Changes In Fe Content Research Articles

The detection of elemental content changes in electrode coating using laser-induced breakdown spectroscopy

The elemental content of battery electrode coating is prone to change due to the production technology and ambient factors. To ensure the consistent performance and safety of a lithium battery, the elemental content of the electrode coating needs to be kept strictly consistent. This study proposes an internal mixed matrix method that combines laser-induced breakdown spectroscopy and chemometric method to achieve rapid and accurate detection of elemental content changes in electrode coating. The stoichiometric ratios of analytical elements are calculated by using the spectra of laser-induced breakdown spectroscopy. The relationships between that stoichiometric ratios and the actual content of analytical elements are studied and show that they are linear. Thus, the content change of the analytical element can be determined by calculating the change of the stoichiometric ratio. The average relative errors for content changes of iron, lithium, and phosphorus are 6.43%, 2.96%, and 4.12%, respectively, and the lowest detection limits are 278.2 mg/kg, 20.5 mg/kg, and 105.4 mg/kg, respectively. Furthermore, the internal reference method is proposed to correct the effect of ambient gases and improve detection accuracy. The results are that when Fe I 372.751 nm and Fe I 373.485 nm are used as analytical lines, after correcting for the effect of ambient gases, the average relative errors of Fe content changes are reduced by 62% and 72%, respectively, and the lowest detection limits are increased by 67% and 71%, respectively.

Large barocaloric and magnetocaloric effects in MnFe0.8+xNi1.2−xSiGe0.5 high-entropy intermetallics

High-entropy intermetallics (HEIs) are a category of materials that exhibit special functional properties. Among the many excellent properties of high-entropy materials, the magnetocaloric performance has a promising future. We design of HEIs of MnFe0.8+xNi1.2−xSiGe0.5 (x = 0, 0.2, 0.3, and 0.4) based on the MnNiSi. The change of Fe content establishes a stable magnetic structure transition from paramagnetic hexagonal phase to ferromagnetic orthorhombic phase, and a large magnetic entropy change of 25.8 and 32.8 J·kg−1 K−1 is obtained in x = 0.2 and 0.3 materials under the field of 3 T. Moreover, the transition temperature of the MnFeNiSiGe0.5 HEI decreases with increasing pressure, and a low-pressure-induced large reversible barocaloric effect is achieved with the transformation entropy change of 43.72 J·kg−1 K−1 by applying hydrostatic pressure of 10 kbar. Our findings demonstrate that MnFe0.8+xNi1.2−xSiGe0.5 HEIs have promising potential as high-performance solid state refrigeration materials.

Microstructure evolution mechanism of single and multi-pass in laser cladding based on heat accumulation effect for invar alloy

This work explores how the process parameters in laser cladding affect the evolution of the microstructure of the single-pass and multi-pass cladding layers of Invar alloys. The research examined the cladding layers from three aspects: (1) the transformation of grain size, heat-affected zone (HAZ) width, ratio of the columnar crystal to the equiaxed crystal, and change of Fe content of the cladding layer; (2) the effects of heat accumulation on grain size, HAZ width, and remelting zone; and (3) the hardness distribution of single-pass and multi-pass cladding layers. The investigation has the following four findings: (1) the cladding layer is composed of equiaxed crystals at the top and columnar crystals at the bottom of the cladding layer; (2) the processing parameters have significant effects on the width of the HAZ, proportion between the columnar and equiaxed crystals, and the change of Fe content of the cladding layer; (3) the gradual accumulation of heat causes the increase in HAZ width, the grain size, and the area of the remelting zone; and (4) the hardness progressively reduces from the top to the bottom along the direction of the centerline of the cladding layer.

