Fe Inclusion Research Articles

Microstructure, mechanical properties and corrosion resistance of low-cost Ti–Al–Cr–Fe alloys processed via powder metallurgy

A variety of economical Ti–3Al–6Cr-xFe (x = 0, 1, 2 wt%) alloys were prepared utilizing typical powder metallurgy (cold pressing and sintering) to explore the impact of Fe concentration on the densification behavior, phase evolution, microstructure, mechanical properties and corrosion resistance. The inclusion of Fe increases the compressibility. The high diffusivity of the Fe element contributes to the densification but excessive Fe inclusion causes Kirkendall pores to develop. Therefore, Ti–3Al–6Cr–1Fe has the highest density. Every alloy is made up of intermetallic (TiCr2), α, and β phases. The proportion of the β phase rose with the addition of Fe. The optimal combination of mechanical characteristics was obtained by Ti–3Al–6Cr–1Fe (ultimate tensile strength of 1093 MPa and ductility of 3.1%), which is explained by the interaction of higher density and solid solution strengthening effects. Ti–3Al–6Cr–2Fe has the greatest corrosion resistance due to the relatively high density and maximum β phase proportion.

Optical bandgap variation and photo-Fenton property evolution in Fe-doped Bi2YO4Cl

The current study addresses the existing research gap on the effects of transition metal doping in layered Bi2YO4Cl and searches for a new visible light photocatalyst in the bismuth-based oxychloride system. The extent of Fe substitution in place of Y in Bi2YO4Cl and its consequences on the structure, optical, and catalytic properties have been examined by synthesizing the samples using a solution combustion method. Nearly 20 mol% of Fe could be introduced in a monophasic layer structural arrangement. The Fe-containing samples have also been characterized by electron microscopic and vibrational spectroscopic techniques. The optical absorbance shifted to the visible region with the Fe inclusion, and the bandgap decreased from 2.40 eV (pristine) to 1.77 eV (20 mol % Fe-substituted). XPS analysis of the Fe-containing sample indicated that Fe existed majorly in the III oxidation state with traces of the II oxidation state. The photo-Fenton function of Bi2Y1-xFexO4Cl (x = 0.10 and 0.20) for the oxidative degradation of RhB and MB dye molecules under LED illumination has been demonstrated. From scavenger experiments, OH• radicals and holes have been identified as the reactive oxidation species (ROS) involved in these reactions. The catalyst showed recyclability and structural integrity.

Synthesis of Fe–Pr co-doped ZnO nanoparticles: Structural, optical and antibacterial properties

In the present work, we studied the role of Fe and Pr addition on the structural, optical and antibacterial properties of spherical ZnO nanoparticles synthesized via sol gel method. The lattice constants values increased, while the average crystallite size decreases as the Pr concentration varies from 0.00 to 0.04. The Fe and Pr cations insertion in the Wurtzite structure were also confirmed by the changes in Zn–O bond length (1.9763 Å to 1.9793 Å for 0.00 ≤ y ≤ 0.04). Raman and FTIR spectroscopies validated the ZnO single-phase formation, and the analysis suggests the existence of oxygen vacancies. The samples showed agglomerated spherical morphology and formation of nanoplate homogeneously organized, while the textural properties were affected by the Fe inclusion. All samples presented band gap values lower than expected for bulk ZnO and the lowest values were obtained for samples containing Fe and Pr. The analysis and deconvolution of photoluminescence spectra confirmed the structural defects formation, caused by the synthesis conditions used and dopants ions inclusion. The antimicrobial activity against Escherichia coli and Staphylococcus aureus using the direct contact method showed superior activity for S. aureus due to the nanoparticles-bacteria interactions. The synergistic effect of dopants may have contributed to the better performance observed against S. aureus, while the Pr concentration directly influenced the inhibitory effect of E. coli. Therefore, the synthesized materials are promising to eliminate pathogenic microorganisms.

