High Saturation Magnetization Value Research Articles

Magnetic and optical properties of green synthesized nickel ferrite nanoparticles and its application into photocatalysis

Spinel NiFe2O4 nanoparticles have been synthesized via hydrothermal route using Mangifera indica flower extract (MIFE) as a green surfactant and reducing agent. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy techniques have been used to determine the structure and morphology. The formation of single-phase, monodispersed NiFe2O4 with mixed morphology, the predominant shape being of equi-axed nanoparticles having an average particle size ≲45 nm, is observed. The thermal magnetization of as-synthesized NiFe2O4 nanoparticles shows ferromagnetic to paramagnetic phase transition at T c ∼ 825 K. These nanoparticles show a very high saturation magnetization (M s) value of 55 emu g−1 close to the bulk material and amongst the highest reported values for green synthesized NiFe2O4 nanoparticles. This material has a coercivity (H c) of 0.15 kOe and remanent magnetization (M r) of 8.5 emu g−1. The as-synthesized NiFe2O4 nanoparticles show bandgap energy of 2.02 eV, derived from UV–vis absorption measurement, which is suitable for effective solar photocatalytic reactions. When exposed to sunlight in the presence of as-synthesized NiFe2O4 nanoparticles, 93% of MB-dye degradation is measured in 80 min, indicating excellent photocatalytic properties. Based on the as-synthesized NiFe2O4 nanoparticles’ observed properties, the effectiveness of MIFE as an environmentally friendly surfactant, and the low-cost dye-degradation prospects of green synthesized NiFe2O4 nanoparticles are affirmed.

Perpendicularly magnetized ferromagnetism in Mn/Al bilayer thin films on Si substrates induced by temperature dependent ion beam mixing

The perpendicularly magnetized τ-phase was achieved in Mn/Al bilayer thin films by ion beam mixing using 400 keV Xe ions. The effect of annealing and irradiation on the structural, microstructural, and magnetic properties of Mn/Al bilayer thin films was investigated in the present study. Mn/Al bilayer thin films (thickness ∼97 nm) were deposited on silicon substrates by the evaporation technique. These as-deposited films were irradiated to the fluences of 5 × 1016 and 1 × 1017 ions cm−2 at three substrate temperatures (Room temperature ∼300 K, 450 K, and 623 K). As-deposited films were also annealed at 450 K and 623 K for 5 h. The ferromagnetic τ-phase was enhanced in annealed and irradiated thin films confirmed from synchrotron x-ray diffraction patterns, MFM images, and magnetic hysteresis curves. The average grain size estimated from the AFM study was found in the range of 78–192 nm. The domain patterns obtained in MFM images confirmed the ferromagnetic nature of the annealed and irradiated films. The hysteresis curves measured at 5 K show the maximum coercivity (7111 Oe) for the sample annealed at 450 K and the highest value of saturation magnetization (60 emu cc−1) for the film irradiated to the fluence of 1 × 1017 ions cm−2 at the substrate temperature of 450 K. Perpendicularly magnetized τ-phase was achieved in the films irradiated to the fluence of 1 × 1017 ions cm−2 at different temperatures. The formation of the ferromagnetic phase by ion beam mixing can be attributed to the combined effect of ballistic mixing and thermal spike mechanisms. This study suggests that the ferromagnetic properties of MnAl thin films can be modified by selecting the proper annealing and irradiation conditions to make them useful for applications in spintronics and magnetic memory devices.

