Ions For Fe3 Research Articles

Theoretical investigations of the spin-Hamiltonian parameters and local structural distortion of Fe3+: ZnAl2O4 crystals

The relations between the spin-Hamiltonian (SH) parameters and the structural parameters of the Fe3+ ions in Fe3+: ZnAl2O4 crystals have been established by means of the microscopic spin Hamiltonian theory and the superposition model (SPM). On the basis of this, the local structure distortion, the second-order zero-field splitting (ZFS) parameter D, the fourth-order ZFS parameter (a-F), and the Zeeman g-factors g factors: g//, g⊥, and Δg(=g//−g⊥) for Fe3+ ions in Fe3+: ZnAl2O4 crystals, for the first time taking into account the electronic magnetic interactions, i.e. the spin–spin (SS), the spin–other–orbit (SOO), and the orbit–orbit (OO) interactions, besides the well-known spin–orbit (SO) interaction, are theoretically investigated using complete diagonalization method (CDM). This investigation reveals that the local structure distortion effect plays an important role in explaining the spectroscopic properties of Fe3+ ions in Fe3+: ZnAl2O4 crystals. The theoretical second-order ZFS parameter D, the fourth-order ZFS parameter (a-F), and the Zeeman g-factors: g//, g⊥, and Δg of the ground state for Fe3+ ion in Fe3+: ZnAl2O4 crystals yield a good agreement with experiment findings by taking into account the lattice distortions: ΔR=0.0191nm and Δθ=0.076°. In conclusion, our research shows that there is a slight local structure distortion for Fe3+ ions in Fe3+: ZnAl2O4 crystals, but the site of Fe3+ still retains D3d symmetry. On the other hand, it is found for Fe3+ ions in Fe3+: ZnAl2O4 crystals that the SO mechanism is the most important one, whereas the contributions to the SH parameters from other four mechanisms, including the SS, SOO, OO, and SO∼SS∼SOO∼OO mechanisms are not appreciable, especially for the ZFS parameter D.

Studies on Physicochemical Characteristics of Anthocyanin from Super Dark Maize

The effects of temperature, light, oxidant, soluble sugar, food additive (i.e. citric acid, benzoic acid, and ascorbic acid) and metal ions of K+, Ca2+, Cu2+, Al3+, Mn2+, Fe3+, Sn2+, Mg2+ on the stability of anthocyanin extracted from the kernels of novel inbred line super dark maize (SDM) with the strategy of HCl-carbinol were systematically analyzed. The results showed that the extracted anthocyanin was steady in acid conditions (pH≤ 3) and stable to heat and light; it had good anti-oxidation and maintained sensitive to reducing agents and insensitive to soluble sugar. Citric acid had positive effect on the stability of anthocyanin while benzoic acid and ascorbic acid negative; metal ions (1 mMol·L-1) of K+、Ca2+、Cu2+、Al3+、Mn2+ exhibited no obvious effect on the anthocyanin while ions of Fe3+、Sn2+、Mg2+ obvious.

Phase evaluation of Li+ substituted CoFe2O4 nanoparticles, their characterizations and magnetic properties

Li+ substituted CoFe2O4 with the chemical formula Li3xCoFe2−xO4 were synthesized by sol–gel auto combustion method. The synthesized samples were annealed at 600°C for 4h. X-ray diffraction data were used to evaluate the structure of the prepared samples. Spinel ferrite phase of CoFe2O4 changes to ordered like lithium ferrite phase with increase in Li+ substitution. Lattice constant increases whereas particle size found to decrease with Li+ substitution. Infrared spectroscopy also confirmed the phase transition of CoFe2O4 after the incorporation of lithium ions. Substitution of Li+ ions for Fe3+ caused a decrease in the saturation magnetization from 69.59emu/g to 47.71emu/g and the coercivity increased from 647Oe to 802Oe. Resistivity and dielectric properties shows inverse relation to each other.