Synthesis and characterization of Fe(III)-Fe(II)-Mg-Al smectite solid solutions and implications for planetary science

AbstractThis study demonstrates the synergies and limits of multiple measurement types for the detection of smectite chemistry and oxidation state on planetary surfaces to infer past geochemical conditions. Smectite clay minerals are common products of water-rock interactions throughout the solar system, and their detection and characterization provides important clues about geochemical conditions and past environments if sufficient information about their composition can be discerned. Here, we synthesize and report on the spectroscopic properties of a suite of smectite samples that span the intermediate compositional range between Fe(II), Fe(III), Mg, and Al end-member species using bulk chemical analyses, X-ray diffraction, Vis/IR reflectance spectroscopy, UV and green-laser Raman spectroscopy, and Mössbauer spectroscopy. Our data show that smectite composition and the oxidation state of octahedral Fe can be reliably identified in the near infrared on the basis of combination and fundamental metal-OH stretching modes between 2.1–2.9 μm, which vary systematically with chemistry. Smectites dominated by Mg or Fe(III) have spectrally distinct fundamental and combination stretches, whereas Al-rich and Fe(II)-rich smectites have similar fundamental minima near 2.76 μm, but have distinct combination M-OH features between 2.24 and 2.36 μm. We show that with expanded spectral libraries that include intermediate composition smectites and both Fe(III) and Fe(II) oxidation states, more refined characterization of smectites from MIR data is now possible, as the position of the 450 cm–1 absorption shifts systematically with octahedral Fe content, although detailed analysis is best accomplished in concert with other characterization methods. Our data also provide the first Raman spectral libraries of smectite clays as a function of chemistry, and we demonstrate that Raman spectroscopy at multiple excitation wavelengths can qualitatively distinguish smectite clays of different structures and can enhance interpretation by other types of analyses. Our sample set demonstrates how X-ray diffraction can distinguish between dioctahedral and trioctahedral smectites using either the (02,11) or (06,33) peaks, but auxiliary information about chemistry and oxidation state aids in specific identifications. Finally, the temperature-dependent isomer shift and quadrupole splitting in Mössbauer data are insensitive to changes in Fe content but reliability differentiates Fe within the smectite mineral structure.

Impact of iron composition on the properties of an additively manufactured solid solution strengthened nickel base alloy

The impact of changes in Fe content from 1 wt% to 4 wt% on the properties of additively manufactured (AM) Inconel® 625 fabricated using laser-based directed energy deposition (DED) is investigated in both the as deposited and post processed hot isostatically pressed (HIP) conditions. While similar solidification structures and microhardness values are observed, the low Fe content build displayed higher yield (520 MPa ± 12 MPa vs. 450 MPa ± 27 MPa) and tensile strengths (860 MPa ± 27 MPa vs. 753 MPa ± 25 MPa) and lower elongations (36% ± 5% vs. 44% ± 9%) in the as-deposited condition. Differences in mechanical properties are connected to differences in the grain size produced with the different Fe contents. In the as deposited condition, fine grains less than 500 µm in size with low aspect ratios were observed with the low Fe content, while large elongated grains in excess of 1 mm in length were observed with the high Fe content. After HIP, the yield strengths for both Fe contents decreased by 14%, while elongation increased similarly. On the other hand, tensile strengths after post processing changed by only 3%, which were correlated to higher levels of strain hardening for the higher Fe content. These differences in behavior can be attributed, in part, to changes in precipitate morphologies. After HIP post processing, the low Fe content build displayed Nb and Mo rich precipitates, while spherical Ti rich precipitates are present in the high Fe content build.

Manufacture and characteristics of Al2O3 composite coating on steel substrate by SHS process

Many steel components are needed to be reinforced on their surface to have a high abrasive resistance and corrosion resistance. Based on self-propagating high-temperature synthesis, a process to making Al2O3 composite coatings on mild steel substrate in atmospheric environment with the help of simple auxiliary facilities was developed successfully. A pre-coated bilayer coating was employed. The effects of Fe content in pre-coated transition layer on phase composition, porosity and interfacial bonding were studied using scanning electron microscopy (SEM), energy-dispersive spectrum (EDS) and X-ray diffraction (XRD). The thermal shock resistance and abrasive resistance were investigated. When Fe content changes from 0 wt% to 50 wt%, the bond quality at first becomes better and then worse gradually. When Fe content is less 20 wt%, there is a small gap between the transition layer and the substrate; when Fe contents are 30 wt% and 40 wt%, working layer, the transition layer and the substrate bond together well. The working layer is mainly composed of Al2O3, Fe–Cr and Al(Cr)2O3 phases and has a dense structure with porosity of less than 1%. The coating has a good thermal shock resistance and abrasive resistance. The abrasive resistance of the working layer is about ten times that of the substrate.