Tailoring the optical and magnetic properties of La-BaM hexaferrites by Ni substitution

We investigate the impact of Ni insertion on the structural, optical, and magnetic properties of Ba0.8La0.2Fe12–x Ni x O19 hexaferrites (Ni substituted La-BaM hexaferrites). Samples were prepared using the conventional co-precipitation method and sintered at 1000 °C for 4 hours to assist the crystallization process. An analysis of the structure of the samples was carried out using an x-ray diffraction (XRD) spectrometer. The M-type hexagonal structure of all the samples was confirmed using XRD spectra. The lattice parameters a and c were found to be in the ranges of 5.8925±0.001 nm–5.8952±0.001 nm and 23.2123±0.001 nm–23.2219±0.001 nm, respectively. The M-type hexagonal nature of the prepared samples was also indicated by the presence of corresponding FT-IR bands and Raman modes in the FT-IR and Raman spectra, respectively. EDX results confirmed the successful synthesis of the samples according to the required stoichiometric ratio. A UV-vis spectrometer was used to record the absorption spectra of the prepared samples in the wavelength range of 200 nm–1100 nm. The optical energy bandgap of the samples was found to be in the range of 1.21 eV–3.39 eV. The M–H loops of the samples were measured at room temperature at an applied magnetic field range of 0 kOe–60 kOe. A high saturation magnetization of 99.92 emu/g was recorded in the sample with x = 0 at a microwave operating frequency of 22.2 GHz. This high value of saturation magnetization is due to the substitution of La3+ ions at the spin-up (12k, 2a, and 2b) sites. The Ni substitution is proven to be a potential candidate for the tuning of the optical and magnetic parameters of M-type hexaferrites. Therefore, we suggest that the prepared samples are suitable for use in magneto-optic applications.

Low temperature rapid sol–gel auto-combustion synthesis and structural, morphological and magnetic study of nickel substituted cobalt nano ferrites

ABSTRACT The nickel substituted cobalt ferrite nanoparticles were synthesized via the sol–gel auto-combustion method. The single cubic spinel structure formation was confirmed from X-ray diffraction and Fourier transforms infrared spectroscopy study. The effect of lattice strain on crystalline size was studied using Williamson–Hall and the size-strain plot method. A microstructural study was performed using high-resolution field emission scanning electron microscopy. The magnetic properties were studied at room temperature using a vibrating sample magnetometer. The saturation magnetization obtained for pure cobalt nano ferrite was 79.66 emu/g comparable with the value for the bulk sample. The anisotropic constant and anisotropy field were found to be erg/cm3 and 88.66 kOe respectively for pure cobalt ferrite. The high value of saturation magnetization, anisotropic constant and anisotropy field of cobalt ferrite are important parameters for the application of prepared samples in data recording devices.

Enhancement in the magnetoelectric and energy storage properties of core-shell-like [formula omitted] multiferroic nanocomposite

Herein we report the development of a core-shell-like CoFe2O4−BaTiO3 multiferroic nanocomposite (1:1 wt ratio) for their enhanced magnetoelectric coupling and energy storage density by the wet chemical route. Rietveld refinement analysis of the XRD pattern verified the formation of cubic spinel (CoFe2O4) and tetragonal perovskite (BaTiO3) structures. Whereas the SEM and EDX analysis confirmed the formation of core-shell-like morphology in the composite. The temperature dependence of dielectric permittivity showed two distinct peaks corresponding to the constituent phases´ structural phase transitions. However, the frequency dependence of low-temperature peak revealed an abnormal relaxor-type behavior, which is elucidated due to intrinsic structural defects that might cause alteration in the octahedron arrangement in BaTiO3. Impedance spectroscopy analysis was utilized to calculate the activation energy (Ea) of respective phases, which was found to be>1 eV that confirms the dominance of doubly ionized oxygen vacancies in governing the thermally stimulated conduction process. It was found that the prepared composite exhibited high dielectric permittivity (~2700) and moderate values of saturation magnetization (20 emu/g) and polarization (6.2 μC/cm2) along with low remnant polarization (3 μC/cm2) at room temperature. Moreover, we also observed enhanced energy storage efficiency (67%) and magnetoelectric coefficient (0.18 V/cm Oe), which are explained due to strong interfacial coupling and reduced leakage current, making this composition promising for multifunctional device applications.

