α-Fe2O3 Phase Research Articles

Fabrication of novel bioceramic α-Fe2O3/MnO nanocomposites: Study of their structural, magnetic, biocompatibility and antibacterial properties

In recent times, a sharp increase in prevalence of bacterial strains showing resistance against currently used antibiotics has severely challenged the modern healthcare system in the treatment of bacterial infections. Therefore, it is needed to find suitable alternatives to counter this problem in order to treat contagious diseases. Nanomaterials/composites based inorganic antibiotic appears to be a feasible option, because these materials kill bacteria by concurrently acting through multiple mechanisms, unlike traditional antibiotics. In this study, Fe/Mn oxide nanocomposites were synthesized via a wet-chemical approach, and well characterized to examine their structural, dimensional, elemental, magnetic, cytotoxic and, antibacterial attributes. The nanocomposites exhibited mixed phases of constituent metal oxides α-Fe2O3 and MnO. The composite samples were of rod shape and shown room temperature superparamagnetism. Further, the prepared samples were found compatible with the cell lines MCF7 and MCF-12A, and exhibited ROS induced excellent bactericidal properties against bacteria E. coli, B. subtilis, S. aureus, and S. typhi. Therefore, the Fe/Mn oxide nanocomposites have the potential to become a promising alternative to the traditional antibiotics.

Rietveld Refinement, μ-Raman, X-ray Photoelectron, and Mössbauer Studies of Metal Oxide-Nanoparticles Growth on Multiwall Carbon Nanotubes and Graphene Oxide

Applying a modified coprecipitation method, maghemite and anatase nanoparticles embedded in graphene oxide and multiwall carbon nanotube frameworks were prepared, and a detailed structural characterization is presented. Transmission electron images have revealed that the multiwall carbon nanotubes and graphene oxide act as substrates to reduce the nanoparticle agglomeration with narrow sizes of ca. 9–20 nm, in agreement with the results of the Rietveld refinement, which have also indicated their crystallite apparent size and shapes using the spherical harmonics approach. In structural studies of maghemite nanoparticles by Raman spectroscopy, it was found that the effect of optical density and laser power intensity plays a significant role. When no optical filter was located between the powder sample and the laser source, a transformation from the γ-Fe2O3 to the α-Fe2O3 phase was observed, as demonstrated by the disappearance of the characteristic broad Raman peak (A1g) of the γ-Fe2O3 phase when increasing the laser power. X-ray photoelectron spectroscopy has also brought insights into the functionalization mechanism, suggesting that the one-pot reduction of the graphene oxide is favored by the alkaline γ-Fe2O3 nanoparticle growth. The temperature dependence of the 57Fe Mössbauer spectra has indicated that the effective anisotropy constant of Fe oxide-based nanoparticles is similar to that of bulk maghemite, and magnetic relaxation of Fe3+ spins depends on particle sizes.

X-rays absorption spectroscopy for local structure determination of magnetolpumbite nanoparticles

Magnetolpumbite nanoparticles of Cr-doped strontium hexaferrites (SrFe12−xCrxO19 x = 0.0–1.0) were synthesized by using sol-gel method. X-ray diffraction (XRD) pattern of the prepared samples showed hexagonal structure, however in some composition hematite phase α-Fe2O3 was also observed. The average crystallite size was found to be in the range of 31–42 nm. By using Williamson-Hall (W-H) Analysis the compressive strains were observed. The lattice parameters showed non-linear dependence on Cr doping. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the appearance of different Octahedral and Tetrahedral stretching vibrations. Further to understand it deeply, the X-Ray Absorption Fine Spectroscopy (XAFS) analysis has been done. The Structural investigations of Cr doped complex SrFe12−xCrxO19 (x = 0.2, 0.4, 0.6, 0.8, 1.0) and pure SrFe12O19 as model have been studied accurately to conclude the oxidation states, chemical shift and site occupancy for Fe and Cr at K absorption edges. The model SrFe12O19 and sample compositions x = 0.2 showed a single Fe3+ oxidation state for Fe K absorption edge however, for all the rest of the sample compositions x ≥ 0.4, Fe2+ and Fe3+ phases were also observed. Chemical shift for Fe absorption edge have also been determined to quantify the shift in the energies. Positive shift has been observed in all the samples as reference from Fe metal. For Cr K absorption edge, oxidation state is also determined. EXAFS data proved helpful in estimating the bond lengths of RFe-O and RCr-O through calculating distance by first shell, both for Fe and Cr K edges. The atomic distortion in the structure is caused by the Cr doping in SrFe12−xCrxO19 system, in a non-regular way. Finally, the XAFS Analysis revealed the presence of hematite which was not figure out by XRD spectrum.

