Fe3O4 Films Research Articles

Synthesis, structural characterization and optical studies of Fe2O3 nanoparticles based polymeric materials for flexible electronic devices

In this work, a thin film containing a flexible polymer nanocomposite of iron oxide (Fe2O3) and poly(4-chloroaniline) P(4-ClAni) was successfully synthesized using the green polymerization fabrication method. To confirm the effective synthesis of the P(4- ClAni)/Fe2O3 nanocomposite, the XRD, SEM, and FTIR analyses were used. The SEM pictures revealed that the nanocomposite contain Fe2O3 nanoparticles distributed throughout the polymer matrix. The optical absorbance of the P(4-ClAni) and P(4-ClAni)/Fe2O3 films was measured at room temperature using a UV-vis spectrophotometer from 190 to 1150 nm. The optical properties of P(4-ClAni)/Fe2O3 films were calculated using Tauc's relation. The Urbach energy of the P(4-ClAni) increases from 0.96 eV to 1.65 eV, 1.73 eV, and 1.86 eV, respectively, when mixed with 2%, 4%, and 6% of Fe2O3. On the other hand, the band gap energy of P(4-ClAni) decreases from 3.57 eV to 3.39 eV, 3.07 eV, and 2.84 eV, respectively, with the addition of 2%, 4%, and 6% Fe2O3. Based on the results of this study, the composite P(4-ClAni)/Fe2O3 sheets can be used for flexible electronic devices.

Unlocking OER catalytic potential and chiral Fe3O4 film as a game-changer for electrochemical water oxidation pathway and by-product control

This work report a Fe3O4 film with inherent chiral structure that effectively promoted OER, owing to its CISS effect on spin aligning intertwined with the capability of half-metallic materials to facilitate the transfer of spin-aligned electrons.

Structural, Optical, and Dielectric Properties of PVA-CMC/Ni0.65Cu0.35Fe2O4 Films for Optoelectronic Applications and Energy Storage Applications

Structural, Optical, and Dielectric Properties of PVA-CMC/Ni0.65Cu0.35Fe2O4 Films for Optoelectronic Applications and Energy Storage Applications

Amorphous Fe2O3 Porous Films Grown on Multilayer Graphene for High-Performance LIB Anodes

Amorphous Fe2O3 has special high electrochemical performance as anode materials of LIBs due to its disorderly arranged atoms. However, the issue of its low intrinsic electric conductivity should be solved rationally and facilely. In this work, amorphous Fe2O3 porous films are chemically deposited on the mechanically exfoliated multilayer graphene (MLG) nanosheets, forming a Fe2O3/MLG/Fe2O3 sandwich nanostructure. The addition of 10[Formula: see text]mg of EDTA-2Na is crucial for the formation of amorphous nature and holes in Fe2O3 films on MLG. This composite exhibits better electrochemical performance as LIB anodes than well-crystallized Fe2O3 nanoparticles, amorphous Fe2O3 films without holes and amorphous Fe2O3 isolated nanoparticles on MLG, which are prepared using 0[Formula: see text]mg, 5[Formula: see text]mg, 20[Formula: see text]mg of EDTA-2Na, respectively. The optimized composite delivers a reversible discharge capacity of 1067[Formula: see text]mAh g[Formula: see text] at 100[Formula: see text]mA g[Formula: see text] after 100 cycles. Moreover, a capacity of 522 mAh g[Formula: see text] is delivered at a high current density of 2[Formula: see text]A g[Formula: see text]. The high electrochemical performance of the composite is attributed to the amorphous nature and porous film structure of Fe2O3, and well combination of Fe2O3 and highly conductive MLG substrate.

