- An investigation of the Dy-Fe-Cr phase diagram: Phase equilibria at 773 K
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Phase equilibria in the Dy-Fe-Cr system were investigated by X-ray powder diffraction (XRD), differential thermal analysis (DTA), scanning electron microscopy (SEM) techniques and the isothermal section at 773 K was obtained. It consists of 8 single-phase
- Yao, Qingrong,Wang, Hailong,Liu, Zhanwei,Zhou, Huaiying,Pan, Shunkan
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- Absorbing properties and structural design of microwave absorbers based on carbonyl iron and barium ferrite
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Carbonyl iron and barium ferrite powder (BaZn1.5Co0.5Fe16O27) were prepared in this work. The complex permittivity and permeability spectra for rubber radar absorbing materials employing carbonyl iron and barium ferrite powders were measured. A database describing the frequency dependence of the permittivities and permeabilities of the carbonyl iron and barium ferrite microwave absorbers with various powder percentage compositions in 2-18 GHz was created. Based on the database, the single-layer and double-layer absorbers were designed and prepared, and their microwave absorption properties were investigated. The results indicate that the carbonyl iron powder prepared via thermal decomposition of iron pentacarbonyl is single cubic iron and of spherical shape. The barium ferrite powder is single W-type ferrite and a hexagonal flake. The absorption band of the double-layer microwave absorber is obviously more than that of the single-layer absorber. The double-layer microwave absorbers with reflection loss -13 dB over the range of 6-18 GHz and reflection loss -8 dB over the range of 2-18 GHz were prepared. The thicknesses of the absorbers are only 3.6 and 3.7 mm, respectively.
- Feng,Qiu,Shen
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- GROWTH OF Fe AND FeAs2 FILMS ON GaAs BY ORGANO-METAL CHEMICAL VAPOR DEPOSITION USING PENTACARBONYL IRON AND ARSINE.
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A number of iron and iron arsenide films have been grown using pentacarbonyl iron and arsine by conventional organo-metal chemical vapor deposition (OM-CVD) on single-crystal GaAs. Auger sputter profile on a 1240A-thick iron arsenide sample gave a composition consistent with the intended compound, FeAs//2, a narrow-gap semiconductor. Infra-red transmission data on the same film yielded an optical gap of 0. 16 plus or minus 0. 01 eV, which compares with the known electrical gap of 0. 22 eV for bulk FeAs//2. An apparent catalytic action of pentacarbonyl with arsine allows the iron arsenide to form from arsine at low temperatures near 300 degree C. The low temperature of growth suggests the possibility of forming heterostructures between a narrow-gap semiconductor and a ferromagnetic film. Such a structure was successfully grown on GaAs.
- Walsh,Bottka
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- SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF THE MIXED-METAL CARBIDO CLUSTER Fe5C(μ2-CO)3(CO)11(μ2-AuPEt3)-(μ4-AuPEt3) AND THE OXIDATION OF Fe-Au CLUSTERS
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Reaction of 2- with excess (PEt3)AuCl/Tl(PF6) affords the mixed-metal cluster Fe5C(μ2-CO)3(CO)11(μ2-AuPEt3)(μ4-AuPEt3) which has been shown by an X-ray structural analysis to exhibit a novel coordination for one of the AuPEt3 groups.This and another Fe-Au cluster, Fe4H(CO)12C(AuPEt3) undergo unusual oxidative rearrangements.
- Johnson, Brian F.G.,Kaner, David A.,Lewis, Jack,Rosales, Maria J.
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- Imaging and magnetometry of switching in nanometer-scale iron particles
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The reversal mechanisms in arrays of nanometer-scale (2 level, nearly 50 times greater than current technology.
- Gider,Shi,Awschalom,Hopkins,Campman,Gossard,Kent,Von Molnar
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- Morphology, diameter distribution and Raman scattering measurements of double-walled carbon nanotubes synthesized by catalytic decomposition of methane
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Double-walled carbon nanotubes (DWNTs) were synthesized by catalytic decomposition of methane in the presence of Fe catalyst at 1373 K. The microstructure of the as-prepared DWNTs was characterized by high-resolution transmission electron microscopy (HRTEM) and resonant laser Raman spectroscopy. HRTEM observations revealed that the dominant type of the as-prepared product was DWNTs, which are mostly bundle-like. A triangular lattice arrangement of DWNTs in a DWNT bundle was observed. The as-prepared DWNTs show corresponding peaks from resonant Raman spectra of the radial breathing mode (RBM), which are considered to be associated with inner tubes as well as outer tubes of the DWNTs. The outer and inner tube diameters of the DWNTs, as determined from HRTEM images, are in the range of 1.6-3.6 and 0.8-2.8 nm, in agreement with the results from the resonant Raman scattering measurements. Moreover, the interlayer spacing of DWNTs is not a constant, ranging from 0.34 to 0.41 nm.
- Ren, Wencai,Li, Feng,Chen, Jian,Bai, Shuo,Cheng, Hui-Ming
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- Mechanochemical synthesis of Wuestite, Fe1-xO, in high-energy apparatuses
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It is shown that high-energy milling of Fe2O3 + Fe mixtures leads to the formation of nanocrystalline, metastable wuestite Fe1-xO. Its stoichiometry varies systematically with processing time.
- Emel'yanov,Korolev,Mikhailenko,Knot'ko,Oleinikov,Tret'yakov,Boldyrev
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- Field emission properties of vertically aligned iron nanocluster wires grown on a glass substrate
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The synthesis of vertically aligned nanocluster wires (NCW) on indium-tin-oxide-coated glass substrates by the thermal decomposition of Fe(CO)5 with a resistive heater under a magnetic field was discussed. It was shown that the aligned NCW was controlled by varying the flow rate of carrier gas. It was found that the low-density NCWs showed better field emission characteristics, with a low turn-on field of about 4 V/μm and a current density as high as 3 mA/cm2 at 7.6 V/μm. The field enhancement factor (γ) was determined to be ～1200 for high-density NCWs and ～1600 for low-density NCW.
- Kim, Do-Hyung,Jang, Hoon-Sik,Lee, Hyeong-Rag,Kim, Chang-Duk,Kang, Hee-Dong
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- Atomic Iron Recoil in Multiphoton Dissociation of Ferrocene
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The translational energy of atomic iron, produced by a three-photon dissociation of bis(cyclopentadienyl)iron (ferrocene), has been measured by using the atomic multiphoton ionization Doppler line width at 440 nm.The iron atoms have an appreciable amount of recoil, indicating that the ferrocene dissociation process is nonconcerted and does not preserve a center of symmetry.This is also evidence for a dissociation via one or more repulsive electronic states, rather than by statistical, unimolecular decay of a hot ground state.
- Liou, H. T.,Ono, Y.,Engelking, P. C.,Moseley, J. T.
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- Investigation on the temperature-dependent growth rate of carbon nanotubes using chemical vapor deposition of ferrocene and acetylene
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Carbon nanotubes (CNTs) were synthesized using chemical vapor deposition of ferrocene and acetylene in the temperature range 600-800°C. The growth rate increases exponentially with the temperature, providing an activation energy 30 kcal/mol which is close to the diffusion energy of carbons in the bulk iron metal. We compared the growth rate with those of the CNTs grown using other thermal methods reported previously and suggest a simple kinetic model to explain the growth rate depending on the method. The supply rate of C atoms in gas phase would influence the growth rate of CNTs.
- Kim, Ki-Eun,Kim, Kang-Jin,Jung, Woo Sung,Bae, Seung Yong,Park, Jeunghee,Choi, Junghyun,Choo, Jaebum
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- Preparation, surface modification and microwave characterization of magnetic iron fibers
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In this paper, magnetic iron fibers of 3-10 μm diameter and an adjustable aspect ratio were synthesized successfully by a method involving pyrolysis of carbonyl under a magnetic field. A surface modification technology was also investigated. The electromagnetic parameters of the iron-fiber-wax composites were measured using the transmission/reflection coaxial line method in the microwave frequency range of 2-18 GHz. The results show that the prepared iron-fiber-wax composites exhibit high magnetic loss that can be further improved after phosphating. On the other hand, the complex permittivity was significantly decreased after phosphating. As a result, this kind of iron fiber may be useful for thin and lightweight radar-absorbing materials.
- Nie, Yan,He, Huahui,Zhao, Zhenshen,Gong, Rongzhou,Yu, Hongbin
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- Aqueous electrodeposition of iron group-vanadium binary alloys
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Electrodeposition of binary iron group (IG)-vanadium (V) alloys from aqueous citrate solutions was investigated. Addition of NH3(aq.) and increasing solution pH resulted in increased deposit V content, but non-metallic deposits were obtained at solution pH > 7. Increasing current density resulted in an almost linear decrease in V content and a sharp increase in hydrogen evolution (decreased current efficiency). In general, the amount of V deposited with the IG metal increased as follows: Ni Fe ≤ Co. XRD spectra indicated that preferred orientations from 25 °C solutions were not displaced by elevated temperature deposits. Changes in orientation may contribute to the deposit magnetic properties; e.g., Co-V deposits with (1 0 0) planes exhibit harder magnetization than deposits with (0 0 2) planes.
- Yoo,Schwartz,Nobe
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- Effect of tantalum on phase formation in the Fe-S system
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Phase formation in the Fe1 - x -Ta x -S system with 0 x 0.5 has been studied at temperatures up to 1273 K using X-ray diffraction. When the constituent elements are heated to 823 K, troilite (Tr), pyrrhotites (PoI, PoII, and Pos
- Vershinin,Mar'evich,Chumarev,Selivanov
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- Nitrogen storage properties based on nitrogenation and hydrogenation of rare earth-iron intermetallic compounds R2Fe17 (R=Y, Ce, Sm)
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The nitrogen storage properties for the rare earth-iron intermetallic compounds, R2Fe17 (R=Y, Ce, and Sm), were investigated. These intermetallic compounds formed the corresponding metal nitrides by heating in a mixed gas of NH3-H2 at 350-450°C and the nitrogen was incorporated into interstitial sites of the crystal lattices. The nitrogen stored as the metal nitrides was reversibly released as NH3 by the following heating in H2 at 450°C. An amount of the nitrogen released per unit volume of these intermetallic compounds is larger than that of a conventional nitrogen container charged at 15 MPa. The nitrogen storage capacity of Sm2Fe17Nx was increased by repeating the nitrogenation-hydrogenation cycle owing to the formation of FeNx/RNy composites with large surface areas derived from the starting intermetallic compound through the cycle. Furthermore, the nitrogen storage characteristics of Sm2Fe17 powders were effectively improved by surface loading with Ru metal that is active for ammonia generation.
- Itoh, Masahiro,Machida, Ken-Ichi,Nakajima, Hiroharu,Hirose, Kazuhiro,Adachi, Gin-Ya
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- Mechanochemical reduction of magnesium ferrite
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The changes in magnesium ferrite, MgFe2O4, due to high-energy milling in a stainless steel vial have been investigated by Moì?ssbauer spectroscopy, X-ray diffraction, electron microscopy, and thermal analysis. The milling process reduces the average crystallite size of MgFe2O4 to the nanometer range. Prolonged mechanical treatment leads to the chemical reduction of MgFe2O4 and to the formation of a solid solution of FeO and MgO. In addition to the solid solution, metallic iron has been found as a byproduct. The fraction of the reaction products increases with increasing milling time. The range of thermal stability of the metastable milled reduction products has been determined by studying their response to changes in temperature.
