Structure Of Iron Oxide Nanoparticles Research Articles

Structural, magnetic and optical properties of nickel doped iron oxide nanoparticles based on Logas natural sand for environmental application

The iron oxide nanoparticles have been prepared by mechanical milling method using Logas natural sand as a raw material. The products of ball milling were doped with Ni nanoparticles at different doping concentrations (0, 1, 2, 3, and 4 wt.%). The effect of doping concentration on the structural, magnetic, and optical properties was studied. The structural, magnetic, and optical properties of the prepared samples were studied using an X-ray diffractometer (XRD), vibration sample magnetometer (VSM), and UV-Vis spectroscopy, respectively. The X-ray diffraction pattern shows that the ball milling product is hematite (α-Fe2O3) nanoparticles and highly crystalline with a rhombohedral structure. It is very interesting to find that Ni doping nanoparticles cannot change the structure of iron oxide nanoparticles however, the average crystallite size decreases from 39.43 to 32.64 nm with increasing Ni doping concentration from 0 to 4 wt. %, respectively. The crystallite size based on the dominant peak (104) varies as Ni doping concentration increases. The magnetic properties of the samples show the ferromagnetic nature of the prepared nanoparticles. The saturation, remanence magnetization, and coercivity increase with increasing Ni concentration. The optical band gaps calculated through UV-Vis absorption measurements confirm that the decrease in crystallite size is accompanied by a decrease in the band gap value from 2.03 to 1.92 eV as the doping concentration increases from 0 to 4 wt. %.This study demonstrates the simple way of preparing Ni-doped iron oxide nanoparticles for environmental application.

Effect of Calcination Temperature and Time on the Synthesis of Iron Oxide Nanoparticles: Green vs. Chemical Method

Nowadays, antioxidants and antibacterial activity play an increasingly vital role in biosystems due to the biochemical and biological reactions that involve free radicals and pathogen growth, which occur in many systems. For this purpose, continuous efforts are being made to minimize these reactions, including the use of nanomaterials as antioxidants and bactericidal agents. Despite such advances, iron oxide nanoparticles still lack knowledge regarding their antioxidant and bactericidal capacities. This includes the investigation of biochemical reactions and their effects on nanoparticle functionality. In green synthesis, active phytochemicals give nanoparticles their maximum functional capacity and should not be destroyed during synthesis. Therefore, research is required to establish a correlation between the synthesis process and the nanoparticle properties. In this sense, the main objective of this work was to evaluate the most influential process stage: calcination. Thus, different calcination temperatures (200, 300, and 500 °C) and times (2, 4, and 5 h) were studied in the synthesis of iron oxide nanoparticles using either Phoenix dactylifera L. (PDL) extract (green method) or sodium hydroxide (chemical method) as the reducing agent. The results show that calcination temperatures and times had a significant influence on the degradation of the active substance (polyphenols) and the final structure of iron oxide nanoparticles. It was found that, at low calcination temperatures and times, the nanoparticles exhibited small sizes, fewer polycrystalline structures, and better antioxidant activities. In conclusion, this work highlights the importance of green synthesis of iron oxide nanoparticles due to their excellent antioxidant and antimicrobial activities.

Correlation on precipitation parameters towards ferromagnetism and stabilization of the magnetite nanoparticles

The conventional synthesis methods of magnetite nanoparticles by hydrothermal required high temperature and aging process, which results in an unstable magnetite phase. In this work, the focus is on producing magnetite nanoparticles by simple and sustainable titration methods with the variable in parameters on the precipitate growth rate and structure of iron oxide nanoparticles utilizing a single sulphate precursor. Iron salt precursor hydrolysis was faster at temperatures of 30 ​°C and 45 ​°C; hence the number of hydroxyl ions (OH−) needed to reach the equivalence point for the precipitate to form is lower, creating the highest percentage of magnetite nanoparticles. However, at 45 ​°C, larger magnetite nanoparticles were obtained hence higher magnetization through lower coercivity. Precipitating agent rate of addition increase leads to reaction sequence delay, favoring goethite nanoparticle formation and lower magnetization. The novel understanding of precipitation parameter synergistic effect has resulted in promising ferromagnetic and stabilization properties of magnetite nanoparticle synthesis.

