Vibrating Sample Magnetometery Research Articles

Novel silica coated trimetallic ferrite functionalized with amino acid-based protic ionic liquid (Mn0.5Fe0.25Ca0.25Fe2O4-SiO2@[L-Tyr][HSO4]): A versatile bio-nanostructure to catalyze green synthesis of poly-substituted hydroquinolines and pyrido[2,3-d]pyrimidine-triones

In this research a magnetized inorganic-bioorganic nanocomposite prepared through coating the Mn0.5Fe0.25Ca0.25Fe2O4 core by silica layer, and consequent functionalization by the L-tyrosinium hydrogen sulfate ionic liquid. The structure of the hybrid nanocomposite (Mn0.5Fe0.25Ca0.25Fe2O4-SiO2@[L-Tyr][HSO4]) studied by density functional theory (DFT) calculations which contains L-Tyr protonation step and the chemisorption of L-Tyr cation on silica layer. The novel synthesized bio-nanocomposite (Mn0.5Fe0.25Ca0.25Fe2O4-SiO2@[L-Tyr][HSO4]) characterized by Fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDAX), vibrating-sample magnetometery (VSM), thermogravimetric (TGA/DSC), X-ray powder diffractometery (XRD), X-ray fluorescence (XRF), and transmission electron microscopy (TEM) analysis. The hybrid bio-nanocomposite applied for solvent-free diastereoselective synthesis of dispiro[tetrahydroquinoline-bis(2,2-dimethyl[1,3]dioxane-4,6-dione)] derivatives via one-pot pseudo eight-component reaction of meldrum’s acid, aromatic aldehydes, and arylamines at 50 °C. Also, the bio-nanocatalyst utilized for the aqua-mediated green synthesis of 5-aryl-5,6-dihydropyrido[2,3-d]pyrimidine-2,4,7(1H,3H,8H)-triones at 70 °C through the reaction of meldrum’s acid, aryl aldehydes, and 6-aminouracil. The recovery and reusability of the bio-nanohybrid also examined within 2 runs successfully.

Investigation of Crystallographic, Morphological, Magnetic and Electrochemical Properties of La‐Doped Cu‐CoFe2O4 Spinel Ferrites

AbstractThis research presents the successful synthesis of Cu0.79Co0.21LaxFe2‐xO4 (0.0 ≤ x ≤ 0.8) (spinel ferrite) nanoparticles via the sol‐gel auto combustion technique, with varying La3+ dopant concentrations. In this study, the estimated crystallite size (D) is found to be in the range of (27.92–40.90) nm. The microstructural parameter determination in XRD data is improved using Rietveld refinement. Fourier Transform Infrared Spectroscopy (FTIR) spectra exhibit two distinct metal stretching vibrational bands within (400–600) cm−1 range, a characteristic fingerprint region for all ferrites. Field Emission Scanning Electron Microscopy (FESEM) analysis reveals the agglomeration of particles due to magnetic interactions and non‐uniform distribution of average particle sizes ranging from (1.06–1.87) µm. Energy Dispersive X‐Ray Analysis (EDX) validates the chemical composition's accuracy. Owing to the dilution effect resulting from the introduction of non‐magnetic La3+ ions into the ferrite structure, there is a reduction in the saturation magnetization value, decreasing from 37.28 to 6.24 emu g−1 in the Vibrating Sample Magnetometery (VSM) study. The electrochemical analysis reveals the impressive electrochemical characteristics of the newly developed ferrites, highlighting a remarkable specific capacitance of 270.0 F g−1. This finding positions them as highly promising contenders for a wide range of energy storage supercapacitor applications.