Influence of the shaker mill in the properties of ZnO processed by high energy milling

This work evaluates how the High Energy Ball Milling (HEBM) in a shaker mill influences the optical, physical, and microstructural properties of ZnO. The procedure also combines Fe inclusion from the grinding medium with particle size reduction. ZnO powder was milled by 1, 2, 3, 4, and 5 h, which resulted in a particle size reduction to the nanometric scale with a mean size of around 50 nm and a crystallite size reduction by three times when processed from 4 h. Milling has proven to be an efficient process for obtaining nanoparticles with an incredibly short processing time and changed the morphology of the particles from random to spherical shapes. Results also indicate the processing progressively expanded the ZnO hexagonal structure due to the imposed strain and Fe inclusion, which can help to decrease the bandgap and slow down the recombination rate of the electron-hole pairs, improving the photocatalysis activity. The optical results showed no additional band appeared due to milling processes and diminished the bandgap from 3.37 to 3.21 eV. Milling also led to an increase in the c value from 5.2076 to 5.2112 Å, which is one of the most important factors for improved antibacterial activity. HEBM has proved to be a suitable process for obtaining ZnO nanoparticles with properties useful for various applications.

Effect of yttrium substitution in Fe-doped ZnO nanoparticles: An EPR study

In this work, we investigated the effect of Y3+ inclusion in ZnO nanoparticles doped with Fe3+ synthesized by the sol gel method. Transmission Electron Microscopy (TEM) images showed agglomerated nanostructures with different shapes and average particle size distributions ranging from 6 nm to 44 nm in diameter. Electron Paramagnetic Resonance (EPR) studies of the Zn0.98−yY0.02FeyO (y=0.00, 0.02, 0.03 and 0.04) were carried out using X band (9.7 GHz) at room temperature. For undoped ZnO and doped with Y3+, complex line shapes were observed as a result of oxygen vacancies (VO+1). In addition, the Y3+ inclusion provokes an enhancement of the linewidth and the resonance field due to intrinsic defects in the hexagonal structure. This observation is compatible with a shortest relaxation time by reason of the particle size reduction and an extra antiferromagnetic local field as a result of the Y3+ presence. For co-doped ZnO samples, the EPR spectra confirms the presence of Fe3+ and Y3+ at the core Zn sites, altering the lattice strain of the ZnO structure. This result was monitored by the zero-field splitting (ZFS) parameters of the spin Hamiltonian, corroborating a reduction in the Fe - Fe interaction. The presence of Y ions was also confirmed in interstitial sites, resulting in a small g-shift from 4.2 to 4.0 associated with modifications of the rhombic component, E, of the Spin–Hamiltonian. This study contributes to the understanding of structural defects caused by the Y and Fe inclusion in the Wurtzite crystal structure of ZnO, a material with potential applications in spintronic devices.

Piezo/pyro/photo‐catalysis activities in Ba0.85Ca0.15(Ti0.9Zr0.1)1‐xFexO3 ceramics

AbstractBa0.85Ca0.15(Ti0.9Zr0.1)1‐xFexO3 (x = 0, 0.5, and 1%) ceramics were studied for piezocatalysis, photocatalysis, and pyrocatalysis using dye degradation in the simulated wastewater. The effect of electrical poling was also performed and found a significant impact of poling on all three catalytic reactions. Fe decreased the optical bandgap of Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZTO) to the visible region. Bandgap for x = 0, 0.005, and 0.01 was found to be 3.14 eV, 2.75 eV, and 2.61 eV, respectively. Interestingly, visible light photocatalytic activity was observed after Fe inclusion in BCZTO lattice. These compositions have also demonstrated dye degradation under ultrasonication (piezocatalytsis) and during temporal temperature change (pyrocatalysis). Results indicate promising multicatalysis in BCZTO ceramics which can be tuned using Fe substitution.

Rapid detection of inclusion particles in recycled aluminum materials by laser-induced plasma optical emission spectrometry with scanning laser beam

This paper describes an analytical method to evaluate the kind and the number of inclusion particles on the surface of a recycled Al ingot using laser-induced breakdown spectrometry (LIBS) with scanning laser beam. The surface was observed with scanning electron microscope - energy dispersive X-ray spectrometry (SEM-EDX) as well as scanning LIBS in the same viewing positions, in which inclusion particles of Si and Fe compounds were found. By measuring the emission intensity of the Fe I 358.119-nm and Si I 288.160-nm lines, the lateral distribution of Si and Fe inclusion particles was estimated from 2D intensity maps of these emission lines. The lateral resolution of the scanning LIBS was about 100 μm, which was restricted by the size of an ablated crater and the surrounding area; therefore, it is difficult to evaluate the actual number of fine inclusion particles (one or more particles may be counted to be a single particle). Nevertheless, the scanning LIBS has an advantage that the analysis can be conducted easily and rapidly compared to conventional analytical methods for inclusions. In our LIBS apparatus, the analysis for a sample surface of 4.0 × 5.0 mm2 was finished in about 40 min. and the time would be reduced if the spectrum analysis is automated on a computer. Accordingly, it is expected that the scanning LIBS can be utilized to consult on the quality of recycled Al materials in the recycling sites.

