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Spray pyrolysis at various temperatures was employed to produce non-crystalline and crystalline iron oxide (α-Fe 2 O 3) thin films on glass. The amorphous and crystalline characteristics of α-Fe 2 O 3 thin films were affirmed via X-ray diffraction analysis. With low deposition times (5 min) and at various substrate temperatures, iron oxide seems almost in a non-crystalline structure. As for the increase in deposition time (40 min), the crystallinity's degree was enhanced. According to Tauc's law, the direct gap energy E d for both the amorphous and the crystalline phases, were found to be 1.95 and 2.125 eV, respectively. Moreover, the indirect gap energy, E in = 1.65 and 1.71 eV were obtained for the amorphous phases and the crystalline phases, respectively. The linear and non-linear optical features of amorphous and crystalline structure were meticulously and adaptably detailed. It is observed that the behavior of the refractive index n (λ) and extinction coefficient k (λ) of the crystalline state was lower than that of the amorphous state. The real and imaginary linear dielectric constant and also the thin film quality factor were estimated for both the amorphous and crystalline states as well as the volume and surface energy loss functions for the crystalline and amorphous states. In conclusion, amorphous and crystalline α-Fe 2 O 3 nanocrystalline films improved their optical properties, making them potential candidates for multifunctional applications such as optoelectronics and spintronics electronics devices. [ABSTRACT FROM AUTHOR]

Iron oxide (Fe 2 O 3) thin films have been prepared starting from iron chloride (FeCl 3) precursor by spray pyrolytic decomposition of FeCl 3 on an ordinary glass substrate at 450 °C. The precursor concentration (C) has been varied from 0.06 to 0.3 mol l−1 keeping the other deposition parameters fixed. The (C) effect on the structural, optical and electrical properties has been studied. The XRD analysis shows that Fe 2 O 3 thin film has a rhomboedric structure with (104) plane as preferential orientation. A degradation of crystallinity followed by a change in plan orientation from (104) to (110) has been observed, when (C) has been raised to 0.2 mol.l−1.The optical transmittance spectrum shows that T(λ) decreases at higher precursor concentration. Optical band gaps w decreased from 2.21 to 2.08 eV for direct transition and from 2.03 to 1.99 eV for indirect transition when (C) increases from 0.06 to 0.3 mol l−1. The extinction coefficient (k) and refractive index (n) were also has been estimated and studied. The films deposited with C = 0.14 mol l−1 has shown the maximum mobility of 62 cm2 V−1.s−1 at room temperature. All physical properties of Fe 2 O 3 thin films investigated in this work were strongly dependent upon the precursor concentration. The obtained results provide valuable information about structural, optical, photoluminescence and electrical properties of sprayed Fe 2 O 3 , which is a very helpful issue for better understanding and perfection of the semiconductor quality for the optoelectronic application. • Iron oxide thin films were grown successfully on glass substrate by chemical spray pyrolysis technique. • Precursor concentration effects were investigated. • Structural, optical and electrical properties were studied. [ABSTRACT FROM AUTHOR]

The (WO 3 ) 1−x –(Fe 2 O 3 ) x (0 ≤ x ≤ 1) nano-particle thin films with various compositions have been deposited onto the fluorine thin oxide (FTO) coated glass substrate using sol-gel, spin-coating technique. An electrode/electrolyte interface has been formed between an n-type (WO 3 ) 1−x –(Fe 2 O 3 ) x composite semiconductor and a 0.5 mol L −1 Na 2 SO 4 aqueous solution. The photo-catalytic activity of the films has been investigated through the photocurrent-voltage. UV-visible spectroscopy, SEM and XRD have been used to characterize solar absorption, surface morphology and the crystallinity of samples, respectively. The photo-electrochemical (PEC) experiments were performed under solar irradiation to evaluate the amount of electron-hole generation in different samples. All the composite nano-particles indicated higher efficiency compared to pristine iron and tungsten oxides. A clear relationship was also confirmed between band gap energy and photo-catalytic activity of thin films. The band-gap energy of mixed thin films decreased linearly with the increasing Fe 2 O 3 content in the film samples. The maximum photocurrent density of 2.34 mA cm −2 has been obtained for sample with x = 0.25 at 1.4 V vs. RHE. The result revealed that the sample also has the highest photon-to-current efficiency (0.87%), and solar absorption. [ABSTRACT FROM AUTHOR]