Synthesis and characterization of ginger (Z. officinale) extract mediated iron oxide nanoparticles and its antibacterial activity

Abstract Green synthesis is one of the simple, eco- friendly and cost effective method of nanoparticles synthesis. Different biological things are used in this method. The iron oxide nanoparticles which are generally synthesized by physical and chemical methods are also synthesized by using ginger (Zingiber officinale) extract. Ferric chloride was used as a precursor and ginger extract acts as reducing agent. The formation of iron oxide nanoparticles were characterized by UV– visible spectroscopy, Fourier transform infrared spectroscopy (FTIR) X- ray diffraction technique (XRD) and scanning electron microscopy (SEM). The iron oxide nanoparticles showed characteristic peak at 406 nm. The different functional groups attached to it were analyzed by FTIR spectroscopy. In X-ray diffraction analysis of nanoparticles, it showed highest peak at (3 1 1) crystal plane with 2 θ value 32.43. The stabilized and cubic structure of iron oxide nanoparticles were determined by SEM analysis. The synthesized nanoparticles from ginger extract have antibacterial activity against Gram negative bacteria E. coli with zone of inhibition 22 mm diameters. The synthesized iron oxide nanoparticles are expected to have potential antioxidant and antifungal activity. This new approach of nanoparticles synthesis is found to be more convenient than any other method.

Vibrational properties of nanoparticles iron oxide by Raman spectroscopy

The crystal structure and atomic dynamics of Fe3O4 nanoparticles have been studied. The crystal structure of iron oxide nanoparticles was determined by X-ray diffraction. The analysis showed that the crystal structure of [Formula: see text] 50–100 nm dimensional iron oxide corresponds to a high symmetry cubic crystal structure. Calculations have shown that there are four infrared active, five Raman active and seven hyper-Raman active modes in the space group Fd-3m with cubic symmetry. Four of these modes have been observed using Raman spectroscopy: 213, 271, 380 and 591 cm[Formula: see text]. The vibrational modes are interpreted by Gaussian function. It was found that these vibration modes correspond to the vibration of O–Fe–O bonds and iron-oxygen polyhedra.

Inhomogeneous nematic-isotropic phase transition of a thermotropic liquid crystal doped with iron oxide nanoparticles

We elucidate the local distribution and aggregated structure of iron oxide nanoparticles (IONPs; 6 nm in diameter) doped in the matrix of a nematic liquid crystal (LC), 4-cyano-4'-pentylbiphenyl, utilizing in situ cryogenic transmission electron microscopy and polarized light microscopy. We show that tens of IONPs aggregate into a sphere-like morphology, and the aggregates combine into elongated clusters with a length of hundreds of nm. With the IONP-doped LC matrix confined to a thin glass cell, we study the nematic-isotropic (N-I) phase transition, and suggest that local heterogeneity of LC textures as seen in polarized microscopy is caused by the existence of IONP aggregate clusters. These clusters act also as nuclei for the formation of isotropic domains upon heating.

Magnetically-stimulated transformations in nanostructure of lipid mesophases: Effect of structure of iron oxide nanoparticles

Nanostructured lipid-based liquid crystalline (LLC) systems can display different drug release rates and also be stimuli-responsive, rendering them the potential to serve as ‘on-demand’ drug delivery systems. In this study, a magnetically-responsive cubic phase nanocomposite was engineered by doping iron oxide nanoparticles (IONPs) into a phytantriol (PHYT)-based lipid that exhibits transformation in nanostructure under external alternating magnetic field (AMF). The effects of IONP surface hydrophilicity/hydrophobicity, size and concentration were determined in dispersed systems, and the effect of hydration state of the system was also assessed. Time-resolved small angle X-ray scattering (SAXS) was used to probe the impact of these variables on the transformation of nanostructure with and without the application of AMF. The inclusion of both hydrophobic and hydrophilic IONPs reduced the temperature of the phase transition from the inverted bicontinuous cubic (V2) phase to inverted hexagonal (H2) phase and imparted magnetic-responsiveness to the systems. The size of the IONPs played an important role in governing the phase reversibility of the dispersed systems, while the concentration of the IONPs had more impact on the phase behaviour of the bulk systems. These successfully demonstrated a completely reversible magneto-responsive phase transition in the nanostructured LLC systems through optimising the selection of IONPs.