Antibacterial activity of ultra-small copper oxide (II) nanoparticles synthesized by mechanochemical processing against S. aureus and E. coli.

In this paper, ultra-small CuO nanoparticles (NPs) were synthesized through a mechanochemical method using two different Cu-containing precursors (i.e. CuSO4·5H2O and CuCl2·2H2O), and their structure and antibacterial activity were studied. From the microstructural studies, it was observed that CuO NPs have a spherical morphology and a narrow size distribution with 7 and 14 nm median particle sizes for CuCl2·2H2O and CuSO4.5H2O precursors, respectively. The CuCl2·2H2O derived nanoparticles showed more antibacterial activity than CuSO4.5H2O derived nanoparticles. The minimum inhibitory concentration (MIC) of the synthesized nanoparticles (derived from both precursors) against E. coli and S.aureus were 3.75 and 2.50 mg/ml, respectively, which are higher than those reported in the literature for CuO NPs synthesized by other methods. This difference may be originated from ultra-small size of the synthesized nanoparticles, high bandgap energy and Fe inclusion entering from milling media and their effect on oxidative stress-mediated cytotoxicity of CuO NPs. The higher MIC value reported in this work indicates that the synthesized NPs not only show good antibacterial activity, but also they yield lower cytotoxicity, which extends their applications in the biomedical field.

Efficient photocatalytic degradation of rhodamine-B by Fe doped CuS diluted magnetic semiconductor nanoparticles under the simulated sunlight irradiation

The present work is planned for a simple, inexpensive and efficient approach for the synthesis of Cu1-xFexS (x = 0.00, 0.01, 0.03, 0.05 and 0.07) nanoparticles via simplistic chemical co-precipitation route by using ethylene diamine tetra acetic acid (EDTA) as a capping molecules. As synthesized nanoparticles were used as competent catalysts for degradation of rhodamine-B organic dye pollutant. The properties of prepared samples were analyzed with energy dispersive analysis of X-rays (EDAX), X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible optical absorption spectroscopy, Fourier transform infrared (FTIR) spectra, Raman spectra and vibrating sample magnetometer (VSM). EDAX spectra corroborated the existence of Fe in prepared nanoparticles within close proximity to stoichiometric ratio. XRD, FTIR and Raman patterns affirmed that configuration of single phase hexagonal crystal structure as that of (P63/mmc) CuS, without impurity crystals. The average particle size estimated by TEM scrutiny is in the assortment of 5–10 nm. UV-visible optical absorption measurements showed that band gap narrowing with increasing the Fe doping concentration. VSM measurements revealed that 3% Fe doped CuS nanoparticles exhibited strong ferromagnetism at room temperature and changeover of magnetic signs from ferromagnetic to the paramagnetic nature with increasing the Fe doping concentration in CuS host lattice. Among all Fe doped CuS nanoparticles, 3% Fe inclusion CuS sample shows better photocatalytic performance in decomposition of RhB compared with the pristine CuS. Thus as synthesized Cu0·97Fe0·03S nanocatalysts are tremendously realistic compounds for photocatalytic fictionalization in the direction of organic dye degradation under visible light.

Nickel-iron oxyhydroxide oxygen-evolution electrocatalysts: the role of intentional and incidental iron incorporation.

Fe plays a critical, but not yet understood, role in enhancing the activity of the Ni-based oxygen evolution reaction (OER) electrocatalysts. We report electrochemical, in situ electrical, photoelectron spectroscopy, and X-ray diffraction measurements on Ni(1-x)Fe(x)(OH)2/Ni(1-x)Fe(x)OOH thin films to investigate the changes in electronic properties, OER activity, and structure as a result of Fe inclusion. We developed a simple method for purification of KOH electrolyte that uses precipitated bulk Ni(OH)2 to absorb Fe impurities. Cyclic voltammetry on rigorously Fe-free Ni(OH)2/NiOOH reveals new Ni redox features and no significant OER current until >400 mV overpotential, different from previous reports which were likely affected by Fe impurities. We show through controlled crystallization that β-NiOOH is less active for OER than the disordered γ-NiOOH starting material and that previous reports of increased activity for β-NiOOH are due to incorporation of Fe-impurities during the crystallization process. Through-film in situ conductivity measurements show a >30-fold increase in film conductivity with Fe addition, but this change in conductivity is not sufficient to explain the observed changes in activity. Measurements of activity as a function of film thickness on Au and glassy carbon substrates are consistent with the hypothesis that Fe exerts a partial-charge-transfer activation effect on Ni, similar to that observed for noble-metal electrode surfaces. These results have significant implications for the design and study of Ni(1-x)Fe(x)OOH OER electrocatalysts, which are the fastest measured OER catalysts under basic conditions.