Effect of Germanium Incorporation on the Electrochemical Performance of Electrospun Fe2O3 Nanofibers-Based Anodes in Sodium-Ion Batteries

Fe2O3 and Fe2O3:Ge nanofibers (NFs) were prepared via electrospinning and thoroughly characterized via several techniques in order to investigate the effects produced by germanium incorporation in the nanostructure and crystalline phase of the oxide. The results indicate that reference Fe2O3 NFs consist of interconnected hematite grains, whereas in Fe2O3:Ge NFs, constituted by finer and elongated nanostructures developing mainly along their axis, an amorphous component coexists with the dominant α-Fe2O3 and γ-Fe2O3 phases. Ge4+ ions, mostly dispersed as dopant impurities, are accommodated in the tetrahedral sites of the maghemite lattice and probably in the defective hematite surface sites. When tested as anode active material for sodium ion batteries, Fe2O3:Ge NFs show good specific capacity (320 mAh g−1 at 50 mA g−1) and excellent rate capability (still delivering 140 mAh g−1 at 2 A g−1). This behavior derives from the synergistic combination of the nanostructured morphology, the electronic transport properties of the complex material, and the pseudo-capacitive nature of the charge storage mechanism.

Water oxidation electrocatalyst: A new application area for Ruthner powder waste material

Ruthner powder is a by-product of the steel hot-rolling process. This study introduces a new application area for this waste material by investigating its activity for the oxygen evolution reaction. Ruthner powder with the α-Fe2O3 phase structure was deposited on the carbon paper substrates using the electrophoretic deposition (EPD) process to fabricate the electrodes. The effect of the concentration of cetrimonium bromide ([CTAB]) and the Ruthner powder ([RP]) in the EPD cell on the morphology and activity of the electrodes were investigated by SEM, LSV, and EIS techniques. The results revealed the formation of a homogenous layer on the carbon paper when [CTAB] and [RP] were respectively 0.4g.l−1 and 0.2g.l−1. The obtained electrode showed the best activity among all fabricated electrodes. In particular, its onset overpotential and overpotential at a current density of 10mA.cm−2 were respectively 85% and 25% lower than those of bare carbon electrodes.

Evolution of structure and magnetic properties in MnZn ferrite-silica nanocomposites fabricated by sol–gel method

We explore the influence of the silica matrix on size, spinel phase stability, and magnetic properties of MnZn ferrite. For this purpose, Mn0.6Zn0.4Fe2O4 (MZF) nanoparticles (NPs) dispersed in silica (SiO2) matrix [MZF1−x/(SiO2)x x = 0, 10, 30%] synthesized by one-pot sol–gel process. The evolution of a pure spinel phase is apparent from the as-prepared (AP) MZF/SiO2 (30%) amorphous state on annealing in the temperature range 600–900 °C in air, whereas the AP free-standing MZF NPs exhibit a secondary phase of α-Fe2O3 along with spinel structure in this temperature range. The crystallite size is 5 ± 1 nm for a 600 °C annealed sample and increases to 10 ± 1 nm for a 900 °C annealed sample. From the detailed analysis of the temperature and magnetic field-dependent magnetization data, it is found that the AP sample exhibits weak magnetic behavior. However, annealed samples exhibit a maximum in zero-field-cooled magnetization at a certain temperature (TP), which increases with the increase of annealing temperature. The M–H curves above TP indicate the presence of superparamagnetic (SPM)-like behavior. From the present study, we show that the phase stability and magnetic properties of MZF/SiO2 composites have improved compared to bare MZF NPs.