Facile in situ synthesis and characterization of Fe@Si/zeolite Na composites with magnetic core–shell structures from natural materials for enhanced curcumin loading capacity

Curcumin is a natural polyphenol that is used in various traditional medicines. However, its inherent properties, such as its rapid degradation and metabolism, low bioavailability, and short half-life, are serious problems that must be resolved. To this end, a drug carrier incorporating natural magnetic cores in a zeolite framework was developed and applied to the loading of curcumin in ethanol solutions. In this system, curcumin is encapsulated in a zeolite Na (ZNA) magnetic core–shell structure (Fe@Si/ZNA), which can be easily synthesized using an in situ method. Synthesis of Fe3O4 nanoparticles was carried out from natural materials using a co-precipitation method. Analysis of the prepared magnetic core–shell structures and composites was carried out using vibrating-sample magnetometery, Fourier transform infrared spectroscopy, transmission electron microscopy, and x-ray diffraction. The cumulative loading of curcumin in the ZNA composite with 9% nanoparticles was found to reach 90.70% with a relatively long half-life of 32.49 min. Stability tests of curcumin loading in the composite showed that adding magnetic particles to the zeolite framework also increased the stability of the composite structure. Adsorption kinetics and isotherm studies also found that the system follows the pseudo-second-order and Langmuir isotherm models.

Thickness dependence of magnetic properties of Ir/FeV-based systems

Ir-buffered ${\mathrm{Fe}}_{0.7}{\mathrm{V}}_{0.3}$ (FeV) thin films of variable thickness ($1.4\phantom{\rule{0.28em}{0ex}}\mathrm{nm}\ensuremath{\le}{t}_{\mathrm{FeV}}\ensuremath{\le}10\phantom{\rule{0.28em}{0ex}}\mathrm{nm}$) were sputtered on thermally oxidized Si substrate and capped with Cu or MgO films. Vibrating sample magnetometery measurements allowed deducing their magnetization at saturation and the magnetic dead layer thickness, found to be capping layer independent. Microstrip line ferromagnetic resonance measurements under in-plane and perpendicular to the film plane applied magnetic fields are employed to investigate the perpendicular magnetic anisotropy (PMA) and damping. PMA is found to result from a uniaxial interfacial contribution which is slightly capping layer dependent. In contrast, the second-order PMA constant, which could result from the inhomogeneous distribution and the spatial fluctuations at the nanoscale of the uniaxial PMA at interface, is significantly stronger for Ir/FeV/Cu films. The damping dependence on the inverse of FeV effective thickness revealed a low Gilbert damping constant for FeV $({\ensuremath{\alpha}}_{\mathrm{FeV}}=1.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3})$ and allowed concluding that damping enhancement is mainly induced by Ir/FeV. The zero frequency linewidth for in-plane configuration is attributed to two magnon scattering contribution, found to be higher for Cu capped FeV. The investigation of the FeV thickness dependence of interfacial Dzyaloshinskii-Moriya interaction (iDMI) of both systems via Brillouin light scattering allowed to conclude to the zero iDMI constant of FeV/Cu. It also led to deduce iDMI constants of Ir/FeV and FeV/MgO, estimated to be ${D}_{\mathrm{s}}^{\mathrm{Ir}/\mathrm{FeV}}=(0.13\ifmmode\pm\else\textpm\fi{}0.02)\phantom{\rule{0.28em}{0ex}}\mathrm{pJ}/\mathrm{m}$ et ${D}_{s}^{\mathrm{FeV}/\mathrm{MgO}}=(\ensuremath{-}0.07\ifmmode\pm\else\textpm\fi{}0.02)\phantom{\rule{0.28em}{0ex}}\mathrm{pJ}/\mathrm{m}$, respectively.

One-pot synthesis of novel 3D graphene/Fe3O4/agro-based waste material (Sesamum indicum) nanocomposite for wastewater treatment and artificial neural network modeling

