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In this study, novel iron-based spiky microparticles (approximately 1–2$\mu$m in diameter) were synthesized using iron oxalate precursors using a straightforward one-step hydrothermal reaction. The microparticles’ morphological, mineralogical and chemical properties were investigated using scanning electron microscopy (SEM), X-ray diffractometry (XRD), Raman spectroscopy and UV-Vis spectroscopy. The physico-chemical characteristics of spiky microparticles were also compared with cubic iron microparticles synthesized using standalone iron as well as with the addition of glycine. XRD and Raman analyses identified substantial presence of humboldtine, a type of ferrous oxalate dehydrate mineral, in the resultant yellowish solid hydrothermal product. The mechanism involving reactions of species in the hydrothermal process was described herein. The results described in this study afford vital insights into the design of iron oxalate-based microparticles synthesis processes.

The decomposition of goethite and goethite/siderite concentrates into hematite with thermal modification was studied through the measurements of X-ray diffraction (XRD), scanning electronic microscope (SEM) and thermal gravimetric analysis (TGA). The experimental results showed that goethite decomposed into hematite directly at around 300°C without any intermediate phase and the decomposition of siderite completed at 500°C. Nanoscale granular structures were observed in the thermally treated products. It deserves highlighting that the decomposition processes proceeded from surfaces into bulks.

Investigation of the role of hydrothermal temperature on hematite nanoparticles structural, magnetic, and ferromagnetic resonance (FMR) properties was done. Ferric chloride and sodium hydroxide were used as the starting precursors. The hydrothermal temperature was varied in the range of 140–200^∘C by a step of 20^∘C. XRD, SEM, VSM, and FMR analyses were used to check the particles’ properties. The prevailing strongly phase was hematite with some small peaks related to other phases. A reduction in lattice constant and increase in the crystallite size to more than 27nm is observed. The particles’ morphology exhibited polygon particles down to spherical particles as the average particle size gets larger up to 45nm. The hysteresis loops showed unsaturated curves with rising coercivity up to 150Oe. The antiferromagnetism permeability, magnetization saturation, and dipole moment were found by Langevin fitting to the experimental hysteresis loops, where all of them have the same behavior represented by an initial drop followed by increase in their values. The FMR spectra are characterized by low intensities and low linewidths accompanied by very low blue shift in the resonance field. All samples showed Lorentzian distribution as checked by the Lorentz function. Landé $g$-factor has values very close but less than 2 due to the effect of crystal field and particle magnetic moment variations.

α-Fe₂O₃ nanoparticles were obtained by a mechanical alloying of micrometer-sized powder at different milling times. Samples were characterized by X-ray powder diffraction, scanning electron microscope (SEM), Mössbauer spectrometry, and vibrating sample magnetometer (VSM). A qualitative and quantitative phase analyses using the Rietveld method have been performed based on the XRD data. The results did not reveal any phase change during the milling. The average particle size decreases with a prolongation of milling times, while the lattice parameters, unit cell volume, and microstrain increase. Mössbauer measurement shows that there are two components, one nanometric and other micrometric. The magnetic hysteresis loops shows that the samples are typical of ferromagnet with superparamagnetic fraction in the material.

Web-like carbon nanotubes were synthesized via Laser Ablation Deposition (PLAD) in a T-shape stainless steel chamber. An Nd-YAG laser with a 532 nm wavelength was used to irradiate a target of graphite and a catalyst, with a 5–7 ns pulsed width. Fe₂O₃ was used as a catalyst to produce a reactive graphite target. The vacuum level was kept at 5 Torr with argon gas flowing from the bottom of the chamber. The plume that was deposited on a glass substrate was then characterized using a Scanning Electron Microscope (SEM), Energy Dispersive X-ray (EDX) analysis, a Transmission Electron Microscope (TEM), and a Vibrating Sample Magnetometer (VSM). Web-like CNT structures were deposited on the glass substrate. These web-like structures were randomly aligned with sizes of 99 nm to 234 nm. TEM images confirmed that these web-like structures were CNTs. VSM results showed that the encapsulation of the Fe₂O₃ catalyst had influenced the magnetic properties of the CNTs. The magnetic property of CNTs was increased with the increasing amount of the Fe₂O₃ catalyst filling the CNTs. We assert that the starting catalyst material was transformed from hematite to magnetite via maghemite by a structural change under a reduced oxygen atmosphere during the laser ablation.

This work presents an important analysis and comparative study between two organic waste rhodamine B (RhB) and methyl orange (MO) dyes as pollutant models degeneration under sunlight. Hematite ($\alpha$-Fe₂O₃) nanorods were synthesized and deposited on glass substrates using an efficient and simple one-step hydrothermal method. The nanorods were characterized by XRD, FESEM, EDX, and UV–Vis equipment. The photodegeneration parameters of $\alpha$-Fe₂O₃ films were calculated by modeling the photodegradation of MO and RhB dyes as pollutants under sunlight irradiation for 150min. Results revealed that the degradation efficiency of $\alpha$-Fe₂O₃ films of MO and RhB dyes was 72.7% and 91.9%, respectively. The optimized photocatalyst degraded RhB more efficiently than the MO solution.