Nd-Zn Co-substituted M-Type Strontium Hexaferrites with Enhanced Magnetic Properties

In this work, we report the synthesis of Nd-Zn co-substituted M-type strontium hexaferrites Sr1-xNdxFe12-xZnxO19 (0.0 ≤ x ≤ 0.5) by the solid-state method. The analysis of X-ray diffraction (XRD) shows that the single M-type hexaferrite structure can be obtained as the doping concentration is lower than 0.3, while the other side phase (α-Fe2O3) will appear in the XRD patterns for x ≥ 0.3. Furthermore, the specific hexagonal structure is also confirmed by Fourier transform infrared (FTIR) spectroscopy, and field emission scanning electron microscopy (FE-SEM) also discloses the micromorphology of the series samples over the entire range of substitution. Through the systematical magnetic measurements, enhanced magnetic properties can be acquired due to the effective substitution, especially for intrinsic coercivity (Hcj), which increases from 1800 Oe (x = 0.0) to 3230 Oe (x = 0.5) at room temperature. In addition, the doping sample also exhibits a considerable thermal stability because of a high ferromagnetic–paramagnetic (FM–PM) transition temperature (i.e., Curie temperature TC). In consideration of the magnetic performance and high FM–PM phase temperature, Sr1-xNdxFe12-xZnxO19 series of samples can be considered as promising candidates for magnetic recording devices because of such high saturation magnetization and considerable coercivity.

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.

Biosynthesis of hematite phase α-Fe2O3 nanoparticles using an aqueous extract of Rosmarinus officinalis leaves

Biosynthesized hematite phase α-Fe2O3 nanoparticles (NPs) have been successfully demonstrated via an entirely green process mediated aqueous extract of Rosmarinus officinalis (rosemary) leaves acting as both stabilizing and capping agents. The synthesis was free of solvents and surfactants to adhere to green chemistry principles and the impartation of environmental benignity. To achieve the goal of this study, the main physical properties of the biosynthesized α-Fe2O3 NPs were carried-out using complementary techniques namely, field emission scanning electron microscopy (FESEM) which revealed the self-assembled, highly agglomerated NPs, and the average size was found to peak at 6.531 ± 0.148 nm while X-ray diffraction (XRD) exhibited several Bragg diffraction peaks in line with the rhombohedral structure and the crystallinity nature of α-Fe2O3 NPs with an average size within the range of 7.412–10.742 nm in agreement with the FESEM results. The energy-dispersive X-ray spectroscopy (EDS) elucidated the presence of Fe and O in addition to contaminating elements from the natural extract while attenuated total reflectance-Fourier transform infrared (ATR-FTIR) depicted Fe-O chemical bonds. Besides, the photoluminescence (PL) emission spectrum indicated the existence of surface defects and oxygen vacancies.

Structural and Optical Characterization of Sprayed nanostructured Indium Doped Fe2O3 Thin Films

Nanostructured pure and Indium doped iron oxide thin films were deposited via spray pyrolysis technique (SPT). The effects of Indium (2 and % 4) concentration was studied. X-ray diffraction patterns disclosed that Fe2O3 films have a rhombohedral crystalline of α-Fe2O3 phase and their crystallite size was vary from (12.13 – 13.84) nm with Indium content. The strain(%) parameter decrease from 28.57 to 25.04, AFM images of films show changes in morphology with decreased in surface roughness from 2.75 nm to 1.7 nm with Indium 4% doping, The 3-D images and grain size distribution are illustrated that they exhibit spherical nano-grains ranged from 72.72 nm for pure Indium to 51.22 nm for 4% Indium doped Fe2O3. The transmittance decreases with increasing Indium concentration. The bandgap energy of Fe2O3 thin film was 2.75 eV and it decreases to 2.55 eV for Fe2O3:4% In.