A One-Step hydrothermal process was applied in this study to synthesize magnetic Fe3O4/3D graphene/Sesamum indicum nanocomposite (M3DGSN). Acid Red 88 (AR88) was set at the target pollutant to be adsorbed and removed by the synthesized nanocomposite from the aqueous media. Field Emission scanning electron microscopy, Fourier transform infrared spectroscopy, vibrating sample magnetometery, and X-Ray diffraction analyses were applied to characterize the product. Artificial neural network modeling has also been employed in the adsorption process of AR88 using M3DGSN. Adsorption studies were performed in the dye concentration range of 5–30 mg L-1 with the adsorbent weight of 25–100 mg. It was observed that the dye removal efficiency using M3DGSN was dependent on different operational parameters and increased with rising pH, time, and weight of M3DGSN. Also, decreasing the dye concentration demonstrated the enhancement of dye removal efficiency. The optimum adsorbent amount and dye concentrations were observed to be 100 mg and 5 mg L-1, respectively. Also, the optimum removal performance was seen at the pH of 9.

Influence of capping agents on fraction of Fe atoms occupying octahedral site and magnetic property of magnetite (Fe3O4) nanoparticles by one-pot co-precipitation method

Magnetite (Fe3O4) nanoparticles were synthesized by one-pot coprecipitation method using five different capping agents: Sodium citrate, Poly vinyl pyrrolidone (PVP), Chitosan, Cetyltrimethylammonium bromide (CTAB) and Citric acid. The influence of the various capping agents on the size, oxidation and fraction of Fe atoms occupying Octahedral against Tetrahedral sites in relation to the saturation magnetization (Ms) of the magnetite nanoparticles were studied. X-ray Absorption Fine Structure (XAFS) spectroscopy, X-ray Absorption Near Edge Structure (XANES), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Fourier-Transform Infra-Red (FTIR) spectroscopy, Zeta potential, and Vibrating Sample Magnetometery (VSM) are used to study the various effects. The results reveal that the capping agents affect the size, oxidation and ratio of Fe atoms occupying octahedral vs tetrahedral site. The graph of Ms against size, oxidation and fraction of Fe atoms are plotted. Statistical analysis shows that Ms of the magnetite nanoparticles is highly dependent on the fraction of Fe atoms and the Size of the nanoparticles. The results reveal the Ms increases with size of the nanoparticles but decreases with the fraction of Fe atoms occupying octahedral vs tetrahedral site. However, there is no direct correlation between oxidation of Fe and Ms.

Structural, magnetic, and microwave absorbing properties of NiTiO3/CoFe2O4 composites

In this study, different volume ratios (NiTiO 3 : CoFe 2 O 4 = 1:3, 2:3, 1:1) of NiTiO 3 /CoFe 2 O 4 composites were synthesized using the sol-gel method. The effects of different NiTiO 3 volume ratios on the structural, morphological, magnetic, and microwave properties were systematically investigated by X-ray diffraction spectroscopy (XRD), field-emission scanning electron microscopy (FE-SEM), Raman spectroscopy (RAMAN), vibrating-sample magnetometery (VSM), and vector network analysis. Electromagnetic wave absorption analysis indicated that 1:3 composite sample showed the greatest reflection loss (−21.7 dB at 17.1 GHz frequency) at a thickness of 10.0 mm. The microwave absorbing properties decrease with the increasing NiTiO 3 volume ratio. The observed improvement can be attributed to the low degree crystallization of NiTiO 3 that increases magnetic losses through increased exchange resonance. • Different volume ratios of NiTiO 3 /CoFe 2 O 4 were synthesized by sol-gel method. • Microwave absorbing properties of NiTiO 3 are very poor, nearly no broad peak with lower than − 10 dB. • 1:3 composite sample showed greatest reflection loss (−21.7 dB at 17.1 GHz) at 10.0 mm thickness. • The improvement attributed to low degree crystallization of NiTiO 3 that increases exchange resonance.

