Mn Ferrites Research Articles

Structural, Magnetic, and AC Measurements of Nanoferrites/Graphene Composites.

As a contribution to the graphene-based nanoferrite composites, this article is intended to present Mn, Co, and Co-Mn nanoferrites for the preparation and investigation of such samples. Nanoparticles of Co ferrite, Mn ferrite, and Co-Mn ferrite were chemically synthesized by the coprecipitation method. The composites of ferrite/graphene were made by incorporating weight ratios of 25% graphene to 75% ferrite. Various structural and characterizing investigations of ferrite samples and ferrite/graphene composites were performed, including XRD, EDX, SEM, VSM hysteresis loops, AC conductivity, and dielectric behavior. The investigations ensured the formation of the intended nanoferrite powders, each having a single-phase crystal structure with no undesired phases or elements. All samples exhibit a soft magnetic behavior. They show a semiconducting behavior of AC electrical conductivity as well. This was proved by the temperature dependence of the AC’s electrical conductivity. Whereas the dielectric function and loss tangent show an expected, well-explained behavior, the ferrite/graphene composite samples have lower saturation magnetization values, lower AC conductivity, and dielectric constant values than the pure ferrites but still have the same behavior trends as those of the pure ferrites. The values obtained may represent steps on developing new materials for expected applications, such as manufacturing supercapacitors and/or improved battery electrodes.

Physicochemical Aspects of Oxidative Consolidation Behavior of Manganese Ore Powders with Various Mn/Fe Mass Ratios for Pellet Preparation.

With the depletion of rich manganese ore resources, plentiful manganese ore powders with various Mn/Fe mass ratios are produced. The physicochemical aspects of oxidative consolidation behavior of manganese ores with various Mn/Fe mass ratios were investigated in this work to determine whether manganese ore powders with high iron content (Fe-Mn ore) can be prepared as high-quality pellets. Physicochemical properties of the pellets were investigated, including cold compression strength (CCS), phase transformation, microstructural evolution, Vickers hardness (HV), porosity, and lattice parameter. CCS testing indicated that the strength of roasted Fe-Mn ore pellets was observably lower than that of pure hematite or manganese ore pellets. Phase and morphology results showed that in Fe-Mn ore pellets, an Mn ferrite phase was generated between hematite and pyrolusite particles. However, newborn Mn ferrites and hematite had an obvious crystal boundary in the crystallographic particles. Moreover, poorly crystallized Mn ferrite particles were evident, along with Mn and Fe element concentration gradients, due to the inadequate diffusion of metal ions. This resulted in poor mechanical properties of the Fe-Mn ore pellets. A temperature over 1275 °C and a roasting time of 15 min is required for the oxidative consolidation of Fe-Mn ores. In such optimized cases, Mn, Fe, O, and Al elements were uniformly distributed in the well-crystallized Mn ferrite grains, which provided favorable mineralogy for the consolidation of Fe-Mn ore powders.

Preparations and characterizations of Ca doped Ni–Mg–Mn nanocrystalline ferrites for switching field high-frequency applications

Ca-doped Ni–Mg–Mn spinel ferrites with compositions of Ni0·5Mg0·3Mn0.2CaxFe2-xO4 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) were prepared via sol-gel auto-ignition technique. TGA/DTA, FTIR, XRD, FESEM, and VSM were employed to evaluate the thermal, spectral, structural, morphological, and magnetic features of Ca-doped Ni–Mg–Mn spinel ferrites. TGA/DTA curves show the weight loss in the sample. This weight loss was attributed to the oxidation and decomposition of the sample contents at a temperature of 500 °C. XRD reveals a single-phase structure of the Ni–Mg–Mn nano ferrites. A single-phase orthorhombic structure was confirmed for Ca-doped Ni–Mg–Mn ferrites. Structural parameters such as lattice parameter, ‘da’, ‘db’, ‘dc’, and ‘dv’ were evaluated using unit cell software. The absorption peaks at 427 to 538 cm−1 confirmed the spinel structure, which was evaluated using FTIR. FESEM analyses showed that the agglomerations increased with the doping of Ca in Ni–Mg–Mn ferrites. Remanence, Y–K angles, saturation, coercive force, magnetic squareness, magnetic moment, and anisotropy constant were determined for Ca-doped Ni–Mg–Mn spinel ferrite samples. It is noticed that saturation increases from 29.157 to 51.322 emu/g, whereas remanence increased from 5.34 to 9.40 emu/g, respectively. The permeability, anisotropy constant, and magnetic moments were also found to increase with Ca doping. However, the Y–K angles increased with Ca concentration in Ni–Mg–Mn nano ferrites. In addition, the switching field distribution (SFD) and high-frequency response of all the Ca-doped Ni–Mg–Mn samples were also evaluated. Ca-doped Ni–Mg–Mn samples are suggested to be suitable for switching, filters, inductors, and microwave absorption applications because of the superparamagnetic nature of the prepared spinel ferrites.