Structural and magnetic properties of SrFe12−2xTixRuxO19

The magnetic properties of M-type Strontium hexaferrites can be modified by partially substituting Fe ions by other metallic ions. In this work, we report on the effect of the substitution of Ti2+ and Ru4+ ions for Fe3+ ions on the magnetic properties of the system, and the dependence of these properties on the cationic distribution in the lattice. SrFe12−2xTixRuxO19 hexaferrite samples were prepared by ball milling and sintering at 1100°C the appropriate amounts of the starting powders. The structural and magnetic properties of the fabricated samples were investigated using X-ray diffraction, SEM, Mössbauer spectroscopy, and vibrating sample magnetometry. It was found that Ti–Ru substitution improved the crystallinity of the prepared samples slightly, and did not influence the particle size appreciably. Mössbauer spectroscopy revealed that Ti2+ and Ru4+ ions substituted Fe3+ ions at the 4f2, (4f1+2a) and 2b sites for x values up to 0.2, and at the 12k site for x>0.2. The saturation magnetization increased up to x=0.2, and then decreased for higher x values, while the coercivity decreased monotonically, recording a reduction of 70% at x=0.3. The magnetic properties of the system were interpreted in terms of the distribution of Ti2+ and Ru4+ ions in the hexagonal lattice.

Sol-gel auto-combustion synthesis of Li3xMnFe2−xO4 and their characterizations

Ferrite samples of Li+ substituted MnFe2O4 nano particles were synthesized by sol-gel auto-combustion method. The samples were obtained by annealing at relatively low temperature at 600 °C and characterized by x-ray diffraction, transmission electron microscopy, vibrating sample magnetometry, and infrared (IR) spectroscopy. Lattice parameter, x-ray density, specific surface area, and porosity are found to increase, whereas bulk density and crystallite size showed the decreasing trend with the Li+ content. Splitting of major absorption bands related to Li+ substituted ferrites were observed in IR spectra. Substitution of Li+ ions for Fe3+ caused a decrease in the saturation magnetization from 75.69 to 58.57 emu/g and the coercivity increased from 157 to 308 Oe. DC resistivity decreases with increase in Li+ content. The temperature dependent results indicate that the values of dielectric constant (ε′) and loss tangent (ε″) increase with the increase in temperature.

Improvement of the coercivity of strontium hexaferrite induced by substitution of Al3+ ions for Fe3+ ions

Al-doped strontium hexaferrites (SrAlxFe12−xO19) with nominal Al content of x=0–4 are prepared by glycin–nitrate method and subsequent annealing in a temperature ranging from 700 to 1250°C. The content of Al in the SrAlxFe12−xO19 increases with increasing annealing temperature and the nominal Al doping content. The Al3+ ion substitutes for Fe3+ ion with spinning upward in the SrAlxFe12−xO19. The coercivity of the SrAlxFe12−xO19 increases with increasing nominal Al doping content at a fixed annealing temperature, but increases firstly with increasing annealing temperature and then decreases at a fixed nominal Al doping content. The largest coercivity of 17570Oe is obtained in the SrAl4Fe12O19 prepared at an annealing temperature of 1000°C, which is much larger than the coercivity of the SrFe12O19 (5356Oe) and exceeds even the coercivity of the Nb2Fe17B (15072Oe). The mechanism of the improvement of the coercivity induced by Al doping is discussed in the present work.

Effect of Low-Energy Electron Irradiation on DNA Damage by Fe3+Ion

We investigated the combined effects of low-energy electron irradiation and Fe(3+) ion on DNA damage. We used lyophilized pBR322 plasmid DNA films with various concentrations (0 ~ 7 mM) of Fe(3+) ions and irradiation with monochromatic, low-energy 3 or 5 eV electrons for these studies. DNA-Fe(3+) films were recovered and analyzed by agarose gel electrophoresis to identify and compare the effects of Fe(3+) ions and/or low-energy electrons alone or in combination on DNA damage. In nonirradiated DNA-Fe(3+) films, there was little DNA damage observed (less than 10% of the total DNA loaded on the gel appeared damaged) for Fe(3+) ion up to 7 mM concentration. In irradiated DNA films without Fe(3+) ions, there was also very little DNA damage observed (less than 3% of the total DNA loaded on the gel appeared damaged). However, when DNA-Fe(3+) films, were irradiated with low-energy electrons, DNA damage was significantly increased compared to the sum of the damage caused both by either Fe(3+) ion or low-energy electrons irradiation alone. We proposed that both DEA and/or electron transfer processes might play a role in the enhanced DNA damage when DNA-Fe(3+) films were irradiated by low-energy electrons.

