Properties Of Fe1 Research Articles

Crystal growth and characterization of Fe1+δSe1-xTex (0.5 ≤ x ≤ 1) from LiCl/KCl flux

An eutectic LiCl/KCl flux method in a horizontal configuration has been used to grow a series of homogeneous Fe1+δSe1-xTex single crystals of high quality with 0.5 ≤ x ≤ 1. Compared with previously used melt-growth method, the stable crystallization process in LiCl/KCl flux below their peritectic temperatures results in better homogeneity and crystalline perfection identified by energy dispersive spectrometer and x-ray diffraction. The interstitial Fe value δ remains small within 0.5 ≤ x ≤ 0.85 where the superconducting temperature TC is not sensitive to the Te content with sharp superconducting transition widths ΔTC < 1 K and a maximum of TC = 14.3 K at x = 0.61. The value δ starts to increase quickly accompanied by a deviation of linear behavior of crystal lattice parameters as well as the broadening of ΔTC = 2.1 K at x = 0.91, then suddenly rises up to δ > 0.1 followed by the disappearance of superconductivity and emergence of antiferromagnetic order at x ≥ 0.96. We also observed a metallic to semiconducting transition in the normal state resistivity of Fe1+δSe1-xTex with increasing Te content which is related to a localized electronic state induced by the interstitial Fe. The interstitial Fe value δ might be a key physical parameter to understand various properties of Fe1+δSe1-xTex system.

Efficacy of combination of endo-xylanase and xylan-debranching enzymes in improving cereal bran utilization in piglet diet.

This study was aimed to explore the efficacy of combination of endo-xylanase (Xyn) and xylan-debranching enzymes (arabinofuranosidase, Afd and feruloyl esterase, FE) in improving utilization of bran in piglet diet. In vitro experiments were firstly conducted to examine the enzymological properties of Xyn, Afd, and FE, concurrent with their effect on degradation of arabinoxylan (Abx) in bran. In vivo experiment was then implemented by allocating two hundred and seventy 35-d-old postweaning piglets into 3 groups (6 replicates/group), which received bran-containing diet supplemented with Xyn (1,600 U/kg) or its combination with Afd (0.8 U/kg) and FE (4 U/kg) or without enzyme. Both Xyn, Afd, and FE are relatively stable against the changes in temperature and pH value. Combining Xyn with Afd and FE had a superiority (p<0.05) over Xyn alone and its combination with Afd or FE in promoting (p<0.05) degradation of Abx in different brans. Combined treatment with Xyn, Afd, and FE was more beneficial than Xyn alone to induce increasing trends (p<0.10) of average daily gain, final body weight and feed efficiency of piglets fed bran-containing diet. Moreover, combination of Xyn, Afd, and FE showed advantages (p<0.05) over Xyn alone in causing reductions (p<0.05) in diarrhea rate and cecal pH value, concurrent with increases (p<0.05) in cecal and colonic acetic acid and total volatile fatty acid concentrations, as well as cecal butyric acid concentration of piglets fed bran-containing diet. Combining Xyn with Afd and FE was more beneficial than Xyn alone in promoting degradation of Abx in bran, along with growth performance and intestinal volatile fatty acid profile of piglets received bran-containing diet. Thereby, combination of Xyn, Afd, and FE had a superior efficacy relative to Xyn alone in improving application of cereal bran in piglet diet.

Impact of bridging oxygens formation on optical properties of Fe3+ doped Li2O–Al2O3–SiO2–TiO2 glasses

In this study, the structural chemistry of Fe3+ doped Li2O–Al2O3–SiO2–TiO2 (LAST) glasses has been analyzed utilizing UV-Vis spectroscopy. Optical parameters like absorption and extinction coefficients, indirect and direct optical band gaps, Urbach energy as well as Fermi energy level of samples were estimated via their absorption spectra. Then, it was tried to make a relationship between the variation of mentioned parameters and structural chemistry of different doped samples. Results of the investigation illustrated that even a little change in the microstructure of glassy samples has an effect on optical parameters and accordingly it could be sensible. Furthermore, it was revealed that Fe3+ ions have the role of network forming in the structure of glass by increasing the formation of bridging oxygens (BOs) in the matrix.