Effect of Dy3+ substitution on microwave behaviour of nanocrystalline Mn-Zn Ferrite

Microwave-hydrothermal (M-H) method had been employed to synthesize a series of Dy3+doped Mn-Zn ferrite Mn0.6Zn0.4Fe2–xDyxO4 (x=0, 0.01, 0.03, 0.05, 0.07, 0.09) nanopowders at 160°C/30 min. The prepared samples have been characterized by Fourier Transform Infrared Spectrometer. The grain size of sintered ferrites are in the range of 60-70 nm. Decrease in saturation magnetization and increase in coercivity were observed with an increase of Dy3+ concentration in Mn-Zn ferrites. The complex permeability and complex permittivity of the prepared samples were measured in the frequency range of 2–18 GHz using a using a vector network analyzer. It is observed that small variation of Dy3+ substitution in spinel ferrite tailored microwave absorbing parameters dramatically. The reflection loss (RL) increased with the Dy3+ content upto x ≤ 0.03. The sample with x=0.03 of thickness 2.3 mm showed minimum reflection loss of -20.5 dB with a bandwidth of 3.8 GHz. Thus the present materials exhibit good microwave absorption properties and hence can act as EMI suppressors. Copyright © 2018 VBRI Press.

TUNING OF CRYSTALLITE SIZE, ENERGY GAP, AND MAGNETIC PROPERTY OF Mn-DOPED CoFe2O4 NANOPARTICLES

This paper focuses on the synthesis and structural, optical, and magnetic characterization of Mn-doped CoFe2O4 nanoparticles synthesized by a simple chemical co-precipitation method. Synthesized magnetic nanoparticles were characterized by XRD, FTIR, UV-Vis, PL, TEM, VSM, and EPR spectroscopy. XRD analysis confirmed the significant reduction in the crystallite size from [Formula: see text][Formula: see text]nm to 10[Formula: see text]nm as the Mn content is increased from 0 to 1. UV-Vis spectra confirmed that the Co–Mn ferrite is a direct bandgap magnetic material that possesses an energy gap from 3.92[Formula: see text]eV to 4.33[Formula: see text]eV. FTIR vibrational frequency observed between 468 and 548 [Formula: see text]confirmed the existence of metal–oxygen bond at tetrahedral and octahedral sites. Photoluminescence spectra confirmed the red emission of the samples from the peak at 680[Formula: see text]nm. TEM analysis suggests that the single domain of CoFe2O4 nanoparticles may vary between 38 and 72[Formula: see text]nm. Composition analysis confirmed the homogeneous mixing of Co, Mn Fe, and O atoms in the synthesized samples. The VSM study confirmed that Mn substitution favors transition from ferromagnetic to superparamagnetic. VSM analysis also confirmed the lessening in saturation magnetization and coercivity on Mn doping. The X-band electron paramagnetic resonance spectrum recorded at room temperature conveys that the superexchange interaction is increased with the increase in Mn concentration.

