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Sample records for 57fe moessbauer spectroscopy

  1. Transient Moessbauer spectroscopy: experiments with 57Fe

    Transient methods are widely used in NMR and laser spectroscopy. In the γ-energy region coherent transients are a relatively new discovery. So far most transient measurements have been performed with the very narrow Moessbauer resonance of 67Zn. Results of 57Fe measurements have also been reported. We discussed here recent improvements in transient Moessbauer spectroscopy with 57Fe. 6 refs., 3 figs. (author)

  2. Transient Moessbauer spectroscopy with 57Fe

    Transient Moessbauer experiments with 57Fe are described. A time resolution of 0.7 ns is achieved with a BaF2 scintillator. Polar polyvinylidene fluoride film is shown to be well suited for producing fast mechanical modulation. Pulses of recoilless gamma radiation, of width ∼30 ns and height 3.5 times the Moessbauer absorption, are generated with stepwise source motion. The efficiency of transient methods in extracting Moessbauer data is demonstrated with sinusoidal motion. (Auth.)

  3. Hyperfine interactions of 57Fe implanted in solids studied by conversion electron Moessbauer spectroscopy

    The hyperfine interactions of stable 57Fe nuclei implanted in various matrices were studied using conversion electron Moessbauer spectroscopy. The results obtained for 57Fe implanted in aluminium in d-metals in silicon and germanium are presented. The properties of the implantation produced materials and the lattice location of iron impurities are discussed. The information concerning the volume dependence of the hyperfine interactions and the origin of the electric field gradients in solids were obtained. (author)

  4. {sup 57}Fe quadrupole splitting and isomer shift in various oxyhemoglobins: study using Moessbauer spectroscopy

    Oshtrakh, M. I., E-mail: oshtrakh@mail.utnet.ru [Ural Federal University (The former Ural State Technical University-UPI), Faculty of Physical Techniques and Devices for Quality Control (Russian Federation); Berkovsky, A. L. [Hematological Scientific Center of the Russian Academy of Sciences (Russian Federation); Kumar, A.; Kundu, S., E-mail: sumankundu@south.du.ac.in [University of Delhi South Campus, Department of Biochemistry (India); Vinogradov, A. V.; Konstantinova, T. S. [Ural State Medical Academy, Faculty of Internal Diseases Propedeutics (Russian Federation); Semionkin, V. A. [Ural Federal University (The former Ural State Technical University-UPI), Faculty of Physical Techniques and Devices for Quality Control (Russian Federation)

    2010-04-15

    A comparative study of normal human, rabbit and pig oxyhemoglobins and oxyhemoglobin from patients with chronic myeloleukemia and multiple myeloma using Moessbauer spectroscopy with a high velocity resolution demonstrated small variations of the {sup 57}Fe quadrupole splitting and isomer shift. These variations may be a result of small structural differences in the heme iron stereochemistry of various hemoglobins.

  5. 57Fe Moessbauer spectroscopy of (Bi, Pb)-2223 and (Tl, Bi)-1223 superconductors

    (Bi0.93Pb0.17)2Sr1.9Ca2.05(Cu1.0257Fe0.01)3Oy and (Tl0.74Bi0.25)(Ba0.2Sr0.8)2Ca2(Cu0.9957Fe0.01)3Oy superconductors were synthesized and investigated by Moessbauer spectroscopy. The samples were carefully characterized by x-ray diffraction, by scanning electron microscopy in combination with energy dispersive x-ray fluorescence (EDX) and by electrical resistivity measurements. Introduction of small quantities of Fe led to a modest decrease in the critical temperatures but the samples remained superconductors. EDX analysis confirmed that iron entered the superconducting phase. The 57Fe Moessbauer spectra of these compounds could be evaluated based on two doublets. The two doublets were assigned to Fe located in the square planar fourfold oxygen coordinated Cu sites and to Fe in the square pyramidal fivefold oxygen coordinated Cu sites in the 2223 and 1223 lattices. The Moessbauer parameters derived in this study were compared with the results obtained for (Tl, Pb)-1223 and (Hg, Pb)-1223 compounds measured earlier. Based on the combined set of data, information on the different chemical bonding of the apical and basal oxygen in the square pyramids and on the layered electronic structure of these superconductors was derived. (author)

  6. 99Ru and 57Fe Moessbauer spectroscopy of a ruthenium alloy, RuFe2Si

    99Ru and 57Fe-Moessbauer spectroscopic and magnetization measurements were made in order to clarify the magnetic properties of a Huesler alloy, RuFe2Si. The result obtained from 99Ru-Moessbauer spectrum leads to the conclusion that Ru atoms were substituted by both Fe[A,C] and Fe[B], but the latter preferentially. (author) 6 refs.; 5 figs

  7. Unfolding the role of iron in Li-ion conversion electrode materials by {sup 57}Fe Moessbauer spectroscopy

    Tirado, Jose L., E-mail: iq1ticoj@uco.es; Lavela, Pedro; Perez Vicente, Carlos; Leon, Bernardo; Vidal-Abarca, Candela [Universidad de Cordoba, Laboratorio de Quimica Inorganica (Spain)

