The electron spin resonance and photoluminescence results show that Zn-Ni ferrites are good candidates for blue LEDs and in gas sensing applications.

Efficient adsorptive removal of 2,4-dichlorophenoxyacetic acid (2,4-D) using biomass derived magnetic activated carbon nanocomposite in synthetic and simulated agricultural runoff water

This study focused on evaluating the efficacy of a magnetic activated carbon material (CPAC@Fe3O4) derived from pods of copper pod tree in adsorbing the toxic herbicide, 2,4- (2,4-D) from aqueous solutions. The synthesized CPAC@Fe3O4 adsorbent, underwent various characterization techniques. FESEM images indicated a rough surface, incorporating iron oxide nanoparticles, while EDS analysis confirmed the presence of elements like Fe, O, and C. Notably, the CPAC@Fe3O4 exhibited high surface area (749.10 m2/g) and pore volume (0.5351 cm³/g), confirming its mesoporous nature. XRD investigations identified distinct signals associated with graphitic carbon and magnetite nanoparticles, while VSM analysis verified its magnetic properties with a high magnetic saturation value (2.72 emu/g). The adsorption process was exothermic, with a decrease in adsorption capacity at higher temperatures. Freundlich isotherm provided the best fit for the adsorption, and the pseudo-second-order equation effectively described the kinetics. Remarkably, the maximum adsorption capacity ranged from 246.43 to 261.03 mg/g, surpassing previously reported values. The ΔH° value (−8.67 kJ/mol) suggested a physisorption mechanism, and the negative ΔG° values established the spontaneous nature. Furthermore, the synthesized adsorbent demonstrated exceptional reusability, allowing for up to five cycles of adsorption-desorption operations. When applied to simulated agricultural runoff, CPAC@Fe3O4 showcased a significant adsorption capacity of 160.71 mg/g for 50 mg/L 2,4-D, using a 0.2 g/L dosage at pH 2. This study showcased the transformation of copper pod biomass into a valuable magnetic nanoadsorbent capable of efficiently eliminating the noxious 2,4-D pollutant from aqueous environments.

Double ferromagnetic barriers resonant tunneling diodes (RTD) based on the surface of a topological insulator

Resonant tunneling diodes (RTDs), which are based on double barrier quantum well structures, are typically achieved by combining different materials with varying band gap sizes. However, this approach often poses challenges such as material mismatching and dislocations. In this study, we present a novel resonant tunneling diode scheme utilizing the unique properties of topological insulator materials. Specifically, we exploit the gap opening in the band structure of the topological insulator by employing perpendicular magnetization. In this proposed RTD platform, the barrier regions are formed from a ferromagnetic topological insulator through the proximity effect. By adjusting the thickness and spacing of the ferromagnetic barriers, a well region with confined states emerges between the barrier regions. Theoretical analysis reveals that by tuning the back gate voltage, the I-V characteristics exhibit two significant behaviors: negative differential resistance (NDR) and step-like behavior for Fermi energy values of EF = −3 and EF = 3, respectively. Furthermore, we observe an increase in the peak-to-valley ratio (PVR) with higher magnetization values. Notably, the PVR reaches a value of 7.13 for a magnetization value of m = 9. Additionally, we investigate the influence of the well width and barrier thickness on the transport properties of the device.

Adsorption properties and catalytic activity of Fe3O4-Ag nanostructures

The morphology and magnetic properties as well as adsorption capacity and catalytic activity of Fe3O4-Ag nanoparticles synthesized by the solvothermal method were studied in dependence on the duration of the thermolysis process (3, 6, and 8 h). X-ray diffraction, transmission electron microscopy, and energy-dispersive spectroscopy measurements showed that the morphology of nanoparticles changed strongly as the duration of thermolysis increased. At 6 and 8 h duration, Fe3O4 nanocrystals grow and assemble into porous spherical globules with an Ag core (samples 2 and 3). These samples demonstrate high magnetization value and very low coercivity. The adsorption capacity of nanoparticles was studied with respect to two organic dyes: cationic methylene blue (MB) and anionic Congo red (CR). The particles showed preferential adsorption of the cationic dye. High catalytic activity towards four dyes: MB, methyl orange (MO), CR, and Rhodamine C (RhC) at the presence of NaBH4 is the remarkable property of these samples. The rate constant of the catalytic reaction was 1.4 min−1. Simultaneous exposure of CR and MO dyes to nanoparticles and NaBH4 caused their irreversible 100 % degradation while in the case of MB and RhC, a transition to their leuco form occurred.