Effect of biologically synthesized iron-oxide nanoparticles insulating layer on current-voltage characteristics of Ni/Cr/Ni/n-GaN Schottky junction

The microstructural and electrical properties of a prepared Ni/Cr/Ni/FeO/n-GaN metal/oxide/semiconductor (MOS) heterojunction (HJ) (as-deposited and after 600 °C annealing) with biologically synthesized iron oxide (FeO) nanoparticles as an insulating layer are investigated. The formation of FeO films at the junction is confirmed by the measurements of FESEM and XRD analysis. The HJ electrical results are associated with Ni/Cr/Ni/n-GaN metal/semiconductor (MS) Schottky junction (SJ) results. The as-deposited and 600 °C annealed HJs exhibit exceptional rectifying efficiency and incredibly low reverse leakage current compared to the SJ. The 600 °C annealed HJ had a higher Φb than both as-deposited HJ and SJ, indicating that the FeO insulating layer has an impact on the Φb of the devices. The outcomes demonstrate that the Φb values are better for 600 °C annealed junctions. Furthermore, Cheung’s, Norde, and ΨS-V method-based plots are used to analyze the Φb, series resistance (RS), ideality factor (n), and the resultant values are found to be comparable, indicating consistency and validity. Due to the fact that the HJs interface state density (NSS) is lower than that of SJ, the FeO layer is crucial to the decreased NSS. A transition from Poole-Frenkel emission at low voltages to Schottky emission at high voltages was also seen in the SJ. Furthermore, the HJ showed Schottky emission throughout the whole voltage range. Furthermore, trustworthily energy level band diagrams may be used to explain the Φb modulation process, leading to the conclusion that the FeO layer is a suitable material for the design of novel electronic device applications.

Biodegradable Chitosan-Based Films as an Alternative to Plastic Packaging.

The impact of synthetic packaging on environmental pollution has been observed for years. One of the recent trends of green technology is the development of biomaterials made from food processing waste as an alternative to plastic packaging. Polymers obtained from some polysaccharides, such as chitosan, could be an excellent solution. This study investigated the biodegradability of chitosan-metal oxide films (ZnO, TiO2, Fe2O3) and chitosan-modified graphene films (CS-GO-Ag) in a soil environment. We have previously demonstrated that these films have excellent mechanical properties and exhibit antibacterial activity. This study aimed to examine these films' biodegradability and the possibility of their potential use in the packaging industry. The obtained results show that soil microorganisms were able to utilize chitosan films as the source of carbon and nitrogen, thus providing essential evidence about the biodegradability of CS, CS:Zn (20:1; 10:1), and CS:Fe2O3 (20:1) films. After 6 weeks of incubation, the complete degradation of the CS-Fe2O3 20:1 sample was noted, while after 8 weeks, CS-ZnO 20:1 and CS-ZnO 10:1 were degraded. This is a very positive result that points to the practical aspect of the biodegradability of such films in soil, where garbage is casually dumped and buried. Once selected, biodegradable films can be used as an alternative to plastic packaging, which contributes to the reduction in pollution in the environment.

Structure and energetics of FeO/Fe(001) interfaces

We report results of density functional theory calculations of structure and properties of 1–5 monolayer thin FeO(001) films and their interactions with the Fe(001) surface. It is found that deposition of an iron-oxide film affects weakly geometry of the Fe(001) support, causing small 2% expansion of the first interplanar distance compared to clean iron surface. Analysis of the electronic structure of the FeO/Fe system shows that after interface formation, the oxide layer remains semiconducting and the substrate metallic. Electronic structure of the FeO(001) layer in direct contact with the Fe(001) surface exhibits metallic character. Magnetism of the metal/semiconductor interface is only slightly disturbed compared to that of isolated components. The FeO adlayers preserve antiferromagnetic (AFM) nature of the oxide and the sharp boundary between higher AFM phase of FeO and lower ferromagnetic phase of Fe is observed at the interface.

Ti3C2Tx MXene@STPP novel waterborne long-term anti-corrosion coating with "3 + 1" multiple high-performance active-passive protection barrier mechanisms