    2012-03-15

    {sup 57}Fe Moessbauer spectroscopy is particularly useful in the study of oxide and oxalate conversion anode materials for Li-ion batteries. After reduction in lithium test cells, all these materials showed Moessbauer spectra ascribable to iron atoms in two different environments with superparamagnetic relaxation. The spectra recorded at 12 K revealed the ferromagnetic character in agreement with particle sizes of ca. 5 nm. The two types of iron can be ascribed then to surface and core atoms. Core iron atoms play an important role to retain high faradic capacity values for a large number of cycles. These atoms are preserved from irreversible reactions with the electrolyte and hence they promote a high reversibility and rate capability.

  8. Moessbauer spectroscopy of 57Fe and the evolution of the solar system

    The article starts with a brief review of ideas on the origin of the solar system, with emphasis on the cosmic history of the element iron. Some examples of the application of Moessbauer spectroscopy to the study of iron compounds from various types of meteorites, which represent different stages of the evolution of the planetary system, then follow. (orig.)

  9. Study of Kinetics of Iron Minerals in Coal by 57Fe Moessbauer and FT-IR Spectroscopy During Natural Burning

    The process of burning of sulphur rich coal from Jaipur mine in North-Eastern India was carried out at a temperature of (675 ± 5) oC for different time intervals. 57Fe Moessbauer spectroscopy was applied to study the reaction products of iron compounds in each step of thermal treatment. The transformation of Szomolnokite (FeSO4.H2O) and Pyrite (FeS2) in the as received coal sample finally transformed to γ-Fe2O3 and α-Fe2O3. Other clay minerals produce some low spin silicate ash. Fourier Transmission Infrared (FT-IR) spectroscopy gives the ratio of several structural parameters such as Har/Hal and Har/Car. DTA analysis of the coal sample gives the exothermic reaction at different temperatures. TGA and TG analysis of the coal sample in an inert atmosphere shows the weight loss of the coal sample in different temperature ranges.

  10. Phase analysis of iron-oxides by 57Fe-Moessbauer spectroscopy

    Many attempts have been made so far to develop processes and techniques for a synthesis of nanosize powders with specific functional properties. The chemical methods including precipitation techniques, sol.gel processes, and inverse-micelle methods have been used to successfully synthesize narrowly distributed nanosize powders. However, since these processes are based on chemical-media, the resulting powders often undergo a surface contamination or agglomeration of the particles. On the other hand, the dry methods represented by a gas condensation process have been developed to obtain high purity nanosize powders, in which it is expected to suppress an agglomeration of the particles. In the present study, nanosize iron-oxide powders were synthesized by gas-phased method such as the pulsed wire evaporation (PWE). These are known as one-step synthetic technique with high efficiency and high production rate compared with other wet processes involving several treatment steps. Especially, we focus on the phase variation and characterization using Moessbauer spectroscopy of the nanopowders produced under various ambient gas conditions. As for the iron-oxide nanopowers, a mixed gas of Ar/O2 was used as an ambient gas. The phase analysis for the produced iron-oxide powders was systemically investigated by using Moessbauer spectra and the results show that classified phases of Fe2O3 and Fe3O4 can be controlled by regulating the oxygen concentration in the mixed gas during the PWE process

  11. 57Fe Moessbauer investigation of naturally oxidised chlorite

    The green chlorite, occurring as monomineralic mass in the Sukinda (India) area has been investigated by 57Fe Moessbauer spectroscopy together with IR, XRD and XRF analysis. The Moessbauer spectra (at RT and 100 K), split into four symmetric doublets, show hyperfine parameters suggesting Fe2+ at cis and brucite sites and Fe3+ at trans and cis sites. The results show that susceptibility to oxidation (Fe2+ → Fe3+) is highest in the trans site, moderate in the cis site, and least in the brucite site. (orig.)

  12. Visible light activated catalytic effect of iron containing soda-lime silicate glass characterized by 57Fe-Moessbauer spectroscopy