An alternative and clean utilisation of refractory high-phosphorus oolitic hematite: P for crop fertiliser and Fe for ferrite ceramic

High-P oolitic hematite is recognised as one of the most refractory mineral resources because of the special oolitic structure. Conventional selective reduction roasting is characterised by high energy consumption and large greenhouse gas emissions. In this study, a clean utilisation of refractory high-P oolitic hematite via phase reconstruction was proposed to make the P for crop fertiliser and Fe for ferrite ceramic. Phase reconstruction indicated that the oolitic and finely disseminated structure was dramatically changed by the oxidisation roasting with Mn ore at 1100°C–1250 °C. After reconstruction, 85 wt%–90 wt% Fe and Mn were concentrated in the magnetic ferrite phase whilst 90 wt%–100 wt% P, K, Ca, Si, Mg, and Al impurities were enriched in the nonmagnetic P-bearing tailings. After separation, the separated Mn ferrite and P-bearing tailings after activation could be used as ingredients in ceramic and fertiliser production. The as-purified ferrite showed good electromagnetism performance whilst almost all nutrients in the P-bearing tailings were activated via high-temperature melting and water quenching and can thus be readily absorbed by the crop roots. Moreover, the phase reconstruction mechanism and feasible granular fertiliser preparation from P-bearing tailings were discussed. All elements in the high-P oolitic hematite were utilised without emission of greenhouse gases.

Low-cost nanoparticulate oxidation catalysts for the removal of azo and anthraquinic dyes.

This study aimed to test the activity of Mn ferrite, hematin-Mn ferrite and colloidal maghemite in decomposition of Orange II (O-II) and Alizarin Red S (ARS) in model aqueous solutions. Color removal was explored at room temperature using magnetic stirring with and without a magnetic bar, taking advantage of the solids' magnetism. Decomposition of H2O2 was also studied separately and as radicals provider in dye decomposition. Catalyst/dye solution was fixed at 10mg/4mL. pH and dye concentration were variable. Absorbance was measured during 120min by UV-Vis. Reuse of catalysts was also performed. Azo dyes such as O-II are more resistant to oxidative removal using hydrogen peroxide than anthraquinone-like ARS. CITMD5 reduced ARS absorbance up to 71.9% when dye was less than 250mg/L. HEM-Mn-MAG completely decolorized a 62.5mg/L O-II solution at pH11 while CITMD5 reached half of that conversion under the same conditions. The highest color removal in O-II/ARS mixtures was obtained with HEM-Mn-MAG, 40% absorbance reduction in 2h. Mn-MAG is not active to remove O-II in presence of hydrogen peroxide in the 3-9 pH range at rt. The high activity of Mn-MAG in hydrogen peroxide decomposition may be assigned to the combination of Mn+2/Mn+3 and Fe+2/Fe+3, because the MnOx is active in the decomposition of hydrogen peroxide. Mn-MAG can be reused, preserving high activity in this reaction. Mn-based magnetic nanoparticles should be considered as inexpensive materials to treat textile wastewaters. The online version contains supplementary material available at 10.1007/s40201-021-00640-x.

Influence of Ho3+ substitution on structural and magnetic properties of Mg–Mn ferrites

Influence of Ho3+ substitution on structural and magnetic properties of Mg–Mn ferrites

Insights on the Heating Characteristics of Mn and Co Ferrites

The heating characteristics of ferrite nanoparticles are inconsistent due to various factors that affect the optimum particle size required for maximum power dissipation. The heating mechanism of Fe3O4, MnFe2O4, and Co0.5Fe2.5O4 in the size range 10–40 nm with varying particle size distribution is correlated with the effective specific absorption rate (ESAR). The effective magnetic anisotropy of the ferrite samples determined using electron spin resonance is between 11.8 and 24.8 kJ· m−3. The thermal profiles of Fe3O4, MnFe2O4, and Co0.5Fe2.5O4 are probed employing infrared thermography where the measured ESAR is between 1.74 and 3.16 nHm2·kg−1. The theoretical ESAR of 16.63 and 9.19 nHm2·kg−1 are obtained for the Co substituted Fe3O4 and MnFe2O4, respectively, for an average size of 40 nm. The analysis of particle size distributions in combination with theoretical estimations gives the percentage of particles contributing to the power dissipation as 80 % for narrow dispersion and 45 % for broad dispersion deviating from the predicted optimum size range. In addition to ascertaining the functioning regime of the linear response theory, an increase in ESAR with decreasing anisotropy energy is observed. The discrepancy between the simulations and experimentations is prudently examined, taking the intrinsic as well as extrinsic parameters into account.