- Sì?epelaì?k, Vladimiì?r,Menzel, Marcus,Becker, Klaus Dieter,Krumeich, Frank
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- Electrodeposited Ni-Fe-C cathodes for hydrogen evolution
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Tailoring of active nickel alloy cathodes for hydrogen evolution in a hot concentrated hydroxide solution was attempted by electrodeposition. Electrodeposited iron is naturally more active for hydrogen evolution than nickel, but Ni-Fe alloys show further high activity for hydrogen evolution, although the rate-determining step being assumed as proton discharge is not changed. The carbon addition to iron or nickel remarkably enhances the activity for hydrogen evolution and changes the mechanism of hydrogen evolution. Ternary Ni-Fe-C alloys show the highest activity for hydrogen evolution, and the Tafel slope of hydrogen evolution is about 33 mV/dec, suggesting the rate-determining step of desorption of adsorbed hydrogen by recombination. XPS analysis reveals that the charge transfer occurs from nickel to iron in alloys and the carbon addition particularly enhances the charge transfer. Accelerated proton discharge due to enhanced charge transfer from nickel to iron seems responsible for the high activity of the Ni-Fe-C alloys for hydrogen evolution.
- Meguro, Shinsaku,Sasaki, Teruhito,Katagiri, Hiroshi,Habazaki, Hiroki,Kawashima, Asahi,Sakaki, Takashi,Asami, Katsuhiko,Hashimoto, Koji
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- Ferrofluids from prism-like nanoparticles
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Decomposition of iron pentacarbonyl in kerosene in the presence of octanoic acid and bis-2-ethylhexylamine leads to very monodisperse iron nanoparticles and thus to monodisperse magnetic nanoparticles. These latter can be spherical or appear as triangles on MET pictures. SAXS and AFM indicate that particles are more likely prisms. They can be dispersed in cyclohexane to produce ferrofluids.
- Ramaye,Neveu,Cabuil
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- Dispersing and coating of transition metals Co, Fe and Ni on carbon materials
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Interaction between transition metals Co, Fe and Ni and carbon materials, such as multi-walled carbon nanotubes (MWNTs), single-walled carbon nanotubes (SWNTs), activated carbon (AC) and layered graphite (LG), has been investigated at high temperatures. Complete wetting for AC, partial wetting for MWNTs, and almost no wetting for SWNTs and LG have been observed, respectively. It is found that the defects in the carbon materials play a key role in the interaction.
- Zhong, Ziyi,Liu, Binghai,Sun, Lianfeng,Ding, Jun,Lin, Jianyi,Tan, Kuang Lee
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- Synthesis of a Highly Efficient Oxygen-Evolution Electrocatalyst by Incorporation of Iron into Nanoscale Cobalt Borides
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High-performance catalysts for the oxygen-evolution reaction in water electrolysis are usually based on expensive and rare elements. Herein, mixed-metal borides are shown to be competitive with established electrocatalysts like noble metal oxides and other transition-metal(oxide)-based catalysts. Iron incorporation into nanoscale dicobalt boride results in excellent activity and stability in alkaline solutions. (Co0.7Fe0.3)2B shows an overpotential of η=0.33 V (1.56 V vs. RHE) at 10 mA cm?2 in 1 m KOH with a very low onset potential of ≈1.5 V vs. RHE, comparable to the performance of IrO2 and RuO2. XPS shows that the original catalyst is modified under the reaction conditions and indicates that CoOOH and Co(OH)2 are formed as active surface species, whereas the Fe remains in the catalyst, contributing to an improved catalyst performance. The nanoscale borides are obtained by a one-step solution synthesis, calcined, and characterized by XRD, energy-dispersive X-ray spectroscopy, and SEM. Single crystals of (Co1?xFex)2B grown under chemical transport conditions were used for an unambiguous specification of the nanostructured particles by relating the cobalt/iron ratio to the lattice parameters.
- Klemenz, Sebastian,Schuch, Jona,Hawel, Stefan,Zieschang, Anne-Marie,Kaiser, Bernhard,Jaegermann, Wolfram,Albert, Barbara
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- Electrodeposition of metal iron from dissolved species in alkaline media
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The electrodeposition of metal iron from iron dissolved species in alkaline media has been investigated. Dissolved ferric species in equilibrium with hematite (α -Fe2 O3) have been electrochemically identified and their reduction to iron was demonstrated. The reduction efficiency was poor, however, because of the low concentration of dissolved matter (2.6× 10-3 M). In order to determine more precisely the electrochemical features of the deposition reaction from iron ions, more concentrated solutions at 1.9× 10-2 M have been obtained using an iron anode as the ion source. Voltammetric and chronoamperometric investigations using a rotating disk electrode revealed that such concentrated solutions contain ferric and ferrous species, with higher concentration of the trivalent form. Metal can be deposited with higher current efficiency in these concentrated solutions with less than 30% of the current spent in hydrogen evolution.
- Allanore,Lavelaine,Valentin,Birat,Lapicque
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- A general strategy for metallic nanocrystals synthesis in organic medium
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Herein we report a general synthesis strategy for metallic nanocrystals in a two-phase liquid-liquid system, which involves a quite fast nucleation stage overlapped with the growth stage within 10 min.
- Huang, Peng,Lin, Jing,Li, Zhiming,Hu, Hengyao,Wang, Kan,Gao, Guo,He, Rong,Cui, Daxiang
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- Structure and magnetic properties of electrodeposited Fe-Ni alloy films
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Fe-Ni alloy films with a composition of Invar region were prepared on copper substrates by electrodeposition. The crystal structures and magnetic properties of the films were investigated. The region which formed α phase in the films was different from that shown in the equilibrium phase diagram for bulk samples of Fe-Ni system, that is, the region shifts toward the nickel richer composition. The drop region the magnetization in the electrodeposited film shows a tendency to shift to the nickel richer composition (45 at.%Ni-Fe) corresponding with the shift of the α phase at the film deposition. The magnetic moment at low temperatures in the electrodeposited film decreases more rapidly with the increase of temperature as compared with the result observed in the bulk crystal.
- Ueda, Yuji,Takahashi, Minoru
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- Electrodeposition of iron in sulphate solutions
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The kinetics of iron electrodeposition from acid sulphate solutions onto a platinum electrode was investigated by means of stationary polarisation curves and electrochemical impedance spectroscopy. Together with interfacial pH data previously obtained, the effect of pH was analysed. The formation of at least three adsorbed intermediates at the cathode surface was evidenced in all pH values. The relative rate of their formation and its surface concentration depend on the solution pH as well as on the electrode potential. It is suggested that two of these species catalyses the H+ reduction whereas the other one may have a blocking effect on this reaction.
- Díaz,Calderón,Barcia,Mattos
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- New syntheses with magnesium hydride. Part 3: Preparation of nanocrystalline or amorphous metals by hydride reduction
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The tribochemical reduction of metal halides by magnesium hydride in organic solvents allows the synthesis of nanosize or amorphous metals.
- Knott, Wilfried,Frommeyer, Georg,Klapdor, Astrid,Windbiel, Dagmar
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- Electrodeposition of monodispersed Fe nanocrystals from an ionic liquid
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Monodispersed Fe nanocrystals up to ～2 nm thick, ～50 nm wide and ～120 nm long have been electrodeposited from the ionic melt AlCl 3-1-methyl-3-butylimidazolium chloride {AlCl3-[MBIm] +Cl-} at room temperature on
- Aravinda,Freyland
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- Magnetic nanoparticles separation based on nanostructures
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This study describes a magnetic array, which consists of depositing Fe nanowires on a porous alumina membrane. Such a device can be used as a planar magnetic separator. Its performance for the collection of Fe3O4 nanoparticles is experimentally shown. For magnetization of such iron nanowires in the vertical direction, we propose equations to calculate the theoretical absorption ratio.
- Sun, Jianfei,Xu, Rui,Zhang, Yu,Ma, Ming,Gu, Ning
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- Association Reactions of Manganese, Iron, and Ruthenium with Nitric Oxide
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The gas-phase association reactions of ground-state manganese, iron, and ruthenium atoms with nitric oxide are reported. The transition metal atoms were produced by the 248 nm photodissociation of 2-methylcyclo-pentadienylmanganese tricarbonyl, ferrocene, and ruthenocene. Detection of these transition metal atoms was by laser-induced fluorescence. Manganese was found to be the least reactive with nitric oxide of the transition metals in this work. The limiting low-pressure third-order rate constant, k0, of Mn + NO + Ar can be expressed as (9.5 ± 2.5) × 10-33 exp[-1.5 ± 0.4 kcal mol-1/(RT)] cm6 molecule-2 s-1. k0 for Fe + NO + N2 at 296 K is (2.3 ± 0.5) × 10-32 cm6 molecule-2 s-1; this reaction is independent of temperature over the range 296-622 K. Ruthenium was found to be the most reactive toward NO. In Ar buffer, k0 = (7.3 ± 1.0) × 10-30 cm6 molecule-2 s-1 and the limiting high-pressure rate constant k∞ = (3.8 ± 0.8) × 10-11 cm3 molecule-1 s-1 for a fixed broadening factor of Fc = 0.6. The uncertainties here represent precision. Recent density functional theory calculations on transition metal mononitrosyls were combined with RRKM calculations to estimate the binding energies of the Mn-NO and Fe-NO adducts.
- McClean, Roy E.,Campbell, Mark L.,Vorce, Michelle D.,Medhurst, Laura J.
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- Photocatalytic hydrogen evolution under highly basic conditions by using Ru nanoparticles and 2-phenyl-4-(1-naphthyl)quinolinium ion
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Photocatalytic hydrogen evolution with a ruthenium metal catalyst under basic conditions (pH 10) has been made possible for the first time by using 2-phenyl-4-(1-naphthyl)quinolinium ion (QuPh+-NA), dihydronicotinamide adenine dinucleotide (NADH), and Ru nanoparticles (RuNPs) as the photocatalyst, electron donor, and hydrogen-evolution catalyst, respectively. The catalytic reactivity of RuNPs was virtually the same as that of commercially available PtNPs. Nanosecond laser flash photolysis measurements were performed to examine the photodynamics of QuPh+-NA in the presence of NADH. Upon photoexcitation of QuPh+-NA, the electron-transfer state of QuPh+-NA (QuPh?-NA ?+) is produced, followed by formation of the π-dimer radical cation with QuPh+-NA, [(QuPh?-NA?+) (QuPh+-NA)]. Electron transfer from NADH to the π-dimer radical cation leads to the production of 2 equiv of QuPh?-NA via deprotonation of NADH?+ and subsequent electron transfer from NAD? to QuPh+-NA. Electron transfer from the photogenerated QuPh?-NA to RuNPs results in hydrogen evolution even under basic conditions. The rate of electron transfer from QuPh ?-NA to RuNPs is much higher than the rate of hydrogen evolution. The effect of the size of the RuNPs on the catalytic reactivity for hydrogen evolution was also examined by using size-controlled RuNPs. RuNPs with a size of 4.1 nm exhibited the highest hydrogen-evolution rate normalized by the weight of RuNPs.