Abstract: This paper deals with the structural properties of FeTe2 thin films obtained using a simple and non-toxic experimental procedure. First, iron oxide thin films have been prepared by the spray pyrolysis technique from an aqueous solution containing FeCl3 6H2O (0.03M) as a precursor onto glass substrates heated at 623K. Second, these films were subjected to a heat treatment under tellurium atmosphere at various temperatures (723–803K) for 24h. XRD analysis revealed that FeTe2-ortorombic phase films were obtained at a heat treatment of the order of 773K. This film has a good crystalline state with a preferential orientation of the crystallites along (111) direction. Moreover, AFM as well as SEM morphological observations show a relatively perturbed surface state. To date, this simple and low cost route process to obtained FeTe2 thin films has not yet been used. [Copyright &y& Elsevier]

• FeO-Fe 3 O 4 composite 111-oriented films are grown at room temperature under 10−5 Pa. • metal-oxide composite films are epitaxially grown at room temperature from a Fe target. • Fe film grown at room temperature under vacuum shows a rectangle on hexagon epitaxy. Magnetite (Fe 3 O 4) and wustite (FeO) are well-known oxides for their promising magnetic properties. However, growing stable FeO x thin films with controlled iron oxidation states could be of interest for further applications. In this work, we highlight the formation of different FeO x -based thin films grown by pulsed-laser deposition (PLD) from Fe or α-Fe 2 O 3 targets onto sapphire substrates. Based on X-ray diffraction and Rutherford backscattering spectroscopy analyses, we report on films with various O/Fe ratios obtained by controlling both the substrate temperature and the oxygen pressure in the 10−5 – 10 Pa range during the PLD growth. Thus, the different crystalline phases of the Fe-O system can be grown: metallic iron, α-Fe 2 O 3 , Fe 3 O 4 , and the thermodynamically metastable phase FeO. On one hand, we demonstrate that at low pressures (< 10−4 Pa) metal-oxide composite thin films with both metallic Fe and Fe 3 O 4 phase are epitaxially grown on the sapphire substrates even at room temperature. On the other hand, we highlight that using a α-Fe 2 O 3 target, films composed with a mixture of wustite and spinel phases have been obtained at room temperature. The precise growth conditions leading to the formation of FeO-based films or metal-oxide composite films are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Iron oxide (α-Fe2O3) films were prepared in isopropyl alcohol with the addition of different concentrations of acetic acid (AcOH). The agglomeration properties of nano-particulated iron oxides and hydroxides precipitated from isopropyl alcohol–water solutions differ from those obtained by precipitation from aqueous solution. Subsequent aging of the precipitated oxides and hydroxides in a weak solution of acetic acid modifies their micro/nanostructure. X-ray diffraction and scanning electron microscopy results demonstrate that use of an isopropyl–water reaction medium produces a material with improved dispersion behavior. The homogeneity of films prepared from the reaction products aged in acetic acid (AcOH) shown to depend on the concentration of acetic acid employed. Increasing concentration of AcOH promotes the coarsening of the nanoparticles and the porosity reduction. Optical spectroscopy analysis indicates that band gap of the materials is ∼2.16eV, which expected for α-Fe2O3. The crystal structure, morphology and optical absorption studies confirm that it is an efficient method to produce high quality iron oxide films. [Copyright &y& Elsevier]

Abstract: In this work, iron films were deposited on fluorine-tin-oxide coated glass substrate using radio frequency sputtering. Self-oriented iron oxide nanorod array thin films were obtained by anodizing the sputtered films. Anodization was carried out in an ethylene glycol solution containing 0.1 M NH4F and various content of water. We studied the mechanism of anodization of iron thin films, and investigated the effects of some parameters on the properties of the iron oxide thin films. Nanorod-like structures were observed from cross-sectional field-emission scanning electron microscope images. The size of the pores between the nanorods varies from 48 to 140 nm. The pore size increases as the conductivity of the electrolyte was increased from 596 to 957 μS/cm by adjusting water content. The direct energy band gaps of the samples are found to vary from 1.95 to 2.2 eV. The flat-band potentials were obtained from Mott-Schottky analysis and found to be in the range of −0.7 V to −0.75 V. The maximum photocurrent density was 0.72 mA/cm2 with a bias voltage of 0.5 V (V vs. Ag/AgCl), under a 300 W xenon lamp system. [Copyright &y& Elsevier]