Enhanced electrical and photocatalytic properties of porous TiO2 thin films decorated with Fe2O3 nanoparticles

In this work, we developed a facile synthetic process for the fabrication of porous heterojunction Fe2O3/TiO2 using a two-step method to be employed as a visible light photocatalyst. In the first step, porous TiO2 thin films were successfully prepared by a sol–gel method using polyethylene glycol (PEG). The porous TiO2 thin film was further annealed and then decorated with nanoparticles of Fe2O3 using the direct electrodeposition method. The photocatalysts were structurally investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and Raman spectroscopy. The Fe2O3/TiO2 heterojunction presented both an anatase TiO2 phase and rhombohedric structure of hematite α-Fe2O3. The optical properties have been investigated for all the materials, in which the TiO2 material present in porous heterojunction exhibited a remarkable absorption and red shift in the visible region from 3.2 to 3.0 eV compared to the pure heterojunction Fe2O3/TiO2. Moreover, the electrochemical behavior of the samples was investigated. Photocatalytic activity was assessed from methylene blue degradation with remarkable degradability performance under visible light. The photodegradation of the porous heterojunction Fe2O3/TiO2 exhibited an enhanced photodegradation up to 70% after 150 min of irradiation.

Synthesis of Magnetic Iron Oxide Nanoparticle from Logas Natural Sand and Its Application for the Catalytic Degradation of Methylene Blue

Structural properties, morphology, and the catalytic activity of hematite (α-Fe2O3) nanoparticles for degradation of methylene blue have been studied. For this purpose, the hematite particles were synthesised from Logas natural sand by 2 steps ball milling method. X-ray diffraction (XRD) confirmed the presence of a hematite (α-Fe2O3) phase. However, other phases such as SiO2 and FeTiO3 are also confirmed by XRD. Scanning electron microscopy (SEM) showed a wide distribution of particle sizes. Moreover, the shape of the grains is irregular form. The effect of reaction time and hematite nanoparticles dosage which affect the efficiency of catalytic reaction was investigated. Catalytic activity of hematite nanoparticles in the degradation of methylene blue (MB) was studied through ultraviolet visible spectroscopy (UV-Vis).

Structural and Morphological Properties of Undoped and Manganese Doped Hematite Nanoparticles Prepared by Ball Milling Method

Hematite nanoparticles of undoped and manganese doped were synthesized from natural sand of Logas District Kuansing Regency Riau Province by ball milling method. Structural and morphological properties of these compounds were studied using X-Ray Diffractometer (XRD) and Scanning electron microscope (SEM) respectively. Crystalline structure, lattice parameters, morphologies of the synthesized compounds were studied and the results are discussed. X-ray diffraction (XRD) confirmed the presence of a hematite (α-Fe2O3) phase. Average crystallite size based on flections (1 0 4) for undoped and manganese doped magnetic iron oxide particles are 39.2 nm and 38.2 respectively. The intensity of (1 0 4) reflection is stronger for magnetic iron oxide synthesized for 60 hours than that of 2 step (60+60) hours ball milling. This indicates the product grown along (1 0 4) direction. The average crystallite size decreases when magnetic iron oxide is doped with 10% Mn as confirmed by SEM images.