Magnetic and optical properties of transition metal (Fe, Co) and rare-earth (Tb, Dy) doped ZnS nanoparticles

In the present work, hydrothermally synthesized transition metal (TM = Fe, Co) and rare earth (RE = Tb, Dy) doped ZnS nanoparticles were investigated for its structural, morphological, optical and magnetic properties. Phase and microstructural analysis confirmed cubic phase of ZnS having spherical shaped nanoparticles. TM doped showed relatively smaller crystallite size (~3.61 nm) compared to RE (~5.23 nm). The optical band gap found tunable in the range of 3.69–3.86 eV with doping. All nanoparticles were ferromagnetic in nature and highest value of saturation magnetization was observed for Fe doped ZnS. The tunable optical and ferromagnetic properties in RE and TM doped ZnS suggests their potential use in optoelectronic and spintronic devices.

DMSA-Coated Cubic Iron Oxide Nanoparticles as Potential Therapeutic Agents

Aim: Superparamagnetic cubic iron oxide nanoparticles (IONPs) were synthesized and functionalized with meso-2,3-dimercaptosuccinic acid (DMSA) as a potential agent for cancer treatment. Methods: Monodisperse cubic IONPs with a high value of saturation magnetization were synthesized by thermal decomposition method and functionalized with DMSA via ligand exchange reaction, and their cytotoxic effects on HeLa cells wereinvestigated. Results: DMSA functionalized cubic IONPs with an edge length of 24.5±1.9nm had a specific absorption rate value of 197.4W/gFe (15.95kA/m and 488kHz) and showed slight cytotoxicity on HeLa cells when incubated with 3.3×1010, 6.6×1010 and 9.9×1010 NP/mL for 24, 48 and 72h. Conclusion: To the best of our knowledge, this is the first study to investigate both the cytotoxic effects of DMSA-coated cubic IONPs on HeLa cells and hyperthermia performanceof these nanoparticles.

Synthesis and investigation of structural, optical, magnetic, and biocompatibility properties of nanoferrites AFeO2

Sol-gel method has been used for the synthesis of biocompatible superparamagnetic nanoferrites of AFeO2 (A = Li, Na, K, Ca). Structural study of the nanoferrites reveals that LiFeO2 exhibits cubic phase on the other hand NaFeO2, KFeO2, CaFeO2 nanoparticles possess orthorhombic phase. Transmission electron microscopy (TEM) suggests that synthesized nanoferrites are nano-sized with spherical morphology. Optical properties confirm that nanoferrites emit and absorb light in a visible range of the electromagnetic spectrum. International Commission on Illumination (CIE) study discloses that the nanoparticles can be used to produce light of various colors. Magnetic study reveals that the nanoferrites exhibit superparamagnetic nature with high values of saturation magnetization 40.26 emu/g, 41.69 emu/g, 57.16 emu/g, and 43.66 emu/g, respectively for LiFeO2, NaFeO2, KFeO2, and CaFeO2. Biocompatibility study of the nanoferrites has been performed using Sulforhodamine B (SRB) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The reason behind the observed properties and behavior has been discussed.

An advancement in the synthesis of unique soft magnetic CoCuFeNiZn high entropy alloy thin films

Discovery of advanced soft-magnetic high entropy alloy (HEA) thin films are highly pursued to obtain unidentified functional materials. The figure of merit in current nanocrystalline HEA thin films relies in integration of a simple single-step electrochemical approach with a complex HEA system containing multiple elements with dissimilar crystal structures and large variation of melting points. A new family of Cobalt–Copper–Iron–Nickel–Zinc (Co–Cu–Fe–Ni–Zn) HEA thin films are prepared through pulse electrodeposition in aqueous medium, hosts nanocrystalline features in the range of ~ 5–20 nm having FCC and BCC dual phases. The fabricated Co–Cu–Fe–Ni–Zn HEA thin films exhibited high saturation magnetization value of ~ 82 emu/g, relatively low coercivity value of 19.5 Oe and remanent magnetization of 1.17%. Irrespective of the alloying of diamagnetic Zn and Cu with ferromagnetic Fe, Co, Ni elements, the HEA thin film has resulted in relatively high saturation magnetization which can provide useful insights for its potential unexplored applications.