Effective removal of Pb(II) ions using piperazine-modified magnetic graphene oxide nanocomposite; optimization by response surface methodology

In this research, the piperazine-modified magnetic graphene oxide (Pip@MGO) nanocomposite was synthesized and utilized as a nano-adsorbent for the removal of Pb(II) ions from environmental water and wastewater samples. The physicochemical properties of Pip@MGO nanocomposite was characterized by X-ray diffraction analysis (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDAX), Thermo-gravimetric analysis (TGA), Vibrating Sample Magnetometery (VSM) and Fourier-transform infrared spectroscopy (FT-IR) analysis. In this method, the batch removal process were designed by response surface methodology (RSM) based on a central composite design (CCD) model. The results indicated that the highest efficiency of Pb(II) removal was obtained from the quadratic model under optimum conditions of prominent parameters (initial pH 6.0, adsorbent dosage 7 mg, initial concentration of lead 15 mg L−1 and contact time 27.5 min). Adsorption data showed that lead ions uptake on Pip@MGO nanocomposite followed the Langmuir isotherm model equation and pseudo-second order kinetic model. High adsorption capacity (558.2 mg g−1) and easy magnetic separation capability showed that the synthesized Pip@MGO nanocomposite has great potential for the removal of Pb(II) ions from contaminated wastewaters.

Synthesis and Characterization of Zinc and Vanadium Co-Substituted CoFe2O4 Nanoparticles Synthesized by Using the Sol-Gel Auto-Combustion Method.

In recent years, cobalt ferrite has attracted considerable attention due to its unique physical properties. The present study aimed to produce cobalt ferrite magnetic nanoparticles doped with zinc and vanadium using the sol-gel auto-combustion method. For this purpose, Co1−xZnxFe2−yVyO4 (where x = 0.0, 0.1, 0.2, 0.5 and y = 0.00, 0.05, 0.15, 0.25) precursors were calcined at 800 °C for 3 h. The prepared samples were characterized with the X-ray diffraction (XRD) method in combination with Rietveld structure refinement, field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetometery (VSM). The XRD patterns confirmed the formation of crystalline spinel structure for all samples. However, the diffraction peaks of hematite and iron vanadium oxide phases were observed in the patterns of some doped samples. The average crystallite size for all the synthesized samples was found to be in the range of ~45–24 nm, implying that it decreased by simultaneously doping cobalt ferrite with Zn and V. The FT-IR spectrum confirmed the formation of the spinal structure of ferrite through the observed vibrational bands assigned to the tetrahedral (υ2) and octahedral (υ1) interstitial complexes in the spinel structure. The FE-SEM images showed that morphology, average grain size, and agglomeration of the synthesized powders were affected by doping, which was due to the interactions of the magnetic surface of nanoparticles. The VSM curves demonstrated that saturation magnetization and coercivity values changed in the range of 30–83 emu/g and from 27–913 Oe, respectively. These changes occurred due to the alteration in cation distribution in the spinel structure. This can be attributed to the change in superexchange interactions between magnetic ions by co-substitution of Zn and V ions in Cobalt ferrite and the changes in magnetocrystalline anisotropy.

Aptamer functionalized magnetic metal–organic framework MIL-101(Cr)-NH2 for specific extraction of acetamiprid from fruit juice and water samples

An aptamer-functionalized magnetic metal–organic framework (MMIL-Apt) was prepared and used for selective magnetic solid phase extraction (MSPE) of acetamiprid. To examine the morphology of the adsorbent, different techniques such as FT-IR spectrometry, vibrating sample magnetometery, TEM, FE-SEM and EDS were employed. The MMIL-Apt combines the advantages of aptamers and magnetic MMIL-101(Cr)–NH2 such as specific recognition of analyte, good stability and fast separation. To reach high MSPE recovery, various extraction parameters were examined and optimized. The limit of detection (LOD) was reached 0.0018 μg L-1. This method showed perfect linearity (0.006–1800 μg L-1) with a good correlation coefficient (R2 = 0.9993). The relative standard deviations for intra- and inter-day analyses were 3.61% and 8.10%. The extraction recoveries in water samples and fruit juices were obtained from 80.20% to 101.81 %. The results indicated the modified sorbent is practically applicable for the specific extraction of trace amounts of acetamiprid from different matrices.