Abstract: We report on the structural properties of epitaxial FeO layers grown by molecular beam epitaxy on MgO(111). The successful stabilization of polar FeO films as thick as 16 monolayers (ML), obtained by deposition and subsequent oxidation of single Fe layers, is presented. FeO/MgO(111) thin films were chemically and structurally characterized using low-energy electron diffraction, Auger electron spectroscopy and conversion electron Mössbauer spectroscopy (CEMS). Detailed in situ CEMS measurements as a function of the film thickness demonstrated a size-effect-induced evolution of the hyperfine parameters, with the thickest film exhibiting the bulk-wüstite hyperfine pattern. Ex situ CEMS investigation confirmed existence of magnetic ordering of the wüstite thin film phase at liquid nitrogen temperature. [Copyright &y& Elsevier]

Abstract: Iron oxide thin films were grown by multiple cycles of iron deposition and oxidation at different annealing temperatures. The oxide layers were characterized in-situ by X-ray diffraction and LEED and after the preparation ex-situ by confocal Raman microscopy. The results show that well ordered films of wüstite, magnetite, and hematite can be grown on Ag(111). Wüstite was observed at the initial stages of growth for films of ~10Å thickness prior to magnetite formation. Magnetite films of several unit cells thickness were grown and studied by XRD and Raman spectroscopy. The magnetite films could be oxidized to epitaxial hematite films at low oxygen pressures. For our films, transformation from magnetite to hematite is reversible by annealing in UHV. [Copyright &y& Elsevier]

Abstract: We report on a facile low temperature method for the preparation of high surface area, nanostructured α-Fe2O3 (hematite) thin films and their application as photoelectrochemical (PEC) water splitting electrodes. The hematite films are fabricated by thermal oxidation in air of DC sputter deposited iron films at temperatures as low as 255°C. This method results in films with a higher surface area than typically obtained by directly sputtering α-Fe2O3. It is shown that beyond a minimum iron thickness, α-Fe2O3 nanowires result upon thermal treatment in atmospheric conditions. Structural and optical characteristics of the resulting films are analyzed. The oxidation process is studied in detail and correlated to the photoelectrical properties. The Fe films oxidize in stages via Fe-oxide layers of increasing oxidation states. Resulting photoelectrochemical performance of fully oxidized films is a balance between optical absorption and charge collection, which varies with film thickness. The optimum film achieved a net photocurrent density of 0.18mA/cm2 in 1M NaOH at 1.23V vs. RHE under simulated AM1.5 sunlight, amongst the highest values reported for undoped hematite films produced at low temperature. [Copyright &y& Elsevier]

Abstract: The overshoot of the in-plane lattice parameter above its expected value was previously observed for iron oxides on different substrates for initial stages of the film growth. The reasons for the overshoot provided in the previously published experimental studies have not satisfactorily explained the effect. In the present article the overshoot is explained in terms of the surface atom displacements at low thicknesses due to the strong lattice relaxation via dislocation formation. The ilmenite–hematite solid solution is used as an example for the experimental and theoretical descriptions of the overshoot. The theoretical model, based on the dislocation density, can be directly applied to describe the lattice relaxation as a function of the film thickness for other iron-based oxide films with a strong film/substrate lattice mismatch. [Copyright &y& Elsevier]

Abstract: Thin films of aluminium incorporated Fe2O3, synthesized by simple chemical spray pyrolysis on to glass substrates using aqueous solutions of analytical reagent grade ferric trichloride and aluminium nitrate as precursors. The influence of aluminium doping on to morphological properties, contact angle, X-ray photoelectron spectroscopy, photoluminescence and thermal conductivity properties have been investigated. The preparative parameters have been optimized to obtain good quality thin films which are uniform and well adherent to the substrate. The FE-SEM and AFM micrographs depict the films are compact and homogeneous (spindle-shaped hematite nanostructures) with varying grain sizes (average grain size ~20–60nm). Contact angle measurement show the films are hydrophobic in nature. The chemical composition and valence states of constituent elements in Fe2O3 are analyzed by X-ray photoelectron spectroscopy. The excitonic strong violet emission has been observed in photoluminescence. The specific heat and thermal conductivity study shows the phonon conduction behavior is dominant in these polycrystalline films. We studied interparticle interactions like grains, grain boundary effects using complex impedance spectroscopy. [Copyright &y& Elsevier]

