High Saturation Magnetization Value Research Articles

NiCr2−xGdxO4 ceramics’ magnetic, structural and electrical conductivity as well as their activation energy properties

The goal of this work is to synthesize and characterize nanoscale nickel chromites nanoparticles doped with Gd using the economical solution combustion method. Numerous analytical techniques, including energy formation, electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction, are used for in-depth characterization. The results show that at low values of coercivity, high values of saturation magnetization, and low values of remnant magnetization, the chromites correspond. The crystalline size of Gd-doped nickel chromites decreases. For the normal spinel structure’s tetrahedral and octahedral coordinated forms, respectively. The present research shows that agglomerated forms and irregular, spherical structures formed by SEM (Scanning Electron Microscope) form regular structures. The present investigation uses a transmission electron microscope (TEM) to illustrate the formation of regular-shaped particles. As demonstrated by Gd-doped NiCr2O4 and pure NiCr2O4, stable interstitial positions are among the typical interstitial positions of the metal oxides. Investigations of magnetic properties from the paramagnetic to the ferromagnetic phase formation. Electrical conductivity and activation energy dropped with Gd doping of nickel chromites and showed an inverse relationship with particle/crystallite sizes. Lastly, applications for NiCr2−x GdxO4 particles were examined and future research directions were also suggested.

Structural and Magnetic Properties of Nano Manganite La0.6Sr0.4MnO3 Obtained by Mechanochemical Synthesis Influenced by Preparation Conditions

Single phase La0.6Sr0.4MnO3 nanoparticles with perovskite structure ( R3̅C symmetry) were successfully prepared by ball milling (mechanochemical synthesis) for 1 and 10 h followed by annealing treatment at temperature 900 or 1100 °C. It was found that, the lattice parameters increase with the increase of milling time or annealing temperature. The increase of the annealing temperature results in the increase of crystallite size and the particle size. The obtained samples were found to be ferromagnetic at room temperature. The sample obtained by one hour of milling and 900 °C annealing showed high value of saturation magnetization (about 56 emu g−1) and small value of coercivity (about 31 Oe) at room temperature, while the other samples show reduced value of magnetization and higher value of coercivity. The obtained magnetic results are discussed in light of the core/shell model of nanoparticles. The effect of the presence of oxygen vacancies on the lattice parameters and magnetic properties of the obtained samples is also discussed.

Spin dynamics investigation and structural analysis of ambient scalable Sr2+ doped zirconium ferrite nanoparticles synthesized by low temperature auto combustion route

Microwave spin resonance behaviour of Sr2+ doped Zirconium ferrite Zr1-xSrxFe2O4; (0 ≤ x ≥ 0.20) nanoparticles synthesized by auto combustion route has been investigated by electron paramagnetic resonance (EPR) which show a broad ferromagnetic resonance signal with a superimposed hump signal which is attributed to ferrite Fe3+ ions and oxygen vacancies which is in agreement with XRD and XPS. EPR shows low spin concentration and smaller relaxation time for Zr0.80Sr0.20Fe2O4 which can be used for hyperthermia and for use as a MRI contrast agent. EDS and XPS confirms the presence of Zr, Sr, Fe, O, and C and HRTEM images confirm growth along (220) and (311) with an interatomic distance of 0.3327 nm and 0.2622 nm respectively, thus, authenticating the formation of spinel structure in agreement with FTIR studies. The magnetic behaviour (M − H loop) shows high saturation magnetization and higher value of effective magnetocrystalline anisotropy (Keff) for Zr0.80Sr0.20Fe2O4.