Investigation of cation distribution in single crystalline Fe3−xMnxO4 microspheres based on Mössbauer spectroscopy

Monodispersed Fe3−xMnxO4 (x = 0, 0.25, 0.5, 0.75, and 1.0) microspheres were prepared by a solvothermal reaction method. Field emission scanning electronmicroscope (FESEM) and high resolution transmission electron microscope (HRTEM) measurements showed that the size of the monodispersed particles was around 200 ∼ 400 nm, with single crystalline spots in the selected-area electron diffraction (SAED) patterns. From the detailed Rietveld refinement analysis, the crystal structure was determined to be cubic spinel with lattice constant a0, linearly increasing from 8.3956 to 8.4319 Å with the Mn concentration. Also, with Mn concentration, saturation magnetization decreased from 76.9 to 60.3 emu/g at 295 K and 99.5 to 78.4 emu/g at 4.2 K, while coercivity decreased from 66 to 36 Oe at 295 K and 271 to 185 Oe at 4.2 K. We have analyzed the recorded Mössbauer spectra as 3 sets with six lines of tetrahedral A site and octahedral B1 and B2 sites at 295 K and 4.2 K. From the isomer shift values, the valence state of the A and B1 site was determined to be ferric, while the B2 site was ferrous. The corresponding area ratio of the A site increased from 40 to 50%, while that of the B site decreased from 60 to 50% as the Mn concentration changed from x = 0 to 1.0. Here, the changes in the area ratios of A and B sites are due to the changes in the cation distributions at the A and B sites, originating from the randomly substituted Mn ions in Fe3−xMnxO4 microspheres.

Photocatalytic mineralization of dimethoate in aqueous solutions using TiO2: Parameters and by-products analysis

Abstract Photocatalytic mineralization of dimethoate using nanosized TiO2 at different conditions has been investigated. The objective of this work was to study the influence on the photocatalytic mineralization of dimethoate, of various parameters and identify intermediates formed during photocatalytic treatment. The mineralization efficiency of dimethoate increased with elevated concentration of humic acid up to 5 mg/L, while the efficiency reduced when the concentration was above 5 mg/L due to competitive adsorption. The presence of CH3COCH3 can significantly inhibit dimethoate mineralization and the half-life of mineralization efficiency was increased by about 3 times. The photo mineralization efficiency changed with increasing concentrations of inorganic ions. With respect to the ions of Fe3+, Cu2+, Zn2+, HCO3− and NO3−, the mineralization efficiency increased with increasing concentration of ions and reached a maximum at optimal concentrations, which was followed by a decrease with a further increase in ion concentrations. By contrast, the mineralization of dimethoate was strongly inhibited by Cl− and Cr3+ ions. Intermediate products from dimethoate were identified by means of GC–MS and four possible by-products were identified. A proposed mineralization pathway for dimethoate is presented.

Studies of the EPR parameters and defect structure for tetrahedral Fe3+ centers in zinc oxide

AbstractThe relations between the electron paramagnetic resonance (EPR) parameters and crystal structure of Fe3+:ZnO crystals have been established. On the basis of this, the EPR parameters D, (a‐F) and the zero‐field splitting (ZFS) δ1, δ2 of the ground state for Fe3+ in Fe3+:ZnO crystals are theoretically investigated using the complete diagonalization method (CDM). The theoretical second‐order EPR parameter D, the fourth‐order EPR parameter (a‐F), and the ZFS of the ground state: δ1, δ2 for Fe3+ in Fe3+:ZnO yield a good agreement with experimental findings when the three O2– ions below the Fe3+ ion rotate by Δθ in the range 0.475–0.562° away from the [111] axis. Hence, the local structure distortion effect plays an important role in explaining the spectroscopic properties of Fe3+ ions in Fe3+:ZnO crystals. Our approach takes into account the spin–orbit (SO) interaction as well as the spin–spin (SS), spin–other–orbit (SOO), and orbit–orbit (OO) interactions omitted in previous studies. This shows that although the SO interaction is the most important one, the contributions to the EPR parameters from the other three interactions are appreciable and should not be omitted, especially for the EPR parameter D. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Effect of Selected Metal Ions on the Photodegradation of Ciprofloxacin in the Solid Phase

The photodegradation of ciprofloxacin in the solid phase was investigated by using the chromatographic-densitometric method in the presence and absence of selected metal ions. It was shown that both ion concentration and ion type have an effect on the degradation process that leads to the generation of 2 new products with R(f) values of approximately 0.45 and 0.56, which are different from the R(f) of approximately 0.68 for ciprofloxacin. It was found that CU2+ and Fe3+ ions have the strongest effect on ciprofloxacin photodegradation compared with photodegradation carried out without these ions and also with photodegradations carried out in the presence of Zn2+, Cr3+, Ni2+, and Co2+ ions. To identify the photodegradation products, we used amine-specific chromatographic reactions, UV spectra recorded directly from the chromatograms, and proton nuclear magnetic resonance and IR spectroscopic methods. The chemical structures of the degradation products were found to be 7-[(2-aminoethyl)amino]-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-quinoline-3-carboxylic acid and 7-amino-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid.