Preparation of Iron Oxide Magnetic Nanoparticles Natural Sand of Rokan River Synthesis with Ball Milling

Natural sand samples taken from the Rokan river, Riau Province, Indonesia, have been ball milled for 100 (one hundred) hours using a ball with a diameter of 1.5 cm and a constant rotation angular velocity of the tube of 100 revolutions / minute. Neodymium Iron Boron (NdFeB) strong magnets are used to separate magnetic minerals from their non-magnetic minerals. Magnetic induction was measured using the Pasco PS-2162 probe and its value was used to calculate the magnitude of magnetic susceptibility, it turns out that the magnetic susceptibility value of the 100-hour Ball Milling results increased significantly when compared to the magnetic susceptibility before Ball Milling, 968,245x 10−5 becomes 19.471x 10−5. The results of the X-Ray Fluorescence (XRF) test showed that the percentage of Fe milled increased from 1.669% to 35.187%, the particle size obtained from the scanning electron microscope (SEM) results was in the nanometer order of 78 nm and the X-Ray Difractometer (XRD) results.) shows that the magnetic nanoparticles produced are dominated by the hematite phase (α-Fe2O3) and the others are in the magnetite (Fe3O4) phase..

Deposition of Single Phase Polycrystalline α-Fe2O3 Thin Film on Silicon and Silica Substrates by Spray Pyrolysis

Thin films of polycrystalline single phase α-Fe2O3 have been deposited on single crystal silicon and amorphous silica (silica) substrates by spray pyrolysis technique in a single step using a mixture of water and ferrocene dissolved in xylene. The films have been characterized by X-ray diffraction, scanning electron microscopy and Raman spectroscopy techniques. The uniformity of the grown films was evident from the electron microscopic images on both the substrates. The crystallinity and band gap were investigated using X-ray diffraction and absorption spectroscopy respectively. Raman measurements of the prepared films have been carried out using two excitation wavelengths of 633 nm and 785 nm to investigate the depth of homogeneity of the films. The wavelength dependent Raman measurements reveal that the film is uniform across the thickness of the film on both the substrates.

Multifunctional Green Synthetic Hematite (α-Fe2O3) Nanoparticles Mediated by Camellia Sinensis (Indian Tea Plant) Extracts towards Antioxidant and Antiproliferative Activities against MCF-7 Cell Lines

Among nanoparticles used for medical applications, Camellia Sinensis Nanoparticles (CSNPs) are among the least investigated. This study was undertaken to develop CSNPs by green synthesis using Camellia sinensis tea (Theaceae) plant extract to produce the NPs. The Camellia sinensis, Indian tea plant used from ancient time to increase appetite. Other medicinal uses have also been employed for the synthesis of super paramagnetic α Fe2O3 nanoparticles (NPs). The plant extracts revealed the phenolic groups bifunctional nature and capping nature through the –OH bonding over the nanoparticles (NPs) surface. The prepared nanoparticles (NPs) shows α-Fe2O3 phase among iron oxides and spherical morphology with an average size around 5 nm. The magnetic measurements proved the superparamagnetic behaviour of NPs with non-saturating MS value of 8.5 emu/g at room temperature (300 K). The CSNPs were characterized by UV-V is spectroscopy and X-ray Diffractometry, and evaluated with Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR). The CSNPs were spherical (size 7-20 nm) and contained phenols and flavonoids acquired from the Camellia sinensis extract. CSNPs has good 1-Diphenyl-2-Picrylhydrazyl (DPPH), OH, and NO scavenging properties. MTT assay showed that CSNPs (IC50 = 0.006 μM) were more antiproliferative toward the human MCF-7 cells than the Camellia sinensis tea extract (IC50 = 0.894 μM), Gemcitabin (IC50 = 2.133 μM). The anticancer cell effects of CSNPs on MCF 7 are mediated through the induction of apoptosis and G2/M cell-cycle arrest.

X-Ray Diffraction and Magnetic Properties of Nd Substituted NiZnFe2O4 Characterized by Rietveld Refinement

Solid-state method developed neodymium-doped Ni-Zn ferrites exhibit additional orthoferrite and α-Fe2O3 phases. The change in magnetic properties and lattice parameters are influenced by above mentioned extra phases other than the Nickel-Zinc ferrite spinel structure. Observations indicate that curie temperature, as well as saturation magnetization, reduce with an increase in Neodymium concentration. At the same time, for Nd = 0.02, initial permeability has been slightly increased. This paper explains the reason for these changes in terms of diluted octahedral sites replaced with Nd ions instead of Fe-ions and the number of additional phases that are present.