- Yamada, Yusuke,Miyahigashi, Takamitsu,Kotani, Hiroaki,Ohkubo, Kei,Fukuzumi, Shunichi
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- Growth of single-walled carbon nanotubes by a novel technique using nanosized graphite as carbon source
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Single-walled carbon nanotubes (SWCN) have been produced treating nanosized graphitic powders with atomic hydrogen fluxes in a purpose-designed reactor. The Fe-catalyzed synthesis process yielded rather dense networks of nanotubes forming continuous layers adherent to the substrates. Raman spectroscopy in the 140-250 cm-1 region, high-resolution transmission electron microscopy and reflection electron diffraction in selected area configuration have been used to define the structural details of the nanotubes. The analysis evidenced a nanotubes population belonging prevalently to the (n,0) achiral symmetry subclass. This new experimental approach for SWCNs growth provides promising conditions for maximizing yields and generating selected tubular configurations.
- Terranova,Piccirillo,Sessa,Sbornicchia,Rossi,Botti,Manno
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- Iron thin films from Fe(CO)5 and FeCp2/H2O under atmospheric pressure
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Iron layers were first obtained from iron pentacarbonyl in metallorganic chemical vapor deposition (MOCVD) process under atmospheric pressure, in the temperature range 473- 773 K, in a vertical cold wall reactor. Films of good purity were obtained with or without hydrogen as co-reactant, no chemical additives being used. The experiments showed that the velocity of the gas stream and, to a lower extent, the precursor molar fraction are the key parameters to be controlled, in order to monitor film growth rate and purity. In a second step, Fe thin layers were obtained by atmospheric pressure MOCVD starting from the reactive gas mixture FeCp2 and H2 O in the temperature range 973- 1073 K. A thermochemical simulation of the Fe-C-H-O system allowed optimum processing conditions to be approached. X-ray diffraction and microprobe analysis showed that the highest iron content in the layer was obtained for H2 O FeCp2 ratios between 4 and 6. Film growth occurs in two steps: the initial formation of a black, powdered, and porous layer that becomes densified as a result of the grain growth on increasing the deposition time in order to form compact gray metal films. This two-step mechanism was confirmed by kinetic and in situ IR pyrometric observations.The Electrochemical Society
- Senocq,Duminica,Maury,Delsol,Vahlas
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- Visible multiphoton dissociation of Fe(CO)5 for production of iron atoms
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Ground state (a 5D) and metastable excited state (a 5F and a 3F) iron atoms have been produced by visible multiphoton dissociation of Fe(CO)5 at 552 nm in a static pressure gas cell at room temperature.The distribution of iron atoms among these states has been measured by using a pump and probe arrangement in which the probe laser pulse excites resonance fluorescence from iron atoms at variable time delay following the photolysis pulse.Collisional relaxation processes of metastable a 5F and a 3F iron atoms have been investigated by using a simple model to describe the main features of the overall relaxation process.Results for a variety of quenching gases including N2O, C2H4O, and O2 indicate that relaxation occurs mainly by transitions between adjacent multiplets, with little intermediate intramultiplet relaxation and no detectable removal by chemical reaction.An interpretation of these results is given in terms of schematic potential energy curves which represent the bonding capabilities of specific-electronic configurations of iron atoms.These curves are discussed in an accompanying paper on studies of chemical reactions of ground state iron atoms.
- Mitchell, S.A.,Hackett, P.A.
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- Mercurous nitrate as a reductimetric reagent. The interference of the more common cations and anions in the determination of iron
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The interfering effect of most of the more common cations and anions on the titration of ferric iron with mercurous nitrate has been examined. As would be expected, ions capable of oxidising ferrous iron interfere. Certain other cations and anions interfere, but in several cases this effect can be eliminated. Copper and thallium must be completely absent, and ions which give coloured products with thiocyanate ions, e.g., molybdenum.
- Belcher,West
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- On the use of amine-borane complexes to synthesize iron nanoparticles
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The effectiveness of amine-borane as reducing agent for the synthesis of iron nanoparticles has been investigated. Large (2-4 nm) Fe nanoparticles were obtained from [Fe{NACHTUNGTRENUNG(SiMe3)2}2]. Inclusion of boron in the nanoparticles is clearly evidenced by extended X-ray absorption fine structure spectroscopy and M?ssbauer spectrometry. Furthermore, the reactivity of amine-borane and amino-borane complexes in the presence of pure Fe nanoparticles has been investigated. Dihydrogen evolution was observed in both cases, which suggests the potential of Fe nanoparticles to promote the release of dihydrogen from amine-borane and amino-borane moieties. Copyright
- Pelletier, Frédéric,Ciuculescu, Diana,Mattei, Jean-Gabriel,Lecante, Pierre,Casanove, Marie-José,Yaacoub, Nader,Greneche, Jean-Marc,Schmitz-Antoniak, Carolin,Amiens, Catherine
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- Investigation of the reduction kinetics of wustite fine powders
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The reduction of wustite (FeO) by hydrogen was investigated over the temperature range 723 to 873 K. The reduction mechanism depends on temperature relative to an effective eutectoid decomposition temperature of 803 K. Above this temperature the reaction
- Coombs,Munir
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- Interaction of diamond with ultrafine Fe powders prepared by different procedures
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We have studied the interaction of synthetic diamond crystals with ultrafine Fe powders during catalytic diamond gasification in a hydrogen atmosphere at 900°C. The Fe powders were prepared by three procedures: reduction of Fe2O3 nan
- Chepurov,Sonin,Chepurov,Zhimulev,Tolochko,Eliseev
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- Magnetic properties of nanocrystalline iron group thin film alloys electrodeposited from sulfate and chloride baths
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Systematic studies of iron group binary (NiCo and CoFe) and ternary (CoNiFe) thin film alloys relating their magnetic properties with film composition, grain size and the corresponding crystal structure were investigated. Anions influence current efficiencies, magnetic properties, surface morphology and phases of electrodeposited films. Higher current efficiencies in chloride baths compared to sulfate baths were observed for CoFe, NiCo and CoNiFe alloys. The higher deposition current efficiencies in chloride baths were attributed to a catalytic effect. Anion types in CoFe and CoNiFe thin film alloys influenced the microstructures and the resulting magnetic properties (coercivity and squareness). The microstructures of NiCo alloys depend on the deposit Co contents rather than anion types. The surface morphologies of CoFe, NiCo and CoNiFe thin films were independent of anion types. CoFe deposits exhibited relatively smooth surface morphology and turned into fine crystallites with increasing solution Fe+2 concentration. NiCo deposits showed very smooth surface morphology. CoNiFe deposits had the surface morphology of polyhedral crystallites. The deposit Fe content in CoFe electrodeposits linearly increased with increasing solution Fe+2 concentration for both chloride and sulfate baths. Similar linear behavior of deposit Co contents was observed in NiCo electrodeposits.
- Kim, Daheum,Park,Yoo,Sumodjo,Myung
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- Reduction and adsorption of Pb2+ in aqueous solution by nano-zero-valent iron - A SEM, TEM and XPS study
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This study reports the synthesis, characterisation and application of nano-zero-valent iron (nZVI). The nZVI was produced by a reduction method and compared with commercial available ZVI powder for Pb2+ removal from aqueous phase. Comparing with commercial ZVI, the laboratory made nZVI powder has a much higher specific surface area. XRD patterns have revealed zero-valent iron phases in two ZVI materials. Different morphologies have been observed using SEM and TEM techniques. EDX spectrums revealed even distribution of Pb on surface after reaction. The XPS analysis has confirmed that immobilized lead was present in its zero-valent and bivalent forms. 'Core-shell' structure of prepared ZVI was revealed based on combination of XRD and XPS characterisations. In addition, comparing with Fluka ZVI, this lab made nZVI has much higher reactivity towards Pb2+ and within just 15 min 99.9% removal can be reached. This synthesized nano-ZVI material has shown great potential for heavy metal immobilization from wastewater.
- Xi, Yunfei,Mallavarapu, Megharaj,Naidu, Ravendra
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- Disproportionation of LaNi5 and TiFe in 4 MPa H2 at 300°C
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The disproportionation of LaNi5 and TiFe under 4 MPa H2 at 300°C was investigated. It was found that under this condition LaNi5 reacted with hydrogen disproportionally at a noticeable rate, while TiFe remained stable owing to the lower mobility of its lattice atoms. The disproportionation reactions are discussed in relation to the intrinsic cycling degradations of LaNi5 and TiFe.
- Zhu, H. Y.,Wu, J.,Wang, Q. D.
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- Ligational and biological studies of Fe(III), Co(II), Ni(II), Cu(II), and Zr(IV) complexes with carbamazepine as antiepileptic drug
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Carbamazepine (CBZ) is considered to be the preferred drug for fractional seizures and may also use in the prevention of primary generalized tonic–clonic seizures. The chelates of CBZ with Fe(III), Co(II), Ni(II), Cu(II), and Zr(IV) were designed and characterized on the basis of elemental analysis, FT-IR, 1H NMR, UV-visible, mass spectra, thermal analysis (TG, DTG, and DTA), molar conductivity, and magnetic moment. IR spectra emphasize that CBZ acts as a neutral bidentate ligand with metal ions through amide oxygen and amino nitrogen. UV-visible spectra and magnetic moment demonstrate that all chelates have geometric octahedral structures. Complexes thermal behavior is systematically analyzed employing TG and DTA technicality. TG findings signalize that water molecules (hydrated and coordinated) are extracted the first and second phases, while CBZ ligand is splitted in the second and subsequent steps. From the DTA curves, the obtained data reflect that the degradation processes are endothermic or exothermic peaks. Assorted thermodynamic factors are calculated, and the results are explicated. Antimicrobial activity was examined against two Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) and two Gram-negative bacteria (Escherichia coli and Pseudomonas aeuroginosa). Anti-fungal efficacy of the compounds has been tested. The Co(II) complex was highly significant against the antifungal Candida albicans and significantly against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis.
- Mohamed, Amira A.,Sadeek, Sadeek A.
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- Single crystal growth, structural characterization and magnetic properties study of an antiferromagnetic trinuclear iron(III) acetate complex with uncoordinated hexamine
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Structural characterization of novel Fe(III) basic acetate with 1,3,5,7-tetraazaadamantane (hexamine – HEX), [Fe3(μ3-O)(OAc)6(H2O)3)](NO3)(HEX)2(H2O)5] (1), revealed a molecular structure typical for Fe(III) basic carboxylates, with a triangular array formed by three iron atoms being equilateral and with an uncoordinated hexamine molecule and nitrate anion present in the crystal structure. Despite the hexamine molecule being uncoordinated, it plays a crucial role in the formation of a supramolecular network. The magnetic properties of the compound were characterized by magnetic susceptibility, M?ssbauer and EPR spectroscopy. These studies indicate the presence of high-spin iron ions in +3 oxidation state with non-Curie-like behaviour. A small room temperature value of the effective magnetic moment and a decrease of the product χT with decreasing temperature both speak in favour of antiferromagnetic interactions between the three individual Fe(III) ions of complex 1 with a total ground state spin of St = 1/2 per trinuclear cluster. EPR spectroscopy confirmed the formation of a St = 1/2 ground state, but also suggested the presence of weak intermolecular exchange interactions between two (or more) clusters of neighbouring molecules. The temperature-dependent M?ssbauer spectra show a slowing-down of the fast spin-lattice relaxation rates of the paramagnetic Fe(III) ion below about 60 K, however, yet no static spin regime is reached down to 3.6 K.