    A relationship between local structure and visible light activated catalytic effect of iron containing soda lime silicate glass with the composition of 15Na2O·15CaO·xFe2O3·(70-x)SiO2, x = 5-50 mass %, abbreviated as NCFSx was investigated by means of 57Fe-Moessbauer spectroscopy, X-ray diffractometry (XRD), small angle X-ray scattering (SAXS), electrospray ionization mass spectrometry (ESI-MS) and ultraviolet-visible light absorption spectroscopy (UV-Vis). Moessbauer spectra of NCFSx glass with 'x' being equal to or larger than 30 after isothermal annealing at 1,000 deg C for 100 min consisted of a paramagnetic doublet and a magnetic sextet. The former had isomer shift (δ) of 0.24 mm s-1 and quadrupole splitting (Δ) of 0.99 mm s-1 due to distorted FeIIIO4 tetrahedra, and the latter had δ of 0.36 mm s-1 and internal magnetic field (Hint) of 51.8 T due to hematite (α-Fe2O3). The absorption area (A) of α-Fe2O3 varied from 47.2 to 75.9, 93.1, 64.8 and 47.9 % with 'x' from 30 to 35, 40, 45 and 50, indicating that the amount of precipitated α-Fe2O3 varied with the Fe2O3 content of NCFSx glass. The precipitation of α-Fe2O3 was also confirmed by XRD study of annealed NCFS glass with 'x' larger than 30. A relaxed sexted with δ, Hint and Γ of 0.34 mm s-1 and 37.9 T and 1.32 mm s-1 was observed from the Moessbauer spectra of annealed NCFSx glass with 'x' of 45 and 50, implying that the precipitation of non-stoichiometric iron hydroxide oxide with the composition of Fe1.833(OH)0.5O2.5 having the similar structure of α-Fe2O3 and α-FeOOH. A remarkable decrease in the concentration of methylene blue (MB) from 10 to 0.0 μmol L-1 with the first-order rate constant (k) of 2.87 × 10-2 h-1 was observed for 10-day leaching test using annealed NCFS50 glass under visible light irradiation. ESI-MS study indicated that existence of fragments with m/z value of 129, 117 and 207 etc. originating from MB having m/z of 284. This result evidently showed that the MB concentration

  13. Low temperature 57Fe Moessbauer study of cucumber root

    Iron uptake and distribution in cucumber root were studied with the help of 57Fe Moessbauer spectroscopy at low temperature applying external magnetic field. Cucumber was grown in iron sufficient modified Hoagland nutrient solution. Moessbauer spectra of the frozen roots taken at 4.2 and 1.5 K, at 5 T external magnetic field support the identification of the main iron species (FeIII-carboxylates, hydrous ferric oxides, FeIII-sulfate-hydroxide) suggested according to its Moessbauer spectra taken between 35-200 K [1]. The magnetic ordering temperature of the hydrous ferric oxide and FeIII-sulfate-hydroxide was found to be in the range of 4.2-1.5 K, which suggests the incorporation of H3O+, PO43- and citrate into these minerals.

  14. Low temperature {sup 57}Fe Moessbauer study of cucumber root

    Kovacs, K; Kuzmann, E; Homonnay, Z; Vertes, A [Institute of Chemistry, Eoetvoes Lorand University, PO Box 32, 1512 Budapest (Hungary); Fodor, F [Department of Plant Physiology and Molecular Plant Biology, Eoetvoes Lorand University, PO Box 32, 1512 Budapest (Hungary); Machala, L, E-mail: kkriszti@chem.elte.h [Centre for Nanomaterial Research, Palacky University, Svobody 26, Olomouc 771 46 (Czech Republic)

    2010-03-01

    Iron uptake and distribution in cucumber root were studied with the help of {sup 57}Fe Moessbauer spectroscopy at low temperature applying external magnetic field. Cucumber was grown in iron sufficient modified Hoagland nutrient solution. Moessbauer spectra of the frozen roots taken at 4.2 and 1.5 K, at 5 T external magnetic field support the identification of the main iron species (Fe{sup III}-carboxylates, hydrous ferric oxides, Fe{sup III}-sulfate-hydroxide) suggested according to its Moessbauer spectra taken between 35-200 K [1]. The magnetic ordering temperature of the hydrous ferric oxide and Fe{sup III}-sulfate-hydroxide was found to be in the range of 4.2-1.5 K, which suggests the incorporation of H{sub 3}O{sup +}, PO{sub 4}{sup 3-} and citrate into these minerals.

  15. Provenance study of obsidians from the archaeological site of La Mana (Ecuador) by electron spin resonance (ESR), SQUID magnetometry and 57Fe Moessbauer spectroscopy

    Obsidians from major Ecuadorian sources (outcrops) were analyzed by electron spin resonance, SQUID magnetometry and 57Fe Moessbauer spectroscopy. If the last technique allows to discriminate obsidians from the Quiscatola source, an association of ESR with SQUID magnetometry permits to differentiate obsidians from the sources of Cotopaxi volcano, from the Quiscatola and Mullumica-Callejones sources of the Chacana caldera and to infer that the 12 analyzed obsidians from the pre-Hispanic site of La Mana come from the Mullumica-Callejones source.