Selective magnetometry of superparamagnetic iron oxide nanoparticles in liquids.

We show that the properties of superparamagnetic iron oxide nanoparticles suspended in liquids can be effectively studied using Magnetic Circular Dichroism in Resonant Inelastic X-ray Scattering. Analysis of the spectral shape and magnetic contrast produced by this experiment enables an assessment of the site distribution and magnetic state of metal ions in the spinel phase. The selective magnetization profile of particles as derived from the field dependence of dichroism empowers an estimation of particle size distribution. Furthermore, the new proposed methodology discriminates sizes that are below the detection limits of X-ray and light scattering probes and that are difficult to spot in TEM.

Novelty of Bioengineered Iron Nanoparticles in Nanocoated Surgical Cotton: A Green Chemistry.

The current focus of nanotechnology is to develop environmentally safe methodologies for the formulation of nanoparticles. The phytochemistry of Zingiber officinale inspired us to utilize it for the synthesis of iron nanoparticles. GC-MS analysis revealed the phytochemical profile of ginger. Out of 20 different chemicals, gingerol was found to be the most potent phytochemical with a retention time of 40.48 min. The present study reports a rapid synthesis method for the formation of iron nanoparticles and its potential efficacy as an antibacterial agent and an antioxidant. Because of its antibacterial property, ginger extract was used to coat surgical cotton. Synthesized ginger root iron nanoparticles (GR-FeNPs) were characterized by UV-visible spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction analysis, and particle size analysis. XRD confirmed the crystalline structure of iron oxide nanoparticles as it showed the crystal plane (2 2 0), (3 1 1), (2 2 2), and (4 0 0). The particle size analyzer (PSA) showed the average size of the particles, 56.2 nm. The antimicrobial activity of the FeNPs was tested against different Gram-positive and Gram-negative bacteria. E. coli showed maximum inhibition as compared with the other organisms. Antioxidant activity proved the maximum rate of free radicals at 160 µg/mL produced by nanoparticles. In addition, the antimicrobial activity of nanocoated surgical cotton was evaluated on the first day and 30th day after coating, which clearly showed excellent growth inhibition of organisms, setting a new path in the field of medical microbiology. Hence, iron-nanocoated surgical cotton synthesized using green chemistry, which is antimicrobial and cost effective, might be economically helpful and provide insights to the medical field, replacing conventional wound healing treatments, for better prognosis.

Nanoscale Physical and Chemical Structure of Iron Oxide Nanoparticles for Magnetic Particle Imaging

In this work, the role of the nanoscale chemical and magnetic structure on relaxation dynamics of iron oxide nanoparticles in the context of magnetic particle imaging (MPI) is investigated with Mössbauer spectroscopy (MS) and electron energy loss spectroscopy (EELS). Two samples of 27 nm monodisperse iron oxide nanoparticles are compared, with and without an additional oxidation optimization step, with corresponding differences in structure and properties. Iron oxide nanoparticles synthesized in the presence of sufficient oxygen form single crystalline, inverse‐spinel magnetite (Fe3O4) and display magnetic properties suitable for MPI. A secondary wüstite (FeO) phase is observed in the diffraction pattern of unoptimized nanoparticles, which is antiferromagnetic and therefore unsuitable for MPI. Mössbauer spectra confirm the composition of the optimized nanoparticles to be ≈70% magnetite, with the remaining 30% oxidized to maghemite; in contrast, the as‐synthesized particles (without the oxidation step) contained about 40% wüstite and 60% magnetite. The authors use scanning transmission electron microscopy (STEM) with electron energy loss spectroscopy (EELS) to probe iron 2p‐3d electronic transitions and correlate their intensities with the oxidation state with sub‐nanometer spatial resolution. The optimally oxidized nanoparticles are uniform in crystallography and phase, while the mixed phase nanoparticles are core‐shell wüstite/magnetite. Further confirming the core‐shell structure of the mixed phase nanoparticles, considerable spin canting in the in‐field Mössbauer spectrum, likely caused by interface coupling, is observed.