Arginine and chitosan modified magnetic nanoparticles in ciprofloxacin delivery: A comparative, characterization andin vitrorelease study

Recently, magnetic iron oxide nanoparticles (IONPs) have become great potential nanocarriers for drugs and biomaterials. Chitosan (Chi) and Arginine (Arg) were utilized to coat magnetite nanoparticles to produce Chi-IONPs and Arg-IONPs. The preparation Chi-IONPs and Arg-IONPs was carried out by a two-step process. Initially, magnetite (Fe3O4) was prepared from Fe+2and Fe+3ions which were added into a solution of soda by a co-precipitation method. In the second step, prepared IONPs were coated with Chi and Arg polymers. The Chi-IONPs and Arg-IONPs were then conjugated with ciprofloxacin (Cip) to produce Cip-Chi-IONPs and Cip-Arg-IONPs nanocomposites. Characterization was performed using X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Zeta Potential determination, vibrating-sample magnetometery (VSM), UV-Vis spectroscopy and cytotoxicity. From the XRD, the plane (311) of magnetic nanoparticles remained without shift, indicating that they remained in the structure as the core of the carrier. The Chi and Arg polymers bound to IONPs were estimated by calculating the difference in weight loss by thermal gravimetric analysis (TGA). The loading of Cip to the IONPs was confirmed by FTIR analysis. The percent loading of Cip onto the Chi-IONPs and Arg-IONPs was measured using UV-Vis spectroscopy, and found to be around 15% and 9%, respectively. The size of Cip-Chi-IONPs and Cip-Arg-IONPs nanocomposites were ~13 nm, which was measured by TEM. From the VSM experiment, the Ms saturation value for IONPs, Cip-Chi-IONPs and Cip-Arg-IONPs was 79 emu/g, 38 emu/g, and 26 emu/g, respectively, and field coercivity (Hc) for each was each 7.37, 16.12 and 13.69 Gauss, respectively. In the release study, Cip-Arg-IONPs demonstrated a faster rate of release compared with Cip-Chi-IONPs and followed a second order kinetic mode with diffusion mechanism. In the cytotoxicity study for Cip-Chi-IONPs and Cip-Arg-IONPs nanocomposites, the results showed that there were no toxic properties up to 100μg/mL. This work showed that the development of Cip-Chi-IONPs and Cip-Arg-IONPs nanocomposites have a great potential for use as drug delivery systems.

Hf thickness dependence of perpendicular magnetic anisotropy, damping and interfacial Dzyaloshinskii-Moriya interaction in Pt/CoFe/Hf/HfO2

Vibrating sample magnetometery (VSM) combined with Brillouin light scattering (BLS) were used to investigate the Dzyaloshinskii-Moriya interaction (iDMI), the perpendicular magnetic anisotropy (PMA) and the damping in ${\mathrm{Co}}_{0.5}{\mathrm{Fe}}_{0.5}$-based systems grown by sputtering on $\mathrm{Si}/{\mathrm{SiO}}_{2}$ substrates, using Pt or Cu buffer layers and Hf capping layer of variable thickness $(0\ensuremath{\le}{t}_{\mathrm{Hf}}\ensuremath{\le}2\phantom{\rule{0.28em}{0ex}}\mathrm{nm})$. VSM measurements revealed a significant decrease of the areal magnetic moment at saturation as ${t}_{\mathrm{Hf}}$ increases, most likely due to the increase of the magnetic dead layer thickness at CoFe/Hf interface up to $0.73\ifmmode\pm\else\textpm\fi{}0.06\phantom{\rule{0.28em}{0ex}}\mathrm{nm}$ for ${t}_{\mathrm{Hf}}=2\phantom{\rule{0.28em}{0ex}}\mathrm{nm}$. Damping measurements allowed concluding to the weaker spin pumping contribution by the CoFe/Hf interface compared to Pt/CoFe. The analysis of the ${t}_{\mathrm{Hf}}$ dependence of damping within a model considering the contribution of each interface allowed us to determine the spin diffusion length of Hf, found to be 1.7 nm. The Hf thickness dependence of iDMI and PMA constants revealed significant (weak) contribution of the CoFe/Hf interface to PMA (iDMI). The surface iDMI constant of CoFe/Hf interface was estimated to be $(\ensuremath{-}0.37\ifmmode\pm\else\textpm\fi{}0.12)\ifmmode\times\else\texttimes\fi{}{10}^{--7}\phantom{\rule{0.28em}{0ex}}\mathrm{erg}/\mathrm{cm}$. This suggests that the iDMI sign of Hf and Pt are opposite, and an additive behavior can be obtained when they are placed in opposite sides of the CoFe layer, allowing thus to strengthen the iDMI, needed for some applications. Quadratic correlations between PMA and iDMI constants and linear dependence of damping versus PMA constant were obtained confirming their relationship with the spin-orbit coupling.