Microstructures and properties of Fe1.25CoNi1.25CrxAl0.25 high-entropy alloys after cold-rolling and annealing

Microstructures and properties of Fe1.25CoNi1.25CrxAl0.25 (x=0.5, 0.75, 1) high-entropy alloys (HEAs) fabricated by copper mold suction casting were studied in this paper. The crystal structure of the alloy is composed of single-phase FCC solid solution, and the crystal structure does not change with the change of Cr content. The yield strength of as-cast alloys is below 200 MPa, and the elongation is above 50%. After cold-rolling and annealing, the strength and hardness of the alloy increase with the increase of Cr content. The comprehensive mechanical properties of the alloy with x=1 reach the best. The yield strength, tensile strength and elongation are 498 MPa, 770 MPa and 40%, respectively. The cubic texture of {001}<100> is the strongest texture of the specimen with x=0.5. The appropriate addition of Cr is beneficial to improve the corrosion resistance of the alloy. The alloy with x=0.75 has the best corrosion resistance in 0.5 mol/L H2SO4. The reduction of Cr content is advantageous to improve the soft magnetic properties of alloys, and Fe1.25CoCr0.5Ni1.25Al0.25 shows excellent magnetic properties. The Fe1.25CoCr0.5Ni1.25Al0.25 HEA, meanwhile, has good processability with the elongation over 50%.

Effect of Al content on microstructures and properties of Fe1.25CoCrNi1.25Al x high-entropy alloys

The effect of Al content on microstructures and properties of Fe1.25CoCrNi1.25Al x (x = 0.1, 0.25, 0.4) high-entropy alloys was studied. The alloys arecomposed of a single-phase face-centered cubic solid solutionand do not change with the change of Al content. The tensile yield strength of as-cast alloys is below 200 MPa, and the elongation is above 55%. After cold-rolling and annealing, the strength and hardness increase with the increase of Al content. The comprehensive mechanical properties of the alloy with x = 0.25 reach the best. The texture composition of Fe1.25CoCrNi1.25Al0.4 gradually changes from {100} <001> to {110} <101> after cold-rolling and annealing. Trace Al is beneficial to improve the corrosion resistance of the alloys.

Influences of annealing temperature on properties of Fe2+:ZnSe thin films deposited by electron beam evaporation and their applications to Q-switched fiber laser**Project supported by the National Natural Science Foundation of China (Grant No. 11574221) and the Graduate Student’s Research and Innovation Fund of Sichuan University, China (Grant No. 2018YJSY008).

Fe2+:ZnSe thin films are prepared on sapphire substrate at room temperature by electron beam evaporation and then annealed in vacuum (about 1 × 10–4 Pa) at different temperatures. The influences of thermal annealing on the structural and optical properties of these films such as grain size and optical transmittance are investigated. The x-ray diffraction patterns show that the Fe2+:ZnSe thin film is preferred to be oriented along the (111) plane at different annealing temperatures. After the film is annealed, the full-width-at-half-maximum ( FWHM ) of the x-ray diffraction peak profile (111) of the film decreases and its crystal quality is improved. Scanning electron microscope images show that the films are more dense after being annealed. Finally, the sample is used as a saturable absorber in ZBLAN fiber laser. The annealed Fe2+:ZnSe thin films can be used to realize stable Q-switching modulation on ZBLAN fiber laser. The results demonstrate that the Fe2+:ZnSe thin film is a promising material for generating the high-power pulses of mid-infrared Q-switched fiber lasers.

Impact of iron composition on the calculated electronic and magnetic properties of Fe3−xNixSi

ABSTRACTThe structural, electronic and magnetic properties of Fe3−xNixSi alloys with variable iron composition (0 ≤ x ≤ 1) have been investigated within by using Projector augmented wave (PAW) method. The exchange–correlation potential was treated with the generalised gradient approximation (GGA) for the calculation of the structural properties and for the computation of the electronic and magnetic properties in order to treat the d states. These alloys crystallize in cubic Heusler structures; The Fe3Si and Fe2NiSi have a regular structure DO3 and L21 respectively. To describe the experimental proprieties we use the on-site Coulomb interactions of Ueff(Ni) = 3.1 eV and Ueff(Fe) = 3.4 eV. A good agreement between calculated and experimental magnetic moments is found for the cubic Heusler phases without the addition of Hubbard-model. The obtained results of the density of states and the spin-polarized band structure show that the Fe2NiSi alloy has half-metallic property. Through the obtained values of the total spin magnetic moment, we conclude that in general, the Fe2NiSi alloy is half-metallic ferromagnet material whereas the Fe3Si alloy has a metallic nature.

