Mössbauer study of Japanese ancient iron slag

Mössbauer spectroscopy was applied to an investigation of ancient iron slags, excavated at the ancient ruins for iron manufacturing in order to deduce the raw materials and operative conditions of the furnace. From the Mössbauer spectra, it was found that the slags consisted of fayalite, wüstite, ulvöspinel and magnetite.     

Superparamagnetic behavior of iron oxides supported on porous silica gels

Spinel iron oxide (Fe₃O₄-γ-Fe₂O₃) particles were supported on microbeads of silica gel by the calcination of the silica gel base adsorbing citric acid and Fe³⁺ ions. The X-ray diffraction patterns and the⁵⁷Fe Mössbauer spectra measured for the spinel iron oxide indicated that the particle size of the oxide was regulated by the mean pore diameter (4–82 nm) of the silica gel support employed. In the case of α-Fe₂O₃ particles prepared by using the same silica gel beads, it was revealed by the Mössbauer spectra and the electron micrographs that there were relatively large particles of the oxide on the surface of the beads, in addition to the particles in the silica gel micropores.     

First order magnetic transition,magnetic structure,and vacancy distribution in Fe2P

The para- to ferromagnetic transition in Fe₂P has been studied using Mössbauer spectroscopy. The magnetic hyperfine fields drop abruptly from about half of their saturation values to zero at 214.5 K indicating a first order transition. The isomer shifts show a discontinuous change at the transition point. For some samples the transition takes place over a wide temperature range, probably due to impurities and other imperfections in the samples. From the magnetic hyperfine fields at 15 K the magnetic moments can be deduced to be 1.14 μ_B and 1.78 μ_B for Fe(1) and Fe(2), respectively. An assignment of the components in the Mössbauer spectra to the two crystallographically nonequivalent iron positions has been made from the temperature variation of the spectra.The ordering of metal vacancies has been investigated by a Mössbauer study of a nonstoichiometric Fe₂P sample and by an X-ray diffraction study of a nonstoichiometric Mn₂P crystal.     

Etude des propriétés magnétiques de la variété monoclinique du monogermaniure de fer

One of the three allotropic varieties of iron monogermanide has been studied. This phase includes three iron sites located, respectively, at the lattice points 4(i), 2(a), and 2(c). Magnetic measurements revealed the existence of two transition points and an antiferromagnetic behavior, not totally compensated.Using the Mössbauer effect the nature of these magnetic transformations was further studied. It was confirmed by X-ray diffraction spectra and dilatometer measurements.The Mössbauer sites were identified with the cristallographic ones; the magnitude of the hyperfiné fields and of the isomer shift are discussed in terms of spd hybridization. Mössbauer spectroscopy reveals further information on the magnetic interaction existing between the three iron sublattices. These conclusions are confirmed by the effects seen when cobalt and nickel are substituted for iron.     

Mössbauer spectroscopy with high velocity resolution: an increase of analytical possibilities in biomedical research

Mössbauer spectroscopy is a useful technique for biomedical applications. To increase analytical possibilities and quality of its biomedical applications a new Mössbauer spectrometric system was developed. This system based on a highly stable, sensitive and precision spectrometer SM-2201 with high velocity resolution and a temperature variable liquid nitrogen cryostat with a moving absorber. The first results of Mössbauer spectroscopy with high velocity resolution demonstrated a decrease in the experimental error in the determination of ⁵⁷Fe hyperfine parameters and, therefore, an increase of accuracy in analysis of small variations of the iron electronic structure, as well as more reliable fitting of complicated spectra.     

Amorphous iron formation due to low energy heavy ion implantation in evaporated <Superscript>57</Superscript>Fe thin films

Thin films prepared by vacuum evaporation of ⁵⁷Fe and subsequent low energy ion implantation were investigated by conversion electron Mössbauer spectroscopy and AFM measurements. A sextet with Mössbauer parameters of δ = 0.1 mm/s and B = 26 T appearing in the CEM spectra was identified as amorphous iron. Passivation and phosphonation of the thin films revealed the high affinity of amorphous iron in chemical reactions.     