Enhanced Magnetic and Dielectric Properties of YFeO3 Ceramics via Formation of Solid‐Solution with Sr2Bi4Ti5O18 and ZnSnO3 Oxides

In the present investigation, magnetic and dielectric properties of solid‐solution formed between the YFeO3 with the similar crystal structure of other oxide materials are focused on. Orthorhombic crystal structure of YFeO3 (YFO), Sr2Bi4Ti5O18 (SBT), and ZnSnO3 (ZS) nanomaterials are considered to prepare the solid solutions at 1150 °C/3 h. YFO and solid solutions exhibit the orthorhombic crystal structure, which is conformed through Rietveld refinement using X‐Ray powder diffraction pattern. The decreased average grain size is observed for the solid solution (3.0 μm for YFO and ZS and 2.6 μm for YFO and SBT) when compared to YFO (3.4 μm) through scanning electron microscopy. Oxidation state of each atom/ion/element present in the YFO and solid solutions are conformed through X‐Ray photoelectron spectroscopy studies. The solid solution formed between the YFO and SBT exhibits high magnetization value (2.92 emu g−1) and high coercive filed (67.5 Oe) when compared to solid solution formed between the YFO and ZS (magnetization value = 2.48 emu g−1, and coercive filed = 46.4 Oe) and YFO (magnetization value = 1.91 emu g−1, and coercive filed = 61.8 Oe). High dielectric permittivity (εr), low dielectric loss (tan δ), and low conductivity are observed for the solid solution formed between the YFO and SBT, when compared to other materials in this study.

Strong correlation of electrical transport and magnetic properties to ionic states, structure, and morphology of Al-substituted Ni–Co ferrite systems: A comprehensive study

This paper presents the structure, morphology, magnetic, ionic states, and electrical transport characteristics of spinel Ni0.5Co0.5AlxFe2-xO4 (x = 0.0, 0.5, and 1.0) nanocrystalline ferrites, synthesized by using the sol-gel auto-combustion method. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to analyze the structural characteristics. The synthesized ferrites were found to have a crystallite size of less than 40 nm when the Rietveld method was applied to refine XRD patterns in single-phase cubic spinel-related structures that belong to the Fd-3m space group. Furthermore, since the ionic states are visible in X-ray photoelectron spectroscopy (XPS), variations in Al3+ ion concentration have been found to affect the locations, occupancy, and Wyckoff's cationic position of the ions as well as the lattice constant (a), the crystallite size (D), and the micro-strain of the composites. Thermogravimetric analysis was used to examine the temperature-dependent spinel phase formation and % weight loss of the sample. The x = 1.0 composition is said to be the best dielectric material out of the three samples since it has the highest polarization permittivity, the lowest dissipation factors, and exceptional temperature stability. These nanoparticles have relatively high impermanent magnetization values and are ferrimagnetic, according to the vibrating sample magnetometer (VSM) investigation. Additionally, it was found that the presence of Al3+ decreases the magnetization values of the spinel Ni0.5Co0.5AlxFe2-xO4 (x = 0.0, 0.5, and 1.0) system because the Al3+ exclusively occupies the Fe-sites, which reduces the super-exchange interaction between the Fe2+/Fe3+, Co2+/Co3+, and the Ni2+/Ni3+ ions. The unique magnetic characteristic of these compositions below 40 nm is predicted to make them appealing for storage applications.