- Bali?, Tomislav,Jagli?i?, Zvonko,Sadrollah, Elaheh,Jochen Litterst, Fred,Po?kaj, Marta,Baabe, Dirk,Kova?-Andri?, Elvira,Bijeli?, Jelena,Ga?o-Soka?, Dajana,Djerdj, Igor
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supporting information
(2021/03/01)
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- ROMP polymer supported manganese porphyrins: Influence of C[dbnd]C bonds along polymer chains on catalytic behavior in oxidation of low concentration Fe2+
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One unsaturated polymer support was prepared through ring opening metathesis polymerization (ROMP) of norbornene-2,3-dip-toluene sulfonate initiated by Grubbs 2nd initiator and manganese porphyrins were immobilized on polymer through transesterification reaction. To investigate the effect of C[dbnd]C bonds along polymer chains on the catalytic behavior, the obtained polymer supported catalyst (P-PPIXMnCl) was applied in oxidation of low concentration Fe2+ to mimic catalytic behavior of Ceruloplasmin. In the presence of P-PPIXMnCl, the conversion of Fe2+ reaches to 91.92% and 96.46% at 10 °C and 37.5 °C (body temperature), respectively. Compared to manganese porphyrins, P-PPIXMnCl can dramatically increase oxidation rate of Fe2+ and the catalytic kinetic shows that the oxidation reaction changes from second-order to third-order. Upon hydrogenation of ROMP polymer, the oxidation reaction still conforms to the second-order kinetics. Density functional theory (DFT) calculation shows that the C[dbnd]C bonds along polymer chains play an important role in the coordination with Fe2+ in the catalytic microenvironment. The real time morphology of supported catalysts in aqueous environment characterized by Cryo-TEM indicates that hydrogenation can shrink the morphology of polymer-water skeleton. The catalyst could be recycled six times without any significant loss in activity. The liner heterogeneous catalyst is expected to be used as drugs for treating excessive iron accumulation in the human body.
- Li, Fanfan,Wang, Xuan,Zhang, Yanwu,Zhao, Huanhuan
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- Synthesis, Crystal Structures, and Thermolysis Studies of Heteronuclear Transition Metal Aluminum Alcoholates
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Heteronuclear alcoholate complexes [M{Al(OiPr)4}2(bipy)] (2-M, M = Fe, Co, Ni, Cu, Zn) and [M{Al(OcHex)4}2(bipy)] (3-M, M = Fe, Co, Ni, Zn) are formed by adduct formation of [M{Al(OiPr)4}2] (1-M, M = Fe, Co, Ni, Cu, Zn) with 2,2'-bipyridine and transesterification reaction with cHexOAc. According to crystal structure analyses, in 2-M and 3-M the central transition metal ion M2+ is coordinated by two chelating Al(OR)4– moieties and one bipyridine ligand in an octahedral arrangement. Treating 1-Cu with 2,2'-bipyridine leads to a reduction process, whereat the intermediate [Cu{Al(OiPr)4}(bipy)2][Al(OiPr)4] (4) could be structurally characterized. During conversion of the iso-propanolate ligands in 1-Cu to cyclohexanolate ligands, Cu2+ is reduced to Cu+ forming [Cu{Al(OcHex)4}(py)2] (5). UV/Vis-spectra and results of thermolysis studies by TG/DTA-MS are reported.
- Küsel, Sebastian,Krautscheid, Harald
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- COMPOUND
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A purpose of the invention is to provide a novel compound. The novel compound is represented by M[i-C3H7NC(R)N-i-C3H7]2 (where, M=Co or Fe; R=n-C3H7 or i-C3H7) that is a liquid under 25° C. (at 1 atmospheric pressure).
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Paragraph 0080-0085
(2020/10/31)
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- The construction of accelerated catalytic Fenton reaction based on Pd/MIL-101(Cr) and H2
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A novel catalytic Fenton system based on H2 and the solid catalyst Pd/MIL-101(Cr) (MHACF-MIL-101(Cr)) was developed at normal temperature and pressure. In this system, the reduction process of FeIII back to FeII was accelerated significantly. Using only trace levels of FeII at the beginning of the reaction, MHACF-MIL-101(Cr) provided continuous production of hydroxyl radicals and rapid degradation of the model contaminant 4-chlorophenol (10 mg L-1) under the initial conditions of pH 3, 25 μM FeII, 25 mM H2O2, 85 mL min-1 H2 and 2 g L-1 Pd/MIL-101(Cr). The activity of the solid catalyst gradually decreased from 100% to about 70% after 6 consecutive degradation reaction cycles of 18 h. This may mainly be attributed to the structural damage and the surface area reduction of this catalyst.
- Liu, Xin,Gao, Shi-Qian,Fan, Jin-Hong,Li, Xiao-Meng,Qin, He-He,Wang, Jun-Xia,Ma, San-Jian,Liu, Zhong-Xing,Yu, Yang
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p. 8179 - 8188
(2019/06/08)
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- Schiff base metal complexes of 4-methyl-1H-indol-3-carbaldehyde derivative as a series of potential antioxidants and antimicrobial: Synthesis, spectroscopic characterization and 3D molecular modeling
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Novel mononuclear Fe(III), Cu(II), Cd(II), Sn(IV) and binuclear Ni(II) and Hg(II) complexes with the Schiff base ligand: (E)-N'-((4-methyl-1H-indol-3-yl)methylene) nicotinohydrazide were synthesized. The elucidation of the structure of the prepared compounds were performed by elemental analyses, magnetic measurements, thermogravimetry, 3D molecular modeling, molar conductance techniques and by various spectroscopic (IR, 1H NMR, UV–Visible, EPR) tools. Antioxidant activity in vitro by DPPH scanning of the ligand and its metal complexes was studied. The results indicated that all test compounds are excellent antioxidants and better than the standard (Ascorbic acid).[Sn(HL)Cl2(OH)2]·2H2O complex (5) showed the highest antioxidant activity. Moreover, the ligand and its metal complexes were screened against the sensitive organisms Staphylococcus aureus as Gram-positive bacteria, Escherichia coli as Gram-negative bacteria and two strains of fungi (Aspergillus flavus and Candida albicans). The results showed that all metal complexes have higher antimicrobial activity than the metal free ligand and the binuclear [Hg2(HL)Cl4]·EtOH complex (6) possessed excellent antibacterial activity better than the standard drug Ampicillin (antibacterial agent) and showed excellent antifungal activity against Aspergillus flavus, better than Amphotericin B (antifungal agent).
- EL-Gammal, Ohyla A.,Alshater, Heba,El-Boraey, Hanaa A.
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p. 220 - 230
(2019/06/18)
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- The Influence of Cu and Al Additives on Reduction of Iron(III) Oxide: In Situ XRD and XANES Study
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The reduction of Fe-based nanocomposite catalysts doped with Al and Cu has been studied using in situ X-ray diffraction (XRD), in situ X-ray absorption near-edge structure (XANES), and temperature-programmed reduction (TPR) techniques. The catalysts have
- Bulavchenko, Olga A.,Vinokurov, Zakhar S.,Saraev, Andrey A.,Tsapina, Anna M.,Trigub, Alexander L.,Gerasimov, Evgeny Yu.,Gladky, Alexey Yu.,Fedorov, Alexander V.,Yakovlev, Vadim A.,Kaichev, Vasily V.
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p. 4842 - 4850
(2019/04/25)
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- Electro-reduction of hematite using water as the redox mediator
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The primary production of iron from its oxides, about 1.6 billion tons per annum, alone is several times greater than the production capacity of all other metals together. This massive production is conventionally achieved by carbothermal reduction causing several million tons of greenhouse CO2 emissions every year, with catastrophic environmental consequences. Here, we present a green, efficient and economical molten salt route for the electrolytic production of iron from iron oxide (hematite, Fe2O3). The dissolution of water in molten LiCl causes the formation of hydrogen cations in the melt, which can be discharged on cathodically polarized solid iron oxide pellets immersed in the melt, leading to the reduction of Fe2O3 of metallic iron and the regeneration of water. The Fe2O3 pellet was thoroughly reduced to iron under 1.4 V within 5 h, considerably faster and more energy efficient than the current electro-deoxidation methods available. The feasibility of the water induced electrochemical reduction of metal oxides is confirmed using Fe2O3, but this novel methodology should be applicable to a broad range of metal oxides.
- Xie, Kaiyu,Kamali, Ali Reza
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supporting information
p. 198 - 204
(2019/01/28)
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- Revisiting Conversion Reaction Mechanisms in Lithium Batteries: Lithiation-Driven Topotactic Transformation in FeF2
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Intercalation-type electrodes have now been commonly employed in today's batteries as such materials are capable of storing and releasing lithium reversibly via topotactic transformation, conducive to small structural change, but they have limited interstitial sites to hold Li. In contrast, conversion electrodes feature high Li-storage capacity, but often undergo large structural change during (de)lithiation, resulting in cycling instability. One exception is iron fluoride (FeF2), a conversion-type cathode that exhibits both high capacity and high cycling stability. Herein, we report a lithiation-driven topotactic transformation in a single crystal of FeF2, unveiled by in situ visualization of the spatial and crystallographic correlation between the parent and converted phases. Specifically, conversion in FeF2 resembles the intercalation process but involves transport of both Li+ and Fe2+ ions within the F-anion array, leading to formation of Fe preferentially along specific crystallographic orientations of FeF2. Throughout the process, the F-anion framework is retained, creating a checkerboard-like structure, within which the volume change is largely compensated, thereby enabling the high cyclability in FeF2. Findings from this study, with unique insights into conversion reaction mechanisms, may help to pave the way for designing conversion-type electrodes for the next-generation high energy lithium batteries.
- Karki, Khim,Wu, Lijun,Ma, Ying,Armstrong, Mark J.,Holmes, Justin D.,Garofalini, Stephen H.,Zhu, Yimei,Stach, Eric A.,Wang, Feng
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supporting information
p. 17915 - 17922
(2019/01/04)
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- Fabrication of double-shelled Fe2O3/CeO2 boxes from CeO2-modified Prussian blue and their enhanced performances for CO removal and water treatment
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Multiple components and well-defined complex nanostructures may synergistically enhance the performance and application of composite materials. Herein, hierarchical double-shelled Fe2O3/CeO2 microboxes, with the robust Fe2O3 hollow microcubes inside and CeO2 shell outside, were fabricated by a facile wet chemical process, which involved the decoration of Fe4[Fe(CN)6]3 microcubes with CeO2 nanoparticles, followed by the thermal decomposition of this precursor in air. The non-equilibrium heat treatment induced heterogeneous contraction process during the calcination of the Fe4[Fe(CN)6]3/CeO2 precursor in air, which is responsible for the formation of the unique hollow structures. The pre-deposited CeO2 nanoparticles acted as stabilizer for the exterior surface of Fe4[Fe(CN)6]3 cubes, and consequently played a crucial role in the formation of the unique hollow structures. The CeO2 molar concentration of the resultant products could be tailored by simply varying the feeding amount of Ce(NO3)3. As a CO oxidation catalyst, the as-prepared Fe2O3/CeO2 microboxes displayed higher catalytic activity in comparison with both CeO2 particles and Fe2O3 cubes owing to the high specific surface area and the synergetic interaction between Fe2O3 and CeO2. More importantly, the catalytic performance is closely associated with the component ratio between Fe2O3 and CeO2. In addition, the Fe2O3/CeO2 microboxes also exhibited significant adsorption capacity of Congo red, implying their potential application in water treatment.