Although environmentally friendly waterborne epoxy (WEP) coatings have the advantage of low volatile organic compounds (VOCs), their barrier performance is rather inferior to achieve long-term corrosion protection. Herein, we grafted the coupling agents KH560 and KH550 onto the etched Ti3C2Tx and sodium tripolyphosphate (STPP), respectively. On the one hand, Ti-O-Si covalent bonds can be formed to improve the water dispersion stability, and on the other hand, as a bridging agent, the functionalized modification yielded the interface-enhanced Ti3C2Tx@STPP filler. The Ti3C2Tx@STPP/WEP composite coating exhibits a high impedance value of 7.981 × 1010 Ω·cm2 after 120 days of saltwater immersion, which is at least two orders of magnitude higher than that of the pure WEP coating. Likewise, the chelating-passivation advantage of STPP with metal cations is fully exploited. The precipitation-oxidation self-healing corrosion inhibition mechanism was proposed and demonstrated by Tafel, EIS, XPS, and Raman experiments. The remarkable long-term corrosion protection performance can be concluded as (1) interface-enhanced two-dimensional Ti3C2Tx with extraordinary physical barrier to prolong the corrosion path; (2) due to high barrier properties, the further electrochemical reactions of steel surfaces can be effectively inhibited under low utilization of water and oxygen, and the Fe(OH)3 and Fe(OH)2 are converted into non-conductive Fe3O4 and/or Fe2O3 films after water loss, (3) and active protection by the chelation of STPP with iron ions to form iron tripolyphosphate passivation films, and (4) passive defense by the coating and resin itself. Therefore, a novel "3 + 1" high-performance protective coating, which integrates interface enhancement, physical barrier, and active-passive protection, is successfully prepared to achieve long-term corrosion protection of the coating.

Atomic Structure of the Fe3O4/Fe2O3 Interface During Phase Transition from Hematite to Magnetite.

Phase transition between iron oxides practically defines their functionalities in both physical and chemical applications. Direct observation of the atomic rearrangement and a quantitative description of the dynamic behavior of the phase transition, however, are rare. Here, we monitored the structure evolution from a rod-shaped hematite nanoparticle to magnetite during H2 reduction at elevated temperatures. Environmental transmission electron microscopy observations, along with selected area electron diffraction experiments, identified that the reduction preferentially commenced with Fe3O4 nucleation on the surface defective sites, followed by laterally growing into a Fe3O4 film until fully covering the particle surface. The Fe3O4 phase then propagated toward the bulk particle via a Fe3O4/α-Fe2O3 interface with the relationship α-Fe2O3(0001)//Fe3O4(111) in an aligned orientation of [112]Fe3O4||[112̅0]α-Fe2O3. Upon this Fe3O4/α-Fe2O3 interface, the Fe-O octahedra in Fe3O4(111) (as layer A) matches that of α-Fe2O3(0001) at a rotation angle of 30°, and the reduction proceeds in such a pattern that two-thirds of the FeOh in the adjacent layer (layer B) is transformed into FeTe.

DC sputtered iron-doped indium saving indium tin oxide thin films using Fe3O4 target

In the present work, the properties of iron-doped indium tin oxide (ITO) films with reduced to 50 mass% indium oxide (In2O3) content prepared by co-sputtering of ITO and Fe3O4 targets in the mixed argon-oxygen atmosphere were studied by various methods such as four-point probe method, Ultraviolet-Visible spectroscopy, X-ray diffraction and dynamic force microscopy. The influence of different working gas flow rates and heat treatment temperatures on the electrical, optical, structural, and morphological properties of the films was characterized. Iron doping resulted in increasing optical transmittance of ITO thin films. It has been found that films sputtered onto preheated substrites under optimum conditions showed values of volume resistivity 1480 µΩcm that is much lower than that of ITO50:Fe3O4 films sputtered onto unheated substrates and average optical transmittance in the visible range over 85%. It has been revealed that iron-doped ITO thin films deposited under optimum conditions have low root mean square height (S q) 0.67 nm and arithmetical mean height (S a) 0.52 nm.

A-Fe2O3 Nanorods for Degradation of Organic Pollutants Methyl Orange and Rhodamine B Dyes

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 ([Formula: see text]-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 [Formula: see text]-Fe2O3 films were calculated by modeling the photodegradation of MO and RhB dyes as pollutants under sunlight irradiation for 150[Formula: see text]min. Results revealed that the degradation efficiency of [Formula: see text]-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.