S-scheme CoFe2O4/g-C3N4 nanocomposite with high photocatalytic activity and antibacterial capability under visible light irradiation

Photocatalysts with bactericidal capabilities are taken much more into consideration due to the water disinfection aside from water purification Therefore, a magnetically separable CoFe2O4/g-C3N4 nanocomposite has been synthesized via a simple in-situ chemical method, and its performance in degrading methylene blue (MB), methyl orange (MO), and phenol has been investigated. Multiple characterization techniques were conducted to confirm the successful synthesis of cobalt ferrite (CF), graphitic carbon nitride (CN), and cobalt ferrite/graphitic carbon nitride (CF/CN) nanocomposites. The microscopy images indicated a great reduction in the size of CF nanoparticles in nanocomposites. The magnetic characteristics were studied by a vibrating sample magnetometer (VSM). CF showed a high magnetization value (41.4 emu/g) and by compositing CF with CN, the nanocomposite also showed considerable magnetic properties. Optical properties of the photocatalysts were analyzed and the results denoted that heterostructure formation between CF and CN led to better light absorption, reduction in the band gap energy, and enhancement of charge carriers separation. Among the different synthesized nanocomposites, 400 mg/L of the CF/25 wt% CN nanocomposite showed the best photocatalytic activity in 180 min by degrading 100% of MB. The Mott-Schottky analysis and the results of scavenging experiments divulged the superoxide radicals as the main active species along with proposing a S-scheme mechanism on the degradation pathway for CF/CN nanocomposite. The optimized nanocomposite demonstrated high stability after three cycles by over 98% degradation of MB. Eventually, the antibacterial feature of CF/25CN nanocomposite was assessed against Escherichia coli and Staphylococcus aureus bacteria and resulted in a magnificent performance by reducing 99.9% of both bacteria in 30 min.

Rational Design of Magnetic Nanoparticles as T1-T2 Dual-Mode MRI Contrast Agents.

Magnetic nanoparticles (MNPs), either paramagnetic or superparamagnetic depending on their composition and size, have been thoroughly studied as magnetic resonance imaging (MRI) contrast agents using in vitro and in vivo biomedical preclinical studies, while some are clinically used. Their magnetic properties responsible in some cases for high magnetization values, together with large surface area-to-volume ratios and the possibility of surface functionalization, have been used in MRI-based diagnostic and theranostics applications. MNPs are usually used as positive (T1) or negative (T2) MRI contrast agents, causing brightening or darkening of selected regions in MRI images, respectively. This review focusses on recent developments and optimization of MNPs containing Gd, Mn, Fe and other lanthanide ions which may function as dual-mode T1-T2 MRI contrast agents (DMCAs). They induce positive or negative contrast in the same MRI scanner upon changing its operational mode between T1-weighted and T2-weighted pulse sequences. The type of contrast they induce depends critically on their r2/r1 relaxivity ratio, which for DMCAs should be in the 2-10 range of values. After briefly discussing the basic principles of paramagnetic relaxation in MNPs, in this review, the basic strategies for the rational design of DMCAs are presented and typical examples are discussed, including in vivo preclinical applications: (1) the use of NPs with a single type of contrast material, Gd- or Mn-based NPs or superparamagnetic NPs with appropriate size and magnetization to provide T2 and T1 contrast; and (2) inclusion of both types of T1 and T2 contrast materials in the same nanoplatform by changing their relative positions.

