High Saturation Magnetization Value Research Articles

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.

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.

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.

A review paper: Synthesis techniques and advance application of Mn-Zn nano-ferrites

This review study is interesting to discussed about the synthesis techniques and the applications of the Manganese-Zinc (Mn-Zn) ferrites because to their large range of many new applications in great areas or in our daily life. Mn-Zn ferrites are generalized as a smooth magnetic material which have a good-properties in the electrical, optical, magnetic and chemical. Its main properties including with the high value of permeability, resistivity, permittivity, low coercivity and saturation magnetization. This paper examines techniques (synthesis) and applications of the M Fe2O4 (M = Copper, Nickle, Zinc, Manganese) nanosized particles including their advantages. Its maximum level of (coercivity, anisotropy, Curie temperature), moderate saturation magnetization, high resistivity, minimum eddy current losses, significant mechanical hardness, and chemical stability and high-quality redox chemistry which make nano-sized ferrites suitable for potential uses into fields of magnetic and non-conductive materials, light absorption, and hydrolysis. The cation dispersion in the Mn-Zn ferrites also affected in the form which is morphological, electrical and magnetic properties. It alters as cation concentrations and sintering circumstances changes in wide range of applications. As above the methods that is sol–gel method, hydrothermal process, combustion method, biosynthesis methods, solvothermal methods, microwave assists combustion methods, co-precipitation methods are present there with the advantages and disadvantages are given in Table 2. The above-mentioned Mn-Zn ferrites which are also used in the various applications in Fig. 2. These ferrites are used in the electrical and electronical applications, magnetic appliances, biomedical applications, telecommunication and many others. It finds that, it is widely used in our daily life (almost in household appliances) such as television, refrigerator, laptop, desktop, LED bulb, juicer mixer, washing machine, printer, microwave ovens, mobiles, mobile chargers and many other appliances. This review paper mainly focused to discussed on the various synthesis methods and application which we are used in our daily life.

Core-Shell Fe3O4@C Nanoparticles for the Organic Dye Adsorption and Targeted Magneto-Mechanical Destruction of Ehrlich Ascites Carcinoma Cells.

The morphology, structure, and magnetic properties of Fe3O4 and Fe3O4@C nanoparticles, as well their effectiveness for organic dye adsorption and targeted destruction of carcinoma cells, were studied. The nanoparticles exhibited a high magnetic saturation value (79.4 and 63.8 emu/g, correspondingly) to facilitate magnetic separation. It has been shown that surface properties play a key role in the adsorption process. Both types of organic dyes-cationic (Rhodomine C) and anionic (Congo Red and Eosine)-were well adsorbed by the Fe3O4 nanoparticles' surface, and the adsorption process was described by the polymolecular adsorption model with a maximum adsorption capacity of 58, 22, and 14 mg/g for Congo Red, Eosine, and Rhodomine C, correspondingly. In this case, the kinetic data were described well by the pseudo-first-order model. Carbon-coated particles selectively adsorbed only cationic dyes, and the adsorption process for Methylene Blue was described by the Freundlich model, with a maximum adsorption capacity of 14 mg/g. For the case of Rhodomine C, the adsorption isotherm has a polymolecular character with a maximum adsorption capacity of 34 mg/g. To realize the targeted destruction of the carcinoma cells, the Fe3O4@C nanoparticles were functionalized with aptamers, and an experiment on the Ehrlich ascetic carcinoma cells' destruction was carried out successively using a low-frequency alternating magnetic field. The number of cells destroyed as a result of their interaction with Fe3O4@C nanoparticles in an alternating magnetic field was 27%, compared with the number of naturally dead control cells of 6%.

Facile synthesis of layered superparamagnetic Fe3O4-MoS2 nanosheets on chitosan for efficient removal of chromium and ciprofloxacin from aqueous solutions

The discharge of toxic metal ions and pharmaceutical pollutants has become a global issue. This work evaluated the efficiency of the hydrothermally synthesized superparamagnetic Fe3O4-MoS2 nanosheets and its fabrication with chitosan (Fe3O4-MoS2@CS) to remove Cr(VI) and ciprofloxacin (CIP) from simulated wastewater. These nanohybrid materials are characterized by SEM-Mapping, Raman, TEM, XRD, XPS, zeta potential, FTIR, and BET analyses. The affinity and selectivity of Fe3O4-MoS2@CS nanomaterial towards a mixture of Cr(VI), As(II), Pb(II), and Cd(II) metal ions from synthetic solution is studied through ICP-MS at trace levels. The distribution coefficient (Kd) for Cr(VI) (1.2 × 104 mL/g) is higher than the other metal ions, which reveals high selectivity of Fe3O4-MoS2@CS. The Fe3O4-MoS2@CS has also displayed enhanced removal efficiency for ciprofloxacin (emerging contaminant) from synthetic solutions. The Fe3O4-MoS2 and Fe3O4-MoS2@CS nanomaterials possess high saturation magnetization values of 68.00 emu/g and 59 emu/g, respectively. The adsorption process of Cr(VI) highly depends upon the solution pH, and the adsorption isotherm is followed by the Langmuir isotherm model. The kinetics of sorption is followed well by the pseudo-second-order model. The adsorption mechanism is assumed due to functional group complexation, and electrostatic interactions. Fe3O4-MoS2@CS has displayed maximum sorption capacity for Cr(VI) (175.4 mg g−1) and CIP (190.7 mg g−1) respectively. Fe3O4-MoS2@CS has been used in practical applications to remove Cr(VI) (97 %) and CIP (62 %) from real simulated wastewater. The enhanced adsorption efficiency and excellent magnetic recyclability of Fe3O4-MoS2@CS nanohybrid material make it a promising sustainable adsorbent for clean production and wastewater treatment.