Effect of calcium solubility on structural, microstructural and magnetic properties of M-type barium hexaferrite

We report the synthesis of x = 0.00–1.00 at step size of 0.10 for Ba1-xCaxFe12O19 samples using sol-gel auto combustion method. The powder X-ray diffraction (XRD) data of samples calcined at different temperatures indicates a) single phase formation up to x = 0.20 in samples calcined at 900 °C; b) an increase in calcium solubility to 50 at. % (x = 0.50) at 1200 °C; c) a decrease in lattice parameters ‘c’ (from 23.2002 Å (x = 0.00) to 23.0928 Å (x = 0.50)) as well as cell volume (from 696.75 Å3 (x = 0.00) to 692.95 Å3 (x = 0.50)) with increasing ‘x’ and d) the presence of segregated (α–Fe2O3) phase for x ≥ 0.20 at 900 °C and for x > 0.50 at 1200 °C. As the maximum calcium solubility in BaM phase has been noticed at 1200 °C, most of the other characterizations have been performed on these samples only. FESEM micrographs show an increase in particle size with ‘x’. Magnetic measurements reveal that the highest value of saturation magnetization (Ms) is ≈71.82 emu/g (calcined at 1200 °C) in x = 0.50 sample. The coercivity (Hc) decreases from 3765Oe to 1729Oe with increase in ‘x’. Among the samples calcined at different temperatures, the coercivity (Hc) decreases from 4726Oe to 2040Oe with an increase in calcination temperature for x = 0.20 samples. The samples because of their excellent magnetic properties could be vital for magnetic recording and for applications as permanent magnets.

Preparation, structure and magnetic, electronic and thermal properties of Dy3+-doped ZnCr2Se4 with unique geometric type spin-glass

Physico-chemical studies of (Zn1–xDyx)Cr2Se4 and Zn[Cr2–xDyx]Se4 spinel systems (x ​= ​0.05, 0.10) containing dysprosium ions in both tetra- and octahedral positions have shown an enhancement of long-range antiferromagnetic interactions and a weakening of short-range ferromagnetic ones. This resulted in the appearance of geometric type spin-glass in connection with the increase in the length of chemical bonds between chromium ions. This state of spin-glass is also due to the large difference in the absolute values of the superexchange integrals and the small magnetic contribution to the specific heat below the freezing point. Studies of XPS and X-ray absorption near edge structure (XANES) showed that no main edge shift was observed between the tetra- and octahedral positions of dysprosium ions, which indicates that they remain in the +III oxidation state. Thus, significant differences between the effective magnetic moment and the effective number of Bohr magnetons, as well as much higher saturation magnetization values above 6 μB, suggest that chromium ions may have a different oxidation state. These effects may be also generated by spin defects.

Структурно-фазовые превращения при деформации сплавов Fe-Co-V методом кручения под высоким давлением

Fe-Co alloys belong to the soft magnetic materials and have an extremely high value of saturation magnetization σ at room temperature. In particular, Fe-Co alloy with the equiatomic ratio of components at room temperature has the maximal σ value among all known ferromagnetic materials. Unfortunately, it is hard to reproduce the unique magnetic properties of these alloys (especially Fe-Co alloys) due to their high fragility caused mainly by the formation of far atomic ordering according to B2 type in the structure. Adding vanadium to the Fe-Co alloys increases plasticity, but it reduces basic magnetic characteristics. In this paper, using the X-ray structural analysis, transmission scanning microscopy, and magnetometry, the authors analyzed the influence of high-pressure torsion at the temperatures of 77 and 295 K on the structure and phase composition of soft magnetic alloys (Fe-Co)100-xVx (x=0–6.0). As the principal structural parameter before and after deformation, the authors analyzed the magnitude of γ-phase volume ratio in the BCC magnetic matrix. The study identified that plastic deformation causes the suppression of formation of excessive γ-phase in alloys containing (3.0–6.0) % V. The study shows that the loss of γ-phase is observed with the increase of high-pressure torsion deformation firstly in the alloys with the high vanadium proportion and at the deformation effect at higher temperature (295 K). The authors conclude that the detected effect is a consequence of γ→α martensite transformation caused by deformation by analogy to TRIP-effect. The study identified that the suppression of paramagnetic γ-phase leads to a noticeable increase in the specific saturation magnetization.