  16. Quantitative multielemental analysis of titaniferous magnetites by PIXE, EDXRF, and their iron mineral characterization by 57Fe Moessbauer spectroscopy

    Two representative titaniferous magnetite samples procured from Moulabhanj, Orissa, India have been studied by PIXE, EDXRF, Moessbauer spectroscopy, and XRD techniques. Major iron-bearing phases identified in the samples by Moessbauer spectroscopy and XRD are magnetite, hematite, ferrous ilmenite and ferric ilmenite. The Fe2+/Fe3+ ratio and the relative percentages of different minerals were determined from the resonance areas of Moessbauer spectra. Quantitative multielemental analysis was carried out by energy dispersive X-ray fluorescence (EDXRF) and proton induced X-ray emission (PIXE). Nineteen minor and trace elements have been quantified by EDXRF whereas by PIXE eighteen elements have been analyzed quantitatively. Concentrations of trace elements determined by EDXRF and PIXE were used in interpreting the physicochemical condition of the depositional basin. (author)

  17. Room temperature 57Fe Moessbauer spectroscopy of ordinary chondrites from the Atacama Desert (Chile): constraining the weathering processes on desert meteorites

    We report the results of a study on the weathering products of 21 meteorites found in the Atacama Desert (Chile) using room temperature 57Fe Moessbauer spectroscopy (MS). The meteorites are weathered ordinary chondrites (OCs) with unknown terrestrial ages and include the three chemical groups (H, L, and LL). We obtained the percentage of all the Fe-bearing phases for the primary minerals: olivine, pyroxene, troilite and Fe-Ni metal, and for the ferric alteration products (composed of the paramagnetic Fe3+ component and the magnetically ordered Fe3+ components) which gives the percentage of oxidation of the samples. From the Moessbauer absorption areas of these oxides, the terrestrial oxidation of the Atacama OC was found in the range from ∼5% to ∼60%. The amount of silicates as well as the opaques decreases at a constant rate with increasing oxidation level.

  18. Identification of pyrite using 57Fe Moessbauer spectroscopy in core sediments from Erhai Lake, SW China combined with a series of acidic pre-treatments

    A method has been developed for analyzing pyrite quantitatively in the sediments of Erhai Lake in southwest China using 57Fe Moessbauer spectroscopy combined with a series of acidic pre-treatments. Following a washing with an alkaline solution (0.1N NaOH), the sediment samples were successively treated using HCl, HF, and then HCl (65 deg C). The residues thus prepared were analyzed for pyrite using 57Fe Moessbauer spectrometry. The presence of pyrite was also confirmed in the acidic residues of the sediments using sulfur K-edge X-ray absorption near edge structure. This method can be used to measure pyrite in aquatic sediments, especially when the concentration of pyrite is very low and the particles of pyrite are small or the crystallinity is low, and even in amorphous status. In addition, vertical variations of pyrite contents are positively correlated with organic matter and negatively correlated with hematite, superfine paramagnetic ferric iron and sedimentation rate in the cored sediment from the Erhai Lake. All these geochemical indicators may also reflect environmental changes in sedimentary conditions and diagenesis. (author)

  19. Magnetic-electronic pressure studies of natural iron-bearing minerals and materials using 57Fe Moessbauer spectroscopy in a diamond anvil cell

    The possibility of measuring 57Fe Moessbauer spectra of natural isotopic abundance materials at variable high pressures and cryogenic temperatures in a diamond anvil cell (DAC) on a timescale comparable to conventional Moessbauer spectroscopy (MS) is described. This is exemplified by satisfactory spectra obtained for an ilmenite (FeTiO3) sample (absorber) in ∼12 h at temperatures where the sample is paramagnetic and in 20-30 h below spin-ordering temperature of ∼60 K where resonance intensity is reduced due to magnetically split spectral components. A commercially available 57Co(Rh) point source of 14.4 keV resonant radiation and a Kr-CO2 proportional counter have both been used. Sufficiently high count-rates are obtained by using both the 14.4 keV resonant γ-ray and associated 1.8 keV escape peak events. To optimise the resonance effect, careful attention has been paid to minimize non-resonant radiation within the discriminator window set to select the 14.4 keV resonant radiation. This has been achieved by setting an appropriate source-DAC-detector geometry (i.e., solid angle) to reduce scattering events off components of the DAC to a minimum. By using conventional commercially available Moessbauer apparatus, magnetic-electronic properties of iron-bearing minerals and materials with an iron content greater than ∼20% may be investigated to pressures in excess of 10 GPa encompassing many minerals of the earth's interior

  20. Effect of particle size and alloying with different metals on {sup 57}Fe Moessbauer spectra

    Nazir, Rabia; Mazhar, Muhammad, E-mail: mazhar42pk@yahoo.com [Quaid-i-Azam University, Department of Chemistry (Pakistan); Siddique, Muhammad [PINSTECH, Physics Division (Pakistan); Hussain, S. Tajammul [Quaid-i-Azam University, Department of Chemistry (Pakistan)

    2009-02-15

    Iron nanoparticles of various sizes have been synthesized using the chemical route which involves the preparation of iron bipyridine complexes in presence of different capping agents followed by thermal decomposition at 450 deg. C in inert atmosphere. The bimetallic nanoalloys of Fe with Mg and Pd have also been prepared by following the same route. The resulting nanoparticles have been characterized by EDX-RF, XRD, AFM and {sup 57}Fe Moessbauer spectroscopy. The appearance of quadrupole doublets in the Moessbauer spectra of Fe nanoparticles indicates the absence of magnetic interaction and variation in parameters is due to the varying particle size. The Moessbauer spectrum of Fe-Mg{sub 2} bimetallic nanoalloy shows two doublets indicating the presence of superparamagnetism. The two doublets can be attributed to change in s-electron density of iron resulting from its two neighboring magnesium atoms. Fe-Pd nanoalloy Moessbauer spectrum is characterized by having a superparamagnetic doublet and a ferromagnetic sextet.