Geobacter sulfurreducens electroactive biofilms on Fe2O3/FTO support-electrodes for developing a sodium acetate electrochemical biosensor

Geobacter sulfurreducens is an essential microorganism in biogeochemical cycles. It is used biotechnologically in bioremediation and electricity production. The importance of G. sulfurreducens lies in its capacity to contact extracellular electron acceptors, including several electrode materials. Taking advantage of the versatility of G. sulfurreducens to grow on different surfaces, it is possible to design and synthesize new electrodes that can expand and improve the applications of these bacteria. In this work, we performed multidisciplinary research studies to demonstrate an innovative application of this well-known microbial system. The interaction between fluorine-doped tin oxide (FTO) and ordinary glass with G. sulfurreducens was enhanced by modifying the surface with Fe2O3 films. As confocal laser microscopy analyses revealed, the enhancement promoted biofilm development, whose parameters were significantly better than the bare support-electrodes. Furthermore, we provided evidence that G. sulfurreducens interacted with and dissolved the Fe2O3 film during incubation. Then, when we added sodium acetate to the system, the microbial metabolism was activated and decreased the electrochemical response of this compound. We benefited from that behavior to develop a voltammetric-based robust biosensor that could measure sodium acetate at high concentrations with an acceptable linear interval, from 10 to 110 mM, with LOD = 5.9 ± mM and LOQ = 18.1 ± 1.5 mM.

The influence of La/Mg co-doping on the structure, linear and nonlinear optical properties of Fe2O3 nanoparticles for environmentally friendly applications

The structure and linear/nonlinear optical properties of iron oxide (Fe2O3) nanoparticles (NPs) films are examined for environmentally friendly applications. Undoped and La, Mg and La/Mg co-doped Fe2O3 NPs films were equipped using the spray pyrolysis procedure. The structural, morphological and optical properties of the films were characterized by X-ray diffractometer, FT-IR spectrophotometer, FE-SEM and UV–visible–NIR spectrophotometer. XRD analysis exposes that the samples possess a rhombohedral structure of α- Fe2O3 (hematite). Besides, the crystallite size of the undoped Fe2O3 NPs increases from 20.7 nm to 21.8 nm (La/Fe2O3), 23.0 nm (Mg/Fe2O3) and 24.4 nm (La + Mg/Fe2O3). The direct/indirect optical band gap of the undoped Fe2O3 film decreases from 2.47 eV/1.87 eV to 2.43 eV/1.72 eV (La/Fe2O3), 2.37 eV/1.65 eV (Mg/Fe2O3) and 2.31 eV/1.56 eV (La + Mg/Fe2O3). Moreover, the effect of La/Mg co-doping on the refractive index, extinction coefficient, dielectric constants, linear optical susceptibility (χ(1)), third-order nonlinear susceptibility (χ(3)) and nonlinear refractive index (n2) of Fe2O3 NPs have been explored. In instance, the real dielectric constant of the undoped Fe2O3 NPs decreases at 600 nm from 6.46 to 5.00 (La/Fe2O3), 3.80 (Mg/Fe2O3) and 3.17 (La + Mg/Fe2O3). The ability to tailor the linear/nonlinear optical properties of Fe2O3 NPs films upon La/Mg co-doping nominate them for uses in a lot of environmentally friendly applications.

A reversal of positive to negative magnetoresistance in Fe3O4-based heterostructures at room temperature by annealing

In this paper, a transition of magnetoresistance (MR) from positive to negative was obtained at room temperature by vacuum annealing of Fe3O4 (128 nm) / Si (with natural SiO2) heterostructures at 780 °C. Considering the wire-like nanograins with varying length and the effect of interface, the sign of MR is decided by the contribution of two Fe3O4 layers. One is the layer at the Fe3O4/SiO2 interface where the scattering of conducting electrons in the natural SiO2 layer on the top of Si can lead to spin polarization reversal of Fe3O4 and the other is the Fe3O4 far away from the absorbing interface. The reversal sign of MR indicates the dominant contrition of Fe3O4 far away from the absorbing interface as the stabilized SiO2 phase on top of the Si substrate with fewer ion defects by annealing the Fe3O4 film on natural Si at 780 °C. For the Fe3O4 film prepared on the substrate of corroded Si (chemically etching the natural SiO2 layer), positive MR is maintained even vacuum annealed at 780 °C, while for the Fe3O4 film on SiO2, an additional α-Fe2O3 phase is obtained even negative MR for films both as deposited and annealed at 780 °C. It can be concluded that the SiO2 layer on top of the substrate plays an important role in the interface and then the magnetotransport properties of the Fe3O4 heterostructures. Well property and negative spin polarization of Fe3O4 film can be obtained by vacuum annealing the Fe3O4 film on Si substrate with a proper thickness of natural SiO2 layer at 780 °C.