Physical Properties of Fe3+/TiO2 Nanoparticles and Photocatalytic Disinfection of Foodborne Microorganisms

In this article, we studied the preparation of Fe3+/TiO2 nanoparticles and the photocatalytic disinfection effects of two typical foodborne microorganisms, a gram-negative bacterium (Salmonella typhimurium) and a gram-positive bacterium (Listeria monocytogenes), in meat products. The physical properties of Fe3+/TiO2 nanoparticles embedded with various levels of Fe3+ (0%–10%) and synthesized through an impregnation process were investigated using X-ray diffraction, transmission electron microscopy, and UV-vis spectrophotometer, and their photocatalytic activities were evaluated by measuring the degradation of methylene blue dye and the disinfection of foodborne pathogens S. typhimurium and L. monocytogenes under visible light and UV light. Fe3+ ions were found to be scattered across TiO2 surfaces or across TiO2 crystal lattices as microcrystals. However, the capacity for TiO2 nanoparticles to absorb visible light was significantly enhanced after they were embedded with.Fe3+/TiO2 nanoparticles with molar ratios (R) of Fe3+ to TiO2 of 0.001:1, 0.005:1, and 0.01:1 exhibited higher levels of methylene blue dye photocatalytic degradation and higher levels of foodborne pathogen photocatalytic disinfection than the TiO2 control. However, nanoparticles containing &gt;1% Fe3+ exhibited lower levels of photocatalytic activity than the TiO2 control. Salmonella typhimurium was more resistant to the nano-Fe3+/TiO2 treatment than L. monocytogenes under visible and UV light conditions. These experiments demonstrate that embedding Fe3+ in TiO2 nanoparticles does not remarkably influence the TiO2 nanoparticle size or structure. Embedding appropriate levels of Fe3+ content (0.1%–1%) can enhance the photocatalytic activity of TiO2 nanoparticles.

Some Properties of Fe1 +ySexTe1 –x Single Crystals in the Superconducting and Normal States

Despite a large number of publications proving that a number of different materials can be classified as topological insulators, unambiguous proofs of the existence of promising topological superconductors have not been obtained as yet. The implementation of such systems is important not only for solid state physics, but also for applications, because topological superconductors can be used in quantum computers. We have made an attempt to confirm experimentally the assumption put forth in a number of theoretical publications that FeSexTe1 –x with the s-wave pairing, which is the simplest iron-containing superconductors, can become, under certain conditions, a topological superconductor with the π-wave pairing, which must have a superconducting gap in the bulk and the Majorana gapless surface states.

Intrinsic superconducting transport properties of ultra-thin Fe1+y Te0.6Se0.4 microbridges

We investigated the superconducting properties of Fe1+y Te0.6Se0.4 single-crystalline microbridges with a width of 4 μm and thicknesses ranging from 20.8 to 136.2 nm. The temperature-dependent in-plane resistance of the bridges exhibited a type of metal-insulator transition in the normal state. The critical current density (J c) of the microbridge with a thickness of 136.2 nm was 82.3 kA/cm2 at 3K and reached 105 kA/cm2 after extrapolation to T = 0 K. The current versus voltage characteristics of the microbridges showed a Josephson-like behavior with an obvious hysteresis. These results demonstrate the potential application of ultra-thin Fe-based microbridges in superconducting electronic devices such as bolometric detectors.

Structural, Electrical and Electrochemical Properties of Mg0.55Si1.9Al0.1Fe0.1(PO4)3 Ceramic Electrolytes

This study was undertaken to investigate the structural, electrical and electrochemical properties of Fe3+ substituted Mg0.55Si1.9Al0.1(PO4)3 compound synthesized by water-based sol–gel technique. X-ray diffraction showed that the compound crystallized in monoclinic crystalline phase with a space group of P1 21/c1. The sample sintered at 850 ˚C exhibited the highest conductivity of 1.42 × 10-6 S cm-1 at 373 K since it contained the highest number of mobile ions. It also exhibited the highest value of ion mobility, μ of 1.13 × 10-11 cm2 V-1 s-1 at ambient temperature which was attributed to the optimum size of migration channel as indicated by its unit cell volume. Linear sweep voltammetry result showed that the Mg0.55Si1.9Al0.1Fe0.1(PO4)3 was electrochemically stable up to 3.0 V. Meanwhile, its ionic transference number of 0.99 suggested that the majority of the mobile charge carriers were mainly to ions, expected to be Mg2+ ions.

Thermoelectric Properties of Fe1+y Te Prepared by a High Pressure Sintering Method

Enhancing thermoelectric properties by utilizing topological properties of topological insulators has attracted increasing attention. Here, powder metallurgy technology combined with high pressure sintering (HPS) was used to prepare Fe1+y Te (y = 0.1, 0.15, 0.1978, 0.22) alloys at 1173 K. The prepared products were identified by x-ray diffraction, and their microstructures were examined by field-emission scanning electron microscopy (FE-SEM). Electric conductivities (σ) and Seebeck coefficient (S) were measured in the temperature range of 303–623 K. The influence of variation in Fe content on thermoelectric properties was studied. The experimental results show that all HPS samples are nanometer composites consisting of Fe3Te2 and FeTe2. Fe1+y Te have electrical charges on the boundaries of topological insulators, which have the potential to be studied in the future. The Fe1+y Te with y = 0.1 shows the best thermoelectric properties at room temperature.