- Liu, Ling,Shi, Jingjing,Wang, Ruiyu,Cao, Hongxia,Liu, Ziwu
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p. 544 - 556
(2017/07/27)
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- Semi-hard magnetic properties of nanoparticles of cobalt ferrite synthesized by the co-precipitation process
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The nanoparticles ferromagnetic materials CoFe2O4have been synthesized by the co-precipitation method and annealed at various temperatures from 773 to 1223 K. The influence of the heat treatment on the structural, morphological and magnetic properties of CoFe2O4nanoparticles was investigated. The structure, morphology and magnetic properties of the annealing samples were reached by mean of X-ray diffraction (XRD), scanning electron microscopy (SEM) techniques and measurement of hysteresis loop. The average crystallite size, lattice parameter and X-ray density were calculated from X-ray diffraction data. All samples have the cubic spinel structure with average crystallite sizes increasing from 30 to 178 nm with the temperature. The results show that CoFe2O4nanoparticles prepared by this method have small and more uniform size. The measurements of the hysteresis loop, performed at both 10 K and 300 K, indicate a ferromagnetic behavior of nanoparticles. Also the measurement at 300 K shows that the sample annealed at 1023 K is magnetically harder than the other samples. The coercive fields are 1.58 kOe against the values inferior at 0.61 kOe for the other samples. Indeed, the remanent magnetization is 31.85 emu g?1for the hard magnetic sample against 13.02 and 17.29 emu g?1for the soft magnetic samples annealed at 773 and 1223 K, respectively. The origin of the hard-soft magnetic properties of nanoparticles CoFe2O4is discussed in terms of the co-existence of secondary phases β-Fe2O3, CoO2and the distribution of Fe2+and Co2+ions within the lattice.
- Hosni,Zehani,Bartoli,Bessais,Maghraoui-Meherzi
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p. 1295 - 1301
(2016/10/30)
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- Universal Surface Engineering of Transition Metals for Superior Electrocatalytic Hydrogen Evolution in Neutral Water
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The development of low-cost hybrid water splitting-biosynthetic systems that mimic natural photosynthesis to achieve solar-to-chemical conversion is of great promise for future energy demands, but often limited by the kinetically sluggish hydrogen evolution reaction (HER) on the surface of nonprecious transition metal catalysts in neutral media. It is thus highly desirable to rationally tailor the reaction interface to boost the neutral HER catalytic kinetics. Herein, we report a general surface nitrogen modification of diverse transition metals (e.g., iron, cobalt, nickel, copper, and nickel-cobalt alloy), accomplished by a facile low-temperature ammonium carbonate treatment, for significantly improved hydrogen generation from neutral water. Various physicochemical characterization techniques including synchrotron X-ray absorption spectroscopy (XAS) and theory modeling demonstrate that the surface nitrogen modification does not change the chemical composition of the underlying transition metals. Notably, the resulting nitrogen-modified nickel framework (N-Ni) exhibits an extremely low overpotential of 64 mV at 10 mA cm-2, which is, to our knowledge, the best among those nonprecious electrocatalysts reported for hydrogen evolution at pH 7. Our combined experimental results and density functional theory (DFT) calculations reveal that the surface electron-rich nitrogen simultaneously facilitates the initial adsorption of water via the electron-deficient H atom and the subsequent dissociation of the electron-rich HO-H bond via H transfer to N on the nickel surface, beneficial to the overall hydrogen evolution process.
- You, Bo,Liu, Xuan,Hu, Guoxiang,Gul, Sheraz,Yano, Junko,Jiang, De-En,Sun, Yujie
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p. 12283 - 12290
(2017/09/12)
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- Structural Changes of Binary/Ternary Spinel Oxides During Ethanol Anaerobic Decomposition
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Several M-modified iron oxides of the spinel family have proven to be effective electron and O2? vectors for the production of hydrogen in the chemical-loop reforming of bio-alcohols. The present work is specifically focused on investigation of ethanol anaerobic decomposition over spinel oxides, which results in significant structural changes of the oxygen carrier material itself and corresponds to a first step of the chemical-loop reforming process. In particular, a series of binary/ternary M-modified ferrospinels were prepared by a co-precipitation method and tested in terms of both redox properties and intrinsic catalytic activity in addition to a complex ex situ study that encompasses the solid-state chemistry investigations of the fresh and reduced oxygen carrier materials. It was found that Co/Cu incorporation facilitates total/partial oxidation of ethanol, giving rise to high yields of H2, COx, and H2O; whereas Mn incorporation predominantly favored dehydrogenation and condensation reactions, leading to the formation of acetaldehyde and acetone. In addition, the incorporation of Mn contributed to significantly reduce the amount of coke formed; however, it caused a lower intrinsic reducibility, which was explained by the formation of a thermodynamically stable and hardly reducible layer of MnxFeyO solid solution.
- Vozniuk, Olena,Bazzo, Cristian,Albonetti, Stefania,Tanchoux, Nathalie,Bosselet, Fran?oise,Millet, Jean-Marc M.,Di Renzo, Francesco,Cavani, Fabrizio
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p. 2219 - 2230
(2017/06/27)
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- Tri- (M = CuII) and hexanuclear (M = NiII, CoII) heterometallic coordination compounds with ferrocene monocarboxylate ligands: Solid-state structures and thermogravimetric, electrochemical and magnetic properties
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The synthesis and characterization of the hexanuclear [M2(κO-O2CFc)2(μ-O2CFc)2(μ-H2O)(κ2N,N′-tmeda)2] (MII = Ni, 5; Co, 6; Fc = ferrocenyl, (η5-C5H4)(η5-C5H5)Fe; tmeda = N,N,N′,N′-tetramethylethylendiamine) and the trinuclear [Cu(κ2N,N′-tmeda)(κ2O,O′-O2CFc)2 2] (7) coordination compounds are described. Compounds 5–7 were prepared by the consecutive reaction of ferrocene carboxylic acid (FcCO2H; 1) with [nBu4N]OH followed by treatment of in situ formed [nBu4N][FcCO2] with the metal salts [M(tmeda)(NO3)2] (M = Ni, 2; Co, 3; Cu, 4). The structures of 5–7 in the solid state were determined by single crystal X-ray diffraction analysis. Isostructural 5 and 6 crystallise in the triclinic P1ˉ (5) and in the monoclinic space group P21/n (6). The two MII(tmeda) entities of 5 and 6 with MII = Ni, Co, respectively, are syn, syn-bridged by two FcCO2? functionalities and one μ-bridging water molecule. Additionally, two FcCO2? ligands are κO-coordinated to each MII ion to form octahedral MN2O4 coordination setups. A related MN2O4 coordination setup is observed for 7 as well, whereby the CuII ion is coordinated by two O2CFc and one tmeda ligand. Electrochemical investigations reveal that all individual Fc units of 5–7 are oxidized separately. Thermogravimetric analysis showed that 5 and 6 start to decompose at 110 and 125 °C and thus at significantly lower temperatures compared to 7 (200 °C). The mass residues obtained after decomposition are composed of Fe2O3, FeNi3 and Fe0.64Ni = Ni0.36 (5), Fe and Co3O4 (6) and Cu2O and CuFeO2 (7), as determined by powder X-ray diffraction analysis (PXRD). Thermal susceptibility measurements of 5 and 6 determined a weak antiferromagnetic coupling in 5 and 6 with J = 1.1 K and J = 1.9 K, respectively.
- Müller, Karoline,Korb, Marcus,Koo, Changhyun,Klingeler, Rüdiger,Miesel, Dominique,Hildebrandt, Alexander,Rüffer, Tobias,Lang, Heinrich
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supporting information
p. 185 - 193
(2017/10/13)
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- A naphthalene derived Schiff base as a selective fluorescent probe for Fe2+
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A naphthalene pyridine Schiff base 1 as a fluorescent chemosensor was developed for the detection of Fe2+ ions in CH3CN-H2O solution. Its binding properties toward various other heavy and transition metal ions including Fe3+ ions were examined. The sensor showed high selectivity and sensitivity towards Fe2+ ions in aqueous media with the lower detection limit of 1.5 × 10-7 M. The fluorescence "turn-on" recognition process follows the ICT process and C=N isomerisation. In addition, determination of Fe2+ in a variety of samples were analyzed which includes commercially available tablets, tomato juice, dark chocolate and tap water.
- Santhoshkumar,Velmurugan,Prabhu,Radhakrishnan,Nandhakumar
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- REDUCTANT AND METHOD FOR PRODUCING METAL USING THE SAME
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PROBLEM TO BE SOLVED: To provide a novel reductant that can reduce metal ions by a reduction reaction in solvent, and a method for producing metal using the reductant. SOLUTION: A reductant comprises a compound represented by the general formula (where X1 and X2 are the same or different to represent a nitrogen atom or a methine group, R1, R2, R3, R4, R5 and R6 are the same or different to represent a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group or a tert-butyl group). There is also provided a method for producing metal by bringing the reductant into contact with a metal ion source in solvent. SELECTED DRAWING: None COPYRIGHT: (C)2016,JPOandINPIT
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Paragraph 0034
(2017/03/25)
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- Dielectric properties induced by the framework in the hybrid organic-inorganic compounds M(dca)2pyz M = Fe, Co and Zn
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In this work we prepare and study the M(dca)2pyz compounds, where dca = polar dicyanamide N(CN)2- ligand, pyz = pyrazine (C4H4N2) ligand and M = Fe2+, Co2+ and Zn2+ that, according to DSC display a first order phase transition, at Tt ～ 270 K (Fe), ～250 K (Co) and ～240 K (Zn). Very interestingly these compounds, which consist of a rather robust framework with incorporated polar dca ligands, and which does not host guest species in the cavities of the structure, display a dielectric anomaly associated to such phase transition. This latter in fact corresponds to the structural transition from the disordered HT-phase (space group Pnma) to the ordered LT-phase (space group P21/n). From a detailed analysis of the dipole distributions in each of these crystal structures we conclude that the polar dca ligands, which bridge two transition metal cations, display a cooperative electrical arrangement, in which the dipoles of each of the two interpenetrated networks show a ferroelectric (FE) arrangement; nevertheless, the relative antiparallel orientation of both networks finally results in net antiferroelectric (AFE) arrangements both in the LT- and HT-polymorphs. Very interestingly, the dynamic disorder of the dca ligands at Tt gives rise to the observed dielectric anomaly. These materials constitute, therefore, an example of hybrid organic-inorganic compounds where the dielectric response directly arises from the framework -and not from polar guest species- which is a very interesting and novel approach in the search for materials in which the dielectric and magnetic properties can couple more strongly.
