Iron Oxide Phases Research Articles

Small iron oxide nanoparticles as MRI T1 contrast agent: scalable inexpensive water-based synthesis using a flow reactor.

Small iron oxide nanoparticles (IONPs) were synthesised in water via co-precipitation by quenching particle growth after the desired magnetic iron oxide phase formed. This was achieved in a millifluidic multistage flow reactor by precisely timed addition of an acidic solution. IONPs (≤5 nm), a suitable size for positive T1 magnetic resonance imaging (MRI) contrast agents, were obtained and stabilised continuously. This novel flow chemistry approach facilitates a reproducible and scalable production, which is a crucial paradigm shift to utilise IONPs as contrast agents and replace currently used Gd complexes. Acid addition had to be timed carefully, as the inverse spinel structure formed within seconds after initiating the co-precipitation. Late quenching allowed IONPs to grow larger than 5 nm, whereas premature acid addition yielded undesired oxide phases. Use of a flow reactor was not only essential for scalability, but also to synthesise monodisperse and non-agglomerated small IONPs as (i) co-precipitation and acid addition occurred at homogenous environment due to accurate temperature control and rapid mixing and (ii) quenching of particle growth was possible at the optimum time, i.e., a few seconds after initiating co-precipitation. In addition to the timing of growth quenching, the effect of temperature and dextran present during co-precipitation on the final particle size was investigated. This approach differs from small IONP syntheses in batch utilising either growth inhibitors (which likely leads to impurities) or high temperature methods in organic solvents. Furthermore, this continuous synthesis enables the low-cost (<£10 per g) and large-scale production of highly stable small IONPs without the use of toxic reagents. The flow-synthesised small IONPs showed high T1 contrast enhancement, with transversal relaxivity (r2) reduced to 20.5 mM-1 s-1 and longitudinal relaxivity (r1) higher than 10 mM-1 s-1, which is among the highest values reported for water-based IONP synthesis.

Revealing a masked Verwey transition in nanoparticles of coexisting Fe-oxide phases.

The attractive electronic and magnetic properties together with their biocompatibility make iron-oxide nanoparticles appear as functional materials. In Fe-oxide nanoparticle (IONP) ensembles, it is crucial to enhance their performance thanks to controlled size, shape, and stoichiometry ensembles. In light of this, we conduct a comprehensive investigation in an ensemble of ca. 28 nm cuboid-shaped IONPs in which all the analyses concur with the coexistence of magnetite/maghemite phases in their cores. Here, we are disclosing the Verwey transition by temperature dependent (4–210 K) Raman spectroscopy.

Nanometer scale insight on the analysis of limpets mineralized teeth: Special focus on the silica-containing regions

We report the electron microscopy-based analysis of the major lateral tooth of the limpet Colisella subrugosa during early and intermediate stages of development. We aimed to analyze the structural relationship among the needle-like crystals of the iron oxide goethite, the amorphous silica phase that forms the tooth base and occupy inter-crystalline spaces in the cusp, and the chitin fibers of the matrix. Goethite crystals followed the three dimensional organization pattern of the chitin fibers in the cusp. In the tooth base, spherical individual silica granules were found in regions where the chitin fibers cross. The spherical granules near the interface between the tooth base and the cusp (junction zone) formed an almost continuous medium that could easily be ultrathin-sectioned for further analysis. By contrast, the nearby silica-rich region localized on the other side of the junction zone contained needle-like goethite crystals immersed in the matrix and presented a conchoidal fracture. The chitin fibers from the silica granules of the tooth base were dotted or undulating in projection with a periodicity of about 6 nm when observed by high magnification transmission electron microscopy. Very thin goethite crystals were present in the base of the cusp near the junction zone surrounded by silica. On several occasions, crystals presented internal thin straight white lines parallel to the major axis, indicating a possible growth around fibers. We propose that silica and iron oxide phases mineralization may occur simultaneously at least for some period and that silica moderates the dimensions of the iron oxide crystals.