Magnetic Filaments: Formation, Stability, and Feedback

As is well known, magnetic fields in space are distributed very inhomogeneously. Sometimes, field distributions have forms of filaments with high magnetic field values. As many observations show, such a filamentation takes place in convective cells in the Sun and other astrophysical objects. This effect is associated with the frozenness of the magnetic field into a medium with high conductivity that leads to the compression of magnetic field lines and formation of magnetic filaments. We analytically show, based on the general analysis, that the magnetic field intensifies in the regions of downward flows in both two-dimensional and three-dimensional convective cells. These regions of the hyperbolic type in magnetic fields play the role of a specific attractor. This analysis was confirmed by numerical simulations of 2D roll-type convective cells. Without dissipation, the magnetic field grows exponentially in time and does not depend on the aspect ratio between the horizontal and vertical scales of the cell. An increase due to compression in the magnetic field of highly conductive plasma is saturated due to the natural limitation associated with dissipative effects when the maximum magnitude of a magnetic field is of the order of the root of the magnetic Reynolds number Rem. For the solar convective zone, the mean kinetic energy density exceeds the mean magnetic energy density for at least two orders of magnitude, which allows one to use the kinematic approximation of the MHD induction equation. In this paper, based on the stability analysis, we explain why downward flows influence magnetic filaments, making them flatter with orientation along the interfaces between convective cells.

Using Gradiometric Technique to Prospect Archaeological Features in Tell Al-Deylam, South of Babylon City, Middle of Iraq

An extensive vertical magnetic gradiometry survey was carried out over an area spanning 1,188 square meters in the northwestern section of Dilbat; a recently discovered archaeological city within Tell Al-Deylam located approximately 20 km south of Babylon city, so as to reveal the real image of the archaeological features hidden beneath the earth’s surface. The vertical gradiometric survey was done by the Geometrics-G-858 Cesium magnetometer. The gradiometric results showed three clear longitudinal magnetic anomalies in different places on the magnetic contour map. The main anomaly is located on the edge of the northern part of the study area and extends longitudinally in the northwest and southeast direction. This may indicate the presence of the main outer wall, as it extends lengthwise about 30 m, with a width of 3-4 m, and a depth of about 1 m below the surface of the ground, and may contain the main northern gate of the Dilbat Temple. Besides that, this anomaly displayed approximately a high magnetic value of about + 60 nT, which indicates that the wall was built from baked brick composed of clay minerals rich in iron oxides. Furthermore, the magnetic contour map showed two other magnetic anomalies. The first one is located in the western part of the study area and appears perpendicular to the main magnetic anomaly. Meanwhile, the second anomaly occupied the southern part of the study area and is parallel to the main anomaly. The two anomalies showed approximately lower magnetic strength than the outer wall. So, they may represent the remains of the inner room walls built from mud bricks. The thickness of the two supposed walls is about 2.5 m and they are at a depth one meter from the ground. The findings of this method have been a good guide for new excavation, which led to finding the main wall built from fired bricks.

Cationic mismatch effect on structural and magnetic behavior of La0.5-xEuxCa0.5-yBayMnO3 charge-ordered manganites

In this research, we have tried to investigate the effect of the cationic disorder on charge ordering and magnetic phase separation in La0.5-xEuxCa0.5-yBayMnO3 (x = 0, 0.05, and 0.1) compounds synthesized by using the sol-gel method. All the samples possess the same average ionic radius at A site <rA> and the same Mn3+/Mn4+ ratio. Our analysis confirmed the chemical composition by energy dispersive X-ray spectroscopy and verified the structural integrity and purity of the phase by X-ray diffraction, revealing an orthorhombic structure with Pnma space group, which is in agreement with the tolerance factor. The important mismatch effect observed in the substituted specimens induces drastic effects on the structural and microstructural properties. Magnetic measurements indicate a great reduction of Curie temperature for substituted samples (from 250 K for x = 0 to 90 K for x = 0.05 and 85 K for x = 0.1), which indicates a weakening of ferromagnetic double exchange interactions induced by cationic disorder. The Arrott plots and the magnetocaloric study of the Eu−based samples indicate the persistence of the antiferromagnetic charge-ordered state characterizing the pristine compound (x = 0) as well as the presence of a first-ordered metamagnetic transition for all the studied samples, which is ascribed to the presence of antiferromagnetic domains. Such transition induced the appearance of a shoulder peak near 100 K in the magnetic entropy change curves for high magnetic field values, resulting in an extra cooling efficiency.