Crystal structure and magnetic properties of tris(2-hydroxymethyl-4-oxo-4H-pyran- 5-olato-κ2O5,O4)iron(III)

Tris(2-hydroxymethyl-4-oxo-4H-pyran-5-olato-κ²O⁵,O⁴)iron(III) [Fe(ka)₃], has been characterised by magnetic susceptibility measurements Mössbauer and EPR spectroscopy. The crystal structure of [Fe(ka)₃] has been determined by powder X-ray diffraction analysis. Magnetic susceptibility and EPR measurements indicated a paramagnetic high-spin iron centre. Mössbauer spectra revealed the presence of magnetic hyperfine interactions that are temperature-independent down to 4.2?K. The interionic Fe³⁺ distance of 7.31?Å suggests spin-spin relaxation as the origin of these interactions.     

Mössbauer study of the structure of liquid nanophases trapped in porous silicate and solid microemulsion matrix

Mössbauer spectra of liquid solutions fixed as submicroscopic (nanosize) droplets in solid carriers were taken at room temperature and 77 K. A porous silicate (“thirsty glass”) and microemulsions prepared with a paraffin/naphthalene mixture as dispersion medium served as carriers. Solutions of Mössbauer-active tin(IV) and iron(II) complexes were incorporated in these carriers as nanosize droplets. The Mössbauer effect was observed at temperatures above the freezing point of the solutions. For comparison, the systems were also studied in frozen state. Depending on the nature of the system (carrier-solute-solvent) the presence of three types of species was shown in the droplets on the basis of the Mössbauer parameters: (a) situated in bulk position with no interaction with the walls; (b) adsorbed on the internal surface of the holes in the carrier and (c) in bulk position, but with Mössbauer parameters reflecting the influence of the carrier. In some cases surface-bound and bulk species were present together in the sample. The appearance of the Mössbauer effect in liquid state reveals that the Mössbauer-active atoms are fixed in the nanosize pores by a network of hydrogen bonds which form between the solvent molecules, between solvent and solute molecules and between the solvent molecules and the walls of the pores in the carrier. The main parameters determining the rigidity of the network and the situation of the probe molecules are the hydrogen-bonding ability and the polarity of the components of the system. On the basis of the above observations, a new procedure was elaborated for the Mössbauer study of solutions fixed as nanosize droplets in rigid carriers. The analysis of the Mössbauer parameters gives a qualitative picture regarding the solution structure in the interior of the pores, and the adsorption and wetting properties of the system.     

Mössbauer study of the corrosion products of iron

Investigations of the possible use of Mössbauer measurements for the analysis of the corrosion products of iron are reported. The Mössbauer spectrum was measured at room and liquid nitrogen temperatures on two samples produced by different corrosion procedures. The isomeric shift, quadrupole splitting and magnetic splitting observed in the spectra yield information on the chemical composition. In this way, the chemical forms of the compounds in the samples could be established. The magnetic properties, revealed by the spectra taken at different temperatures, permitted the identification of the polymorphous modifications. The rust produced in air saturated with water vapour was found to consist of 50% (w/w) Fe₂O₃,～40% γ-FeOOH, and ～10% β-FeOOH, while the rust produced by periodical immersion in saturated calcium chloride solution is composed of about equal amounts of β-FeOOH and γ-FeOOH. These findings have been confirmed by the thermoanalytical curves of the samples. The Mössbauer effect presents a convenient method for the investigation of the corrosion products of iron.     