Synthesis of Iron Oxide Nanoparticles Optimized by Design of Experiments

Magnetic iron oxide nanoparticles have been widely studied for technological and biomedical applications due to its small size and the possibility of functionalizing the surface with intended molecules. Magnetite is the most used phase because of superparamagnetic characteristic, and it is synthesized by co-precipitation, starting from ferrous and ferric ions in alkaline media. However, depending on parameters of chemical reactions, such as molar ratio between iron and hydroxyl groups, stirring rate, and temperature, different iron oxide structures are formed through distinct pathways. Since several variables can affect the size, chemical composition, and crystalline structure of iron oxide nanoparticles during the synthesis, it is very important to apply experimental routines with a well-defined protocol and planning practical steps can significantly improve the quality of products. Plackett-Burman methodology from design of experiments is a filtration analysis, used in the initial stages of a process to investigate the main effects of factors over a characteristic of the final material. In this work, Plackett-Burman technique was employed in order to optimize bare iron oxide nanoparticle production by co-precipitation method, relating the different crystalline phases produced to the experimental routine. Dynamic light scattering, Fourier transform infrared spectroscopy, and X-ray diffractometry were used to characterize the samples.

Structural characterization, antibacterial and catalytic effect of iron oxide nanoparticles synthesised using the leaf extract of Cynometra ramiflora

In the present investigation, the leaf extract of Cynometra ramiflora was used to synthesize iron oxide nanoparticles. Within minutes of adding iron sulphate to the leaf extract, iron oxide nanoparticles were formed and thus, the method is very simple and fast. UV-VIS spectra showed the strong absorption band in the visible region. SEM images showed discrete spherical shaped particles and EDS spectra confirmed the iron and oxygen presence. The XRD results depicted the crystalline structure of iron oxide nanoparticles. FT-IR spectra portrayed the existence of functional groups of phytochemicals which are probably involved in the formation and stabilization of nanoparticles. The iron oxide nanoparticles exhibited effective inhibition against E. coli and S. epidermidis which may find its applications in the antibacterial drug development. Furthermore, the catalytic activity of the nanoparticles as Fenton-like catalyst was successfully investigated for the degradation of Rhodamine-B dye. This outcome could play a prominent role in the wastewater treatment.

CNT Branching on the 3D Nitrogen-Doped Graphene Architecture for Lithium Ion Battery

The hybridization of 1D CNT with 3D graphene structure has recently attracted attention owing to their large specific surface area, high electronic conductivity, and structural integrity. These features of the hierarchical architectures can provide synergic affect on the energy storage such as supercapacitors, fuel cells and lithium-ion batteries. In addition, the performance has been further improved by doping with different heteroatoms like sulphur, boron, phosphorous and nitrogen because they can play a vital role in changing the local electronic density leading to improved electronic conductivity. In this work, we synthesize 3D nitrogen (N)-doped reduced graphene oxide (rGO) branched by CNT for applications into lithium ion batteries. The hierarchical architecture consisting of the CNT branching on 3D N-doped rGO was characterized by SEM and TEM images. Iron oxide nanoparticles acted as the catalyst for the growth of CNT as well as active materials for lithium storage. The crystalline structure of iron oxide nanoparticles and restacking inhibition of rGO were confirmed by the XRD analysis. The BET data indicate the presence of mesoporous structure with average pore diameter of 21 nm with 400 m2/g surface area. The XPS data identified the presence, composition, and bonding configuration of carbon, iron, nitrogen and oxygen. The electrochemical properties were characterized by cyclic voltametry, impedance spectroscopy, and galvanic charge/discharge curve for lithium ion battery application.