A novel n-methylurea cyanurate single crystal: structural and physical characterizations for magneto-electronics applications

A urea derivative of novel intermittent N-methylurea cyanurate (NMUC) crystalline salt was synthesized using methanol solvent, and thus crystals growing in same medium under the slow evaporation techniques governed by the reflux method. Molecular structure and other crystallography parameters of grown crystalline salt was refined using SHELX program. Crystalline perfection was examined using high resolution X-ray diffraction analysis. Elemental compositions of grown crystal were measured using CHNX analysis. The molecular structure of the grown crystal is further confirmed by 1H and 13C NMR spectral analysis. The Differential scanning calorimetric (DSC) is used to determine the specific heat capacity of the grown crystal in the temperature range from 303 to 373 K. Hardness measurement was performed on the (100), (110) and (001) crystallographic planes of this crystal, which elucidates their hardness nature including the yield strength (σy) and elastic stiffness constant (C11) associated with the applied loads. The Laser induced threshold damage of NMUC was calculated using Nd:YAG laser. The magnetic behaviour of the compound was studied through the hysteresis loop using Vibrating sample magnetometery technique. Photoconductivity analysis was used to measure the dark-current and photocurrent of grown crystal under the applied DC voltage between 20 and 400 V.

Cur-loaded magnetic ZnFe2O4@mZnO-Ox-p-g-C3N4 composites as dual pH- and ultrasound responsive nano-carriers for controlled and targeted cancer chemotherapy

Curcumin (Cur)-loaded zinc ferrite-mesoporous (m) zinc oxide core–shell -oxygen functional groups (carboxyl, carbonyl and hydroxyl) rich mesoporous (p) graphitic (g) carbon nitride (ZnFe2O4@mZnO-Ox-p-g-C3N4) carriers were designed as a potential magnetic drug delivery carrier with pH and ultrasound sensitivity for targeted drug delivery. Application of focused ultrasound can be an effective stimulant for highlighting tumor tissue or activatng delivery of echogenic drugs, which is expected to lower the systemic side effects of chemotherapy. The mixed application of physical/external (ultrasound) and chemical/internal (pH) triggers can allow for targeted release of Cur at chosen sections of tumor tissue. ZnFe2O4@mZnO and ZnFe2O4@mZnO-p-g-C3N4 nano-carriers were characterized using field emission scanning electron microscopy (FESEM), energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD), Fourier rransform infra-red (FTIR) spectroscopy, dynamic light scattering (DLS), zeta potential analysis, transmission electron microscopy (TEM), BET (Brunauer–Emmett–Teller), vibrating sample magnetometery (VSM), thermogravimetric analysis (TGA) and in vitro cytotoxicity assays. The ZnFe2O4@mZnOand ZnFe2O4@mZnO-Ox-p-g-C3N4 magnetic nano-carriers showed high loading efficiency of 51.39 and 67.37%, respectively, were stable in water for 24 h. The carriers Nano-carriersshowed pH- and ultrasound-sesnsitive release of Cur. The release at pH = 5.5 for (ZnFe2O4@mZnO 70.28%) (ZnFe2O4@mZnO-Ox-p-g-C3N4 56.05%) was more than that at pH = 7.4 for (ZnFe2O4@mZnO 66.26%) (ZnFe2O4@mZnO-Ox-p-g-C3N4 45.40%) after 72 h.