- García-Fernández,Bermúdez-García,Castro-García,Artiaga,López-Beceiro,Se?arís-Rodríguez,Sánchez-Andújar
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p. 249 - 255
(2016/07/06)
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- Electrochemical sulfur removal from chalcopyrite in molten NaCl-KCl
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Electrolysis of solid chalcopyrite (CuFeS2) against a graphite inert anode has been studied in equimolar NaCl-KCl melt at 700?°C. During electrolysis, S2? ions are released from the solid CuFeS2 cathode, transfer to the graphite anode and discharge to S2 gas. The reduction mechanism of CuFeS2 was investigated by cyclic voltammetry, potentiostatic and constant voltage electrolysis together with spectroscopic and scanning electron microscopic analyses. The reduction contains mainly three stages: the insertion of Na+ or K+ into CuFeS2, forming LxCuFeS2 (L?=?Na or K, x?≤?1); the partial reduction of LxCuFeS2 to Lx-wCuFe1-yS2-z and Fe; the complete reduction to a mixture of Cu and Fe, which can be magnetically separated. After the separation, pure Cu can be obtained by leaching out the residual Fe with acid. Electrolysis at a cell voltage of 2.4?V has led to a rapid reduction of CuFeS2. The current efficiency and energy consumption were 85% and 1.68 kWh/kg-CuFeS2, respectively.
- Tan, Mingsheng,He, Rui,Yuan, Yating,Wang, Zhiyong,Jin, Xianbo
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p. 148 - 154
(2016/07/27)
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- Effect of SrFe12O19 nanopowder on the hydrogen sorption properties of MgH2
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In this study, the effects of different amounts (5, 10, 15, 20 and 50 wt%) of an SrFe12O19 nanopowder, doped into MgH2 and prepared by the ball milling method, were investigated with the aim of improving hydrogen storage p
- Mustafa,Sulaiman,Ismail
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p. 110004 - 110010
(2016/11/30)
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- Synthesis of nanosized iron(III) oxide and study of its formation features
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Nanosized iron(III) oxide has been obtained by thermolysis of iron(III) acetylacetonate using diphenyl ether as a dispersion medium. It has been shown that increase in thermolysis temperature from 180 to 250°C allows one to half the average size of Fe2O3 nanoparticles. The introduction of surfactant into dispersion medium also leads to decrease of the average size of particles down to 4 nm. The phase composition of the prepared nano-Fe2O3 has been established, the possibility to reduce nano-Fe2O3 into iron metal has been shown by temperature-programmed reduction
- Lyadov,Kochubeev,Koleva,Parenago,Khadzhiev
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p. 1387 - 1391
(2016/11/19)
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- Sonophotocatalytic treatment of Bismarck Brown G dye and real textile effluent using synthesized novel Fe(0)-doped TiO2 catalyst
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Using the novel Fe(0)-TiO2-doped catalyst, the degradation of Bismarck Brown G dye was compared by means of advanced oxidation processes, such as sonolysis (13 mm and 25 mm probe tip diameters), photolysis (UV light) and sonophotolysis. The effect of the initial dye solution pH, H2O2 concentration, gas bubbling (argon, oxygen, air and nitrogen), dye concentration and reaction volume were studied. Understanding the degradation mechanism from these studies, the Bismarck Brown G dye treatment was further intensified by catalytic treatments, such as commercial TiO2, synthesized Fe(0) and synthesized Fe(0)-doped TiO2 under sonolytic, photolytic and sonophotolytic irradiations. SEM, TEM, XRD and DRS characterization studies of the sonolytically synthesized catalyst shows that they were of uniform shape, nanoscale in size and had good absorption properties. Among the processes studied, sonophotocatalytic treatment of Bismarck Brown G dye in the presence of Fe(0)-doped TiO2 showed the highest colour removal with the smallest amount of catalyst addition and for larger reaction volume. The practical applicability of the synergistic effects with real textile effluent signifies that the studied process is highly efficient for a safer environment.
- Dinesh, G. Kumaravel,Anandan,Sivasankar
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p. 10440 - 10451
(2015/02/05)
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- Salt-Free Reduction of Nonprecious Transition-Metal Compounds: Generation of Amorphous Ni Nanoparticles for Catalytic C-C Bond Formation
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A salt-free procedure for the generation of a wide variety of metal(0) particles, including Fe, Co, Ni, and Cu, was achieved using 2,3,5,6-tetramethyl-1,4-bis(trimethylsilyl)-1,4-diaza-2,5-cyclohexadiene (1), which reduced the corresponding metal precursors under mild conditions. Notably, Ni particles formed in situ from the treatment of Ni(acac)2 (acac=acetylacetonate) with 1 in toluene exhibited significant catalytic activity for reductive C-C bond-forming reactions of aryl halides in the presence of excess amounts of 1. By examination of high-magnification transmission electron microscopy images and electron diffraction patterns, we concluded that amorphous Ni nanoparticles (Ni aNPs) were essential for the high catalytic activity.
- Yurino, Taiga,Ueda, Yohei,Shimizu, Yoshiki,Tanaka, Shinji,Nishiyama, Haruka,Tsurugi, Hayato,Sato, Kazuhiko,Mashima, Kazushi
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supporting information
p. 14437 - 14441
(2016/01/25)
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- Structural and magnetic characterization of single-phase sponge-like bulk α′-Fe16N2
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Improvements of the two-step reaction sequence starting from γ-Fe2O3 enabled us to synthesize α″-Fe16N2in single phase according to the applied diffraction methods. Simultaneous Rietveld refinements were carried out on powder X-ray and neutron diffraction data. Scanning electron microscopy images of the in situ formed α-Fe and α″-Fe16N2 indicate the formation of pores during reduction and ammonolysis reaction, respectively, resulting in a sponge-like morphology of the α″-Fe16 N2 particles and simultaneously a large surface area facilitating a complete reaction at comparably low temperatures of 125°C. The large surface area is susceptible to the sorption of impurities and indeed chemical analysis reveals significant oxygen and hydrogen contamination of the sample. From EDX measurements in combination with the results of chemical analysis a sorption of humidity to the surface seems to be more likely to explain this contamination than an incorporation of oxygen into the bulk of the sample. Magnetization measurements on the bulk sample of α″-Fe16N2 did not reveal any indication for the presence of a proposed giant magnetic effect.
- Widenmeyer, Marc,Shlyk, Larysa,Senyshyn, Anatoliy,M?nig, Reiner,Niewa, Rainer
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p. 348 - 354
(2015/03/04)
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- Synthesis of Ti 2SC phase using iron disulfide or iron sulfide post-treated with acid
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This study reports a viable method for the synthesis of Ti2SC phase using iron disulfide or iron sulfide as sulfur source and a post-treatment with acid. The reaction routes to Ti2SC phases starting from two different chemical compositions of 2Ti- FeS2 -2TiC and Ti-FeS -TiC were in detail explored and compared through the analysis of X-ray diffraction, thermo-gravimetry/ differential scanning calorimetry, and scanning electron microscopy results. Unlike the Ti-FeS-TiC composition, the reaction route from 2Ti-FeS2-2TiC composition contained an extra decomposition step in which FeS2 transformed to activated FeS and released molecular state sulfur at temperature around 500° C. The latter at this temperature could successfully trigger the reaction of Ti-S-TiC to form Ti2SC phase, which was an analogous self-propagating high-temperature synthesis with a high transient temperature. On the contrary, only trace of Ti2SC phase could be obtained at temperature as high as 1200° C from the Ti-FeS-TiC composition. The main impurity phases from these iron disulfide reactant systems were Fe and FeS, and they could be easily purified by dissolution in H2SO4solution, which resulted in Ti2SC phase with a minor TiC phase in the final product.
- Chen, Ke,Ye, Qun,Zhou, Jie,Shen, Lu,Xue, Jianming,Huang, Qing
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p. 1074 - 1079
(2015/04/14)
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- Nanoporous networks as effective stabilisation matrices for nanoscale zero-valent iron and groundwater pollutant removal
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Nanoscale zero-valent iron (nZVI), with its reductive potentials and wide availability, offers degradative remediation of environmental contaminants. Rapid aggregation and deactivation hinder its application in real-life conditions. Here, we show that by caging nZVI into the micropores of porous networks, in particular Covalent Organic Polymers (COPs), we dramatically improved its stability and adsorption capacity, while still maintaining its reactivity. We probed the nZVI activity by monitoring azo bond reduction and Fenton type degradation of the naphthol blue black azo dye. We found that depending on the wettability of the host COP, the adsorption kinetics and dye degradation capacities changed. The hierarchical porous network of the COP structures enhanced the transport by temporarily holding azo dyes giving enough time and contact for the nZVI to act to break them. nZVI was also found to be more protected from the oxidative conditions since access is gated by the pore openings of COPs.
- Mines,Byun,Hwang,Patel,Andersen,Yavuz
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p. 632 - 639
(2016/01/08)
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- Cobalt catalysts: Very efficient for hydrogenation of biomass-derived ethyl levulinate to gamma-valerolactone under mild conditions
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Hydrogenation of ester levulinate to gamma-valerolactone (GVL) is an interesting reaction in biomass conversion to produce value-added chemicals. Exploration of efficient and robust catalysts is crucial for large-scale application. In this work, we conducted the reaction catalyzed by a Co catalyst, and it was found that commercially available Co3O4 was very efficient for this reaction under mild conditions after reduction by H 2. The effects of temperature, hydrogen pressure, amount of the catalyst used, and reaction time on the yield of GVL were studied. Under optimized conditions, the yield of GVL could reach 98%. The catalyst could be reused at least 10 times without notable loss of the activity and selectivity. The catalyst was characterized by scanning electron spectroscopy (SEM), transmission electron spectroscopy (TEM), X-ray photoelectron spectroscopy (XPS), and powder X-ray diffraction (XRD). It was demonstrated that the metallic Co0 was the active species for the hydrogenation reaction. As far as we know, this is the first work conducting the reaction using Co as the catalyst. This journal is the Partner Organisations 2014.
- Zhou, Huacong,Song, Jinliang,Fan, Honglei,Zhang, Binbin,Yang, Yingying,Hu, Jiayin,Zhu, Qinggong,Han, Buxing
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p. 3870 - 3875
(2014/08/05)
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- Solar-Fenton removal of malachite green with novel Fe0-activated carbon nanocomposite
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Zero valent iron-activated carbon nanocomposite (FeAC) was synthesized using liquid phase reduction method. Both FeAC and micro zero valent iron (ZVI) were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), UV-visible (UV-vis) spectral techniques. The size of Fe1-AC was observed to be 50 nm. The catalytic efficiency of FeAC was explored for the removal of malachite green dye (MG) from aqueous phase. Fe1-AC induced solar-Fenton removal of MG was investigated in the presence of H 212 and citrate (cit.).Solar FeAC system exhibited highest removal efficiency among investigated photocatalytic systems. The dye removal was strongly influenced by solar light, pH, Fe1-AC dosage, Hand citrate concentration in reaction system. The reaction was maximal at pH 6.75. MG was completely decolorized in 60 min using solar/H21 2/cit./Fe1-AC system. Hydroxyl radicals (OH2) were the main oxidizing specie during solar-Fenton process. Fe1-AC proved to be a potential adsorbent for MG. Fe1-AC showed high recycle efficiency due to easier separation from aqueous phase. The lower concentration of dissolved Fe(II) ions in reaction solution indicated the stability of Fe1-AC during MG removal. On the basis of obtained results, the most plausible mechanism for oxidative removal MG of was proposed.