Quantitative calculation on atomic site occupation during precipitation of Ni3(Al1–xFex) by microscopic phase-field study

Microscopic phase-field method was used to simulate the site occupation of a series of alloys with a stoichiometric composition of Ni75Al25–xFex (x=0, 5–10) aged at 1273 K. With the change of Fe content, quantitative calculations were made on each atomic site occupation probability (SOP) in L12-Ni3 (Al1–xFex), so as to find out the dynamic response law. The result of the study shows that, with the increase of Fe content, the Fe atom preferentially occupies the B sites (corner sites of FCC) with its SOP value being increased gradually, and the SOP of the Al atom on the B sites is greatly decreased. Meanwhile, AlNi and FeNi anti-sites form in the precipitation of L12 phase. Moreover, with the increase of Fe content, the formation of AlNi and FeNi anti-sites becomes much easier. In addition, it has been found that the instantaneous dynamic evolution of the atomic SOP is completed at the early stage of the growth of L12 phases.

Non-stoichiometric synthesis and electrochemical performance of LiFe1-xPO4/C cathode materials for lithium ion batteries

Non-stoichiometric LiFe 1-x PO 4/ C composites were synthesized by a simple sol–gel method. Different impurities were detected in the X-ray diffraction measurements with the change of Fe content. The effects of Fe -poor on the structure and electrochemical performance of LiFePO 4 were investigated. Compared with stoichiometric LiFePO 4/ C , non-stoichiometric samples show better electrochemical performance because they have smaller impedance and faster lithium ion diffusion. Among these non-stoichiometric samples, LiFe 0.94 PO 4/ C cathode delivers the highest capacity of 149 mAh g-1 at 0.2 C and 103 mAh g-1 at 5 C and no capacity loss was found after 100 full cycles.

Cysteine 295 indirectly affects Ni coordination of carbon monoxide dehydrogenase-II C-cluster

A unique [Ni–Fe–S] cluster (C-cluster) constitutes the active center of Ni-containing carbon monoxide dehydrogenases (CODHs). His261, which coordinates one of the Fe atoms with Cys295, is suggested to be the only residue required for Ni coordination in the C-cluster. To evaluate the role of Cys295, we constructed CODH-II variants. Ala substitution for the Cys295 substitution resulted in the decrease of Ni content and didn’t result in major change of Fe content. In addition, the substitution had no effect on the ability to assemble a full complement of [Fe–S] clusters. This strongly suggests Cys295 indirectly and His261 together affect Ni-coordination in the C-cluster.

Structural, magnetic, and electron transport properties of MnBi:Fe thin films

The structural, magnetic, and electron transport properties of Mn55−xFexBi45 (x = 0, 2, 4, 5, 8, 11, 13, 16) films prepared by multilayer deposition and annealing using e-beam evaporation have been investigated. Fe doping has produced a significant change in the magnetic properties of the samples including the decrease in saturation magnetization and magnetocrystalline anisotropy and increase in coercivity. Although the magnetization shows a smooth decrease with increasing Fe concentration, the coercivity jumps abruptly from 8.5 kOe to 22 kOe as Fe content changes from 4% to 5%, but the change in coercivity is small as the concentration goes beyond 5%. The temperature dependence of resistivity shows that the samples with low Fe concentration (≤4%) are metallic, but the resistivity increases unexpectedly as the concentration reaches 5%, where the resistance increases with decreasing temperature below 300 K. First-principle calculations suggest that the observed magnetic properties can be understood as the consequences of competing ferromagnetic and antiferromagnetic exchange interactions between the interstitial atom and the rest of the MnBi lattice.