Structural, dielectric and magnetic characteristics of Zr–Ni substitution on Barium X-type hexagonal ferrites synthesized through sol–gel autocombustion method

Zr–Ni substituted barium hexaferrites with chemical compositions Ba2Co2Fe28-2xZrxNixO46 (x = 0.0, 0.25, 0.50, 0.75, 1.0) are fabricated through sol–gel autocombustion approach. The composites characteristics before and after substitution are examined through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), vibrating sample magnetometery (VSM) and dielectric measurements techniques. The XRD spectrum confirmed the formation of single phase X-type ferrites with crystallinity lying in the range of 24.57–29.11 nm. FTIR results revealed the specific absorption bands in the range of 300–900 cm−1. SEM micrographs demonstrate platelet shape grains along some agglomeration. The M–H loops analysis deduce about saturation magnetization (Ms), retentivity (Mr), coercivity (Hc) and squareness ratio (Mr/Ms), and these results show ferrimagnetic nature of prepared particles. The magnetic dilution in magnetic moment of molecules cause reduction in Mr and Ms. Reduction in coercivity is related to magnetocrystalline anisotropy. After Zr–Ni substitution, a significant decrease is observed in remanance, saturation magnetization and coercivity. The dielectric parameters are determined in 20 Hz–1 MHz frequency range. The dielectric parameters are studied on the basis of frequency change. The behavior of dielectric parameters analyzed on the basis of Wagner and Koop’s phenomenological theory.

Preparation and application of Fe3O4@ SiO2@ poly (o-phenylenediamine) nanoparticles as a novel magnetic sorbent for the solid-phase extraction of tellurium in water samples and its determination by ET-AAS

A novel magnetic polymer (Fe3O4@ SiO2@ PoPD) is synthesized for the magnetic solid-phase extraction (MSPE) of tellurium from water samples and its determination by electrothermal atomic absorption spectroscopy (ET-AAS). The morphology, composition and magnetic properties of the synthesized nanoparticles are characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometery (VSM). The factors affecting separation and preconcentration of tellurium including the amount of sorbent, composition of sorbent material, extraction time and temperature, desorption time and temperature, pH and ionic strength of the sample solution, desorption solvent type, concentration and volume are studied. Under optimized experimental condition, the linear range and the detection limit of the method are 0.08–1.9 ng mL−1 (R2 = 0.9879) and 0.05 ng mL−1, respectively. The percent recovery of tellurium from real samples spiked at 0.5 ng mL−1 is more than 98%. The intraday and interday relative standard deviations for a batch of the sorbent at above concentration level are 4.3 and 5.6%, respectively. The sorbent-to-sorbent RSD% is 8.9%. Finally, the developed method is successfully applied to the analysis of tellurium in some real samples.

Synthesis and characterization of [Fe3O4@CQDs@Si(CH2)3NH2@CC@EDA@SO3H]+Cl− and Fe3O4@CQDs@Si(CH2)3NH2@CC@EDA@Cu nanocatalyts and their application in the synthesis of 5-amino-1,3-diphenyl-1H-pyrazole-4-carbonitrile and 1-(morpholino(phenyl)methyl)naphthalen-2-ol derivatives

The current study provides a synthetic approach to prepare two novels magnetic Fe3O4@CQDs based catalyst. Accordingly, an ionic-liquid based and copper-based nano-magnetic solid acid catalyst, namely, [Fe3O4@CQDs@Si(CH2)3NH2@CC@EDA@SO3H]+Cl− and Fe3O4@CQDs@Si(CH2)3NH2@CC@EDA@Cu were synthesized. Carbon quantom dot (CQD), as a green and sustainable support, was used to coating the nano-Fe3O4 instead of conventionl SiO2. Various techniques, in sequence, were used to characterize the as-synthesized catalysts, including infrared (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive x-ray spectroscopy (EDX), thermal gravimetric analysis (TGA), differential thermal analysis (DTA), and vibrating sample magnetometery (VSM). The activity of the as-prepared catalysts was examined in the synthesis of 5-amino-1,3-diphenyl-1H and (morpholino(phenyl)methyl) derivatives. Interestingly, the pyrazole ring formation is followed by an anomeric effect assisted oxidation reaction even at room temperature. Optimum reaction conditions of morpholino(phenyl)methyl) derivative were determined via design of experiment (DOE).