Magnetization behaviour of Fe3O4–water and γ-Fe2O3–water magnetic nanofluids

Magnetic nanofluids are colloids that contain magnetic nanoparticles dispersed in a base fluid. In the presence of the external magnetic field, they can be magnetized and manipulated. Moreover, their thermophysical properties may be tuned. Therefore, it is important to investigate the magnetization behaviour of them. For this purpose, magnetization behaviours of magnetite (Fe3O4)-water and maghemite (γ-Fe2O3)-water which are commonly used in the available literature were investigated by a vibrating sample magnetometer (VSM). Various samples with different volume concentrations for Fe3O4-water (1 and 2%) and γ-Fe2O3-water (1.1 and 2.2%) nanofluids were used in the measurements. The results indicated that γ-Fe2O3-water magnetic nanofluid has higher saturation magnetization values than Fe3O4-water magnetic nanofluid. The measurements also pointed out that as the volume concentration increases, the magnetization of both magnetic nanofluids increases as well.

Growth and characterization of La0.67Sr0.33MnO3/YBa2Cu3O7−δ bilayers

Understanding the interplay of ferromagnets and superconductors requires high quality interfaces. To this end, we have fabricated heterostructures of the cuprate superconductor YBa2Cu3O7−δ (YBCO) with the metallic ferromagnet La0.67Sr0.33MnO3 (LSMO) via pulsed laser deposition on SrTiO3 (STO) (001) and (LaAlO3)0.3(Sr2TaAlO6)0.7 (LSAT) (001) substrates. By varying the YBCO thickness from 1.7-13.6 nm while keeping the LSMO thickness at 12 nm, we have studied the interplay between ferromagnetism and superconductivity in the in-plane transport and magnetic properties of the bilayers. X-ray reflectivity data indicate the presence of a 2-3 nm thick interfacial layer between the LSMO and YBCO layers in all heterostructures. In-plane transport measurements exhibit suppression of the superconducting transition temperature from bulk YBCO values. Magnetometry measurements indicate high LSMO saturation magnetization values for samples grown on STO substrates and even higher (bulk-like) magnetization for bilayers grown on LSAT substrates. Together these results indicate that the interdiffused layer is largely attributed to a modified YBCO layer.

Sulfonic acid-functionalized core-shell Fe3O4@carbon microspheres as magnetically recyclable solid acid catalysts

Green and recyclable solid acid catalysts are in urgent demand as a substitute for conventional liquid mineral acids. In this work, a series of novel sulfonic acid-functionalized core-shell Fe3O4@carbon microspheres (Fe3O4@C-SO3H) have been designed and synthesized as an efficient and recyclable heterogeneous acid catalyst. For the synthesis, core-shell Fe3O4@RF (resorcinol-formaldehyde) microspheres with tunable shell thickness were achieved by interfacial polymerization on magnetic Fe3O4 microspheres. After high-temperature carbonization, the microspheres were eventually treated by surface sulfonation, resulting in Fe3O4@C-x-SO3H (x stands for carbonization temperature) microspheres with abundant surface SO3H groups. The obtained microspheres possess uniform core-shell structure, partially-graphitized carbon skeletons, superparamagnetic property, high magnetization saturation value of 10.6 emu/g, and rich SO3H groups. The surface acid amounts can be adjusted in the range of 0.59–1.04 mmol/g via sulfonation treatment of carbon shells with different graphitization degrees. The magnetic Fe3O4@C-x-SO3H microspheres were utilized as a solid acid catalyst for the acetalization reaction between benzaldehyde and ethylene glycol, demonstrating high selectivity (97%) to benzaldehyde ethylene glycol acetal. More importantly, by applying an external magnetic field, the catalysts can be easily separated from the heterogeneous reaction solutions, which later show well preserved catalytic activity even after 9 cycles, revealing good recyclability and high stability.