Structural, Optical, and Magnetic Properties of o‐TbFeO3 Nanomaterials Synthesized by the co‐Precipitation Method

AbstractFollowing the co‐precipitation method for producing terbium orthoferrite (TbFeO3), the final products were denoted as TbFeO3‐650, −750, and −850. A single‐phase of orthorhombic TbFeO3 crystals (o‐TbFeO3) was obtained with a calcination temperature of up to 850 °C, while in the range of 650–750 °C there was still a small amount of terbium and iron oxide phases. The average size of o‐TbFeO3 crystallites for the TbFeO3‐850 sample was about 76 nm and was larger than that of TbFeO3‐650 (~45 nm) and TbFeO3‐750 (~47 nm). The o‐TbFeO3 crystal structure in all samples was found to be distorted. In the applied field from −15 to +15 kOe, all of the samples had low values of coercive field (5–11 ⋅ 10−3 Oe) but high values of net magnetization (2.06–2.40 emu ⋅ g−1); the samples appeared to behave as paramagnetic materials. It was shown that the TbFeO3‐850 sample has slightly better magnetic properties than the two others. An average grain size of about 79 nm was found in the TbFeO3‐850 sample, which exhibited a morphology of sphere‐like shapes with highly agglomerated grains. The TbFeO3‐850 sample demonstrated a high absorbance at wavelengths of 400–600 nm, with a direct bandgap of about 2.68 eV.

Quasi‐hexagonal nanopatterned porous cobalt ferrite thin films prepared via block copolymer self‐assembly

AbstractWe present a novel method for fabricating dense and nanopatterned porous cobalt ferrite (CoFe2O4) thin films with a remarkable thickness of 65 nm, achieved through direct block copolymer self‐assembly. By decomposing the block copolymer and inducing crystallization of the spinel phase, we successfully produce films exhibiting quasi‐hexagonal arrays of pores with an average diameter ranging from 60 to 80 nm. The resulting nanopatterned porous thin films demonstrate exceptional orderliness, as the pores are intricately designed by the cobalt ferrite grains, and the platinum substrate offers complete accessibility in the pore area. Our findings reveal high magnetization values, comparable to those of bulk CoFe2O4, in the dense film. Additionally, in the case of the nanopatterned porous film, we observed a distinctive contribution of perpendicular magnetization. This innovative approach holds great promise for advanced magnetization and thin‐film engineering applications.

Enhancement in the Magnetic Properties of Yttrium Orthoferrite Materials by the Addition of BaO–Bi2O3–B2O3 Glass Sintering Aid

The addition of powdered BaO–Bi2O3–B2O3 (BBBO) glass (0.25–1.5 wt%) to yttrium orthoferrite materials (YFeO3) powder facilitates an increased crystallite size, resulting in improved magnetic properties. The required YFeO3 (YFO) materials are synthesized through the sol–gel route using tartaric acid as a chelating agent, while BBBO glass is obtained via the conventional melt‐quenching technique. The crushed glass is added to YFO powders in different wt% and compacted at room temperature, subsequently; the compacted samples are sintered at 1000 °C for 3 h. The X‐ray powder diffraction studies infer that a maximum 1.0 wt% of BBBO glass is incorporated into YFO without showing any impurity phase. The optical bandgap of each sample is calculated using the UV data with the help of the Kubelka–Munk and Tauc relation, decreasing from 2.10 to 2.04 eV with an increase of BBBO content from 0 to 1.0 wt% in YFO. The highest magnetization value (4.02 emu g−1) is observed with 1.0 wt% BBBO added in YFO surpassing pure YFO and other BBBO‐added YFO samples. In conclusion, the improved magnetization value of the 1.0 wt% BBBO added in the YFO sample can be potentially utilized in different applications.

Modification of the Codeposition Method for the Synthesis of Iron-Oxide Nanoparticles with a High Magnetization Value and a Controlled Reaction Yield

Modification of the Codeposition Method for the Synthesis of Iron-Oxide Nanoparticles with a High Magnetization Value and a Controlled Reaction Yield