  1. 57Fe Moessbauer effect in UPdSn

    Previously, the transitions to the noncollinear antiferromagnetic structures accompanied by the structural distortions have been studied by a variety of X-ray, magnetic and neutron-diffraction methods. For this aim we have applied the Moessbauer effect by doping the 57Fe isotope to UPdSn. Below TN, except for the magnetic component, the presence of the paramagnetic doublet with the intensity diminishing with decreasing temperature have also been observed. As a possible reason for the occurrence of this doublet in Moessbauer spectra even far below TN, among others, the fluctuation model of two magnetic phases being in thermal equilibrium has been postulated. Moreover, we have calculated and discussed the dipolar hyperfine fields at the Pd sites (occupied also by the iron isotope) for various types of magnetic structures reported in the literature. On this basis, the so-called 'body diagonal' model of the magnetic structures of UPdSn has been found as being more probable. We have also shown that the Moessbauer parameters exhibit an anomalous behaviour at the critical points, connected with both the structural and magnetic transitions which thus coincide in this compound. (orig.)

  2. Moessbauer studies of 57Fe substitution of Cu ions in superconducting oxides

    Since the discovery of high-Tc superconductivity in YBa2Cu3O7 oxides several studies of metal ions substitutions were reported. The observed depression on Tc without a systematic correlation with the charge and magnetic moment of Cu substituents claims for more detailed information about its local properties as can be revealed by 57Fe Moessbauer spectroscopy. The results for different iron concentrations combined with modifications of the superconducting transition are discussed concerning the presence of magnetic moments on the Fe ions and the preferential occupation of Cu(1) sites, recently confirmed by neutron and electron diffraction experiments. The oxygen coordination for the different iron species are proposed on the basis of their dependence on Fe concentration, their behavior at high temperatures as well as the electron diffraction and electron microscopy measurements reported for Fe: YBa2Cu3O7 samples. (author)

  3. Crystal chemical and 57Fe Moessbauer study of chromite from the Nuggihalli schist belt (India)

    In the Nuggihalli schist belt (India), chromite bodies were affected by intense serpentinization followed by weathering. In spite of the strong oxidation of the chromite grains, some unaltered cores were preserved, and they were characterized using electron probe microanalysis, single-crystal x-ray diffraction and low temperature 57Fe Moessbauer spectroscopy. Results of such investigations revealed that chromite cores from the Nuggihalli schist belt are effectively not oxidized, and their study revealed that chromite was not affected by greenschist-facies metamorphism. The apparently highly ordered cation distribution of the chromites, which would suggest low equilibration temperature, is just caused by the very high Cr contents, which prevent Mg-AI exchange between T and M sites. Using Fabries (1979) geothermometer a temperature of about 1180 oC was retrieved (Mitra and Bidyananda, 2003), which therefore corresponds to the quenched-in igneous equilibrium. (author)

  4. A Moessbauer study of single-crystal Zr-0.065 at% 57Fe

    Single crystals of Zr-0.065 at% Fe (95% 57Fe), from a common parent, have been studied by Moessbauer spectroscopy, using both transmission and conversion-electron modes. In the ''as grown'' state the Fe is present as the meta-stable phase, t-Zr2Fe. Vacuum annealing, in the range 795-973 K, results in gradual decomposition of t-Zr2Fe and the diffusion of Fe from the bulk to the surface, where it forms the stable Zr3Fe phase. The kinetics of Zr3Fe formation show fair accord with the known diffusion properties of Fe in α-Zr. Some results for other dilute Zr(Fe) single crystals are reported. ((orig.))

  5. Moessbauer spectroscopy

    This book is addressed to persons interested in learning about what has been done and what can be done with Moessbauer spectroscopy. In an introductory chapter the basic principle is explained and the general parameters governing Moessbauer spectroscopy are tabulated. For the following chapters various disciplines are chosen and the wide applicability of this measuring technique is demonstrated. The second chapter discusses a few representative examples of chemical interesting information being reflected by isomer shifts and quadrupole splittings, particularly with respect to bonding and structural properties. The third chapter deals with some applications of Moessbauer spectroscopy for characterizing magnetic compounds and its use for magnetic structure investigations, particularly by making use of polarized radiation. The fourth chapter describes the use of the Moessbauer spectroscopy for studying iron in biological molecules. As an example of recent applications to mineralogy and geology the results of the studies of lunar samples are reviewed in the fifth chapter. Finally, in the last chapter, work is described on the use of Moessbauer spectroscopy in physical metallurgy, particularly quantitative analyses which have enabled metallurgists to solve many old problems. (orig./FW)