High-efficiency, air-stable manganese–iron oxide nanoparticle-pigmented solar selective absorber coatings toward concentrating solar power systems operating at 750 °C

Solar selective absorber coating with long-term thermal stability at high temperatures ≥750 °C in air is an important component to reduce the levelized cost of energy (LCOE) of concentrating solar power (CSP) systems toward 50% power efficiency and dispatchable solar electricity. Conventionally, solar spectral selectivity requires multilayer-interference coatings implemented by stringently controlled vacuum deposition, and these coatings degrade significantly at >700 °C in air. Herein, we established a quantitative design approach and demonstrated a proof-of-concept air-stable, manganese–iron oxide nanoparticle (NP)-pigmented solar selective coatings with a high solar absorptance of ~93%, a relatively low thermal emittance of ~52%, and an optical-to-thermal energy conversion efficiency >89% under 1,000× solar concentration at 750 °C toward Generation 3 CSP systems. These coatings demonstrate spectral selectivity using cost-effective spray coating approach, a notable improvement over conventional vacuum-deposited, multilayer solar selective coatings for low-cost, high-efficiency solar thermal receivers. In contrast to the thermal degradation of spectrally non-selective benchmark Pyromark 2500 coatings at 750 °C in air, the solar absorptance of the MnFe2O4-pigmented coatings on stainless steel 310 (SS 310) substrates is increased to ~92.9% and the optical-to-thermal energy conversion efficiency is improved to 89.7% after serving at 750 °C in air for 700 h. X-ray diffraction results reveal that this improvement is due to the transformation of MnFe2O4 NPs into more thermodynamically stable, non-stoichiometric manganese-rich manganese ferrite and iron-rich manganese–iron oxide phases after 500 h aging at 750 °C. For >1,000 h-endurance testing at 750 °C in air and the subsequent 19 day-night thermal cycling between 750 °C (12 h/cycle) and 25 °C (12 h/cycle) on SS 310 substrates, the thermal degradation is mainly due to the CrOx microflake formation from SS 310 substrates rather than the coatings, which can be suppressed by preoxidizing the surface of SS 310. With lower emittance matrix material and further optimization of pigment NP stoichiometry, concentration, and coating thickness, it is promising to achieve an optimized thermal efficiency ≥92.5% with long-term thermal stability at 750 °C for Generation 3 CSP systems.

Synthesis of molybdenum oxide on AISI-316 steel using cathodic cage plasma deposition at cathodic and floating potential

This study aims to synthesize a molybdenum oxide coating through cathodic cage plasma deposition (CCPD), employing a molybdenum cathodic cage and evaluating both cathodic and floating potentials treatment. Structural, morphological, and wear properties of coated AISI 316 samples are investigated by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, Rockwell-C adhesion test, and ball-on-disc wear tester. Cathodic potential treatment results in a coating containing agglomerated nanostructures (spherical nanoparticles) composed by molybdenum oxide (MoO3), iron-oxide (Fe2O3), Fe2Mo3 and Fe3Mo phases. The coating generated by floating potential mainly contains molybdenum oxide (MoO3) phase and shows homogeneously dispersed microplatelets with quite a regular shape. The Rockwell-C adhesion test showed that the layers on both samples exhibit good adhesion strength with the substrate. The samples treated at floating potential reveal better wear resistance and lowest/smooth friction coefficient. This shows that molybdenum oxide coating by CCPD using floating potential can be used as a solid lubricant in tribological applications.

Crystalline iron oxides stimulate methanogenic benzoate degradation in marine sediment-derived enrichment cultures

Elevated dissolved iron concentrations in the methanic zone are typical geochemical signatures of rapidly accumulating marine sediments. These sediments are often characterized by co-burial of iron oxides with recalcitrant aromatic organic matter of terrigenous origin. Thus far, iron oxides are predicted to either impede organic matter degradation, aiding its preservation, or identified to enhance organic carbon oxidation via direct electron transfer. Here, we investigated the effect of various iron oxide phases with differing crystallinity (magnetite, hematite, and lepidocrocite) during microbial degradation of the aromatic model compound benzoate in methanic sediments. In slurry incubations with magnetite or hematite, concurrent iron reduction, and methanogenesis were stimulated during accelerated benzoate degradation with methanogenesis as the dominant electron sink. In contrast, with lepidocrocite, benzoate degradation, and methanogenesis were inhibited. These observations were reproducible in sediment-free enrichments, even after five successive transfers. Genes involved in the complete degradation of benzoate were identified in multiple metagenome assembled genomes. Four previously unknown benzoate degraders of the genera Thermincola (Peptococcaceae, Firmicutes), Dethiobacter (Syntrophomonadaceae, Firmicutes), Deltaproteobacteria bacteria SG8_13 (Desulfosarcinaceae, Deltaproteobacteria), and Melioribacter (Melioribacteraceae, Chlorobi) were identified from the marine sediment-derived enrichments. Scanning electron microscopy (SEM) and catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH) images showed the ability of microorganisms to colonize and concurrently reduce magnetite likely stimulated by the observed methanogenic benzoate degradation. These findings explain the possible contribution of organoclastic reduction of iron oxides to the elevated dissolved Fe2+ pool typically observed in methanic zones of rapidly accumulating coastal and continental margin sediments.