Abstract: Thin films of (WO3)1–x–(Fe2O3)x composition were deposited by thermal evaporation on glass substrates and then all samples were annealed at 200–500 °C in air. Optical properties such as transmittance, reflectance, optical bangap energy, and the optical constants of the “as deposited” and the annealed films were studied using ultraviolet-visible spectrophotometry. It was shown that the annealing process changes the film optical properties which were related to Fe2O3 concentration. Moreover, using X-ray photoelectron spectroscopy, we have indicated that WO3 is stoichiometric, while iron oxide was in both FeO and Fe2O3 compositions so that the FeO composition converted to Fe2O3 after the annealing process. Using atomic force microscopy, it was observed that surface of the “as deposited” films were smooth with a nanometric grain size. The film surface remained unchanged after annealing up to 300 °C. Surface roughness and the grain size of the films with x = 0, 0.05, and 0.75 highly increased at higher annealing temperatures (400 and 500 °C), but were nearly unchanged for medium x-values (0.3 and 0.4). [Copyright &y& Elsevier]

Abstract: Nanostructured semiconductor thin films of Zn-Fe2O3 modified with underlying layer of Fe-TiO2 have been synthesized and studied as photoelectrode in photoelectrochemical (PEC) cell for generation of hydrogen through water splitting. The Zn-Fe2O3 thin film photoelectrodes were designed for best performance by tailoring thickness of the Fe-TiO2 film. A maximum photocurrent density of 748 μA/cm2 at 0.95 V/SCE and solar to hydrogen conversion efficiency of 0.47% was observed for 0.89 μm thick modified photoelectrode in 1 M NaOH as electrolyte and under 1.5 AM solar simulator. To analyse the PEC results the films were characterized for various physical and semiconducting properties using XRD, SEM, EDX and UV–Visible spectrophotometer. Zn-Fe2O3 thin films modified with Fe-TiO2 exhibited improved visible light absorption. A noticeable change in surface morphology of the modified Zn-Fe2O3 film was observed as compared to the pristine Zn-Fe2O3 film. Flatband potential values calculated from Mott–Schottky curves also supported the PEC response. [ABSTRACT FROM AUTHOR]

Abstract: Iron oxide thin films were prepared by spray pyrolysis technique (SPT) at various substrate temperatures (T sub ) and different deposition time. X-ray diffraction (XRD) analysis showed that, at T sub ≥350°C, a single phase of α-Fe2O3 film is formed which has the rhombohedral structure. Moreover, the crystallinity was improved by increasing T sub . The effect of T sub as well as deposition time on the optical dispersion of these films has been investigated. The optical transmittance and reflectance measurements were performed by using spectrophotometer in the wavelength range from 300 to 2500nm. The refractive index was determined by using Murmann''s exact equation. It was observed that, the refractive index increased with increasing in both the T sub and film thickness. The optical dispersion parameters have been evaluated and analyzed by using Wemple–Didomenico equation. The obtained results showed that, the dielectric properties have weak dependencies of growth temperature and film thickness. At T sub ≥350°C, the average values of oscillator energy, E o and dispersion energy, E d were found to be 5.96 and 34.08eV. While at different thickness, the average values of dispersion energies were found to be 3.93 and 17.08eV. Also, the average values of oscillator strength S o and single resonant frequency ω o were estimated 10.78×1013 m−2 and 5.99×1015 Hz, while at different thickness were evaluating 4.81×1013 m−2 and 6.11×1015 Hz. Furthermore, the optical parameters such as wavelength of single oscillator λ o , plasma frequency ω p , and dielectric constant ɛ have been evaluated. The carrier concentration N opt by using Drud''s theory was obtained the range of 5.07×1025 m−3 to 1.04×1026 m−3. [Copyright &y& Elsevier]

Abstract: This study focuses on the biomimetic formation and growth of thin iron oxide films under Langmuir monolayers. These coherent film structures were formed in the presence of different iron chloride solutions during the addition of an ammonia atmosphere. Stearic acid, stearyl amine and stearyl alcohol were used as film forming surfactants while the subphase contained FeCl2, FeCl3 or a mixture of both salts. The thin, coherent films consisted of X-ray amorphous iron oxide, hydroxide or oxyhydroxide. The films were studied by scanning electron microscopy, atomic force microscopy, X-ray diffraction, dynamic light scattering and surface potential measurements. Based on the experimental results we propose a growth mechanism that is guided by the formation of nanoparticles in the subphase and their assembly and aggregation underneath the Langmuir films. [Copyright &y& Elsevier]