Stabilizing magnetic order of cobalt-based anisotropic nanoparticles prepared using NaBH4 as a reducing agent

A one-pot chemical method was used to prepare cobalt nanoparticles (Co NPs) by employing sodium borohydride (NaBH4) as a reducing agent, as well as graphite and activated carbon as stabilizer materials. The resulting NPs were characterized by XRD, FE-SEM, EDX mapping and VSM measurements before and after annealing under a mixture of argon and hydrogen atmosphere at 600 ℃, in order to study their structural, morphological, and magnetic properties. This study focused on the shape and size of Co NPs, involving the formation of Co and Co3O4 phases with the effect of oxygen as the main factor that can significantly contribute to the magnetic anisotropy. Co NPs exhibited a high saturation magnetization (Ms) value after performing the annealing process, achieving Ms> 99 emu/g when using the graphite stabilizer. The results indicate that surface atoms play a significant role in the modification of magnetic characteristics of Co NPs.

Purification, Characterization, and Assessment of Anticancer Activity of Iron Oxide Nanoparticles Biosynthesized by Novel Thermophilic Bacillus tequilensis ASFS1‏.

Magnetic nanoparticles (MNPs), particularly iron oxide nanoparticles (IONPs), are a fascinating group of nanoparticles that have been considerably investigated for biomedical applications because of their superparamagnetic properties, biodegradable nature, and biocompatibility. A novel Gram-positive moderately thermophilic bacterial strain, namely Bacillus tequilensis ASFS.1, was isolated and identified. This strain is capable of producing superparamagnetic Fe3O4 nanoparticles and exhibiting magnetotaxis behavior. This strain swimming behavior was investigated under static and dynamic environments, where it behaved very much similar to the magnetotaxis in magnetotactic bacteria. This study is the first report of a bacterium from the Bacillaceae family that has the potential to intracellular biosynthesis of IONPs. MNPs were separated by a magnetic and reproducible method which was designed for the first time for this study. In addition, UV-visible spectrophotometer, Fourier-transform infrared spectroscopy, vibrating sample magnetometer, field emission scanning electron microscopy (FESEM), X-ray diffraction, and thermal gravimetric analysis were utilized to characterize the bio-fabricated magnetite nanoparticles. Analysis of the particle size distribution pattern of the biogenic MNPs by FESEM imaging revealed the size range of 10-100 nm with the size range of 10-40 nm MNPs being the most frequent particles. VSM analysis demonstrated that biogenic MNPs displayed superparamagnetic properties with a high saturation magnetization value of 184 emu/g. After 24 h treatment of 3T3, U87, A549, MCF-7, and HT-29 cell lines with the biogenic MNPs, IC50 values were measured to be 339, 641, 582, 149, and 184 μg mL-1, respectively. This study presents the novel strain ASFS.1 capable of magnetotaxis by the aid of its magnetite nanoparticles and paving information on isolation, characterization, and in vitro cytotoxicity of its MNPs. The MNPs showed promising potential for biomedical applications, obviously subject to additional studies.

Impact of ZnO nanoparticles on Mn0.5Fe2.5O4@C/ZnO-DOX nanocomposites as antibacterial agents and drug loading materials

A series of Mn0.5Fe2.5O4@C/ZnO-DOX nanocomposites were successfully synthesized using the hydrothermal method with different ZnO masses. The novelty of this study was the obtained Mn0.5Fe2.5O4@C/ZnO-DOX nanocomposite as a good candidate as an antibacterial agent and drug delivery material. The IR spectra showed that the samples were successfully formed. The vibrations of Fe–O and Mn–O were detected at 678.94–563.21cm−1, and that of Zn–O was located at 933.55–867.97cm−1. Meanwhile, the XRD pattern showed that the samples have two crystal phases, i.e. magnetite and ZnO. The nanostructure of the samples was studied by SAXS, showing that the Mn0.5Fe2.5O4@C/ZnO-DOX nanocomposite formed clustering particles that were structured by secondary and primary particles. The secondary particles in the samples contained about 3–4 primary particles. The magnetic properties were characterized using VSM, showing that the samples have superparamagnetic behavior. The increase in ZnO mass affected the saturation magnetization value. The highest saturation magnetization value was approximately 8.66 emu/g for the sample with the smallest ZnO mass. The samples contained Fe2+, Fe3+, and ZnO2+ ions, which created oxidative stress that damaged the DNA cells of bacteria, as seen from the results of the antibacterial activity test. In addition, it was found that the Mn0.5Fe2.5O4@C/ZnO-DOX nanocomposite has another potential as a drug loader material. As the ZnO mass increased, the drug loading efficiency also increased up to 75%. Thus, the prepared Mn0.5Fe2.5O4@C/ZnO-DOX nanocomposites have potential as antibacterial agents and drug loading materials.