New sol-gel-derived magnetic bioactive glass-ceramics containing superparamagnetic hematite nanocrystals for hyperthermia application

Although the three main phases of iron oxide – hematite, maghemite, and magnetite – exhibit superparamagnetic properties at the nanoscale, only maghemite and magnetite phases have been explored in magnetic bioactive glass-ceramics aimed at applications in cancer treatment by hyperthermia. In this work, it is reported for the first time the superparamagnetic properties of hematite nanocrystals grown in a 58S bioactive glass matrix derived from sol-gel synthesis. The glass-ceramics are based on the (100-x)(58SiO2-33CaO-9P2O5)-xFe2O3 system (x = 10, 20 and 30 wt%). A thermal treatment leads to the growth of hematite (α-Fe2O3) nanocrystals, conferring superparamagnetic properties to the glass-ceramics, which is enough to produce heat under an external alternating magnetic field. Besides, the crystallization does not inhibit materials bioactivity, evidenced by the formation of calcium phosphate onto the glass-ceramic surface upon soaking in simulated body fluid. Moreover, their cytotoxicity is similar to other magnetic bioactive glass-ceramics reported in the literature. Finally, these results suggest that hematite nanocrystals' superparamagnetic properties may be explored in multifunctional glass-ceramics applied in bone cancer treatment by hyperthermia allied to bone regeneration.

High performance of δ-Fe2O3 novel photo-catalyst supported on LDH structure

A new photocatalyst δ-Fe2O3/MgAl-LDH elaborated by impregnation method with a different iron amount (2, 5, 10 and 20 wt.%) were used to improve the photocatalytic activity of δ-Fe2O3 under visible light. The synthesized samples were characterized by XRF, XRD, SEM, ATG/DSC, RDs and FTIR techniques. Structural studies revealed the formation of layered double hydroxyl structure (LDH) for unmodified materials and the existence of the iron oxide phase with allotropic δ for the modified material. The reconstruction of calcined LDH by the structural memory effect was verified by XRD. Optical studies confirmed the narrower band gap energy suitable for the visible light absorbance. The effect of iron loading, photocatalyst dose, dye concentration and pH were examined to enhance the photodegradation of methylene blue. The degradation rate over δ-Fe2O3/MgAl-LDH calcined at 400, 500 and 600 °C was also discussed. Under visible irradiation, the photocatalysts exhibited an efficient photoreactivity where the removal values increasing from ∼ 19 to 60% upon increasing the% δ-Fe2O3 amount from 2 to 10%. Whereas, using MB concentration of 50 mg/L and a catalyst amount of 0.5 g/L, the photocatalyst with the% δ-Fe2O3 of 10% shown only a yield 67%. The prepared photocatalyst exhibited better reactivity compared to the MgAl-LDHc (less than 10%) and to the iron oxide (26%). A path of degradation based on a mechanism of hollow radicals is proposed.

Microwave-assisted reduction roasting—magnetic separation studies of two mineralogically different low-grade iron ores

The microwave-assisted reduction behaviours of two low-grade iron ores having a similar Fe content of 49wt% but distinctly different mineralogical and liberation characteristics were studied. Their performances in terms of the iron grade and recovery as obtained from statistically designed microwave (MW) roasting followed by low-intensity magnetic separation (LIMS) experiments were compared. At respective optimum conditions, the titano-magnetite ore (O1) could yield an iron concentrate of 62.57% Fe grade and 60.01% Fe recovery, while the goethitic ore (O2) could be upgraded to a concentrate of 64.4% Fe grade and 33.3% Fe recovery. Compared with the goethitic ore, the titano-magnetite ore responded better to MW heating. The characterization studies of the feed and roasted products obtained at different power and time conditions using X-ray diffraction, optical microscopy, vibrating-sample magnetometry, and electron-probe microanalysis explain the sequential reduction in the iron oxide phases. Finally, taking advantage of the MW absorbing character of the titano-magnetite ore, a blend of the same with the goethite-rich ore at a weight ratio of 60:40 (O2: O1) was subjected to MW roasting that resulted in a concentrate of 61.57% Fe grade with a Fe recovery of 64.47%.