- Singh, Pardeep,Raizada, Pankaj,Kumari, Shailza,Kumar, Amit,Pathania, Deepak,Thakur, Pankaj
-
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- The selective hydrogenation of ethyl stearate to stearyl alcohol over Cu/Fe bimetallic catalysts
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Bimetallic and monometallic catalysts including Cu and/or Fe species were prepared by a co-precipitation method and their catalytic performance was tested for the selective hydrogenation of ethyl stearate to stearyl alcohol. The bimetallic catalysts were observed to be even more active for this selective hydrogenation compared to the monometallic catalysts and their physical mixtures. With a bimetallic catalyst of Cu/Fe (4/1 in mole ratio) reduced at 200 °C, a selectivity to the alcohol reached to above 99% at a conversion of 97% in reaction for 4 h at 230°C, 3.0 MPa. Effects of composition and reduction temperature on the catalytic performance were studied and the properties of catalysts prepared under different conditions were examined by XRD, TPR, N2 physisorption, and SEM. The relationship of the performance with the properties of the catalysts was discussed, along with the conditions under which synergistic effects of Cu and Fe species appeared and caused the enhancement of the catalytic performance.
- He, Limin,Li, Xiaoru,Lin, Weiwei,Li, Wei,Cheng, Haiyang,Yu, Yancun,Fujita, Shin-Ichiro,Arai, Masahiko,Zhao, Fengyu
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p. 143 - 149
(2014/06/23)
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- Coexistence of localized and itinerant electrons in the double-perovskite Ba2Fe2/3Mo4/3O6
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A polycrystalline Ba2Fe2/3Mo4/3O 6 double-perovskite has been prepared by decomposition of citrate precursors and subsequent thermal treatment under a reducing atmosphere. The crystal structure has been studied by combined X-ray and neutron powder diffraction (XRPD and NPD). At room temperature, the structure is cubic (Fm3?m) with lattice parameter a = 8.0710(1) ?. It is unchanged between 3 and 320 K. The crystallographic formula is Ba2[Fe 0.52(2)Mo0.48(2)]4a[Fe0.14(2)Mo 0.86(2)]4bO5.9(2). NPD, electron spin resonance (ESR), and magnetization measurements show spontaneous magnetization below the Curie temperature (TC) = 310 K. The ESR behavior is associated with the presence of localized Fe3+ ions, whereas the transport properties (electrical conductivity and Seebeck effect) suggest the presence of highly correlated electrons in a metallic band with disorder, which can be associated with the Mo t2g electrons. The coexistence of localized and itinerant electrons leads to non-negligible magnetoresistance properties.
- L?pez, Carlos A.,Saleta, Martín E.,Pedregosa, José C.,Sánchez, Rodolfo D.,Alonso, José A.,Fernández-Díaz, María T.
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p. 3555 - 3563
(2014/08/18)
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- Synthesis of TiN from FeTiO3 by microwave-assisted carbothermic reduction-nitridation
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Titanium nitride (TiN) was synthesized from ilmenite (FeTiO3) through the microwave-assisted carbothermic reduction-nitridation followed by acid leaching treatment. The predominance area diagrams of Ti-Fe-N-C-O system at different temperatures
- Ru, Juanjian,Hua, Yixin,Xu, Cunying,Zhang, Qibo,Wang, Ding,Gong, Kai
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p. 121 - 127
(2013/10/08)
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- A family of oxide-carbide-carbon and oxide-nitride-carbon nanocomposites
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This paper describes a powerful and versatile approach that combines the benefits of sol-gel processing with controlled phase separation to yield oxide-carbide-carbon or oxide-nitride-carbon nanocomposites. the Partner Organisations 2014.
- Schnepp,Hollamby,Tanaka,Matsushita,Xu,Sakka
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supporting information
p. 5364 - 5366
(2014/05/06)
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- Preparation of reduced iron powder using combined distribution of wood-charcoal by microwave heating
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In this paper, the influences of microwave heating with wood-charcoal as the reducing agent, on the reducing characterization of mill-scale were systematically investigated. The microstructures of the samples were characterized before and after microwave
- Ye, Qianxu,Zhu, Hongbo,Zhang, Libo,Ma, Ji,Zhou, Li,Liu, Peng,Chen, Jian,Chen, Guo,Peng, Jinhui
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p. 102 - 106
(2014/07/08)
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- Coexistence of localized and itinerant electrons in the double-perovskite Ba2Fe2/3Mo4/3O6
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A polycrystalline Ba2Fe2/3Mo4/3O6 double-perovskite has been prepared by decomposition of citrate precursors and subsequent thermal treatment under a reducing atmosphere. The crystal structure has been studied by combined X-ray and neutron powder diffraction (XRPD and NPD). At room temperature, the structure is cubic (Fmbar {3}m) with lattice parameter a = 8.0710(1) ?. It is unchanged between 3 and 320 K. The crystallographic formula is Ba2[Fe0.52(2)Mo0.48(2)]4a[Fe0.14(2)Mo0.86(2)]4bO5.9(2). NPD, electron spin resonance (ESR), and magnetization measurements show spontaneous magnetization below the Curie temperature (TC) = 310 K. The ESR behavior is associated with the presence of localized Fe3+ ions, whereas the transport properties (electrical conductivity and Seebeck effect) suggest the presence of highly correlated electrons in a metallic band with disorder, which can be associated with the Mo t2g electrons. The coexistence of localized and itinerant electrons leads to non-negligible magnetoresistance properties. A double-perovskite Ba2Fe2/3Mo4/3O6 with Fe/Mo (1:2 ratio) mixed valence states was obtained. From a synthesis under reducing conditions we have stabilized the coexistence of itinerant (associated with Mo) and localized (associated with Fe) electrons. This coexistence of electrons leads to non-negligible magnetoresistance properties.
- L?pez, Carlos A.,Saleta, Martín E.,Pedregosa, José C.,Sánchez, Rodolfo D.,Alonso, José A.,Fernández-Díaz, María T.
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p. 3555 - 3563
(2015/04/27)
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- Fluorine insertion into the Ruddlesden-Popper phase La2BaFe 2O7: The structure and magnetic properties of La 2BaFe2O5F4
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Fluorination of the n = 2 Ruddlesden-Popper phase La2BaFe 2O7 occurs at ～300 °C in flowing 10% F2 in N2 to form La2BaFe2O5F 4. This oxide fluoride contains 2F- ions in interstitial sites within the rocksalt regions and 2F- ions that have substituted for O2- ions in apical sites within the rocksalt layers. The fluorination results in an expansion along c of 7.6% to yield a tetragonal unit cell of dimensions a = 3.96237(7) A, c = 22.3972(5) A. The structure and magnetic properties have been examined by Moessbauer spectroscopy, neutron powder diffraction and magnetic susceptibility measurements. La 2BaFe2O5F4 becomes antiferromagnetically ordered at temperatures below ～500 K, and the magnetic order shows a striking resemblance to that observed in La2BaFe 2O7. The magnetic moments on Fe3+ are perpendicular to [001] and aligned along ±{100} directions above 300 K, but at temperatures below 200 K, they rotate by 45° to lie along ±{110}. Moessbauer spectroscopy suggests the presence of Fe 3+ within the primary phase, but also indicates that fluorination results in some particle fragmentation to form a paramagnetic component of the fluorinated material.
- Gurusinghe, Nicola N. M.,Fones, Julia C.,Marco, Jose F.,Berry, Frank J.,Greaves, Colin
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p. 2038 - 2043
(2014/01/17)
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- Critical STEP advances for sustainable iron production
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A transformative, sustainable technology to replace the age-old CO 2-intensive production of iron is presented. Molten calcium inclusive carbonates are introduced for STEP Iron. Understanding the speciation constraints permits iron synthesis at nearly 100% coulombic efficiency, without exotic electrocatalysts, and at low electrolysis energy.
- Cui, Baochen,Licht, Stuart
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supporting information
p. 881 - 884
(2013/07/26)
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- Reductive dechlorination of 2,4-dichlorophenol by Pd/Fe nanoparticles prepared in the presence of ultrasonic irradiation
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Palladium/Iron (Pd/Fe) nanoparticles were prepared by using ultrasound strengthened liquid phase reductive method to enhance dispersion and avoid agglomeration. The dechlorination of 2,4-dichlorophenol (2,4-DCP) by Pd/Fe nanoparticles was investigated to understand its feasibility for an in situ remediation of contaminated groundwater. Results showed that 2,4-DCP was first adsorbed by Pd/Fe nanoparticles, then quickly reduced to o-chlorophenol (o-CP), p-chlorophenol (p-CP), and finally to phenol (P). The induction of ultrasound during the preparation of Pd/Fe nanoparticles further enhanced the removal efficiency of 2,4-DCP, as a result, the phenol production rates increased from 65% (in the absence of ultrasonic irradiation) to 91% (in the presence of ultrasonic irradiation) within 2 h. Our data suggested that the dechlorination rate was dependent on various factors including Pd loading percentage over Fe0, Pd/Fe nanoparticles availability, temperature, mechanical stirring speed, and initial pH values. Up to 99.2% of 2,4-DCP was removed after 300 min reaction with these conditions: Pd loading percentage over Fe 0 0.3 wt.%, initial 2,4-DCP concentration 20 mg L-1, Pd/Fe dosage 3 g L-1, initial pH value 3.0, and reaction temperature 25 °C. The degradation of 2,4-DCP followed pseudo-first-order kinetics reaction and the apparent pseudo-first-order kinetics constant was 0.0468 min -1.
- Zhao, Deming,Li, Min,Zhang, Dexing,Baig, Shams Ali,Xu, Xinhua
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p. 864 - 871
(2013/03/14)
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- Synthesis and coordination chemistry of an enantiomerically pure pentadienyl ligand
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The coordination chemistry of the enantiomerically pure dimethylnopadienyl ligand (Pdl) with early to late transition metals is presented. Dimethylnopadiene is prepared by a Wittig reaction from (1R)-(-)-myrtenal, which is readily available from the chiral pool. Deprotonation of dimethylnopadiene with a Schlosser base gives K(Pdl), which is a good starting material for the preparation of the early- to late-transition-metal open metallocenes [M(η5-Pdl)2] (M = Ti, V, Cr, Fe) and mono(pentadienyl) complexes [(η5-Cp′)Fe(η5-Pdl)] (Cp′ = 1,2,4-(Me3C)3C5H2), [(η7-C7H7)Zr(η5-Pdl)], and [(η4-COD)Ir(η5-Pdl)]. These complexes have been fully characterized by several spectroscopic techniques, elemental analysis, and X-ray crystallography. In all of these cases the Pdl* ligand exhibits excellent face selectivity upon metal coordination, because it coordinates exclusively from the sterically less hindered site of the bicyclic ligand framework. Within the series of open metallocenes [M(η5-Pdl) 2] (M = Ti, V, Cr, Fe) the open ferrocene is the least thermally stable molecule and degrades to iron metal in solution. This instability is attributed to the severe steric demand of this ligand system in combination with the relatively small Fe2+ center.