A soft X-ray synchrotron study of the charge state of iron ions in the ferrihydrite core of the ferritin Dps protein in Escherichia coli

The Escherichia coli Dps protein belongs to a specific family of bacterial ferritins; it is a nanosized particle that contains an inorganic core (~5 nm in diameter) and a protein shell with a size of 8–9 nm. The protein shell consists of 12 identical subunits with the known crystal structure of a dodecamer. The composition and structure of the core have been less studied. The core formation is associated with the oxidation products of Fe2+ ions in the ferroxidase centers of the protein. Thus, Fe2O3 oxides are the main compounds of the core. However, the mineralization properties of Fe2+ ions under anaerobic conditions in vitro may indicate a more complicated composition of the core in the native Dps protein. This paper presents a technique for the preparation of purified Dps samples for ultrahigh vacuum synchrotron experiments by X-ray absorption near edge structure spectroscopy of the iron absorption edge in the soft X-ray region. The conducted synchrotron experiments have revealed the presence of both trivalent and divalent iron ions in the octahedral and tetrahedral environment of oxygen atoms in the prepared biological samples. This points to a complex ionic composition of the core even in the native Dps protein, which has been isolated from aerobically grown bacteria.

The effect of fe-dopant concentration on ethanol gas sensing properties of fe doped ZnO/ZnO shell/core nanorods

In this paper, Fe-doped ZnO/ZnO shell/core nanostructures were synthesized through a simple two-step method and the effects of Fe dopant concentrations (between 0 and 9at%) on the structural, optical, electrical and gas sensing properties were investigated. The X-ray diffraction analysis revealed that all of the samples are crystallized in the same wurtzite hexagonal crystal structure with (002) peak as the main orientation. Nevertheless, the morphology of shell/core nanorods remained stable with increasing of Fe dopant, but the crystallinity improved. The ultraviolet–visible spectroscopy analysis showed that the Fe ions have coordination number of 3+ in the ZnO shell layer. The participation of Fe3+ ions into ZnO layer was also confirmed by Current–Voltage (I–V) curves where the resistance of nanorods was reduced with Fe concentration. Moreover, the ethanol-sensing properties of the Fe-doped ZnO/ZnO shell/core nanorod sensors were systematically investigated. According to the results, optimum gas sensing was obtained by the addition of 0.5at% Fe to ZnO shell layer which lead to significant enhancement in ethanol gas response.

Structural and Electronic Effects on the Properties of Fe2(dobdc) upon Oxidation with N2O.

We report electronic, vibrational, and magnetic properties, together with their structural dependences, for the metal-organic framework Fe2(dobdc) (dobdc(4-) = 2,5-dioxido-1,4-benzenedicarboxylate) and its derivatives, Fe2(O)2(dobdc) and Fe2(OH)2(dobdc)-species arising in the previously proposed mechanism for the oxidation of ethane to ethanol using N2O as an oxidant. Magnetic susceptibility measurements reported for Fe2(dobdc) in an earlier study and reported in the current study for Fe(II)0.26[Fe(III)(OH)]1.74(dobdc)(DMF)0.15(THF)0.22, which is more simply referred to as Fe2(OH)2(dobdc), were used to confirm the computational results. Theory was also compared to experiment for infrared spectra and powder X-ray diffraction structures. Structural and magnetic properties were computed by using Kohn-Sham density functional theory both with periodic boundary conditions and with cluster models. In addition, we studied the effects of different treatments of the exchange interactions on the magnetic coupling parameters by comparing several approaches to the exchange-correlation functional: generalized gradient approximation (GGA), GGA with empirical Coulomb and exchange integrals for 3d electrons (GGA+U), nonseparable gradient approximation (NGA) with empirical Coulomb and exchange integrals for 3d electrons (NGA+U), hybrid GGA, meta-GGA, and hybrid meta-GGA. We found the coupling between the metal centers along a chain to be ferromagnetic in the case of Fe2(dobdc) and antiferromagnetic in the cases of Fe2(O)2(dobdc) and Fe2(OH)2(dobdc). The shift in magnetic coupling behavior correlates with the changing electronic structure of the framework, which derives from both structural and electronic changes that occur upon metal oxidation and addition of the charge-balancing oxo and hydroxo ligands.