MXene/bacterial cellulose/Fe3O4/methyltrimethoxylsilane flexible film with hydrophobic for effective electromagnetic shielding

Electromagnetic (EM) pollution has become a serious problem in modern society as it affects human lives. The fabrication of strong and highly flexible materials for electromagnetic interference (EMI) shielding applications is extremely urgent. Herein, a MXene Ti3C2Tx/Fe3O4 & bacterial cellulose (BC)/Fe3O4&Methyltrimethoxysilane (MTMS) flexible hydrophobic electromagnetic shielding film (SBTFX-Y, X and Y were the number of layers of BC/Fe3O4 and the layers of Ti3C2Tx/Fe3O4), was fabricated. In the prepared film, MXene Ti3C2Tx absorbs a large amount of radio waves through polarization relaxation and conduction loss. Because of its extremely low reflectance of electromagnetic waves, BC@Fe3O4, as the outermost layer of the material, allows more electromagnetic waves to incident inside the material. The maximum electromagnetic interference (EMI) shielding efficiency (SE) of 68 dB was achieved for the composite film at 45 μm thickness. What's more, the SBTFX-Y films show excellent mechanical properties, hydrophobicity and flexibility. The unique stratified structure of the film provides a new strategy for designing high-performance EMI shielding films with excellent surface and mechanical properties.

Effect of neutralization treatment on properties of chitosan/bamboo leaf flavonoids/nano-metal oxide composite films and application of films in antioxidation of rapeseed oil

Neutralization treatment improved the slow-release antioxidant food packaging function of chitosan (CS)/bamboo leaf flavone (BLF)/nano-metal oxides composite films. The film cast from the CS composite solution neutralized by KOH solution had good thermal stability. The elongation at break of the neutralized CS/BLF film was increased by about 5 times, which provided the possibility for its packaging application. After 24 h of soaking in different pH solutions, the unneutralized films swelled severely and even dissolved, while the neutralized films maintained the basic structure with a small degree of swelling, and the release trend of BLF conformed to the logistic function (R2 ≥ 0.9186). The films had a good ability to resist free radicals, which was related to the release amount of BLF and the pH of the solution. The antimicrobial neutralized CS/BLF/nano-ZnO film, like the nano-CuO and Fe3O4 films, were effective in inhibiting the increase in peroxide value and 2-thiobarbituric acid induced by thermal oxygen oxidation of rapeseed oil and had no toxicity to normal human gastric epithelial cells. Therefore, the neutralized CS/BLF/nano-ZnO film is likely to become an active food packaging material for oil-packed food, which can prolong the shelf life of packaged food.

PdRh-Sensitized Iron Oxide Ultrathin Film Sensors and Mechanistic Investigation by Operando TEM and DFT Calculation.

Metal oxide semiconductor (MOS) thin films are of critical importance to both fundamental research and practical applications of gas sensors. Herein, a high-performance H2 sensor based on palladium (Pd) and rhodium (Rh) co-functionalized Fe2 O3 films with an ultrathin thickness of 8.9nm deposited by using atomic layer deposition is reported. The sensor delivers an exceptional response of 105.9 toward 10ppm H2 at 230 °C, as well as high selectivity, immunity to humidity, and low detection limit (43 ppb), which are superior to the reported MOS sensors. Importantly, the Fe2 O3 film sensor under dynamic H2 detection is for the first time observed by operando transmission electron microscopy, which provides deterministic evidence for structure evolution of MOS during sensing reactions. To further reveal the sensing mechanism, density functional theory calculations are performed to elucidate the sensitization effect of PdRh catalysts. Mechanistic studies suggest that Pd promotes the adsorption and dissociation of H2 to generate PdHx , while Rh promotes the dissociation of oxygen adsorbed on the surface, thereby jointly promoting the redox reactions on the films. A wireless H2 detection system is also successfully demonstrated using the thin film sensors, certifying a great potential of the strategy to practical sensors.