α-Fe₂O₃ nanoparticles have wide-ranging applications such as in catalysis, sensoring, painting, etc. This is the reason to study their controlled synthesis. Here we have investigated the synthesis of uniform α-Fe₂O₃ nanoparticles using amino acids as morphology control agents. The products were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetry (TG) and differential thermal analysis (DTA). It was found that the type and the amount of amino acids as well as the reaction temperatures have significant influence on the shape and size of the obtained α-Fe₂O₃ nanoparticles. The use of acidic amino acids (always contain C=O in the side chain) typically leads to the formation of α-Fe₂O₃ nanoparticles with spindle shape. However, rhombohedrally shaped α-Fe₂O₃ nanoparticles were formed in presence of basic amino acids (always contain -NH₂ in the side chain). Increasing the amount of amino acid generally results in α-Fe₂O₃ nanoparticles with decreasing particle sizes.

In this work, highly uniform single crystal Fe₂O₃ nanorods have been synthesized by a facile hydrothermal method in the presence of dihydrogen phosphate ions. Phosphate ions were speculated capping to the sidewalls of Fe₂O₃ nanocrystals, and resulted in the anisotropic growth of hematite crystals along their [006] zone axis. Fe₂O₃ nanorods with various aspect ratios have been realized by applying different phosphate concentration of 0.1–0.4mM. The electrochemical properties of Fe₂O₃ nanorods showed that the samples with the smallest aspect ratio possessed superior specific capacitance and stability. It was speculated that the larger specific area of the Fe₂O₃ nanorods with the shortest axial length facilitated the efficient access of electrolyte ions to the electrode surface, and thus would aid in delivering the high pseudocapacitance. These results provide a promising route to obtain the desired hematite-based energy storage materials.

Pt-treatment and oxygen vacancies incorporation as effective strategies had been extensively used to improve the photoelectrochemical (PEC) water splitting performance of hematite. Herein, by coupling Pt-decoration and oxygen vacancies incorporation through a facile solution route, an efficient hematite photoanode for PEC water splitting was fabricated. PEC measurements indicated that the photocurrent density was increased from 0.80 mA/cm² at 1.23 V versus RHE for the pristine Fe₂O₃ film to 1.15 mA/cm² at 1.23 V versus RHE for the co-modified sample. Based on various characterizations, this improvement could be attributed to the cumulative effect of Pt-decoration and oxygen vacancies incorporation, in which the incorporation of oxygen vacancies could increase the donor density and consequently promote the charge transport in the bulk hematite, while the excellent electrical conductivity of Pt was beneficial for facilitating the charge transfer across hematite/electrolyte interface. This study provides a feasible approach for the development of high-performance hematite photoanodes.

In this study, we report the successful preparation of hematite nanostructures coated with thin titania layer for potential solar water splitting applications. The prepared samples were studied systematically by a range of analysis techniques. We showed that resulting hybrid hematite-titania nanosystem exhibited improved photoelectrochemical activity for solar water splitting compared to the bare hematite only. We also showed that this enhancement was achieved through an improvement in light harvesting and better charge carrier separation. Thus, these findings may open new perspectives for the development of photoelectrodes used in photoelectrochemical water splitting applications.

The dry sliding wear behaviour of cast aluminium reinforced with hematite was investigated by means of pin-on-disc wear testing machine. The composite specimens were prepared using liquid metallurgy technique. Wear rates of the composites varying from 0 to 5 % by weight hematite were measured over a load range of 9.81 to 49.05 N at sliding velocities of 1.35,1.8 and 2.25 m / sec. Detailed scanning electron micrography (SEM) was done to verify the effect of addition of hematite on wear mechanism with and without heat treatment. Observations indicate that wear rate of the composites was less than that of the matrix alloy, but increased with the increase in load and the sliding velocity. Heat treatment at 220-degree centigrade upto 5 hours in steps of 2 hours duration improves the wear resistance of the composites.

The resource of iron ore in our country is relatively deficient. It can not meet the demand of economic development. Every year, large amount of iron ore is imported to meet the demand of metallurgy production. The grade of iron ore in our country is relatively low. Most of the iron ore need to be enrich, so that it can satisfy metallurgy ironmaking production. During the beneficiation process, the resource utilizing level is low. And the grade is high in milltailings. And the recovery rate of metal is low. Especially, the grade of hematite in milltailings is 11—20%. Therefore, reducing grade of tailings is one approach of increasing resource utilizing level. This article analyses the grade factor that the concentrator impacts tailings. Presents a measure to reduce the grade in tailings.

The interactive effect of siderite and hematite and its mechanism were investigated through flotation tests, dissolved components logarithm diagram, calculations of EDLVO theory and SEM. The results of flotation test show that the hematite recovery can be declined in some degree by adding various particle fractions of siderite, which the reason is that some collector will be consumed by various particle fractions of siderite, what's worse, the HCO₃^- and CO₃^2- dissolved from siderite can compete with oleate ions on the surface of hematite. In addition, the recovery of fine siderite can be improved by adding hematite. Calculations of EDLVO theory and SEM indicate that some part of the fine grade siderite cover on the surface of hematite after the addition of coarse hematite, as a result, the apparent grain size of fine siderite as well as the possibility of adhesion between fine siderite and bubble are incresed, what's more, the environment of flotation is optimized as well.