Controlled Preparation of Different Proportions of Metal Fe-Mn from Waste Mn Ferrite by Molten Salt Electrolysis

A novel method for efficiently recovering Fe and Mn from waste Mn ferrite by molten salt electrolysis is firstly proposed. The electrolysis of molten salt (MnCl2 (1.06 wt%)-FeCl3 (2.69 wt%)-NaCl-KCl) was performed at 800 °C. The phase of product at 2.0 V was metal Fe while metal Fe and Mn were obtained by molten salt electrolysis at 2.3 V. The Fe/Mn mass ratio of electrodeposited products at 2.0 V and 2.3 V were 687 and 3.2, respectively. The different proportions of metal Fe-Mn were prepared by controlling the electrolytic voltages. This new method can realize direct transformation of waste Mn ferrite to Fe-Mn alloy.

Influence of the heat treatment conditions on the properties of gallium-strontium-substituted manganese ferrites designed for magnetic hyperthermia applications

Magnetic nanoparticles (MNPs) with cores made of mixed ferrites may find application in the field of magnetic hyperthermia, this due to their intrinsic characteristics such as nanometric sizes, biocompatibility and the capability of transforming mechanical energy into heat under the action of an external magnetic field. In this study, the synthesis of Mn, Ga and Sr-containing ferrites (Mn0.5Ga0.5-xSrxFe2O4, x = 0.05 and 0.1) via sol-gel was carried out evaluating the effect of the heat treatment conditions on the physicochemical properties. The obtained materials were characterized by X-ray diffraction (XRD), vibrating sample magnetometry (VSM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). Additionally, the heating ability of the obtained nanoparticles was evaluated by magnetic induction and an in vitro hemolysis assay was also performed. Within the tested heat treatment conditions (150–600 °C and 30–120 min) it was possible to obtain nanosized magnetic ferrites with a single crystalline phase, corresponding to the cubic inverse spinel structure, and with a behavior close to the superparamagnetic regime. Moreover, selected materials showed heating ability under the application of a magnetic field and were non-hemolytic in contact with human blood red cells, making them suitable for their use as heating agents for the magnetic hyperthermia treatment.

Influence of Mn dopant on the crystallite size, optical and magnetic behaviour of CoFe2O4 magnetic nanoparticles

Cubic spinel structured Co1-xMnxFe2O4 (x = 0, 0.25, 0.5, 0.75 & 1.0) nanoparticles were successfully synthesized by the chemical precipitation method. Increase in Mn content shows a significant reduction on the crystallite size from 16.7 to 10.19 nm. FTIR vibrational bonds between 464 and 585 cm−1 confirm the interaction of metal-oxygen at tetrahedral and octahedral sites, a de-notified vibrations stretch. UV–visible diffuse reflectance spectrum indicates that Co–Mn ferrite is a direct bandgap material with bandgap ranges from 3.84 to 4.02 eV. The red-emission of the samples was confirmed form the peak at 680 nm. Formation of single domain cobalt ferrite nanoparticles of size ~38–72 nm was confirmed by TEM which exhibited morphological transition from nanobar to nanoparticles. Inductively coupled plasma emission - optical emission spectrometer result confirmed the homogeneous mixing of Co, Mn, Fe, and O atoms. The vibrating sample magnetometer study confirmed that Mn concentration favours the magnetic transition from ferromagnetism to superparamagnetism. Saturation magnetization gets reduced from 34.20 to 0.5 emu/g and the and coercivity gets reduced from 0.1112 to 0.0328 T. The X-band electron paramagnetic resonance spectrum recorded at room temperature imparts the increase of superexchange interaction with the increase in manganese concentration.