Discoloration of Fired Kaolinitic Clays (Study of Fe3+ Coordination by Mössbauer and UV‐ViS‐NIR Spectroscopy)

The final color of a ceramic body is generally determined by the contents of Fe3+ ions. The Central European market accepts kaolinitic clays for the production of tableware, electro‐insulators, and wall tiles only if the Fe2O3 in chemical analyses of the kaolin does not exceed 1.0 wt%. The chemical analyses calculate the content of all iron components as if they were in the form of Fe2O3 and then their quantity excludes even good‐quality clay from the ceramic industry of white bodies. We found that oxidizing firing of the samples fired at over 1180°C changes the color in cases where the initial Fe3+ component is in the form of hydro ferric oxide [FeO(OH)] or if the ferric ions were added to the white kaolin samples in the form of ferric nitrate [Fe(NO3)3·9H2O]. The Mössbauer spectroscopy confirms the presence of only diluted Fe3+ ions. The UV‐ViS‐NIR spectroscopy confirms that even if the concentration of Fe2O3 is above 3.0 wt%, these ions of Fe3+ in the case of their initial hydro ferric oxide formed in clay are incorporated into the mullitic structure in tetrahedral coordination. The iron‐coloring effect depends on the coordination of Fe3+ ions with the studied discoloring effect of fired bodies—the very small and well‐distributed particles enter into the formatted mullitic structure.

Controlling the Properties of Manganese-Zinc Ferrites by Substituting In3+ and Al3+ Ions

The effect of substitution of In3+ and Al3+ ions on the electrical and magnetic properties of Mn-Zn ferrites has been investigated. The substitution of In3+ ions for Fe3+ ions resulted in an increase of lattice parameter, owing to the larger size of In3+ ions, whereas lattice parameter was found to decrease on substituting Al3+ ions in place of the Fe3+ ions, owing to the smaller size of Al3+ ions. The dc resistivity was found to increase with the substitution of In3+ and Al3+ ions in the Mn-Zn ferrite system. The improvement in the dc resistivity has been observed at the expense of deterioration in the magnetic properties of Al3+ substituted Mn-Zn ferrites. A significant reduction in the values of initial permeability, saturation magnetization and Curie temperature was observed with successive increase of Al3+ ions. The saturation magnetization and initial permeability were found to increase with incorporation of In3+ ions. A marked increase in the value of initial permeability was found for the Mn0.4Zn0.6In0.5Fe1.5O4 ferrite. Curie temperature was found to decrease with an increase of In3+ ion concentration. These changes in the properties are explained on the basis of their magnetic interactions, a modified cation distribution and various models.

軟磁性フェロックスプラナ型フェライトの高周波磁気特性

Y-type (Ba2Zn2Fe12O22; Y), M-type (BaCo1.1Ti1.1Fe9.8O19; MCT) and mixture of these hexagonal ferrites (Y+xMCT; x=0∼3) were prepared by the conventional solid-state reaction approach. Samples were made with BaCO3, ZnO, CoO, TiO2 and α-Fe2O3 as starting materials. The frequency dependence of the initial permeability of all samples was measured using an impedance analyzer (HP4291B). The initial permeability of Ba3Zn2Co1.1Ti1.1Fe21.8O41 (x=1) was 23 (at 100MHz), which is the highest value in this study and the Snoek's product of this sample has been reached to 14.7GHz. This value is twice larger than that of Zn2Y. The detailed analysis of frequency dependent permeability curves for these samples strongly suggests that this enhancement of the Snoek's product is due to the change of magnetic anisotropy caused by the substitution of Co2+ and Ti4+ ions for Fe3+ ions.

Temperature dependence of magnetic properties of zinc and niobium doped strontium hexaferrite nanoparticles

Zinc and niobium doped strontium hexaferrite nanoparticles, Sr(Zn0.7Nb0.3)xFe12−xO19 (x=0–1.0), were fabricated using a sol-gel method for high density magnetic recording. The structure and temperature dependence of magnetic properties are investigated. The experiments show that strontium hexaferrite with small Zn and Nb substitutions still remains a hexagonal magnetoplumbite phase. The coercive force is reduced from 6.7 to about 2.3 kOe, while the values of saturation magnetization increased to 67–74 emu/g in the substitution range of x=0–1.0. This indicates that the saturation magnetization and coercivity of strontium hexaferrite nanoparticles can be held over a very wide range by an appropriate amount of Zn and Nb doping contents. Simultaneously, it is found that the doped strontium hexaferrite nanoparticles show a small positive temperature coefficient of coercivity. The substitution of Zn2+ and Nb4+ ions for Fe3+ ions also monitors the temperature dependence of magnetization and Curie temperature, and enhances thermal stability in the measured temperature range. This nanoparticle system is, thus, suitable for high-density recording.