Oxygen vacancies induced ferromagnetism in RF-sputtered and hydrothermally annealed zinc ferrite (ZnFe2O4) thin films

We report the inception of substantial magnetization of 4107 G in rf-sputtered and annealed hydrothermally at 180 °C zinc ferrite (ZFO) thin films. The value of electron-phonon coupling strength (λ) calculated using Raman A1g and F32g modes contended the shift of inverse spinel structure of the as-prepared thin films to the normal spinel structure with the enhancement in annealing duration. The shift in spinel structure was further affirmed by X-ray photoelectron spectroscopy (XPS) where inversion parameter, i.e., a fraction of the Zn2+ ions occupied by octahedral sites reduced from 0.18 of as-deposited film to 0.13 of air annealed and 0.14 for hydrothermally annealed films. Additionally, the ZFO thin film annealed hydrothermally for 4 h showed lower value of λ of 0.11 for A1g Raman mode and a high value of the ratio of surface hydroxyl (OH− groups) oxygen ions (Oii) to the lattice oxide (Fe/Zn–O) oxygen ions (Oi) in XPS spectra confirmed the presence of enormous oxygen vacancies. The magnetization analysis suggested that the presence of high oxygen vacancies in 4 h of hydrothermally annealed sample promotes the direct ferromagnetic interaction in Fe3+ ions in octahedral sites leading to a high value of saturation magnetization unlike the air annealed samples.

Enhanced magnetic and ferroelectric properties of K–Hf substituted BiFeO3 multiferroics for magnetoelectric data storage applications

Enhanced magnetic and ferroelectric properties have been observed in Hf substituted Bi0.97K0.9Fe1− x Hf(3/4) x O3 (0.00 ≤ x ≤ 0.20) nanocrystalline multiferroics which were synthesized via auto combustion sol–gel method. Citric acid was used as a solvent. Structural investigation confirmed the development of pure perovskite rhombohedral distorted phase. The enlargement in cell volume was observed with K–Hf substitution due to lattice distortion and the ionic radii of substituents. Ferroelectric loops showed that maximum polarization (P max) was inclined from 0.000376 to 0.391 µc/cm2 as well as remanent polarization (Pr) from 1.000815 to 5.39 µc/cm2. This was due to Hf–K contents which altered Fe–O bond length and increase disturbance in FeO6 octahedra which increase polarization. High values of saturation magnetization (Ms = 4.79 emu/g) and remanent magnetization (Mr = 1.7 emu/g) was attributed to disturbance in antiferromagnetic spin modulated cycloid (λ = 62 nm) structure. Enhancements of magnetic properties along with the formation of P-E loops make these multiferroic nanomaterials the best candidates for magnetoelectric RAMS.

Adsorptive removal of tetracycline from aqueous solutions using magnetic Fe2O3 / activated carbon prepared from Cynometra ramiflora fruit waste

Herein, the sustainable fabrication of magnetic iron oxide nanoadsorbent prepared with activated carbon of inedible Cynometra ramiflora fruit has been investigated. Activated carbon was obtained from phosphoric acid-treated C. ramiflora fruit, which was then utilized for the synthesis of magnetic nanocomposite (CRAC@Fe2O3). The formed nanocomposite was a porous irregular dense matrix of amorphous evenly sized spherical nanoparticles, as visualized by FESEM, and also contained carbon, oxygen, iron, and phosphorous in its elemental composition. FT-IR spectrum depicted characteristic bands attributing to Fe–O, C–OH, C–N, CC, and –OH bonds. VSM and XRD results proved that CRAC@Fe2O3 was superparamagnetic with a moderate degree of crystallinity and high saturation magnetization value (1.66 emu/g). Superior surface area, pore size, and pore volume of 766.75 m2/g, 2.11 nm, and 0.4050 cm3/g respectively were measured on BET analysis of CRAC@Fe2O3 nanocomposite, indicating their suitability for use as an adsorbent. On application of this nanocomposite for adsorption of tetracycline, maximum removal of 95.78% of 50 ppm TC at pH 4, CRAC@Fe2O3 0.4 g/L in 240 min. The adsorption of TC by CRAC@Fe2O3 was confirmed as monolayer sorption by ionic interaction (R2 = 0.9999) as it followed pseudo-second-order kinetics and Langmuir isotherm (R2 = 0.9801). CRAC@Fe2O3 showed a maximum adsorption capacity of 312.5 mg/g towards TC antibiotics indicating its potential for the treatment of antibiotic-contaminated samples. Since negative ΔGo and positive ΔHo and ΔSo values were obtained at all tested temperatures during the thermodynamic studies, the adsorption was confirmed to be endothermic, spontaneous, and feasible with an enhanced degree of randomness.

Simple Co-precipitation synthesis and characterization of magnetic spinel NiFe2O4 nanoparticles

Nickel ferrite nanoparticles were synthesized using Iron (III) nitrate and nickel nitrate as the starting materials along with the hydrazine hydrate via co-precipitation process and the final product obtained calcined at 700 °C. The structural and optical properties of the synthesised product were determined using various characterization techniques viz. UV–visible spectrometry, X-ray diffractometer (XRD), transmission electron microscopy (TEM), Field Emission Scanning Electron Microscopy (FE-SEM) and vibrating sample magnetometer (VSM). The NiFe2O4 nanoparticles showed absorption at ∼ 356 nm corresponds to band gap of 4.1 eV. The elemental analysis was carried out using X – ray Fluorescence (XRF) and Energy Dispersive Spectroscopy (EDS). The synthesized NiFe2O4 were 10–15 nm in size, and exhibited high saturation magnetization value of 72.66 emu/g.