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.

Magnetic properties and microstructure of Ce and Zr synergetic stabilizing Ti-lean SmFe12-based strip-casting flakes

Recently ThMn12-type samarium iron alloys have been promising materials for permanent magnets. Due to the high abundance and low cost, Ce as a possible stabilizer can be introduced into ThMn12-type alloys. The effect of Ce doping on the magnetic moment and phase stability in Ti-lean (Ce,Sm,Zr)(Fe,Co,Ti)12 compounds were predicted by the first-principles calculations. The CexSm0.8-xZr0.2(Fe0.8Co0.2)11.5Ti0.5 (x = 0–0.8) alloys with ThMn12 structure were produced by strip-casting into flakes by a wheel speed of 1.5 m/s and annealed at 1000 °C for 24 h. The Ce0.8Zr0.2(Fe0.8Co0.2)11.5Ti0.5 annealed flake shows a high saturation magnetization value of 13.6 kGs at room temperature. With the increase of Ce substitution in the annealed flakes, the content of α-(Fe,Co,Ti) phase decreases and the saturation magnetization increases. The 1:12 phase and the 1:9 phase have an orientation relationship that can be expressed as [0 0 –1]1:12//[100]1:9 and (020)1:12//(010)1:9. Besides, annealing process promotes the formation of 1:12 phase transformed from 1:9 phase. Coercivity is expected to be improved by obtaining uniform microstructure and suppressing the formation of soft α-(Fe,Co,Ti) phase in the ThMn12-based alloys.

Recapitulation of the magnetic and magnetodielectric properties of (1-x)LiNbO3 - (x)La0.9Na0.1MnO3 (x = 0.1, 0.2, 0.3) composites

The present study provides structural, ferroelectric, magnetic, magnetodielectric and the optical properties of the composite (1-x)LiNbO3-(x)La 0.9Na 0.1MnO3 with different values of x (where x = 0.1, 0.2 and 0.3) at room temperature. Ferroelectric phase LiNbO3(LNB) and magnetic phase La 0.9Na 0.1MnO3(LNMO) were synthesized by conventional solid state reaction method. Rietveld X-ray diffraction pattern reveals the structural purity of the synthesized samples. The ferroic and antiferroic nature of the composites were investigated from M-H hysteresis loop, at x = 0.3 shows highest value of saturation magnetization. The reduced ferroelectric nature of the prepared samples was revealed through P-E hysteresis loop measurement with sample x = 0.1 shows highest value of remnant polarization room temperature. Magnetoelectric coupling nature of the composite sample was confirmed through magnetodielectric measurement. Among the studied composites highest value of magnetodielectric percentage (MD%) at 1 kHz is obtained for sample with x = 0.3. Enhanced magnetodielectric coupling coefficient value of 5.5 is achieved for the sample with x = 0.3. Optical properties were examined from UV absorbance analysis technique. On increasing LNMO content, there was a slight decrease in the band gap energy. The enhanced magnetoelectric coupling property of the present synthesized composite paves the way for more room temperature multifunctional materials.

Ultrafast and highly efficient Cd(II) and Pb(II) removal by magnetic adsorbents derived from gypsum and corncob: Performances and mechanisms