- Fecker, Ann Christin,Gloeckner, Andreas,Daniliuc, Constantin G.,Freytag, Matthias,Jones, Peter G.,Walter, Marc D.
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p. 874 - 884
(2013/03/14)
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- Formation of an Fe-H complex anion in YFe2: Adjustment of imbalanced charge by using additional Li as an electron donor
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The novel complex hydride YLiFeH6 with the Fe-H complex anion ([FeH6]4-) was synthesized by hydrogenation of YFe 2 together with additional Li. Li adjusts the original imbalanced charge between Y3+ an
- Matsuo, Motoaki,Saitoh, Hiroyuki,Machida, Akihiko,Sato, Ryutaro,Takagi, Shigeyuki,Miwa, Kazutoshi,Watanuki, Tetsu,Katayama, Yoshinori,Aoki, Katsutoshi,Orimo, Shin-Ichi
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p. 1013 - 1016
(2013/03/28)
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- Topochemical fluorination of Sr3(M0.5Ru 0.5)2O7 (M = Ti, Mn, Fe), n = 2, Ruddlesden-popper phases
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Reaction of the appropriate Sr3(M0.5Ru 0.5)2O7 (M = Ti, Mn, Fe), n = 2, Ruddlesden-Popper oxide with CuF2 under flowing oxygen results in formation of the oxide-fluoride phases Sr3(Ti0.5Ru 0.5)2O7F2, Sr3(Mn 0.5Ru0.5)2O7F2, and Sr3(Fe0.5Ru0.5)2O 5.5F3.5 via a topochemical anion insertion/substitution process. Analysis indicates the titanium and manganese phases have Ti 4+, Ru6+ and Mn4+, Ru6+ oxidation state combinations, respectively, while Moessbauer spectra indicate an Fe3+, Ru5.5+ combination for the iron phase. Thus, it can be seen that the soft fluorination conditions employed lead to formation of highly oxidized Ru6+ centers in all three oxide-fluoride phases, while oxidation states of the other transition metal M cations remain unchanged. Fluorination of Sr3(Ti0.5Ru0.5) 2O7 to Sr3(Ti0.5Ru 0.5)2O7F2 leads to suppression of magnetic order as the fluorinated material approaches metallic behavior. In contrast, fluorination of Sr3(Mn0.5Ru0.5) 2O7 and Sr3(Fe0.5Ru 0.5)2O7 lifts the magnetic frustration present in the oxide phases, resulting in observation of long-range antiferromagnetic order at low temperature in Sr3(Mn0.5Ru 0.5)2O7F2 and Sr3(Fe 0.5Ru0.5)2O5.5F3.5. The influence of the topochemical fluorination on the magnetic behavior of the Sr3(M0.5Ru0.5)2OxF y phases is discussed on the basis of changes to the ruthenium oxidation state and structural distortions.
- Romero, Fabio Denis,Bingham, Paul A.,Forder, Susan D.,Hayward, Michael A.
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p. 3388 - 3398
(2013/05/08)
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- Irradiation effect on the structure change for Sr2Fe1.5Mo0.5O6-δ perovskite ceramic
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The incorporation of radioactive elements derived from fission products (FPs) into a stabilized crystalline structure is an active area of research in the nuclear fuel cycle. The compound Sr2Fe1.5Mo0.5O6-δ (SFM) incorporates several FPs (Sr and Mo) into the crystalline network simultaneously while maintaining a stabilized perovskite structure. This polycrystalline SFM sample was irradiated with 200 keV He ions to a fluence of 5 × 1016 ions cm-2 (corresponding to a peak dose at 1.2 dpa) at room temperature to study radiation damage effects. Irradiated SFM sample decomposed into a layered Sr4FeMoO8-δ based phase and a Fe metallic phase, resulting in nano-crystalized grains with particle sizes around 7 nm. It was rationalized that He ion irradiation created a reduced atmosphere on the surface of SFM sample by preferentially sputtering oxygen atoms, consequently decomposing SFM and reducing Fe ions into metallic Fe phases. These results suggest that the stability of crystalline structures in reducing atmospheres may be an additional factor for consideration in the search for FP hosts in crystalline materials.
- Wang, Siwei,Tang, Ming,Zhang, Lingling,Xiao, Guoliang,Brinkman, Kyle S.,Chen, Fanglin
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p. 170 - 175
(2015/02/02)
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- Electromagnetic and microwave absorption properties of FeSr 0.8La0.2Fe11.8Co0.2O19 shell-core composites
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Shell-core FeSr0.8La0.2Fe11.8Co 0.2O19 composites are prepared by chemical vapor deposition (CVD) for use as microwave absorbing materials. Scanning electron microscopy and X-ray diffraction analyses show that the CVD method yields Sr0.8La0.2Fe11.8Co0.2O19 powders with a uniform coating of Fe. Compared with Sr0.8La 0.2Fe11.8Co0.2O19, FeSr 0.8La0.2Fe11.8Co0.2O19 composites have higher electrical conductivity, permittivity, and dielectric loss, which gradually increase with increasing Fe content. When Sr 0.8La0.2Fe11.8Co0.2O 19/Fe=7:3, a reflection loss (RL) exceeding -10 dB is obtained in the frequency range of 1014 GHz at a coating thickness of 2.0 mm. A minimum RL of -30 dB was found at 8.0 GHz, corresponding to a matching thickness of 2.8 mm.
- Zhang, Zeyang,Liu, Xiangxuan,Wang, Xuanjun,Wu, Youpeng,Liu, Yuan
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p. 2177 - 2182
(2012/05/07)
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- Highly selective reduction of nitroarenes by iron(0) nanoparticles in water
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Highly selective reduction of nitroarenes has been achieved using iron metal nanoparticles in water at room temperature. A wide spectrum of reducible functionalities remained inert under the reaction conditions. During the reaction a change in shape of Fe nanoparticles was observed.
- Dey, Raju,Mukherjee, Nirmalya,Ahammed, Sabir,Ranu, Brindaban C.
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p. 7982 - 7984
(2012/09/08)
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- Carbon monoxide oxidation by atmospheric oxygen on catalysts prepared by pyrolysis of transition metal β-diketonates on the synthetic foam ceramics
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The results of development of new catalytic systems for the carbon monoxide oxidation to dioxide are systematized. The catalysts were produced by gas-phase thermal decomposition of the transition metal acetylacetonates on the synthetic foam ceramics. The kinetic and activation parameters of the oxidation on the catalysts were studied and their relative activity was explored. The activity of catalysts at the oxidation with air oxygen were found to depend on the nature of the deposited metal and the carrier. A synergistic effect in the bimetallic copper catalysts was revealed.
- Didenkulova,Tsyganova,Shekunova,Aleksandrov
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p. 106 - 115
(2012/06/04)
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- On the preparation of molybdenum carbide-supported metal catalysts
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Carbide-supported metal catalysts have been demonstrated to be highly active for a number of reactions including water gas shift and electrochemical hydrogen evolution. Their activity appears to be a consequence of intimate interactions between the metal and support. These interactions as well as the structures and compositions depend on the conditions used during preparation. The objective of research described in this paper was to define key aspects regarding the adsorption and reaction of metal precursor complexes with unpassivated, high surface area Mo2C powders during wet impregnation. The rate of metal deposition and the final state of the metal were functions of the nature of the precursor (i.e., counter ion), electrostatic interactions, and red-ox reactions with the Mo2C surface. The deposition rate decreased in the following order: H2PtCl6 ～ Pd(NH 3)4(NO3)2 ～ CuCl2 ～ Cu(NO3)2 > Co(NO3)2 ～ Ni(NO3)2 ? CoCl2 ～ NiCl2 ～ FeCl2 ～ Fe(NO3)3. The observed adsorption and red-ox behavior suggest that supporting metals onto native carbide surfaces could result in properties that are significantly different from those for metals supported on oxidized carbide surfaces.
- Schaidle, Joshua A.,Schweitzer, Neil M.,Ajenifujah, Olabode T.,Thompson, Levi T.
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p. 210 - 217
(2012/07/02)
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- Novel magnetic Fe onion-like fullerene micrometer-sized particles of narrow size distribution
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Magnetic polydivinylbenzene (PDVB)/magnetite micrometer-sized particles of narrow size distribution were prepared by entrapping Fe(CO)5 within the pores of uniform porous PDVB particles, followed by the thermal decomposition of the encapsulated Fe(CO)5 at 300 °C in a sealed cell under inert atmosphere. Magnetic Fe onion-like fullerene micrometer-sized particles of narrow size distribution have been prepared by the thermal decomposition of the PDVB/magnetite magnetic microspheres at 1100 °C under inert atmosphere. The graphitic coating protects the elemental iron particles from oxidation and thereby preserves their very high magnetic moment for at least a year. Characterization of these unique magnetic carbon graphitic particles was also performed.
- Snovski, Ron,Grinblat, Judith,Margel, Shlomo
-
-
- Nonstoichiometry, point defects and magnetic properties in Sr 2FeMoO6-δ double perovskites
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The phase stability, nonstoichiometry and point defect chemistry of polycrystalline Sr2FeMoO6-δ (SFMO) was studied by thermogravimety at 1000, 1100, and 1200 °C. Single-phase SFMO exists between -10.2≤log pO2≤-13.7 at 1200 °C. At lower oxygen partial pressure a mass loss signals reductive decomposition. At higher pO2 a mass gain indicates oxidative decomposition into SrMoO4 and SrFeO3-x. The nonstoichiometry δ at 1000, 1100, and 1200 °C was determined as function of pO2. SFMO is almost stoichiometric at the upper phase boundary (e.g. δ=0.006 at 1200 °C and log pO 2=-10.2) and becomes more defective with decreasing oxygen partial pressure (e.g. δ=0.085 at 1200 °C and log pO2=-13.5). Oxygen vacancies are shown to represent majority defects. From the temperature dependence of the oxygen vacancy concentration the defect formation enthalpy was estimated (ΔHOV=253±8 kJ/mol). Samples of different nonstoichiometry δ were prepared by quenching from 1200 °C at various pO2. An increase of the unit cell volume with increasing defect concentration δ was found. The saturation magnetization is reduced with increasing nonstoichiometry δ. This demonstrates that in addition to Fe/Mo site disorder, oxygen nonstoichiometry is another source of reduced magnetization values.
- Kircheisen,Toepfer
-
-
- Various metal nanoparticles produced by accelerated electron beam irradiation of room-temperature ionic liquid
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Various metal nanoparticles including base metal were produced by a brief accelerated electron beam irradiation of 1-alkyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)amide room-temperature ionic liquid without a stabilizing agent, which is usually employed so as to prevent aggregation.
- Tsuda, Tetsuya,Sakamoto, Taiki,Nishimura, Yoshitomo,Seino, Satoshi,Imanishi, Akihito,Kuwabata, Susumu
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p. 1925 - 1927
(2012/03/13)
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