Crystal structure and the magnetic properties of tris(2-chloromethyl-4-oxo-4H-pyran-5-olato-κ2O5,O4)iron(III)

The tris(2-chloromethyl-4-oxo-4H-pyran-5-olato-κ²O⁵,O⁴)iron(III), [Fe(kaCl)₃], has been synthesized and characterized by the crystal structure analysis, magnetic susceptibility measurements, Mössbauer, and EPR spectroscopic methods. The X-ray single crystal analysis of [Fe(kaCl)₃] revealed a mer isomer. The magnetic susceptibility measurements indicated the paramagnetic character in the temperature range of 2 K–298 K. The EPR and Mössbauer spectroscopy confirmed the presence of an iron center in a high-spin state. Additionally, the temperature-independent Mössbauer magnetic hyperfine interactions were observed down to 77 K. These interactions may result from spin–spin relaxation due to the interionic Fe³⁺ distances of 7.386 Å.     

Radiation durability of aluminophosphate glass prepared for the stable storage of high-level nuclear wastes

⁵⁷Fe Mössbauer spectra of 30CaO·15Al₂O₃·5Fe₂O₃·25PbO·25P₂O₅ glass consist of two quadrupole doublets due to distorted Fe(III)O₆ and Fe(II)O₆ octahedra. Mössbauer spectra of the aluminophosphate glass irradiated with⁶⁰Co γ-rays (≈5·10⁴Gy) were essentially the same as those of non-irradiated glass. Mössbauer spectra of γ-ray irradiated aluminophosphate glass, containing 10 stable isotopes (Sr, Y, Zr, Nb, Mo, Ba, La, Ce, Pr, and Nd) as the simulated nuclear waste, were also the same as those of non-irradiated glass. These results indicate that the aluminophosphate glass containing iron and lead has high radiation-durability, in addition to high heat resistivity and high water resistivity.     

In vitro and in vivo evaluation of a <Superscript>64</Superscript>Cu-labeled propylene amine oxime complex as a potential hypoxia imaging agent bearing two 3-nitrotriazole groups

The effect of coating with nine different carboxylic acids (glycolic, propionic, lactic, malic, tartaric, citric, mandelic, caproic and caprylic) on nanostructured magnetite (D ~ 10 nm) was studied by Raman and photoacoustic, magnetic and ⁵⁷Fe Mössbauer measurements. Mössbauer spectra of frozen suspensions showed dominantly magnetically split envelopes at lower temperatures, which were evaluated by hyperfine field distribution method. Mössbauer and Raman spectroscopy indicated similar variation of relative occurrence of magnetite and maghemite phases. These results are discussed on the basis of the hypothesis that different carboxylic acids can promote either the oxidation or reduction of iron oxide nanoparticles.     

On the change in physical properties of Ti4−xFe2 + xOy during hydrogenation II: magnetic data for the ternary oxides Ti4−xFe2 + xOy, β-Ti and the corresponding hydrides

The magnetism of Ti-Fe-based hydrides can be separated into surface and bulk contributions. To distinguish between these properties we performed overall magnetization measurements as well as transmission Mössbauer spectroscopy which is not influenced by small amounts of magnetic surface particles.We examined bulk and powdered specimens of ternary oxides and β-Ti. In all cases we observed the segregation of magnetic particles on heat treatment in a dynamic vacuum of 1 Pa, as used in the activation procedure of TiFe. On severe oxidation the iron Curie point was observed and iron segregation was confirmed by Mössbauer spectroscopy. The change in the magnetic properties of the ternary oxides and of β-Ti on hydrogenation is reported and the role of surface oxides and their magnetic segregation is discussed.     

Mössbauer spectroscopy as a radioanalytical method

The review discusses various analytical chemical applications of the Mössbauer effect. The labelled atoms used are Mössbauer isotopes and the measured parameters for analysis are those of the Mössbauer spectra. High efficiency of the technique is demonstrated by examples in studies of the structure of compounds, polyfunctional with respect to the Mössbauer element, and of the mecahnism of chemical reactions, first of all, low-temperature solid phase reactions. The application of the emission Mössbauer spectroscopy is also discussed for analytical purposes.     

Correlation of Mössbauer and Radiochemical Data on Hexacyanoferrate(III)

Mössbauer spectra of irradiated K₁Fe(CN)₆, observed 3 weeks after irradiation, showed that 3% of iron was converted to Fe(CN)₆^4?, while chemical analysis performed 100 hours after irradiation showed 18% was reduced to Fe(CN)₆^4?, Prussian blue was isolated in the chemical analysis, but not observed in the Mössbauer spectra. The Prussian blue formation was found to be time dependent.     