Formation of New Crystalline Phases upon High-Temperature Annealing of Iron Borate FeBO3 in Different Gas Media

Iron borate FeBO3 crystals are annealed in neutral, oxidizing, and reducing gas media on a specially designed setup. The effect of the chemical medium and annealing modes on the surface morphology and phase composition of the samples is established. It is shown that annealing in a neutral or oxidizing medium leads to the recrystallization of FeBO3 into the hematite α-Fe2O3 phase, whereas annealing in a reducing medium results in the formation of the pyroborate Fe2B2O5 phase and the metal α-Fe iron phase. The difference in the nature of structural transformations is associated with the change in the valence state of iron ions upon annealing in the reducing atmosphere. This result is of interest as a method for the transformation of crystalline phases.

A Facile Route to Synthesis of Ferromagnetic and Antiferromagnetic Phases of Iron Oxide Nanoparticles by Controlled Heat Treatment of Ferritin

Magnetic nanoparticles of ferromagnetic and antiferromagnetic phases were synthesized from controlled heat treatment of dry ferritin powder in a bottom-up approach. Heat treatment paves the way for synthesis of Fe2O3 solid phase from iron molecular complexes stored in the cavity of ferritin; the strong increase (~ 150 times) in saturation magnetization is a sign of the presence of ferromagnetic exchange coupling which exists only in solid phase. In this experimental study, vibrating sample magnetometer (VSM) was used to study magnetic induction. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed for analysis of structure and morphology of the samples. Differential scanning calorimetry (DSC) was used to search for indicators of structural phase transformation through scanning of temperature. The nanoparticle size with highly narrow distribution (mean size ~ 6 nm) was observed by SEM for sample annealed at 430 °C. As indicated by XRD measurements, the majority phase of Fe2O3 nanoparticles was amorphous up to 500 °C, whereas DSC demarcates the crystalline phase transition temperature at 545 °C. The annealing temperature range from 400 to 500 °C was found to be suitable for growing ferromagnetic nanoparticles endowed with high saturation magnetization and low coercivity. At higher range of annealing temperature (500–700 °C), XRD confirms the presence of α-Fe2O3 (haematite) phase which is an antiferromagnetic crystalline system with weak magnetization. A systematic decline of magnetization on increasing the annealing temperature beyond 500 °C was attributed to finite size effects and increased purity of antiferromagnetic phase.

Influence of annealing temperature and electrical conductivity of α-Fe2O3 nanoparticles for Schottky barrier diode

The microwave irradiation route is adopted for synthesizing hematite nanoparticles. The occurrence of different stages in iron oxide nanoparticles due to annealing temperature is validated from its phase transition. The temperature variation for annealing process is made subsequently in this experiment in steps of 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, 800 °C and 900 °C. The formation and deformation of α-Fe2O3 (hematite) phase is identified from this work. The morphology, crystallinity and consistency in particles size are estimated from XRD, SEM and TEM image. The decrease in particle size is due to phase transformation which is identified from 78 to 24 nm. The specified involvement of thermal stability is tested from TGA analysis which is confirmed from phase transition in the XRD. Change in bandgap energy and respective blue shift for less particle sizes are elucidated from UV-DRS and PL spectra. The elemental presence Fe 2p and O 1s spectra indicates the valence states of Fe3+ and O2− from XPS and the VSM results are confirmed according to the increase in saturation and decrease in coercivity tended towards soft magnetic behaviour due to phase transition. The DC electrical conductivity and activation energy are calculated from I–V studies. The Schottky barrier diode parameters of ideality factor (n), barrier height (Φb) and reverse saturation current (I0) is calculated for both dark and light conditions.