Abstract: The visible light photocatalytic activity of α-Fe2O3 nanograin chains coated by anatase TiO2 nanolayer, as a photocatalyst thin film for inactivation of Escherichia coli bacteria, was investigated for the solutions containing 106 colony forming units per milliliter of the bacteria, without and with H2O2 (60μM). Thin films of the α-Fe2O3 nanograins with the grain size of 40–280nm were grown on glass substrates by post-annealing of the thermal evaporated Fe3O4 thin films at 400°C in air. The TiO2 layer with thickness of about 20nm was coated on the nanograins by dipping the Fe2O3 thin films in a prepared TiO2 sol and re-annealing them at 400°C in air. The antibacterial activity of the α-Fe2O3 nanograins with the optical band-gap of 2.1eV (so better activity than the TiO2 in the visible light) was doubled in presence of the low-concentration H2O2. Deposition of the TiO2 nanolayer on the α-Fe2O3 nanograins resulted in 24 and 54% (59 and 276%) improvement in the photocatalytic activity of the TiO2/α-Fe2O3 thin film than the bare α-Fe2O3 nanograin (TiO2) thin film, for the solution without and with H2O2, respectively. In addition, for the TiO2/α-Fe2O3 thin film, the bactericidal activity was improved by a factor of 2.5 in presence of the low-concentration H2O2 as compared to the case without H2O2. A mechanism was proposed based on which the electrons excited in the photocatalytic process were directly or indirectly absorbed by H2O2 to produce active OH− for promoting inactivation of the bacteria. [Copyright &y& Elsevier]

Abstract: Conformal films of amorphous iron(III) oxide and α-Fe2O3 have been coated on zirconia nanoparticles (26 nm) in a fluidized bed reactor by atomic layer deposition. Ferrocene and oxygen were alternately dosed into the reactor at temperatures between 367 °C and 534 °C. Self-limiting chemistry was observed via in situ mass spectrometry, and by means of induced coupled plasma-atomic emission spectroscopy analysis. Film conformality and uniformity were verified by high resolution transmission electron microscopy, and the growth rate was determined to be 0.15 Å per cycle. Energy dispersive spectroscopy, X-ray diffractometry, and X-ray photoelectron spectroscopy were utilized as a means to determine film composition at each deposition temperature. Over all of the deposition temperatures investigated, films were deposited as amorphous iron(III) oxide. However, after heat treatment at 850 °C in air and N2 atmospheres, α-Fe2O3 was the predominant species. [Copyright &y& Elsevier]

• SO 2 adsorption on different thin iron oxide films studied by photoelectron spectroscopy. • SO 4 formation. • Thermal induced dissociation. • Preferential adsorption site on moiré-structure. The adsorption of sulfur dioxide (SO 2) at room temperature on iron oxide surfaces has been studied using core-level photoelectron spectroscopy. A variety of iron oxides, from adsorbate structure to thin film, with different stoichiometries and terminations were grown on common low-index single crystal iron surfaces to model a range of structures in the initial stages of atmospheric oxidation. This permits well-controlled comparisons of differences and similarities in SO 2 interaction. Both non-dissociative and dissociative adsorption of SO 2 were observed, to different relative and absolute coverages, on all surfaces. The only identified non-dissociated species is SO 4. For all surfaces, at least some amounts of atomic sulfur are observed while only for the submonolayer adsorbate structure, also tentative dimerization of sulfur into S 2 or formation of S-O surface is observed. For the two oxides terminated by a complete well-ordered oxygen layer, the absolute sulfur coverage is low. The complete oxygen layer terminated oxide film exhibiting a moiré-pattern had a saturation coverage of one SO 4 species per surface super cell, which indicates a tentative preferred adsorption site. The surface showing the highest SO 4 formation is the Fe 3 O 4 (100) thin film surface with a corrugated row structure. The SO 4 formation is suggested between surface oxygen atoms within the same row. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: In this work we investigate an iron oxide thin film grown with atomic layer deposition for a gas sensor application. The objective is to characterize the structural, chemical, and electrical properties of the film, and to demonstrate its gas-sensitivity. The obtained scanning electron microscopy and atomic force microscopy results indicate that the film has a granular structure and that it has grown mainly on the glass substrate leaving the platinum electrodes uncovered. X-ray diffraction results show that iron oxide is in the α–Fe2O3 (hematite) phase. X-ray photoelectron spectra recorded at elevated temperature imply that the surface iron is mainly in the Fe3+ state and that oxygen has two chemical states: one corresponding to the lattice oxygen and the other to adsorbed oxygen species. Electric conductivity has an activation energy of 0.3–0.5 eV and almost Ohmic current–voltage dependency. When exposed to O2 and CO, a typical n-type response is observed. [Copyright &y& Elsevier]