Ferromagnetic transition metal-doped CdS nanoparticles: a comparative study

In the present work, series of ferromagnetic transition metal-doped (Fe, Co) CdS nanoparticles were synthesized via hydrothermal technique. The particles were characterized for structural, morphological, optical and magnetic properties. The X-ray diffraction confirmed the single wurtzite phase for all compositions. The relatively smaller crystallite size (~ 11.50 nm) was obtained with Fe (x = 0.15) compared to Co doping (~ 13.88 nm). The HR-TEM micrographs revealed spherical morphology of nanoparticles with decrease in average particle size. The increase in optical band gap was observed with doping. In photoluminescence spectra, the main emission peak at 529 nm corresponds to green emission due to d-d intra ion transition. The magnetic analysis confirmed room temperature ferromagnetism in all the compositions and highest value of saturation magnetization has been observed for Fe-doped nanoparticles.

Selective and efficient adsorption of anionic dyes by core/shell magnetic MWCNTs nano-hybrid constructed through facial polydopamine tailored graft polymerization: Insight of adsorption mechanism, kinetic, isotherm and thermodynamic study

It is a big challenge to design advanced adsorbents that have high adsorption capacity and excellent selectivity to efficiently remove organic dyes from complex environmental systems. Herein, by utilizing the adhesion property of polydopamine (PDA) and its crosslinking reaction with polyethyleneimine (PEI), a novel core/shell magnetic MWCNTs/Fe3O4@(PDA + PEI) nano-hybrid that carries superior adsorption performance of dyes was constructed through facile polydopamine tailored graft polymerization. In such hierarchical structure, the inner shell of Fe3O4 nanoparticles and outer shell of (PDA + PEI) contributed to the abundant active adsorption sites, large specific surface area (126 m2/g) and high saturation magnetization value (10.91 emu/g). As a result, the prepared adsorbent exhibited highly selective adsorption performance toward multiple anionic dyes, including MB, CR, and MO with maximum adsorption capacity of 1449, 1006, and 935 mg/g at 298.15 K, respectively. It was found that the main adsorption mechanism was attributed to the hydrogen bonding and electrostatic interaction. The kinetics data fitted well with the pseudo-second-order model, and both the Langmuir and Freundlich isotherm models presented well fit to the isotherm data. The investigation of thermodynamic study indicated that the adsorption of anionic dyes onto core/shell magnetic MWCNTs/Fe3O4@(PDA + PEI) nano-hybrid was spontaneous and endothermic. More importantly, the adsorbent presented excellent regeneration property after multiple adsorption-desorption cycles and prominent stability in harsh environments, especially in the alkaline condition. Therefore, these results revealed the promising applications of hierarchical MWCNTs/Fe3O4@(PDA + PEI) nano-hybrid in water remediation.