Remarkable enhancement in optical and thermal properties of sodium hydrogen phthalate hemihydrate crystals due to Fe3+ doping

Effects of Fe-doping on the solution grown semi-organic non-linear optical sodium phthalate hemihydrate (SP) single crystals have been reported. The structure and morphology of pure and doped crystals were analyzed. The degree of dopant inclusion was ascertained by Atomic Absorption Spectroscopy. The vibrational bands of the crystals were elucidated by Fourier transform infrared and Raman spectra. Fe inclusion in SP crystals resulted in an absorption band at 370nm in UV region and increase in transmittance in entire visible region with no appreciable change in optical band gap. Intensity of photoluminiscent peaks at 412nm and 522nm was enhanced due to Fe-doping with inhomogeneous broadening. Dielectric studies showed lower dielectric tensor component (ε33) and higher dielectric loss in Fe-doped crystals compared to pure SP crystals. Melting point and thermal stability enhanced due to the introduction of small ionic radius Fe3+ ion in the pure SP crystal. SHG efficiency of pure SP crystal was doubled after Fe-doping and became comparable to that of KDP.

Internal α activity: localisation, compositional associations and effects on OSL signals in quartz approaching β saturation

Luminescence signals from hydrofluoric acid etched grains of quartz from Mozambican dunes were investigated in terms of elemental impurities, structural defects, and their relationship to internal α activity, to examine the potential for this to cause differences in signal levels obtainable from natural and laboratory irradiated samples. Optical and scanning electron microscopy (SEM), X-ray fluorescence (XRF) and instrumental neutron activation analysis (INAA) indicated the presence of various types of quartz and mineralogical inclusions. A spatial association of Th and U with Fe in structural defects was observed. Fe concentrations and inclusion sizes indicated that internal α dose rate would affect the defects that contained these impurities, but would be insignificant to the bulk quartz. A broad range of optically sensitive thermoluminescence (TL) peaks were observed from this material, and indicated a preheating regime of 260 °C for 30 s to minimise effects of the observed inclusions and defects on absorbed dose determinations by optically stimulated luminescence (OSL). Growth in OSL with dose from etched coarse grains preheated in this way approached saturation by 332 Gy of β irradiation ( 90Sr/ 90Y) and by 4 kGy of α irradiation ( E ≈ 3.5 MeV: approximate natural soil spectrum average, using converted dose rate from 241Am). This indicated α-efficiency ( k eff) at saturation of less than 0.08. However, the OSL decay curves contained a small ‘medium’ component. Structural defects introduced by milling the grains produced a larger ‘medium’ component with a similar decay rate under optical stimulation, which exhibited high saturation doses (>32 kGyα, >8.4 kGyβ) and α-efficiency ( k eff = 0.34). Maximum dose normalised OSL signals from the milled material greatly exceeded those obtainable from the whole etched grains. It is inferred that the presence of structural defects within a quartz crystal, similar to those produced by milling, can produce OSL components that grow to signal levels and doses exceeding those from the crystalline quartz. In the present study such defects were found to host α-emitting impurities. High localised dose rates in nature could enhance signals from these locations without affecting the bulk crystal, producing high natural signal levels that may be difficult to reproduce in the laboratory. Association of internal α activity with Fe indicates potential for removal of the most α affected grains by magnetic separation. With or without associated α activity, signals from such defects may contribute to observed variability in the dose response of quartz OSL.