  6. Moessbauer spectroscopy

    The emission and absorption of photons taking place without changes in the frequency spectrum of the crystal lattice are known as the Moessbauer effect. It takes place in the low energy levels of heavy nuclei in solid lattices at low temperatures. On the basis of the hyperfine structure of Moessbauer spectra the notions are explained of isomer shift, quadrupole splitting and magnetic splitting. The principle and function are explained of Moessbauer spectrometers and the methods of graphical processing of spectra, also the use of the least square fit. Moessbauer spectroscopy is nondestructive, highly sensitive and selective and makes structural resolution possible. It is used for quantitative and qualitative analysis of compounds. Examples are given of the use of this method for mineralogical and crystallo-chemical analysis of lunar minerals and rocks, for analysis of corrosion products of iron and for phase analysis of alloys. (M.D.)

  7. A 197Au and 57Fe Moessbauer study of the roasting of refractory gold ores

    The transformation of chemically bound gold into metallic gold during industrial scale roasting of an arsenical gold ore concentrate from the Fairview Mine, Eastern Transvaal, has been studied quantitatively by 197Au Moessbauer spectroscopy. The iron compounds in the concentrate, mainly FeAsS and FeS2, and their transformations during roasting have been studied by 57Fe Moessbauer spectroscopy. The bound gold is found to convert into the metal in parallel to the decomposition of FeAsS and the increase in cyanide leachability. This shows that the refractory character of the ore is caused by the chemical bonding of the gold rather than by the physical inclusion of small, discrete metallic particles in the matrix of FeAsS or FeS2. The ratio of the f-factors of gold bound in the FeAsS component of a refractory ore and of metallic gold was determined to be f(Au:FeAsS)/f(Au)=1.48 ± 0.09. (orig.)

  8. 57Fe Moessbauer study of (Er1-xYx)2Fe14B spin reorientation

    The 57Fe Moessbauer spectra for (Er1-xYx)2Fe14B compounds have been measured around the spin reorientation temperature and at reference temperature of 331 K, where all the samples have the same easy magnetization direction. This allows us to study the Y dilution and spin reorientation influence on the hyperfine parameters. ((orig.))

  9. 57Fe Moessbauer study of a deposit in an industrial cooling circuit supplied with raw river water

    In this work, the nature of the deposit found inside an industrial cooling circuit (which consists of a mixture of different iron containing phases) has been characterized in detail by 57Fe Moessbauer spectroscopy. Electron Paramagnetic Resonance spectroscopy was also used to check for the presence of other metals, mainly manganese and copper, detected by the Inductive Coupled Plasma method. We conclude that the deposit contains a large amount of Fe(III), probably consisiting of ferrihydrite nanoparticles and of goethite, either bulk or as large particles. It also contains traces of an Fe(II) species (about 3%), probably adsorbed on the iron oxides. Mn(II) and traces of Cu(II) are also present.

  10. {sup 57}Fe Moessbauer study of a deposit in an industrial cooling circuit supplied with raw river water

    Horner, Olivier; Herbelin, Pascaline; Goudot, Sebastien [Laboratoire National d' Hydraulique et Environnement, EDF Research and Development (France); Boussac, Alain [CEA Saclay, iBiTec-S, URA CNRS 2096 (France); Bonville, Pierre, E-mail: pierre.bonville@cea.fr [CEA Saclay, Direction des Sciences de la Matiere, IRAMIS/SPEC (France)

    2010-02-15

    In this work, the nature of the deposit found inside an industrial cooling circuit (which consists of a mixture of different iron containing phases) has been characterized in detail by {sup 57}Fe Moessbauer spectroscopy. Electron Paramagnetic Resonance spectroscopy was also used to check for the presence of other metals, mainly manganese and copper, detected by the Inductive Coupled Plasma method. We conclude that the deposit contains a large amount of Fe(III), probably consisiting of ferrihydrite nanoparticles and of goethite, either bulk or as large particles. It also contains traces of an Fe(II) species (about 3%), probably adsorbed on the iron oxides. Mn(II) and traces of Cu(II) are also present.