Water and time dependent interaction of iron(III) with indole-3-acetic acid

The influence of water on the interaction between iron(III) and indole-3-acetic acid (IAA) was studied in different organic solutions using rapid-scan stopped-flow spectrophotometry and rapid-freeze/quench Mössbauer spectroscopy. Measurements were also performed in ethanol–water and acetone–water mixtures. The results showed that the interaction between Fe^III and IAA resulted in dimeric Fe^III–IAA complex within 1 s, followed by a slow second step to give Fe²⁺ and IAA(oxidized). No such products were formed in the absence of water. The visible and Mössbauer spectra reflect the nature of the organic solvent and that of the anion of iron(III) salts.     

Mössbauer Spectroscopic Studies of Supported α-Fe2O3 and Fe Catalysts II: The Effect of the Second Metal Addition

The effect of the addition of a second metals such as Zn and Ni on the calcinaton and reduction of alumina, magnesia and silicasupported iron catalysis with total iron loading of 5wt% is investigated by Mössbauer spectroscopy. It is shown that the reducibility of supported α-Fe₂O₃ is gradually increased by adding the second metal. The values of the magnetic hyperfine field obtained from Mössbauer spectra for the Zn or Ni-added α-Fe₂O₃ or Fe catalysts decreased with increasing second metal loading.     

Synthesis and Mossbauer Spectra Studies of Mono-Binuclear Iron(III) Complexes with a Quinquedentate Ligand Derived from Saucylaldehyeds and Diethylenetriamine

Mono- and bi-nuclear iron(III) complexes of general formula [FeXL] and [LFe-Y-FeL](Bph₄)₂ have been prepared, and their spin state of iron atom in the complexes has been studied by means of the temperature dependence of the Mössbauer spectra, electronic spectra and magnetic measurement, where X is a mono- dentate ligand such as Cl-, NCS-, NCO-, N3-, pyridine and L denotes a quinquedentate Schiff base derived from salicylaldehyde and diethylenetriamine, and Y denotes bridged ligand such as pyrazine(pyr), 4,4′-bipyridine(bpy) and 4,4′-vinylenebipyridine(vibpy). On the basis of the Mössbauer and magnetic data, it was concluded that these complexes were all the high-spin (S = 5/2) slate. The effect of gamma ray irradiation for these complexes has been discussed.     

Preparation of magnetic polystyrene latex via the miniemulsion polymerization technique

Magnetic iron oxide (magnetite, Fe₃O₄) nanoparticles were encapsulated with polystyrene to give a stable water‐based magnetic polymer latex, using the miniemulsion polymerization technique. The resulting magnetic latexes were characterized with transmission electron microscopy (TEM), dynamic light scattering (DLS), vibrating sample magnetometer measurements (VSM), and ⁵⁷Fe Mössbauer spectroscopy measurements. TEM revealed that all magnetite nanoparticles were embedded in the polymer spheres, leaving no empty polystyrene particles. The distribution of magnetite particles within the polystyrene spheres was inhomogeneous, showing an uneven polar appearance. The DLS measurements indicated a bimodal size distribution for the particles in the latexes. According to our magnetometry and Mössbauer spectroscopy data, the encapsulated magnetite particles conserve their superparamagnetic feature when they are separated in the polymer matrix. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4802–4808, 2004     

Nitrogen chemisorption on α-Fe nanoparticles studied by in situ Mössbauer spectroscopy

Carbon-supported metallic iron nanoparticles with an average diameter of 2.3 nm were studied by in situ Mössbauer spectroscopy at temperatures down to 5K and with applied magnetic fields up to 4 T. Nitrogen chemisorption at 300, 600 and 700K on the iron particles was found only to affect the iron atoms in the surface layers, resulting in surface iron atoms bonded to nitrogen in a number of different types of environments.