Magnetite-Silica core-shell nanocomposites decorated with silver nanoparticles for enhanced catalytic reduction of 4-nitrophenol and degradation of methylene blue dye in the water

In this study, we synthesized multifunctional Fe3O4@SiO2/Ag magnetic nanocomposites (MNCs) by in situ method with an average size of 583 ± 4 nm. At different temperatures and pH, the catalytic properties of as-prepared MNCs were investigated for the degradation of methylene blue (MB) dye and reduction of 4-nitrophenol (4-NP) in an aqueous solution. The Fe3O4@SiO2/Ag MNCs were capable to remove 96.5% and 97% of MB and 4-NP respectively from aqueous media. The as-prepared MNCs were characterized by using Transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering analysis (DLS), Energy dispersive X-rays analysis (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–visible diffuse reflectance spectra (UV–vis DRS) and vibrating sample magnetometery (VSM). The rate constant for 4-NP and MB were calculated which were 0.385 ± 0.002 and 1.58 ± 0.09 min−1 respectively. The values of thermodynamics parameters enthalpy, Gibbs free energy, Entropy and activation energy were calculated for both MB and 4-NP. This nanocomposite exhibited easy synthesis, cost effective, high stability and fast separation using external magnet.

Impact of Cd content on properties of Ni1-xCdxFe2O4 nanoferrites prepared without post-preparation thermal treatment

We report sol–gel auto-combustion synthesis of Ni1-xCdxFe2O4 (0.0–0.72) nano-ferrites (grain-diameter:13.8–28.6 nm) with no thermal-treatment and, its study by x-ray diffraction (XRD), scanning-electron-microscopy-energy-dispersive-x-ray-spectroscopy (SEM-EDS), vibration sample magnetometery, ultraviolet–visible (Uv–Vis) spectroscopic techniques. XRD, EDS confirm formation of spinel phase, with minor-presence of α-Fe2O3 phase. Results show linear increase of lattice parameter; strong compositional dependence of: cationic-distribution (Fe3+ Ni2+ ions more-populated on B-site, Cd2+ distributed on A, B site); inversion-degree; oxygen-parameter; very-similar mean-particle-agglomerate-size; variation of B-O-B A-O-B A-O-A super-exchange-interaction affect magnetic properties. Magnetism is governed by Yafet-Kittel three-sub-lattice model; studied samples remain in the overlap region between single/ multi-domain structures.

Synthesis and Characterization of Rare Earth (Ce) Substituted Magnesium Ferrite MgCe0.1Fe1.9O4 and Banana Peel BPMgCe0.1Fe1.9O4

In this study, a composite of cerium doped magnesium ferrite (MgCexFe2-xO4 , x= 0.1) and banana peel powder was prepared by hydrothermal method. Crystal structure and phase identification, chemical bonding, and magnetic properties were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) and vibrating sample magnetometery (VSM), respectively. XRD results reveal that the prepared ferrite exhibits single phase face centered cubic (fcc) structure having no impurity in the sample. Addition of banana peel powder has no effect on the crystal structure. The values of structural parameters greatly match with the earlier reported values for the same structure. FTIR results clearly indicate that the prepared ferrite is spinel and have well defined vibrational and stretching peaks due to different molecules present in the compound. Coercivity values for both ferrite and composite materials are found to be a few hundred Oersted which confirm the soft magnetic nature of this ferrite. The observed parameters show that the prepared composite may find technological application for microwave absorption and multi-layer chip inductors.