  11. {sup 57}Fe Moessbauer studies of Fe-Si based amorphous ferromagnetic ribbons and thin films

    Aghamohammadzadeh, H

    1998-04-01

    {sup 57}Fe Moessbauer Spectroscopy has been used to study the mean magnetic moment direction and the distribution of moment directions in ribbon and thin film of amorphous ferromagnets known as Metglass and Finemet. We have studied them in As Received (AR) and Stress Relieved (SR) or Heat Treated (HT) states. These samples are excellent 'soft magnetic materials' with low coercivity of 8 A/m and 0.5 A/m respectively. Annealing has different effects on these samples. Although following annealing coercivity decreases for both Metglass and Finemet samples, in the Finemet it creates a second phase of DO{sub 3} structure which is a nanocrystallite. Our analysis also shows that in the Heat Treated Finemet ribbon 34 % (vol.) of the sample is amorphous and 64 % (vol.) nanocrystalline. In the HT Finemet there are seven different iron sites of which 6 sites belong to the crystalline phase and one site to the amorphous phase. We have studied the distribution of the hyperfine fields, which cause broadening of the spectral lines in the amorphous state. Each iron site has a different environment which is in turn the reason for the field distribution.Our results show that following annealing the mean magnetic field decreases from about 211 kOe in the AR Finemet to 165 kOe in the amorphous phase of the heat treated Finemet which means in this phase there is a depletion in the iron atoms. The spectra were recorded for a range of inclinations between the {gamma}-rays and the normal to the sample plane. Different phenomenological models have been used to investigate the moment direction distribution (anisotropy) in our sample. The results show that in both Metglass and Finemet samples annealing decreases the in-plane anisotropy substantially but not the out-of-plane anisotropy. We also show that the properties of Metglass thin film are quite different from its ribbon sample. Low temperature studies of the Metglass Ribbon sample allow us to investigate the temperature

  12. 57Fe Moessbauer studies of Fe-Si based amorphous ferromagnetic ribbons and thin films

    57Fe Moessbauer Spectroscopy has been used to study the mean magnetic moment direction and the distribution of moment directions in ribbon and thin film of amorphous ferromagnets known as Metglass and Finemet. We have studied them in As Received (AR) and Stress Relieved (SR) or Heat Treated (HT) states. These samples are excellent 'soft magnetic materials' with low coercivity of 8 A/m and 0.5 A/m respectively. Annealing has different effects on these samples. Although following annealing coercivity decreases for both Metglass and Finemet samples, in the Finemet it creates a second phase of DO3 structure which is a nanocrystallite. Our analysis also shows that in the Heat Treated Finemet ribbon 34 % (vol.) of the sample is amorphous and 64 % (vol.) nanocrystalline. In the HT Finemet there are seven different iron sites of which 6 sites belong to the crystalline phase and one site to the amorphous phase. We have studied the distribution of the hyperfine fields, which cause broadening of the spectral lines in the amorphous state. Each iron site has a different environment which is in turn the reason for the field distribution. Our results show that following annealing the mean magnetic field decreases from about 211 kOe in the AR Finemet to 165 kOe in the amorphous phase of the heat treated Finemet which means in this phase there is a depletion in the iron atoms. The spectra were recorded for a range of inclinations between the γ-rays and the normal to the sample plane. Different phenomenological models have been used to investigate the moment direction distribution (anisotropy) in our sample. The results show that in both Metglass and Finemet samples annealing decreases the in-plane anisotropy substantially but not the out-of-plane anisotropy. We also show that the properties of Metglass thin film are quite different from its ribbon sample. Low temperature studies of the Metglass Ribbon sample allow us to investigate the temperature dependence of the moment

  13. {sup 57}Fe Moessbauer probe of spin crossover thin films on a bio-membrane

    Naik, Anil D.; Garcia, Yann, E-mail: yann.garcia@uclouvain.be [Universite Catholique de Louvain, Institute of Condensed Matter and Nanosciences (Belgium)

    2012-03-15

    An illustrious complex [Fe(ptz){sub 6}](BF{sub 4}){sub 2} (ptz = 1-propyl-tetrazole) (1) which was produced in the form of submicron crystals and thin film on Allium cepa membrane was probed by {sup 57}Fe Mossbauer spectroscopy in order to follow its intrinsic spin crossover. In addition to a weak signal that corresponds to neat SCO compound significant amount of other iron compounds are found that could have morphed from 1 due to specific host-guest interaction on the lipid-bilayer of bio-membrane. Further complimentary information about biogenic role of membrane, was obtained from variable temperature Mossbauer spectroscopy on a {approx}5% enriched [{sup 57}Fe(H{sub 2}O){sub 6}](BF{sub 4}){sub 2} salt on this membrane.

  14. Moessbauer spectroscopic study of 57Fe species produced by 56Fe(n,γ)57Fe reaction in iron disulfide

    In order to investigate the physical and chemical effects of neutron capture reaction, a neutron in-beam Moessbauer spectroscopic study on two isomorphs of iron disulfide: pyrite and marcasite, were carried out with a parallel plate avalanche counter at room temperature. In both compounds only two major products accounted for the obtained spectrum: one with Moessbauer parameters close to the parent compound and the other one considered to be a new product. The yield of the parent-like species was different in the two isomorphs. (author)

  15. Hydrometallurgical Extraction of Zinc and Copper - A {sup 57}Fe-Moessbauer and XRD Approach

    Mulaba-Bafubiandi, A. F., E-mail: antoinemulaba@hotmail.com [Technikon Witwatersrand, Extraction Metallurgy Department, Faculty of Engineering (South Africa); Waanders, F. B., E-mail: chifbw@puk.ac.za [North-West University (Potchefstroom campus), School of Chemical and Minerals Engineering (South Africa)