Thermodynamics of Chemical Processes in the System of Nanocrystalline Iron–Ammonia–Hydrogen at 350 °C

Nanocrystalline iron nitriding and the reduction of nanocrystalline iron nitrides in steady states at 350 °C are described using the chemical potential programmed reaction (CPPR), thermogravimetry (TG), 57Fe Mössbauer spectroscopy (MS), and X-ray diffraction (XRD) methods. It was determined that during the process of nitriding of nanocrystalline iron, larger nanocrystallites formed the γ’ phase and the smallest nanocrystallites (about 4%) were transformed into the α” phase. Both phases were in chemical equilibrium, with the gas phase at the temperature of 350 °C. Stable iron nitride α” was also formed in the ε iron nitride reduction process. Taking the α” phase in the system of nanocrystalline Fe-NH3-H2 into account, it was found that at certain nitriding potentials in the chemical equilibrium state, three solid phases in the nitriding process and four solid phases in the reduction process may coexist. It was also found that the nanocrystallites of ε iron nitride in their reduction process were transformed according to two mechanisms, depending on their size. Larger nanocrystallites of iron nitride ε were transformed into the α-iron phase through iron nitride γ’, and smaller nanocrystallites of ε nitride went through iron nitride α”. In the passivation process of nanocrystalline iron and/or nanocrystalline iron nitrides, amorphous phases of iron oxides and/or iron oxynitrides were formed on their surface.

Surface Modification of Magnetic Mesoporous Systems with Aminopropyl Groups and Their Properties

Iron oxide silica FexOy-SiO2 composite systems with aminopropyl (AP) groups on the surface have been synthesized via different routes. The surface modified samples have been studied by X-ray diffraction (XRD) analysis and IR spectroscopy. Magnetic phases of iron oxides have been detected after post-synthetic grafting of AP groups onto the surface of these composite systems. Magnetic properties of these samples have been determined. Only insignificant reduction in the material saturation magnetization and remanent magnetization have been registered upon surface grafting procedure. This approach has been considered to be successful as magnetic properties of the substrate were preserved. Amount of aminoalkyl groups grafted onto the silica composite surface has been determined by thermogravimetric analysis. The mass fraction of grafted aminoalkyl groups has been found to be dependent on the textural properties of the composite sample.

Effect of the phase composition of iron oxide nanorods on SO2 gas sensing performance

α-FeOOH nanorods were synthesized by a facile precipitation method. γ-Fe2O3 and α-Fe2O3 nanorods were then obtained by calcining for 6 h at 200 and 600 °C in ambient air, respectively. A mass-type sensor was developed based on the different iron oxide phase compositions of α-FeOOH, γ-Fe2O3 and α-Fe2O3 coating a quartz crystal microbalance (QCM). The gas sensing properties of three as-prepared sensors were systematically examined for detecting sulphur dioxide gas (SO2) at room temperature. The effect of phase composition of iron oxide nanorods on sensing properties was also discussed. Although as-prepared iron oxides have a similar morphologic structure, the sensor based on γ-Fe2O3 exposes the highest response to SO2. The sensing results show that the γ-Fe2O3 coated QCM sensors had an extremely good performance for SO2 gas in the 2.5–20 ppm range at room temperature.

Obtaining TiO&lt;sub&gt;2&lt;/sub&gt; and Fe&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; from Ilmenite via Alkaline Fusion Method

Tin mining business in Malaysia produce many types of by product such as xenotime, monazite, zircon and ilmenite. Ilmenite is one of the crucial materials that helps the growth of economy in Malaysia. Instead of that, ilmenite becomes an important material in the process of oxygen carrier where it shows a better compare to the other such as olivine, hematite, biotite and cuprite. Incredible mechanical resistance and good thermal properties are playing an important factor for the materials that been used for oxygen carrier and ilmenite is the most suitable material for oxygen carrier process. Instead of its suitable properties, ilmenite also one of the lowest price materials among natural minerals sources. Ilmenite composition can provide titanium dioxide (TiO2) which can be used in many industries such as painting and iron oxide (Fe2O3 or Fe3O4) for catalytic and magnetic industries. TiO2 can be found in three phases which are anatase, rutile and brookite. In order to obtain TiO2, dissolution – precipitation mechanism where titanium arranges into different crystal structure depending on the reactant chemistry. These phase formations were obtained by using hydrothermal treatment at elevated temperatures with the appropriate reactants. The transition temperature and the mechanism of the structural transformation also can be largely influenced the iron oxide phase. Therefor in this study, extractive metallurgy method was used in order to obtain separate TiO2 and Fe2O3.