The utilization of gypsum and biomass in environmental remediation has become a novel approach to promote waste recycling. Generally, raw waste materials exhibit limited adsorption capacity for heavy metal ions (HMIs) and often result in poor solid–liquid separation. In this study, through co-pyrolysis with corncob waste, titanium gypsum (TiG) was transformed into magnetic adsorbents (GCx, where x denotes the proportion of corncob in the gypsum–corncob mixture) for the removal of Cd(II) and Pb(II). GC10, the optimal adsorbent, which was composed primarily of anhydrite, calcium sulfide, and magnetic Fe3O4, exhibited significantly faster adsorption kinetics (rate constant k1 was 218 times and 9 times of raw TiG for Cd(II) and Pb(II)) and higher adsorption capacity (Qe exceeded 200 mg/g for Cd(II) and 400 mg/g for Pb(II)) than raw TiG and previous adsorbents. Cd(II) removal was more profoundly inhibited in a Cd(II) + Pb(II) binary system, suggesting that GC10 showed better selectivity for Pb(II). Moreover, GC10 could be easily separated from purified water for further recovery, due to its high saturation magnetization value (6.3 emu/g). The superior removal capabilities of GC10 were due to adsorption and surface precipitation of metal sulfides and metal sulfates on the adsorbent surface. Overall, these waste-derived magnetic adsorbents provide a novel and sustainable approach to waste recycling and the deep purification of multiple HMIs.

Structural design of La2(CO3)3 loaded magnetic biochar for selective removal of phosphorus from wastewater

High levels of phosphorus released into the environment can cause eutrophication issues in wastewater, therefore discharge concentrations of such element are regulated in many countries. This study addresses the pressing need for effective phosphorus removal methods by developing a novel La2(CO3)3 and MnFe2O4 loaded biochar composite (LMB). A remarkable adsorption capacity towards the three forms of phosphorus from wastewater, including phosphate, phosphite, and etidronic acid monohydrate (as a representative of organic phosphorus), was exhibited by LMB (88.20, 16.35, and 15.95 mg g−1, respectively). The high saturation magnetization value (50.17 emu g−1) highlighted the easy separability and recyclability of the adsorbent. The adsorption process was well described by the Langmuir isotherm model and the pseudo-second-order kinetic model, which mainly involved chemisorption. Characterization results confirm the effective loading of La2(CO3)3 with ligand exchange and electrostatic attraction identified as the primary mechanisms. Importantly, the LMB demonstrated exceptional selectivity for phosphorus in wastewater samples containing various substances, exhibiting minimal interference from competing ions (Cl−, NO3−, SO42−, and CO32−). These findings enhance the understanding of LMB's application in efficient wastewater phosphorus removal. Holding significant promise in wastewater remediation, the LMB acts as an effective adsorbent, contributing substantially to the prevention and control of various types of phosphorus pollutants, thereby mitigating wastewater eutrophication.

Magnetorheological fluids: A comprehensive review

The magnetorheological (MR) fluids contain magnetic micro-sized iron particles, non-magnetic-based fluid, and some additives in order to mitigate sedimentation and agglomeration. The various carrier fluids used in the preparation of MR fluids are mineral oil, silicon oil, castor oil, soybean oil, kerosene, synthetic oils, honge oil, organic oil, water-based oils, etc. However, for obtaining better vibration control, silicone oil is the most preferred one due to its higher viscosity index, lower friction characteristics, higher flash point, and higher shear strength. The MR fluids have various application areas such as dampers, prosthetic knees, valves, brakes, clutches, finishing processes etc. The dampers containing MR fluids are used in automobile cushioning for enhancing passenger comfort and MR suspensions significantly improve steering stability in vehicles. In case of MR brakes, the braking torque on the rotating disks is controlled using the generated shear stress. The carbonyl iron (CI) particles exhibit better rheological characteristics as compared to electrolytic iron (EI) particles. The use of MR fluids produces stable and natural limb movement in orthoses, lower limb prostheses, and exoskeletons. The MR fluids also prove to be very significant in polishing applications. There are various issues with preparation methods and difficulties in the storage of MR fluids. The problems encountered in the synthesis of MR fluids include sedimentation, agglomeration, in-use thickening, corrosion, erosion, etc. The impact of particle proportion, particle shapes, and size has been influential in evaluating MR characteristics. The viscosity and shear stress of MR fluid have been mitigated at higher values of temperature and even CI particles get oxidized at higher temperatures. The CI particles as compared to EI particles are the majority favourable particles used for dispersing state within the MR fluids due to their higher value of saturation magnetization, more availability, and lesser cost. The small-sized particles led to lower wettability, whereas larger-sized particles accounted for an increased sedimentation rate. The currently available MR fluids cost is still on the higher side and the preparation of economical MR fluid is still a big challenge for the researchers. The MR fluids storage is also a big concern. The future scope of MR fluid may be in heavy industries such as nuclear, shipbuilding, oil and gas, space and aviation, etc. to achieve the desired damping response.