Preparations and tailoring of structural, magnetic properties of rare earths (REs) doped nanoferrites for microwave high frequency applications

Rare earths (Res) doped Mn spinel nanoferrites with nominal composition MnR0.2Fe1·8O4 (REs = Tb, Pr, Ce, Y and Gd) were synthesized using sol gel method. FTIR, XRD and FESEM were employed to evaluate the structure, phase, vibrational bands, morphology, grain size and microstructure respectively. VSM was employed to investigate the magnetic features of the Mn nanoferrite and REs doped Mn nanoferrites. XRD confirmed the single-phase cubic structure of Mn nanoferrite whereas tetragonal phase was observed for all REs doped Mn nanoferrites. Unit cell software was used to determine the structural features such as lattice parameter, cell volume, ‘da’, ‘db’, ‘dc’ and ‘dv’ respectively. FTIR results demonstrated the absorption peaks of Mn and REs doped Mn ferrite at 647-674 cm−1. FESEM results depicted the irregular shapes of the particles with large agglomerations in the prepared samples. The grain size evaluated by LIM (line intercept method) found in the range of 94 to 213 nm respectively. Saturation magnetization was increased from 1.332 to 38.097 emu/g whereas remanence was increased from 1.096 to 25.379 emu/g respectively. In addition, other magnetic parameters such as initial permeability, magnetic anisotropy and magnetic moments were also increased. Moreover, Y–K angles showed significant response with REs doping in Mn ferrites. Furthermore, high frequency response and switching field distribution (SFD) of Mn ferrite and REs doped Mn ferrites were also determined. It is found that Y doped Mn ferrite depicted better high frequency and SFD response as compared to Mn ferrite and REs doped Mn ferrites. The coercivity of all these pure Mn ferrite and rare earth's substituted Mn ferrites (425–246 Oe) was higher as compared to the pure Mn and yttrium substituted Mn ferrite (107–217 Oe. Therefore, it was suggested that Y doped Mn ferrite was more suitable candidate for switching, and high frequency absorption applications in microwave regime.

Synthesis, structural characterization, and magnetic properties of Ni–Zn nanoferrites substituted with different metal ions (Mn2+, Co2+, and Cu2+)

Three series of nanocrystalline Ni0.7-xZn0.3MxFe2O4 ferrites (M = Mn2+, Co2+, and Cu2+; x = 0.0, 0.1, 0.3, 0.5, and 0.7) have been synthesized using the citrate method. Several techniques have been used to investigate the influence of the different dopant ions and their doping levels on the structural and magnetic properties of the Ni–Zn ferrites. X-ray diffraction (XRD) analysis confirmed the creation of a single-phase spinel structure. The lattice parameter was found to increase with increasing Mn2+ and Co2+ ion concentrations, but was not altered by adding Cu2+. The density decreased with increasing concentrations of Mn2+ or Co2+, but increased with increasing Cu2+ content. The average particle size estimated from transmission electron microscopy (TEM) images was found to be in the range 21–41 nm, which revealed the manufacture of nanocrystalline ferrites. Two prominent fundamental absorption bands detected in IR spectra between 370 and 570 cm−1 can be ascribed to the intrinsic stretching vibrations of tetrahedral and octahedral complexes. The magnetic properties of the present spinel ferrites were measured by means of a vibrating sample magnetometer (VSM) at room temperature. The measurements showed that the saturation magnetization (Ms) for Ni–Zn–Mn ferrite increased from x = 0.0 to x = 0.3, but then decreased upon doping at x = 0.7, whereas a monotonic increase in saturation magnetization was observed for Ni–Zn–Co ferrite. For Ni–Zn–Cu ferrite, Ms decreased from 54.70 emu/g at x = 0.0–35.4 emu/g at x = 0.1 and then increased with further addition of Cu2+. The variation of Ms with different dopant concentrations can be explained on the basis of Néel's two-sublattice model. Among the investigated series, Ni0.7-xZn0.3CoxFe2O4 nanoferrites achieved high saturation magnetization and coercive field values, indicating that such compositions may find applications in the field of sensors.