Investigations of TM (Ni, Co) doping on structural, optical and magnetic properties of CeO2 nanoparticles

The undoped and Ce0.95TM0.05O2 (TM: Ni, Co) nanoparticles (NPs), synthesized by co-precipitation method, have been investigated. The structural, morphological, and magnetic properties of the synthesized NPs were characterized through X-ray diffraction (XRD), Transmission electron microscopy (TEM), UV–vis absorption spectroscopy, and dc-magnetization. The particle size as obtained through XRD analysis was found in the range of 7.0–13.0 nm. The Rietveld refinement of the XRD pattern confirms the single-phase nature of NPs. The lattice parameters determined using the Rietveld refinement process was found to have minimum value (5.407 Å) for Co doping as compared to pure CeO2. The value of strain is maximum for Co-doped CeO2. The particle sizes obtained by TEM show dissimilarity with the XRD outcomes. However, the defects obtained using dislocation density is larger (2.0 × 10−2) in Co-doped CeO2 NPs. The lowest value of the bandgap has been observed (~1.6 eV) for Co-doped CeO2 NPs. The highest value of saturation magnetization was found to be 8.1 × 10−3 emu/g for Co-doped CeO2 NPs with a small coercivity of 61.5 Oe. The magnetization measurements infer that the pure and TM doped CeO2 nanoparticles show weak ferromagnetic behavior at room temperature.

Utilization of tea resources with the production of superparamagnetic biogenic iron oxide nanoparticles and an assessment of their antioxidant activities

An eco-friendly, low toxic and facile synthetic approach was employed to produce superparamagnetic biogenic iron oxide nanoparticles (SPBIONs) using an aqueous extract of tea-pruning waste as a reducing agent under alkaline conditions. As-biosynthesized SPBIONs were extensively characterized by various analytical tools. For instance, XRD pattern showed crystallinity and FTIR spectra revealed the presence of bioactive molecules required for the reduction of iron oxide ions. AFM and FESEM-EDX images showed agglomerated spherical shape with strong signals of iron metallic ions. The average crystallite sizes of SPBIONs were found to be 20–35 nm by HRTEM analysis. Zeta potential analysis confirmed that the surface charge of the green synthesized SPBIONs was highly negative (−25.2 mV) and stable. TGA curve reported a weight loss of 14%, which occurred in SPBIONs over temperatures ranging from 50 °C to 950 °C due to the removal of water molecules and volatile compounds. VSM analysis revealed that SPBIONs exhibited superparamagnetic properties with a high-saturation magnetization value of 11 emu/g. In addition, the antioxidant property of SPBIONs was investigated with 1,1-Diphenyl-2-picrylhydrazyl (DPPH), a free radical assay, and it was seen that 70 μg/mL (IC50) of SPBIONs was able to neutralize the generation of free radicals and oxidative stress. The present study successfully demonstrated that utilization of tea resources for the production of SPBIONs with superparamagnetic and antioxidant properties might be used to design antioxidant agents and other biomedical applications.

Structural, morphological and magnetic properties investigation of magnetically separable mesoporous carbon

This paper reports on the preparation of nanocomposites containing mesoporous carbon with different molar ratios of Ni or CoFe2O4 nanoparticles as magnetically separable absorbents by facile, reproducible and economical processes including self-assembly soft template hydrothermal route and Pechini-type sol-gel techniques. Accordingly, structural, morphological and magnetic properties of the samples were studied using XRD, FT-IR, FE-SEM, HR-TEM, N2 adsorption-desorption and VSM methods. Based on the VSM results, two different types of magnetic behavior were observed. Composites containing nickel had typical S-shaped hysteresis curves with a very low coercivity (Hc ≈ 84, 97 Oe) and retentivity (Mr ≈ 1.1, 2.4 emu/g), as compared to their relatively high saturation magnetization value (Ms ≈ 3.9, 8.6 emu/g), while the other samples were ferromagnetic. The M − H curves have also revealed that saturation and remnant magnetization, as well as coercivity, were increased by enhancing the magnetic phase content in all nanocomposites. Also, the MC-Ni/CFO nanocomposites performance as the magnetically separable adsorbents for vitamin B12 adsorption was evaluated. The MC-5CFO adsorbent illustrated higher adsorption capacity (325.66 mg/g) than MC-2Ni (139.25 mg/g) in 250 ppm due to the higher BET surface area (589 m2/g) and pore volume (0.71 cm3/g).