Facile one-pot synthesis of the mesoporous chitosan-coated cobalt ferrite nanozyme as an antibacterial and MRI contrast agent.

Cobalt ferrite (CoFe) nanoparticles (NPs) with appropriate physicochemical and biological properties have attracted great attention for biomedical applications. In the present study, chitosan-coated mesoporous CoFe (CoFeCH) NPs were synthesized using a facile one-step hydrothermal method and fully characterized using FE-SEM, EDS, BET, FTIR spectroscopy, DLS, TGA, XRD, and VSM. The spherical, highly colloidal, and monodispersed CoFeCH NPs with an average hydrodynamic size of 177.9 nm, PDI of 0.238 and zeta potential value of -33 represented a high saturation magnetization value of 59.37 emu g-1. N2 adsorption-desorption analysis confirmed the mesoporous structure of CoFeCH NPs with a type IV isotherm, calculated specific surface area of 89.583 m2 g-1 and total pore volume of 0.3668 cm3 g-1. CoFeCH NPs exhibited high antibacterial effects on S. aureus and E. coli, comparable with standard antibiotics, while CH-coating led to higher biocompatibility of CoFe NPs on human cells in vitro. CoFeCH NPs also showed significant peroxidase activity with a Km value of 14.37 and specific activity of 0.632 mmol min-1. CoFeCH NPs were successfully used as a MRI contrast agent with an R2 value of 91.3 mM-1 s-1. The overall results indicated the high potential of synthesized CoFeCH NPs by the present method for biomedical applications, especially as an antibacterial and MRI contrast agent.

Robust ferromagnetism and magneto-dielectric anomalies in (Al, Cr) co-doped iron oxide thin films-microwave mediated sol–gel approach

Research on thin films of iron oxide has gained interest in recent years because of its application in advanced spintronic and electronic devices. Technologically important iron oxide phases can be achieved by adopting novel methodologies and/or selecting suitable dopants. A cost-effective microwave assisted sol–gel approach is adopted in this work to prepare thin films of iron oxide. Undoped and doped sols (2–10 wt% of dopant concentration) are irradiated with MW power of 720 W. Maghemite phase (γ-Fe2O3) is observed to be stable up to a co-dopant concentration of 6 wt%. Further increase in dopant content leads to a phase transition to mixed (γ-Fe2O3+Al2O3) crystal phases. Values of dielectric constant (DC) and loss tangent exhibit normal dispersion response with high DC value (log f 5.5 = ∼92) observed for undoped sample. Cole–Cole plots indicate the effective grain boundary contribution for low dopant concentrations, whereas contributions from grains is observed at higher dopant concentrations. M−H curves show ferromagnetic response with high value of saturation magnetization (Ms) of ∼450 emu/cm3 witnessed at 6 wt%. (Al, Cr) co-doping results in tuning of magnetic response/parameters. MD coupling of (Al, Cr) co-doped thin films of iron oxide makes this material suitable for advanced spintronic and energy storage devices.