Structure of Iron Oxide Nanoparticles Studied by ^{57}Fe NMR

Structure of Iron Oxide Nanoparticles Studied by ^{57}Fe NMR

산화철 나노입자의 크기에 따른 강자성 공명 신호의 선폭 특성

본 연구에서는 열 분해법으로 크기가 각각 D=4.67 nm, 5.64 nm 및 6.34 nm인 균일한 산화철 나노입자를 제조하여 강자성 공명 신호를 측정하였다. 측정된 강자성 공명 신호는 입자의 부피가 로그 정규 확률 분포를 갖는 초상자성 나노입자에 대하여 계산한 결과와 비교 분석하였다. 강자성 공명 신호의 선폭은 나노입자의 크기가 증가함에 따라 넓어졌으며, tanh(<TEX>$V^2$</TEX>)에 비례하는 특성을 보였다. 이러한 나노입자의 크기에 따른 선폭 증가는 나노입자들 표면에 분포하는 표면 스핀과 결정 이방성 특성을 갖는 내부 스핀들에 의한 두 가지 강자성 공명 신호의 중첩에 기인함을 알 수 있었다. We measured the ferromagnetic resonance (FMR) signal using the monodisperse iron oxide nanoparticles with size D=4.67 nm, 5.64 nm and 6.34 nm synthesized by using the thermal decomposition method, respectively. The measured ferromagnetic resonance signals were compared with the calculated ones for superparamagnetic nanoparticles with lognormal volume distribution. The FMR linewidth broadening was propositional to tanh(<TEX>$V^2$</TEX>), where V was volume of nanoparticles. The narrow linewidth of small size nanoparticles was due to the surface spins, while the broad linewidth of large size nanoparticles was due to the bulk spins affected by the crystalline structure of iron oxide nanoparticles. The superposition of surface and bulk effect was confirmed at D=5.64 nm nanoparticles, which was near the critical size for linewidth transition from surface effect to bulk effect.

Structural investigations on differently sized monodisperse iron oxide nanoparticles synthesized by remineralization of apoferritin molecules

We have investigated the structure of iron oxide nanoparticles produced by remineralization and thermal treatment of horse spleen apoferritin molecules. The described procedure allows to synthesize particles with diameters ranging from 4 to 7 nm in size. Atomic force microscopy and transmission electron microscopy (TEM) investigations were performed for shape and size determination, whereas energy-dispersive X-ray (TEM-EDX), high-resolution TEM, and electron diffraction measurements revealed the chemical composition and crystal structure of the particles. We found predominantly single crystalline nanoparticles with a hematite-like (α-Fe2O3) structure.

Atomic pair distribution function (PDF) study of iron oxide nanoparticles in aqueous suspension

Size is the key regulating the crystalline structure of iron oxide nanoparticles. The effect of the crystal size on the microstructure of these nanoparticles was investigated in an aqueous dilute suspension by energy dispersive X-ray diffraction (EDXD) and in an aqueous concentrated suspension by X-ray powder diffraction (XRD), at 293 K. Nanoparticle structure was also investigated by HRTEM. Structural results were interpreted in terms of theoretical models built using structural parameters obtained by the Rietveld method on XRD. The ability of the pair distribution function (PDF) to measure medium-range correlation lengths and size in nanoscale crystalline materials was also investigated and discussed. The sensitivity of the PDF technique allowed modelling of sample polydispersity.

Ultrasonic-assisted preparation of monodisperse iron oxide nanoparticles

Monodisperse iron oxide nanoparticles with 5–20 nm can be synthesized by an inexpensive and simple ultrasonic-assisted method at low temperature. This is based on the decomposition of iron pentacarbonyl in cis–trans decalin. The high energy emitted by ultrasonic irradiation at a short time can promote the crystallization process simultaneously. At low temperature, these crystalline nucleuses can grow to monodisperse nanoparticles. Effects of ultrasonic treatment, the concentration of surfactant and the refluxing time on the size and size distribution of iron oxide nanoparticles were investigated. The morphology and crystal structure of iron oxide nanoparticles obtained at different conditions were characterized by high-resolution transmission electron microscope, X-ray diffraction and selected area electron diffraction.