Transition metal coordination polymers with polycarboxylic acid as bridging ligands: Synthesis and structure characterization of [Fe(m4-bta)0.5(phen)(OH)

A new 2D (two-dimensional) coordination polymer, [Fe(μ4-bta)o.5(phen)(OH)]n (1), has been hydrothermally synthesized with FeCl3 6H2, Na4bta (h4bta = 1,2,4,5-benzentetracarboxylic acid), 1,10-phen (1,10-phenanthroline) and H2O as raw materials. The crystals of the compound belong to monoclinic P21/n space group, a = 1.0129(2) nm, b = 0.9265(2) nm, c = 1.5696(3) nm, β=91.37(3)°V=1.4721(5) nm3,Z=3, final R1=0.0292, wR 2=0.0798 for 2572 [/>2σ(/)] observed reflections. The result of structure determination shows that in the compound each bta ligand is connected with four Fe3, forming a new μ4-coordination mode. Four deprotonated carboxylic groups of bta link to Fe3 ions alternatively through monodentate and bidentate coordination fashion, constructing 2D layer network. The measurement of variable temperature magnetic susceptibility indicates that there exist antiferromagnetic interactions between Fe3 ions in the compound. The TGA spectrum displays relatively fine thermal stability of the compound. In addition, IR and UV-Vis spectra of compound 1 have also been measured.

Magnetic microstructure in strontium hexaferrites with correlated nonisomorphous substitutions

The influence of the correlated nonisomorphous substitution of Mn2+ and Ti4+ ions for Fe3+ ions in M-type hexaferrites on the shaping of their magnetic microstructure is studied. Conclusions regarding the possibility of the distribution of the substituent cations in the structure and their influence on the principal magnetic properties of the hexaferrites studied are drawn on the basis of data from Mossbauer spectroscopy.

Isomorphous substitution of Fe3− in zeolite LTL

Fe-modified L-type zeolites were synthesized hydrothermially, partially substituting iron atoms for the framework aluminum of L-type zeolite. Chemical analysis, XRD, SEM, IR, UV VIS DRS, EPR, XAS, TG DTA, and catalytic activity studies provided the evidence of Fe3 present in the zeolite framework. Both the lattice parameters and the unit cell volume of L-type zeolites containing Fe3 increased with increasing iron content. The change in crystal morphology was obvious from a synthesis mixture in which the molar ratio of Fe2O3Al2O3 is above 0.015. The framework IR bands were shifted to lower frequencies as Fe3 incorporation into the lattice increased, and a new Si-O-Fe bond vibration was located near 668 cm−1. The presence of a signal at g = 4.4 in the EPR spectra was assigned to Fe3 isomorphously substituted in the tetrahedral positions. EXAFS at the Fe K-edge revealed that the Fe3 ions were present in the zeolite framework in a four-fold coordination with an average Fe-O distance of 1.85 A. In the UV VIS spectra, an absorption was observed at 378.7 nm which was assigned to the presence of Fe3 in the zeolite framework. TG DTA studies indicated that Fe-modified L-type zeolite lower thermal stability than the corresponding normal L-type zeolite. A toluene alkylation study reflected the acidity strength of zeolite L being weakened due to the presence of lattice iron species.

Zum promotierenden Einflu� von Molybdaten in Multikomponent-Molybdat-Katalysatoren

The Mutual Promotion Effect of Molybdates in Multicomponent Molybdate Catalysts Multicomponent molybdate catalysts (e.g. of the composition Bi2Fe1,5Co7Cr10Mo19Oy) are produced by coprecipitation, drying and calcination. These catalysts exhibit high activity and selectivity in the ammoxidation of propene to acrylonitrile. The individual molybdates (Co-, Fe- and Cr-molybdate) exhibit no selectivity in the ammoxidation of propene. Therefore a mutual promotion effect of these molybdates exists. The cause of the promotion effect is the formation of the active and selective phase from the β-phase of Co-molybdate by exchange of protons with ions of Fe3+ and Cr3+ from the molybdates of Fe and Cr. The structure of this catalytic active and selective phase is similar to the structure of the β-phase of Co-molybdate.