Structural, Morphological, and Magnetic Properties of Ba, Sm Doped and Ba–Sm Co‐Doped BiFeO3 Nanocrystalline Thin Films Deposited by a Spin Coating Method

AbstractIn the present work, the BiFeO3, Bi0.9Ba0.1FeO3, Bi0.9Sm0.1FeO3, and Bi0.9Ba0.05Sm0.05FeO3 nanocrystalline thin films on Pt/TiO2/SiO2/Si (100) substrate are synthesized using the spin coating method, and the structural, morphological, and magnetic properties are systematically investigated. The X‐ray diffraction studies reveal that BiFeO3, Bi0.9Ba0.1FeO3, and Bi0.9Sm0.1FeO3 films exhibit a polycrystalline distorted rhombohedra crystal structure and belong to the R3c space group, whereas, Bi0.9Ba0.05Sm0.05FeO3 nanocrystalline film has shown a pure rhombohedral crystal structure. The grain size of the films is found to be 86, 75, and 63 nm for Bi0.9Ba0.1FeO3, Bi0.9Sm0.1FeO3, and Bi0.9Ba0.05Sm0.05FeO3, respectively. M−H measurements show that the magnetization considerably increases with Ba and Sm doping, and the highest magnetization is found to be 29 and 22 emu cm−3 at 10 and 300 K, respectively, in Bi0.9Sm0.1FeO3 film. Further, the blocking temperatures are found to be 100, 150, 130, and 50 K for BiFeO3, Bi0.9Ba0.1FeO3, Bi0.9Ba0.05Sm0.05FeO3, and Bi0.9Sm0.1FeO3, respectively.

The effect of flow velocity and material microstructure on FAC behavior and mechanism in simulated PWR conditions

In this study, combined with room-temperature electrochemical and hydrodynamic numerical simulation techniques, rotating disc tests in a high-temperature, high-pressure water environment were conducted to investigate the mechanisms of flow velocity and microstructure of SA106B on Flow Accelerated Corrosion (FAC). It has been demonstrated that the microstructure of SA106B influenced the corrosion potential and consequently the corrosion resistance. The normalization treatment changed the pearlite morphology from a segregated band to a diffuse island, which shifted the corrosion potential of SA106B in a positive direction, increased the polarization resistance, greatly reduced the local corrosion degree, increased the corrosion resistance, and noticeably slowed down the FAC rate of SA106B. On the other hand, the FAC rate increased linearly with an increase in flow rate, and its slope was related to the corrosion potential. The difference between the FAC rates of the as-received and normalized SA106B strongly depended on the flow velocity, and became more pronounced as the flow rate increased. When the flow velocity approached 4.34 m/s, the decrease degree of FAC rate of normalized SA106B compared to that of as-received SA106B increased dramatically, which may be related to the thickening and cracking reduction of Fe3O4 film on the normalized SA106B.

Cover Picture: Materials and Corrosion. 4/2023

Cover: Second-harmonic generation (SHG) was used to monitor in-situ compositional changes to carbon steel surfaces immersed in aqueous solutions and during electrochemical experiments. For passive film formed on carbon steel samples, the response in SHG intensity showed a peak in presence of Fe3O4, while it shows a decrease in presence of Fe2O3. Upon application of cathodic protection for 30 minutes, SHG response revealed the formation and growth of a Fe3O4 film on the carbon steel surface. In this work, the results obtained with SHG were compared with in-situ active reflectance spectroscopy measurements. More detailed information can be found in: Federico Martinelli-Orlando, Eric Dénervaud, Rachel Grange, Ueli Angst, Second-harmonic generation technique for in-situ study of passive film formation on carbon steel surfaces in aqueous solutions, Materials and Corrosion 2023, 74, 508.