Abstract: Majority of the authors report elaboration of iron oxide thin films by reactive magnetron sputtering from an iron target with Ar–O2 gas mixture. Instead of using the reactive sputtering of a metallic target we report here the preparation of Fe1–x O thin films, directly sputtered from a magnetite target in a pure argon gas flow with a bias power applied. This oxide is generally obtained at very low partial oxygen pressure and high temperature. We showed that bias sputtering which can be controlled very easily can lead to reducing conditions during deposition of oxide thin film on simple glass substrates. The proportion of wustite was directly adjusted by modifying the power of the substrate polarization. Atomic force microscopy was used to observe these nanostructured layers. Mössbauer measurements and electrical properties versus bias polarization and annealing temperature are also reported. [Copyright &y& Elsevier]

Abstract: Iron oxide thin films doped with Ca and Pd, prepared by a liquid-phase deposition method (LPD) from aqueous solution, have been investigated as potential ethanol gas sensors. SEM and XRD analyses were used to characterize Fe2O3 LPD films. Hematite (α-Fe2O3), having an average crystallite size in the range between 20 and 30nm, was the only crystalline phase detected on all undoped and doped films. The electrical response towards ethanol (100–500ppm) has been studied in the temperature range of 300–500°C. Both Ca and Pd promoters have shown a positive effect on the sensitivity of Fe2O3 films at the lower temperature investigated, whereas at higher temperature the undoped Fe2O3 film has shown better performances. The sensing properties of undoped and doped Fe2O3 thin films towards different interfering gases like NO2, CO and NH3 have been also investigated, showing that the selectivity to ethanol benefits of the Ca addition. [Copyright &y& Elsevier]

Abstract: Effects of iron introduction in RGTO prepared tin oxide gas sensors are presented. The films were deposited by sputtering from a tin target with the introduction of an adjustable number or iron inset. Iron content was varied in the range 0–7%. The thin films are investigated by the volt-amperometric technique for electrical and gas-sensing properties. The layers are capable of sensing CO and ethanol, no evidence of surface poisoning is detected, and recovery of the resistance is complete. The response of the sensors is stable and reproducible at all operating temperatures tested (200–500°C) during 3 months of operation. [Copyright &y& Elsevier]

Abstract: Electrodeposition of semiconducting poly(o-anisidine)/γ-Fe2O3 (maghemite) thin films was carried out using an aqueous alkaline medium containing ferrous sulphate and o-anisidine. Potentiostatic composite deposition was made at 55°C. X-ray diffraction and FTIR analysis indicated the presence of iron oxide (maghemite), o-anisidine, and chemical interaction between the components. The magnetic characterization of the resulting composite indicated a magnetically ordered state for the polymer/maghemite composite. Mössbauer characterization suggested the formation of nanoparticulate γ-Fe2O3 clusters. Cyclic voltammetry evidenced electroactivity with characteristic peaks of a conducting polymer as well as the presence of γ-Fe2O3. [Copyright &y& Elsevier]

Abstract: Thin films of (WO3)1− x –(Fe2O3) x composition were deposited by thermal evaporation on glass substrates and then all samples were annealed at 400 °C in air. Optical properties such as transmittance, reflectance, and optical bandgap energy of the “as deposited” and the annealed films were studied using ultraviolet–visible spectrophotometry. It was shown that the annealing process did not substantially change the optical transmittance and reflectance of all the films except the films having x =0.75. By increasing Fe2O3 content in the films from x =0 to x =0.75, optical bandgap energy decreased from 3.4 to about 1.3 eV and from 3.1 to 2.1 eV for the “as deposited” and the annealed samples, respectively. Moreover, using X-ray photoelectron spectroscopy, we have shown that the “as deposited” (WO3)0.25–(Fe2O3)0.75 films contained Fe3O4, and it converted to Fe2O3 after the annealing process. Using atomic force microscopy, it was found that the grain size and surface roughness of the annealed films were greater than the “as deposited” ones. In addition, for the annealed films with intermediate x''s, we have observed a smoother surface with smaller grain size as compared to films with the other x''s. [Copyright &y& Elsevier]