Hydrothermal synthesis of highly aligned Fe3O4 nanosplates on nickel foam

In the present work, a facile hydrothermal route is employed for the synthesis of highly aligned arrays of Fe3O4 nanoplates on a 3D nickel foam substrate. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations reveal the crucial role of the nickel foam substrate on the morphology of the produced Fe3O4. Synthesis on a nickel foam results in a nanoplate morphology while in absence of the substrate, highly agglomerated Fe3O4 nanoparticles are achieved. SEM studies show that, in the early stages of hydrothermal treatment, small Fe3O4 nuclei form on the surface of the Ni foam which grow into nanoplates by increasing the duration from 2 to 18 h. According to X-ray diffraction studies Fe3O4 nanoplates are single phase. Brunauer-Emmett-Teller (BET) measurements, show that Fe3O4 decorated Ni foams have a surface area 26 times higher than the as-received foam. Vibrating sample magnetometer (VSM) studies also show that Fe3O4 decorated Ni foams have a superparamagnetic behavior with a high magnetization saturation value of 69.97 emu g-1. Such high surface area and magnetism makes this 3D composite an excellent material for electromagnetic shielding applications.

Enhanced magnetic, electrochemical and gas sensing properties of cobalt substituted nickel ferrite nanoparticles prepared by hydrothermal route

The cobalt doped nickel ferrite nanoparticles were successfully synthesized via hydrothermal method at low reaction temperature. X-ray diffraction analysis confirmed the cubic spinel structure with an average crystallite size of 41 nm for pure nickel ferrite (NF) and in the range (38–33) nm for substituted samples. High resolution transmission electron microscope observations revealed the cubic-like shaped nanosized particles. Ultraviolet diffuse reflectance spectroscopy indicated an increase in the energy bandgap with increasing Co content. X-ray photoelectron spectroscopy confirmed the oxidation states of constituents, +2 for Ni, +2 for Co, and +3 for Fe. The AC conductivity was enhanced with increasing frequency. The observed higher value of saturation magnetization and coercivity, manifests its suitability in high density recording media. Besides, the ratio of Hcr/Hc confirmed the pseudosingle domain nature of the synthesized nanoparticles. The valency and occupancy of the Fe ion in tetrahedral-A and octahedral-B sites within the spinel cubic structure were elucidated by Mossbauer spectroscopy analysis. The cyclic voltammetry (CV) studies revealed the pseudocapacitance behaviour with high specific capacitance value at low scan rates. The sensor activity towards liquified petroleum gas (LPG) at 100 ppm showed the response and recovery time as 52 and 13s respectively.

Realization of improved magnetodielectric coupling and electrochemical performance of microwave assisted sol-gel prepared spinel manganese chromium oxide nanopowders

Microwave assisted sol-gel approach is used to successfully produce spinel phase of manganese chromium oxide nanoparticles. Hydrous manganese chloride, hydrous chromium chloride and ethylene glycol are used as precursors and solvent. Ratio of Mn/Cr (0.20–0.65) is varied during synthesis. Microwave radiations (720 W) are used to obtain nanopowders of manganese chromium oxide nanoparticles. Mn/Cr ratios of 0.20–0.25 produce amorphous behavior, while Mn/Cr ratios of 0.30, 0.35, 0.40, 0.45, and 0.65 produce mixed phases. Single phase of spinel MnCr2O4 nanoparticles is observed at Mn/Cr ratios of 0.50, 0.55, and 0.6. Normal dispersion behaviour with high value of dielectric constant (~60 at log f=5), low tangent loss (0.004 at log f =5) and low conductivity values are observed for Mn/Cr ratio of 0.6. Cole-Cole plots show a single semicircle, indicating that grain boundary resistance plays a significant role. The results of the vibrating sample magnetometer show that all the samples have ferromagnetic behavior, with a high saturation magnetization value (~ 15 emu/g) for Mn/Cr ratio of 0.6. Large and positive magnetodielectric response is observed for Mn/Cr ratio of 0.55 & 0.6. Cyclic voltammetry curves demonstrate high specific capacitance for Mn/Cr ratios of 0.55, and 0.6. Results obtained under as-synthesized conditions suggest suitability of the optimized material for magnetic and energy storage applications.