Nanostructural Evolution: From One-Dimensional Tungsten Oxide Nanowires to Three-Dimensional Ferberite Flowers

Based on a W18O49 nanowire template, iron-substituted W18O49 nanowires and FeWO4 ferberite flowers have been generated by using mixed FeCl3 and WCl6 at different ratios in a simple solvo-thermal process employing cyclohexanol as the solvent. Detailed characterization by electron microscopy and spectroscopy has shown that increasing the FeCl3 concentration during solvo-thermal synthesis promotes a morphological evolution from the long one-dimensional nanowires of the precursor through short Fe-containing W18O49 nanowires and two-dimensional platelets to three-dimensional flowers with sixfold symmetry. The driving force for these transformations is attributed to Fe inclusion in the W18O49 template at low Fe concentrations, which introduces internal stresses to the W18O49 nanowires. At high Fe concentrations, close to the stoichiometric composition of FeWO4, the formation of the flower is triggered by the intrinsic sixfold symmetry of crystalline ferberite, via a combination of initial nanoblade nucleation a...

Morphological and Chemical/Physical Characterization of Fe-Doped Synthetic Chrysotile Nanotubes

In the field of thin-layer-structured inorganic nanotubes, morphological, structural, and chemical/physical modifications induced in synthetic stoichiometric chrysotile nanotubes have been evaluated as a function of the extent of Fe doping. Fe-doped synthetic chrysotile nanocrystals have been obtained in the range from 0.29 wt.-% up to 1.37 wt.-% Fe. A partial Fe replacement for Si and Mg has been observed through the modification of Fourier-transform infrared (FTIR) absorption bands. FTIR spectroscopic, X-ray diffraction, and thermogravimetric analyses provide evidence for Fe inclusion into the chrysotile crystal structure, in both octahedral and tetrahedral sites, which induces a flattening of the curved brucite-like layers in the stoichiometric chrysotile. Further characterization by morphological analysis (scanning electron microscopy, transmission electron microscopy, and atomic force microscopy) has revealed the effect of Fe doping on the aggregation of chrysotile nanotubes. The results appear interesting in light of the proposed possibilities of synthetic chrysotile fibers to represent an alternative to carbon nanotubes for innovative technological applications.

Growth mechanism of Fe nanoisland array on Cu( [formula omitted])–c(2×2)N surfaces

Growth mechanism of Fe nanoisland array is studied on Cu(0 0 1)–c(2×2)N surfaces where 5×5 nm 2 patches of N-adsorbed c(2×2) structure are squarely arranged and separated by a few nm wide lines of clean Cu surface. The correlation between the site of the Fe inclusions in the clean Cu surface and that of the nucleated Fe islands is confirmed using scanning tunneling microscopy. The Fe inclusions effectively act as nucleation centers of the monolayer islands at very low coverage while the sticking process of Fe adatoms to the edge of the islands dominates the island growth at the increased coverage. On the Cu(0 0 1)–c(2×2)N surfaces, preferential island growth at the intersections of the clean Cu lines is ascribed to the large sticking probability. Difference of the surface strain on the clean Cu lines is the origin of the site selections both for the Fe inclusion in the surface and for the sticking probability of mobile Fe adatoms to the edge of the islands.

Phase transformations in Fe-doped cupric oxide

This work is a study of 57Fe-doped CuO samples intended to obtain a compound of nominal composition (Cu 1− x Fe x )O ( x = 0.005; 0.010) through the nitrate route and solid state reactions. Afterwards, the samples were mechanically ground for different times. The specimens were characterized by Mössbauer Spectroscopy and X-ray diffraction. For samples that were not mechanically ground, the iron phases were tetragonal and cubic CuFe 2O 4 spinel, and CuFeO 2, delafossite, independent of the preparation method with no evidence of Fe inclusion into the CuO lattice. For mechanically ground samples, a metastable paramagnetic phase has been found.

Crystal Structure and ESR Study of a Bimetallic Copper/Iron Crown Ether Inclusion Complex

AbstractBimetallic inclusion complexes have been synthesized by a secondary coordination interaction between the guest complex [Fe(η5‐C5H5)(CO)2(NH3)][PF6] and copper(II) complex 1a or nickel(II) complex lb containing crown‐ether hosts. The X‐ray crystal‐structure analysis established that the Cu,Fe inclusion complex 2 crystallize as a centrosymmetric dimer with a CuCu separation of 3.73 Å and a novel out‐of‐plane CuN interaction. The magnetic parameters for 2 were obtained by ESR and ENDOR spectroscopy. ESR susceptibility measurements down to 6 K exclude the presence of any antiferromagnetic coupling interaction between the CuIIcenters of the dimer.