Impact of Gadolinium on the Structure and Magnetic Properties of Nanocrystalline Powders of Iron Oxides Produced by the Extraction-Pyrolytic Method.

Interest in magnetic nanoparticles is primarily due to their practical use. In this work, for the production of nanocrystalline powders of pure and gadolinium doped iron oxides, the extraction-pyrolytic method (EPM) was used. As a precursor, either iron-containing extract (iron (III) caproate in caproic acid) or its mixture with gadolinium-containing extract (gadolinium (III) valerate in valeric acid) was used. The mixed precursor contained 0.5 mol %, 2.5 mol %, 12.5 mol %, 50 mol %, and 75 mol % gadolinium in relation to the iron content. The formation of iron oxide phases, depending on the preparation conditions, was investigated. According to the results obtained, it was demonstrated that the presence of more than 2.5 mol % gadolinium additive in the mixed precursor inhibits the magnetite-to-hematite transformation process during thermal treatment. Produced samples were characterized by XRD and SEM methods, and the magnetic properties were studied.

A new hydrous iron oxide phase stable at mid-mantle pressures

The amount of hydrogen stored in the Earth's interior is important for a range of issues, including the volatile incorporation during the Earth formation and the co-evolution of the atmosphere, the hydrosphere, and the interior. Recent experiments found titanium bearing ε-FeOOH in a hydrous basaltic system at 12–19 GPa and 1300 K. Pyrite-type FeOOH was found to be stable at pressures higher than 80 GPa. These discoveries suggest possible hydrogen storage in the mantle transition zone and in the mantle below 1800 km depths, respectively. However, it remains uncertain how the potential deep hydrogen storage can be connected to the shallower storage. Here, we report a new hydrous iron oxide (η-Fe12O18+x/2Hx, x≈2) stable at pressures between the stability fields of the ε- and the pyrite-type FeOOH. Our experiment also shows that the new η phase can exist together with the major lower mantle minerals including bridgmanite and periclase, making it an important hydrogen-bearing phase in the Earth's deep interior. Because of its limited H2O storage capacity, which is less than 1/6 of the storage capacity of the pyrite-type phase and the ε phase, the stability of the η phase would result in H2O loss during water transport in the mid mantle and therefore limit the amount of H2O potentially stored in the Fe–O–H system of the lower mantle. The large channel in the crystal structure of the η phase could provide potential storage sites for other volatile elements in the deep mantle.

Investigation of Structural Phase Conversions of an Iron-Containing Catalyst by Mossbauer Spectroscopy (Part 1)

The active form of an iron-containing catalyst, an Fe(II, III) mixed oxide, was studied by Mossbauer spectroscopy in order to identify the mechanism of formation of catalysts used for upgrading of heavy oil from Ashalchinsk field. The iron-oxide phase participates in the formation process by breaking carbon–heteroatom bonds in high-molecular-mass components (resins and asphaltenes) of heavy oil and reduces their molecular mass. Thus, the disperse iron oxides are enriched in a sulfur-containing phase. Mathematical processing of Mossbauer spectra obtained during the experiment was used to study the quantitative composition of the products of thermocatalytic action at 300°C. Magnetite (Fe3O4), greigite (Fe3S4), pyrite (FeS2), and pyrrhotite (Fe1–xS) were mainly detected in the isolated catalysts. The magnetite content decreased toward formation of iron sulfides (pyrite and pyrrhotite). Hydrogen sulfide and hydrocarbons were formed as a result of cracking, hydrolysis, and hydrogenolysis reactions at 300°C.