Is iron phloem mobile during senescence in trees? A reinvestigation of Rissmüller’s finding of 1874

As long as 130 years ago Rissmüller reported substantial retranslocation of iron (Fe) from beech leaves (Fagus sylvatica L.) shortly before leaf fall. This rather limited report on Fe retranslocation via the phloem in plants was the reason for this research to study changes in Fe content in individual beech leaves in more detail during the vegetative period. Besides Fe, other micronutrients and particularly Ca and K, well known to differ substantially in phloem mobility, were analysed as mineral nutrient markers. In addition to beech, other deciduous and evergreen species of Angiosperms and Gymnosperms were also studied. As expected, there was no evidence of Ca retranslocation from senescent leaves, while K as a phloem mobile mineral nutrient was retranslocated in fall in deciduous but not in evergreen trees. There was no indication to support Rissmüller's finding of Fe retranslocation in any of the different species studied. From these results, we conclude that natural leaf senescence of trees during late season does not induce retranslocation of Fe and other micronutrients. Possible reasons for the absence of a distinct retranslocation of Fe in the species studied during late season senescence are the lack of a sink activity, as for example the development of seeds in annual plant species (e.g., cereals), or the presence of a root system still active enough to provide Fe and other mineral nutrients for plant demand, and both factors have to be considered in further studies. Reviewing the data in the literature on Fe and Zn retranslocation during senescence, we conclude that in principle both micronutrients are potentially phloem mobile. However, various prerequisites are needed for the occurrence of phloem mobility which were absent in the plant species studied. Regardless of this conclusion, we recommend that in general early published research data need a critical re-evaluation.

Manufacture of Bulk Amorphous Crystal and Micro-Crystal for Pr 60Cu (20-x)Ni 10Al 10Fe x and Characteristics of Its Magnetic Apparatus

Bulk amorphous crystal and microcrystal for Pr 60Cu (20-x)Ni 10Al 10Fe x (x = 0, 8, 15, 20) with the diameter of ϕ2 ∼ 6 mm were manufactured by electric arc smelting, high frequency heating and copper mold upper suction casting, and its structure was analyzed by X-ray diffract meter. It showed soft magnetic characteristic gradually when Fe content in it was up to 8%. The material was applied to magnetic-electric sensor as key component, output signal of which was measured with the change of Fe content. It shows that the signal changes from weak to strong with the increase of Fe content and presents the largest peak value when Fe is replaced by Cu completely.

Mössbauer morphological analysis of Fe-filled multiwalled carbon nanotube samples

We have performed morphological analysis of samples of Fe nanowires encapsulated into aligned multiwalled carbon nanotubes (Fe-MWCNTs) via Fe57 Mössbauer spectroscopy. The aligned Fe-MWCNTs were obtained by pyrolysis of ferrocene onto an oxidized Si substrate. Transmission Mössbauer spectroscopy (TMS) and backscattered conversion electron Mössbauer spectroscopy (CEMS) were applied in order to distinguish different Fe phases and their spatial distribution within the whole sample and along the tubes’ height. A characterization (on a large spatial scale) of the aligned CNT samples was performed by obtaining TMS spectra for selected spots positioned at different locations of the sample. While the total Fe content changes considerably from one location to another, the γ-Fe∕α-Fe phase ratio is constant onto a relatively large area. Using TMS and CEMS for all aligned Fe-MWCNT samples it is also shown that along the CNT axes, going to the top of the nanotube the relative content of the γ-Fe phase increases. Going to the opposite direction, i.e., towards the silicon substrate, the relative content of the Fe3C phase increases, which is in agreement with our previous works. The results of an additional Mössbauer spectroscopy experiment in TMS and CEMS modes performed on a nonaligned sample support the conclusion that in our case the iron phases in the channels of carbon nanotubes are spatially separated as individual nanoparticles. The relative intensity ratio of the α-Fe phase Mössbauer sextets shows good magnetic texture along the nanotubes’ axis for one of the aligned samples and the lack of such orientation for the others.