In Ukrainian

In this paper it is discussed the colloidal-chemical method of synthesis of dispersed composite bentonite-ferromagnetic powders that are stable to oxidation. It is shown that for this purpose it is advisable to use acid-activated bentonite clay with a high content of clay mineral - montmorillonite. Modified bentonite is a slightly amorphized silica product that serves as a porous matrix for crystallization of goethite α-FeOOH. The formation of goethite occurs at the centers of crystallization - particles of ferrihydrite stabilized by activated bentonite (Fh) during precipitation with an ammonia solution from a ferrum(ІІІ) hydroxide FeO(OH)×nH2O colloidal solution. In the resulting composite, goethite particles are cemented in the aluminosilicate framework of activated dispersed clay as a result of the interpenetration of the structures of the double layered hydroxide and activated bentonite. Further recrystallization of goethite with the formation of mainly magnetite and possibly maghemite in the structure of activated bentonite is provided by thermal firing of composite goethite powder with the addition of metallic iron powder. The methods of IR spectroscopy, X-ray structural analysis, electron microscopy and the study of magnetic properties showed that the obtained composite powder is environmentally friendly and exhibits the properties of a soft magnetic material. Such powders are promising for use as sorbents for environmental cleaning, as well as for biomedical purposes due to their low toxicity and high value of saturation magnetization.

Facile one-pot rapid sonoelectrochemical synthesis of mesoporous magnetite nanospheres: A Chimie Douce approach

In this study, mesoporous Magnetite (Fe3O4) nanospheres have been synthesized quickly via facile sonoelectrochemical method. The scope of this study is to obtain high yield of active Fe3O4 nanoparticles in a tunable structural morphology with reduced cost, energy, and synthesis time without compromising its quality. The coupling of the electrochemical method with ultrasound could influence higher mass transfer rate, thereby leading to rapid formation of magnetite. Studies on understanding the role of additive and stabilizer have been carried out. Further, the influence of ultrasound amplitude and irradiation time has been examined. Under constant electrochemical parameters, the formation of magnetite of required properties is achieved with added additive and stabilizer under 60% ultrasound amplitude at 15 min of irradiation time. The prepared magnetite nanoparticles under optimized synthesis parameters were spherical in shape with a narrow size distribution of 30–80 nm, mesoporous in nature, and with a surface area of 121.87 m2g-1. The high value of saturation magnetization (65.33 emug−1) conjointly discloses the near superparamagnetic nature. The elemental composition of highly crystalline magnetite nanoparticles with good stability behavior has been demonstrated by deep characterization techniques.

198Au-Coated Superparamagnetic Iron Oxide Nanoparticles for Dual Magnetic Hyperthermia and Radionuclide Therapy of Hepatocellular Carcinoma.

This study was performed to synthesize a radiopharmaceutical designed for multimodal hepatocellular carcinoma (HCC) treatment involving radionuclide therapy and magnetic hyperthermia. To achieve this goal, the superparamagnetic iron oxide (magnetite) nanoparticles (SPIONs) were covered with a layer of radioactive gold (198Au) creating core-shell nanoparticles (SPION@Au). The synthesized SPION@Au nanoparticles exhibited superparamagnetic properties with a saturation magnetization of 50 emu/g, which is lower than reported for uncoated SPIONs (83 emu/g). Nevertheless, the SPION@Au core-shell nanoparticles showed a sufficiently high saturation magnetization value which allows them to reach a temperature of 43 °C at a magnetic field frequency of 386 kHz. The cytotoxic effect of nonradioactive and radioactive SPION@Au-polyethylene glycol (PEG) bioconjugates was carried out by treating HepG2 cells with various concentrations (1.25-100.00 µg/mL) of the compound and radioactivity in range of 1.25-20 MBq/mL. The moderate cytotoxic effect of nonradioactive SPION@Au-PEG bioconjugates on HepG2 was observed. The cytotoxic effect associated with the β- radiation emitted by 198Au was much greater and already reaches a cell survival fraction below 8% for 2.5 MBq/mL of radioactivity after 72 h. Thus, the killing of HepG2 cells in HCC therapy should be possible due to the combination of the heat-generating properties of the SPION-198Au-PEG conjugates and the radiotoxicity of the radiation emitted by 198Au.