A Preliminary Study on the Roles of Fe Content and Neoformed Ca-rich Minerals in the Coloration of Ceramic Glazes

Iron oxides are the essential coloring oxides in traditional ceramic glazes. However, when Fe is involved in the coloration in the form of ions or colloids in glazes with low Fe content, it is difficult to identify the iron oxide phases. Generally, in many these glazes, Ca-rich minerals are observed by X-ray diffraction (XRD) or microscopic images, owing to their devitrification by the high Ca content. This study attempts to elucidate the correlation between the crystalline structure and coloration in the glazes while mainly focusing on neoformed Ca-rich minerals and Fe content. An experimental firing was carried out to produce tree ash glazes, with pine tree ash and Buyeo feldspar. In the case of oxidation glazes, the scanning electron microscopy (SEM) images and XRD patterns did not exhibit any Ca-rich crystals, and all the visible light reflectance spectra lines exhibited a similar shape. In contrast, the reduction glazes divided into blue glazes and other colored glazes according to the shapes of their reflectance spectra. It was confirmed that the influence of Ca-rich minerals on the glaze color was more pronounced than the blue color of the reduction glazes when the Ca and feldspar contents were sufficiently high and low, respectively, to form wollastonite. As the Ca content increased and the elemental composition of the reduction glazes changed, the neoformation of the Ca-rich minerals, such as wollastonite, anorthite, diopside, and akermanite was sequentially observed.

Crystal phase determined Fe active sites on Fe2O3 (γ- and α-Fe2O3) yolk-shell microspheres and their phase dependent electrocatalytic oxygen evolution reaction

Transition metal oxide nanomaterials have been extensively applied to the field of oxygen evolution reaction (OER), but few works have been studied to demonstrate the relationship between their crystal phases and OER performance. Herein, we compare the OER performance of the two different crystal phase iron oxide (α-Fe2O3 and γ-Fe2O3). The iron oxide yolk-shell microspheres were facile realized via one-step solvothermal method and the subsequent annealing treatment. An interesting phenomenon is present that α-Fe2O3 yolk-shell microspheres with a smaller specific surface area have better OER performance than that of γ-Fe2O3 yolk-shell microspheres. The crystal structure and X-ray photoelectron spectroscopy (XPS) results show that α-Fe2O3 yolk-shell microspheres have better electrocatalytic activity, which is due to the presence of more Fe active sites (Fe3+) exposured on the surface. These Fe active sites are beneficial to enhance the adsorption of hydroxyl groups in water molecules, leading to a higher OER performance. As an application example, the Fe2O3 yolk-shell microspheres are employed as an efficient OER electrocatalyst, showing the interdependence between phase and OER behavior.

Mineralogical study of archaeological copper slags found in the area of Krushevets Village, SE Bulgaria

In this article, we present the results of our study on archaeological slags found near the village of Krushevets, Southeast Bulgaria. Chemical analyses of the slags show a high Fe2O3 (40.11–54.57%) and SiO2 (29.32–42.28%) content, increased CaO content (3.01–6.51%), as well as very low quantity of SO3 (from 0.20% to 0.52%) and P2O5 (between 0.23% and 0.30%). The unbound residual copper in the samples is in an amount of 0.41% to 1.07%. The main phases composition of the slags are as follows: fayalite-type silicate phases with impurities, kirschsteinite and laihunite; pyroxenes of the augite-type and amorphous hosted glass; iron-oxide phases (magnetite and maghemite); and copper-containing phases (drops of unbound copper, relicts of ore minerals such as bornite, chalcopyrite), as well as newly formed phases, such as chalcocite, and copper-containing spherical aggregates. The studied samples are a by-product of copper extraction metallurgical activity. The raw material used was of copper-sulfide type with impurities of manganese-, calcium-, magnesium- and aluminium-containing minerals.

Influence of precursor concentration and deposition temperature on the photoactivity of hematite electrodes for water splitting

Hematite nanoparticles were synthesized using chemical spray pyrolysis. Precursor concentrations of 30, 40, and 50 mM, deposition temperatures of 250, 340, and 400 °C were used. X-ray diffraction measurements confirmed the purity of hematite with no other phases of iron oxide. The (104) and (110) diffraction peaks associated with corundum structure of hematite were revealed in all the prepared thin films. The rhombohedral unit cell with space group R3¯C and average lattice constants, a = 5.042 Å and c = 13.673 Å were achieved. Scanning electron microscopy measurements obtained surface morphology of different grain sizes that ranged from 7 to 33 nm. From the UV–vis measurements, bandgaps that ranged from 2.10 to 1.92 eV for all films prepared at different precursor concentrations and temperatures were obtained. Photocurrent densities that ranged from 0.78 to 89 μA cm−2 were obtained for different precursor concentrations and deposition temperatures thin films. Further, all the samples had a donor density of 1018 cm−3 with a positive flat band potential in the range of 0.045 and 0.213 V.