Small-angle neutron-scattering studies of reentrant spin-glass behavior in Fe–Al alloys

Fe–Al alloys around the concentration of 30 at. % Al show very interesting magnetic properties. Alloys with this concentration present magnetic inhomogeneities and their evolution with temperature is also interesting because they show a reentrant spin-glass behavior at low temperatures. Small-angle neutron-scattering measurements were performed in Fe69.5Al30.5,Fe70Al30, and Fe70.5Al29.5 alloys in the temperature range of 4–300 K. Even though the change in Fe content is very small, the response variation is quite large. The results show that the samples have magnetic inhomogeneities that evolve with temperature. Only in the Fe-richest sample the random-field model can be applied.

Heterogeneous catalysis in the Fenton-type system FeZSM-5/H2O2

The work deals with Fe-containing zeolites for the catalytic oxidation of water-dissolved organic substances by H2O2. A detailed study of the system FeZSM-5/H2O2 meant to reveal the nature of the catalysis is presented. For this purpose, the following characteristics of the system were determined: the iron concentration in the filtrate of the catalyst suspension in several reaction runs; Fe content changes in the repeatedly used heterogeneous catalyst; the catalytic activities of the filtrate and of the heterogeneous catalyst in several runs. It has been shown that in the system FeZSM-5/H2O2, the heterogeneous catalysis makes the main contribution to the catalyst activity in the H2O2 decomposition and oxidation of organic substrates. Additionally, in the presence of the iron ions complexing agents, FeZSM-5 showed a significantly different behavior in comparison to the homogeneously dissolved iron cations. For example, in the presence of the P2O74− anions, the rate of the H2O2 decomposition increased by several times in the FeZSM-5 suspension, while it is totally reduced in a homogeneous iron solution.

On the relationship between the hysteresis loop shift and the dipolar interactions in hard–soft nanocomposite samples

We report on the hysteretic and relaxational behavior of Fe–Ba hexaferrite nanocomposite samples prepared by ball milling. This includes data on the temperature dependence of the coercive force, on the relationship between the field evolution of the isothermal and the demagnetization remanences and on the time evolution of the magnetization at those remanences. Our most remarkable result corresponds to the observation, at room temperature and without field cooling the samples, of a displacement (in the sense of the negative fields) of the hysteresis loops measured under a maximum applied field of 0.8 T. The magnitude of that shift oscillates when the Fe content changes. Our results are analyzed in terms of the occurrence of interphase dipolar interactions.

Anomalies of the dependence of the magnetic properties on the chemical composition in amorphous Fe-Si-B alloys

The magnetic properties of Fe x Si 90− x B 10 metallic glasses (68⩽ x⩽83) have been studied. In that group of glassy alloys anomalies of the dependence of the magnetic properties with the Fe content are found. There occurs a maximum of the Curie temperature in the vicinity of x = 75. The saturation magnetic moment varies linearly up to x = 75. For higher Fe content changes of the magnetic moment are small. The spinware stiffness constant is almost constant for x ⩽ 75 whereas for x > 75 it decreases strongly. Among the curves describing the reduced saturation magnetization as a function of the reduced temperature the plot for x = 75 is located highest. It is suggested that there is a gradual transition from normal to Invar-like behaviour in that system.

Composition Limits and Magnetic Properties of Sintered Y2.66Gd0.34FexAl0.677Mn0.09O12 Garnets

Single‐phase garnet solid solutions can be synthesized between the composition limits of x=4.18 and x=4.22 in Y2.66Gd0.34FexAl0.677Mn0.09O12 at temperatures between 1340° and 1500°C in O2. Solid solutions occur only on the Y2O3‐excess side of the stoichiometric garnet composition. Electromagnetic properties and microstructural features of sintered garnets depend critically on small changes in Fe content in the vicinity of the garnet solid‐solution region. An intergranular spinel‐type second phase exists for compositions when x>4.22 and has a deleterious effect on remanent induction and magnetic loss at 3 GHz. The relative density of powder compacts sintered for 16 h at 1500°C in O2 increases with increasing Fe content (i.e. as x increases) in the garnet solid solution.