Wiedemann-Franz law in iron-based superconductor Fe1+dTe1−xSex

We present results of measurements of the transport phenomena in the series of Fe1+dTe1−xSex single crystals. Namely, we investigate the longitudinal and transverse electrical and thermal conductivities in the parent compound Fe1+dTe as well as superconducting Fe1+dTe0.85Se0.15 and Fe1+dTe0.59Se0.41. This set of data allows us to verify validity of the Wiedemann–Franz law in the systems studied and consequently it is stated that the electronic system in the paramagnetic phase of Fe1+dTe behaves like the Fermi liquid being predominantly elastically scattered. In contrast, low temperature properties of Fe1+dTe0.85Se0.15 and Fe1+dTe0.59Se0.41 are affected likely by the emergence of antiferromagnetic fluctuations, which are expected to be (π,0) and (π,π), respectively. These seem to be coupled with the hole-like band in case of Fe1+dTe0.85Se0.15, whereas with the electron-like band in case of Fe1+dTe0.59Se0.41.

Magnetic and electrical properties of Fe0.9Ag0.1In2.3S4.4 single crystals

The magnetic and electrical properties of the Fe0.9Ag0.1In2.3S4.4 single crystal are studied in the temperature range 4–300 K and in magnetic fields of 0–14 T. It is established that the sample under study is paramagnetic. In the ground state, short-range-order correlations typical of a spin glass with a freezing temperature of 10 K are detected. The magnetic ordering temperature is 15 K. The sample is a semiconductor with a resistivity of 3.5 kΩ cm at room temperature. For the Fe0.9Ag0.1In2.3S4.4 single crystal, a mechanism for the formation of magnetic and electrical states is suggested.

Behavior of the Fe impurity in Hg3In2Te6 crystals

Optical and photoelectric measurements reveal that doping with iron leads to the formation of a deep level at Ec–0.69 eV in Hg3In2Te6 crystals. When light is absorbed by Fe2+ impurity centers, both electronic transitions of the impurity-level–conduction-band type and optical transitions between ground and excited states of the aforementioned centers (intracenter transitions) are observed. Investigations of transport phenomena point to the acceptor properties of Fe2+ centers.

Dose-Exposure Proportionality of a Novel Recombinant Follicle-Stimulating Hormone (rFSH), FE 999049, Derived from a Human Cell Line, with Comparison Between Caucasian and Japanese Women After Subcutaneous Administration

Background and ObjectivesFE 999049 is a novel recombinant follicle-stimulating hormone (rFSH) preparation expressed by a human cell line (PER.C6®), in contrast to existing rFSH preparations expressed by Chinese hamster ovary (CHO) cell lines. Since the individual dose of rFSH may be altered depending on the response in women undergoing assisted reproductive technologies, knowledge on the dose-exposure linearity and proportionality is important. The purpose of these studies was to investigate the dose-exposure linearity and proportionality properties of FE 999049 with a comparison between Caucasian and Japanese women. This is the first study in Japanese women regarding pharmacokinetics of rFSH.MethodsForty-eight Caucasian and 31 Japanese healthy women of reproductive age were pituitary down-regulated to suppress endogenous FSH. Following single subcutaneous administration of 37.5, 75, 150, 225, or 450 IU (Steelman–Pohley assay), the serum FSH concentration was followed over 10 days.ResultsThe dose-dependent pharmacokinetic parameters of FE 999049, area under the serum concentration-time curve (AUC) and maximum serum concentration (C max), showed dose-exposure linearity and proportionality over 150–450 IU in Caucasian women, the dose interval available for analysis, and 75–450 IU in Japanese women, which was the dose interval investigated. Comparison between Caucasian and Japanese women showed no differences between the populations. The dose-independent parameters were similar over all doses in both populations. FE 999049 was safe and well tolerated at all doses in both populations with few, mostly mild, adverse events.ConclusionThe results demonstrate dose-exposure proportionality and a predictable dose-dependent exposure of FE 999049, with no differences in Caucasian and Japanese women of reproductive age.

Influence of structurization of amorphous Fe73.5Si13.5B9Nb3Cu1 alloy on its spectral properties

The optical properties of Fe73.5Si13.5B9Nb3Cu1 ferromagnetic alloy in the amorphous, nanocrystalline, and crystalline states have been investigated by optical ellipsometry in the spectral range of 0.22–18 μm. It is established that the crystallization of alloy during heat treatment leads to a significant change in its optical constants, as well as the frequency dependences of dielectric functions calculated based on these constants. The structural ordering is accompanied by a considerable increase in the intensity of the fundamental absorption band and an occurrence of its blue shift. Some characteristics of conduction electrons are determined, the numerical values of which also depend on the degree of atomic order.