Synthesis, morphological and electromagnetic evaluations of Ca doped Mn spinel nanoferrites for GHz regime applications

Calcium (Ca) doped manganese (Mn) spinel nanoferrites with the composition of Ca1−xMnxFe2O4 where x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 are synthesized by sol-gel self-ignition route. XRD, FESEM and FTIR are employed to investigate the cubic crystallite structure, phase, morphology, grain size and vibrational bands respectively. Functional bands and phase of the Ca-doped Mn nanoferrites were evaluated using FTIR. The values of the force constants were increased with Ca substitution in Mn ferrites. The systematic effects of Ca on the microstructure and morphology were also examined using FESEM. The electromagnetic analysis including complex permittivity, permeability, conductivity and loss tangent of the Ca doped Mn nanoferrites in the frequency ranges of 1 GHz–6 GHz are studied using VNA with coaxial probe. Conductivity varies by increasing the Ca substitution in Mn spinel ferrites. This may be due to the electron and polaron hopping between Fe3+ and Fe2+ ions. The quality factor shows highest values after 2.3 GHz frequency region for all the Ca doped nanoferrites. The reasonable conduction mechanism into the higher frequency region may be suited for Mn–Ca nanoparticles as a commercially industrial material for microwave high frequency GHz regime applications.

Degradation of acetamiprid using graphene-oxide-based metal (Mn and Ni) ferrites as Fenton-like photocatalysts.

This study aims to explore the photocatalytic potential of graphene-oxide-based metal ferrites for the degradation of acetamiprid (an odorless neonicotinoid pesticide). Metal (Mn and Ni) ferrites (along with their graphene oxide composites) were prepared by the hydrothermal method while graphene oxide (GO) was synthesized using a modified Hummer's method. The composites were characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The photocatalysts were studied for their Fenton-like advanced oxidation process to degrade acetamiprid. The composites showed excellent activity against acetamiprid degradation (>90%) in 60 min under UV irradiation. The detailed optimization study was carried out to investigate the influential variables (such as pH, catalyst dose, pollutant concentration, irradiation time, oxidant dose, etc.) to achieve enhanced degradation efficiency. Moreover, the findings were endorsed by central composite design (CCD). It was concluded that degradation was enhanced in an appropriate combination of photocatalyst and hydrogen peroxide. The magnetic character of the metal ferrites and their composites played an important role in the easy separation and reusability of these materials. The present findings result in highly effective, easy to handle and stable heterogeneous photo-Fenton materials for wastewater remediation.

Solution combustion synthesis, characterization, magnetic, and dielectric properties of CoFe2O4 and Co0.5M0.5Fe2O4 (M = Mn, Ni, and Zn).

Nanocrystalline CoFe2O4 and Co0.5M0.5Fe2O4 (M = Mn, Ni, and Zn) ferrites were prepared by the solution combustion method using oxalyl dihydrazide as a fuel. These materials were characterized by several physicochemical techniques. X-ray diffraction (XRD) patterns indicate the cubic spinel structure of these ferrites. Field emission scanning electron microscopy (FESEM) images demonstrate the microporous nature of the materials because of the large amount of gas production during their synthesis. High resolution transmission electron microscopy (HRTEM) images show lattice fringes corresponding to the {220} and {311} planes of the spinel structure. Fourier transform infrared (FTIR) spectra exhibit absorption bands around the 500-600 cm-1 wavenumber region which are related to metal-oxygen bonds with tetrahedral coordination. Symmetric and asymmetric stretching and symmetric bending modes associated with tetrahedral and octahedral cations present in the spinel structures have been assessed by Raman spectroscopy. X-ray photoelectron spectroscopy (XPS) studies demonstrate the presence of Co2+, Mn2+, Ni2+, Zn2+, and Fe3+ in tetrahedral and octahedral coordinations in these ferrites. Co0.5Zn0.5Fe2O4 is observed to show the highest saturation magnetization among all these materials. The dielectric measurements reveal that the dielectric constant and loss values decrease with an increase in frequency and the ac conductivity increases at higher frequencies due to mobilization of the charge carriers.