Abstract: The present paper investigates a simple and non-toxic method to transform amorphous iron oxide pre-deposited by spray pyrolysis of FeCl3·6H2O (0.03M)-based aqueous solution onto glass substrates heated at 350°C into FeSe2 thin films. The amorphous iron oxide films were heat treated under a selenium atmosphere (10−4 Pa) at different temperatures for 6h. X-ray diffraction (XRD) was used to investigate the structure of the obtained films. Single FeSe2-phase films having good crystallinity were obtained at a selenisation temperature of 550°C. Optical analyses of the FeSe2 films obtained at 550°C enabled us to deduce a large absorption coefficient (, ). Surface scanning electron microscopy (SEM) observations show inhomogeneous films. Electrical conductivity of the as-prepared films was measured at high and low temperatures. [Copyright &y& Elsevier]

Abstract: Epitaxial iron oxide films are grown on Ag(111) by two methods. The oxide films are characterized using low-energy electron diffraction, X-ray photoelectron spectroscopy, and X-ray photoelectron diffraction. The first growth method is deposition of Fe films with thickness ranging from 1–10 monolayers on Ag(111) and oxidizing these films. The Fe film structure prior to oxidation is identified as poorly ordered bcc-Fe(110), and oxidation leads to the growth of poorly ordered FeO(111) films. The second method is sequential deposition of sub-monolayer Fe films (typically ⩽0.5ML) followed by oxidation. This procedure is repeated until the desired oxide film thickness is achieved. Iron oxide films grown by sequential deposition are identified as FeO(111) for oxide film thickness below ∼10Å with growth of Fe3O4(111) for thicker films. Iron oxide films grown by the sequential deposition method have much better crystallographic order than those grown by oxidizing thicker iron films. Finally, the surface termination of the Fe3O4(111) films is investigated using X-ray photoelectron diffraction. [Copyright &y& Elsevier]

The development of a low-temperature reactive-sputtering process for producing high-quality hematite films was explored. Iron oxide thin films were sputter-deposited under different conditions of oxygen partial pressure and at substrate temperatures up to 200 °C, and characterized for comparison. Although all sample films exhibited structural and compositional characteristics consistent with polycrystalline rhombohedral Fe2O3 (hematite), it was found that the detailed grain features and morphology, as well as the optical and electrical properties, were significantly altered by process parameter variations. Average grain size increased with deposition temperature and decreased with oxygen partial pressure. Measured film conductivities ranged from 10-9 S/cm in 100 °C samples up to 5×10-4 S/cm in the 200 °C samples. Highest conductivities were found in the sample films exhibiting the largest grains, which is attributed to the effects of mobility enhancement through reduced inter-grain scattering. [Copyright &y& Elsevier]

Abstract: We examined the structural properties and the electronic and magnetic structures of an Fe3O4 ultrathin film prepared by oxidizing a low-temperature-grown (T =95K) Fe film on GaAs(100), using the X-ray diffraction, X-ray absorption spectroscopy, and X-ray magnetic circular dichroism measurements. They show no clear contrast to those of an Fe3O4 film that was prepared by oxidizing room-temperature-grown Fe film. The interdiffusions of Ga and As atoms in the Fe3O4 films were further investigated using the resonant Fe3O4(400) diffractions at the Ga K- and As K-edge energies. It is shown that the Fe3O4 film that originated from the room-temperature-grown Fe film contains both Ga and As atoms, while the film that originated from the kinetically-stabilized Fe film contains only Ga atoms. This suggests that the kinetic stabilization in pristine Fe layers can block As interdiffusion effectively even after oxidization. [Copyright &y& Elsevier]

Abstract: A novel method is used to deposit iron oxide thin film. Frozen iron acetate is used as a target for pulsed laser deposition of iron oxide thin film. KrF excimer laser having wavelength of 248nm with pulsed duration of 20ns is used to deposit the film. Structural characterizations were performed using X-ray diffraction and atomic/magnetic force microscopy. The X-ray diffraction patterns confirmed the polycrystalline nature of α-Fe2O3. Temperature dependence magnetic measurements in zero field cooled showed the presence of blocking temperature at ∼60K. The magnetic measurements revealed the existence of superparamagnetic behavior above blocking temperature and freezing of magnetic moments arising from uncompensated surface spins below blocking temperature. [Copyright &y& Elsevier]