Examining alloying effect on K X ray intensity ratios and chemical shifts of the Zn, Mn and mixed spinel ferrites

K X-ray emission spectra of Zn, Mn and mixed (Zn-Mn, Zn- Co, Zn-Ni) spinel ferrites have been acquired by inducing 59.54 keV and 22.1 keV γ-rays emitted from 3 Ci 241Am annular source and 40 mCi 109Cd point source with a HPGe detector. Some vital parameters for XRF, Kβ/Kα X-ray intensity ratios, the full width at half maximum (FWHM) values, asymmetry index (As), peak energies and chemical shifts (ΔE), were defined depending on the alloying effect by working on the spectra. The obtained results exhibited that, compared to the pure states of the metals, chemical shifts aroused due to different crystal structure, valence electron structure, bond type and length in the spectrum of the alloy form. The difference of the electronegativity of the metals forming the ferrite obviously explained the change in the Kβ/Kα X-ray intensity ratios. It has been concluded that the charge transfer mechanism predominates mainly and altered the intensity ratios of the metal by affecting the rearrangement of the 3d electrons in the valence band.

Hyperthermia, Cytotoxicity, and Cellular Uptake Properties of Manganese and Zinc Ferrite Magnetic Nanoparticles Synthesized by a Polyol-Mediated Process.

Manganese and zinc ferrite magnetic nanoparticles (MNPs) were successfully synthesized using the polyol method in ethylene glycol and were found to have high saturation magnetization values (90–95 emu/g at 4 K) when formed by ~30-nm crystallites assembled in an ~80-nm multicore structure. Hyperthermia data revealed a sigmoidal dependence of the specific absorption rate (SAR) on the alternating magnetic field (AMF) amplitude, with remarkable saturation SAR values in water of ~1200 W/gFe+Mn and ~800 W/gFe+Zn for the Mn and Zn ferrites, respectively. The immobilization of the MNPs in a solid matrix reduced the maximum SAR values by ~300 W/gFe+Mn, Zn for both ferrites. The alignment of the MNPs in a uniform static magnetic field, before their immobilization in a solid matrix, significantly increased their heating performance. Toxicity assays performed in four cell lines revealed a lower toxicity for the Mn ferrites, while in the case of the Zn ferrites, only ~50% of cells were viable upon their incubation for 24 h with 0.2 mg/mL of MNPs. Cellular uptake experiments revealed that both MNPs entered the cells in a time-dependent manner, as they were found initially in endosomes and later in the cytosol. All of the studied cell lines were more sensitive to the ZnFe2O4 MNPs.

Synthesis and characterization of oleic acid coated Fe–Mn ferrite based ferrofluid

Mn substituted Fe3O4 ferrite based ferrofluids were synthesized successfully and their structural and magnetic characteristics investigated. The two step method of synthesis was adopted wherein as the first step Mn substituted Fe3O4 ferrite nanoparticles having the chemical formula Fe1-xMnxFe2O4, where x = 0.0 to 0.5 in steps of 0.1 were synthesized by chemical co-precipitation method. The ferrite nanoparticles were characterized for their structural information using X-ray diffraction (XRD) technique. XRD pattern confirmed the formation of single phase spinel structure and the nanocrystalline nature of the samples. These ferrite nanoparticles were then dispersed in kerosene using oleic acid as the surfactant. FTIR spectroscopy was used to confirm the presence of Fe–O bonds and other chemical substance adsorbed on the surface of the particles. Magnetic measurements of the synthesized hydrocarbon based ferrofluids was carried out using Vibrating Sample Magnetometer (VSM) and Electron Paramagnetic Resonance (EPR) spectroscopy at room temperature. Magnetic parameters such as saturation magnetization, coercivity and remanence were evaluated from the M-H curve and the superparamagnetic behavior characteristic of magnetic nanoparticles was confirmed, which has also been observed from the EPR spectra recorded at room temperature.