    2005-02-15

    The most commonly used route in the hydrometallurgical extraction of zinc and copper from a sulphide ore is the concentrate-roast-leach-electro winning process. In the present investigation a zinc-copper ore from the Maranda mine, located in the Murchison Greenstone Belt, South Africa, containing sphalerite (ZnS) and chalcopyrite (CuFeS{sub 2}), was studied. The {sup 57}Fe-Moessbauer spectrum of the concentrate yielded pyrite, chalcopyrite and clinochlore, consistent with XRD data. Optimal roasting conditions were found to be 900{sup o}C for 3 h and the calcine produced contained according to X-ray diffractometry equal amounts of franklinite (ZnFe{sub 2}O{sub 4}) and zinc oxide (ZnO) and half the amount of willemite (Zn{sub 2}SiO{sub 4}). The Moessbauer spectrum showed predominantly franklinite (59%), hematite (6%) and other Zn- or Cu-depleted ferrites (35%). The latter could not be detected by XRD analyses as peak overlapping with other species occurred. Leaching was done with HCl, H{sub 2}SO{sub 4} and HNO{sub 3}, to determine which process would result in maximum recovery of Zn and Cu. More than 80% of both were recovered by using either one of the three techniques. From the residue of the leaching, the Fe-compounds were precipitated and <1% of the Zn and Cu was not recovered.

  16. Hydrometallurgical Extraction of Zinc and Copper - A 57Fe-Moessbauer and XRD Approach

    The most commonly used route in the hydrometallurgical extraction of zinc and copper from a sulphide ore is the concentrate-roast-leach-electro winning process. In the present investigation a zinc-copper ore from the Maranda mine, located in the Murchison Greenstone Belt, South Africa, containing sphalerite (ZnS) and chalcopyrite (CuFeS2), was studied. The 57Fe-Moessbauer spectrum of the concentrate yielded pyrite, chalcopyrite and clinochlore, consistent with XRD data. Optimal roasting conditions were found to be 900oC for 3 h and the calcine produced contained according to X-ray diffractometry equal amounts of franklinite (ZnFe2O4) and zinc oxide (ZnO) and half the amount of willemite (Zn2SiO4). The Moessbauer spectrum showed predominantly franklinite (59%), hematite (6%) and other Zn- or Cu-depleted ferrites (35%). The latter could not be detected by XRD analyses as peak overlapping with other species occurred. Leaching was done with HCl, H2SO4 and HNO3, to determine which process would result in maximum recovery of Zn and Cu. More than 80% of both were recovered by using either one of the three techniques. From the residue of the leaching, the Fe-compounds were precipitated and <1% of the Zn and Cu was not recovered.

  17. Assessment of the optimum degree of Sr3Fe2MoO9 electron-doping through oxygen removal: An X-ray powder diffraction and 57Fe Moessbauer spectroscopy study

    We describe the preparation and structural characterization by X-ray powder diffraction (XRPD) and Moessbauer spectroscopy of three electron-doped perovskites Sr3Fe2MoO9-δ with Fe/Mo = 2 obtained from Sr3Fe2MoO9. The compounds were synthesized by topotactic reduction with H2/N2 (5/95) at 600, 700 and 800 oC. Above 800 oC the Fe/Mo ratio changes from Fe/Mo = 2-1 oC are only in the high-spin Fe3+ electronic state.

  18. Fe4+ content and ordering of anion vacancies in partially reduced AFexTi1-xO3-y (A = Ca, Sr; x≤0.6) perovskites. An 57Fe Moessbauer spectroscopy study

    CaFexTi1-xO3-y (0.05≤x≤0.60) and SrFexTi1-xO3-y (0.20≤x≤0.60) perovskites were prepared by solid state reaction and subjected to different heat treatments in different atmospheres. Moessbauer spectroscopy of the CaFexTi1-xO3-y could detect Fe4+ in all the samples, even in those heated at 1000 deg. C in Ar atmosphere for 10 hours. Fe3+ coordinated by six, five and four anions were also identified and the estimated hyperfine parameters were consistent with those previously reported for the CaFexTi1-xO3-x/2 oxides where all the Fe cations were present as Fe3+. The Fe4+/Fe3+ ratios estimated from Moessbauer data are in agreement with coulometric titration data. The absence of tetracoordinated Fe3+ in SrFexTi1-xO3-y suggests that in contrast to CaFexTi1-xO3-y no ordering of anion vacancies takes place even for x=0.60 and explains the differences in the Fe concentration dependence of the electric transport properties of these materials. (author)

  19. Progressive oxidation of pyrite in five bituminous coal samples: An As XANES and 57Fe Moessbauer spectroscopic study

    Naturally occurring pyrite commonly contains minor substituted metals and metalloids (As, Se, Hg, Cu, Ni, etc.) that can be released to the environment as a result of its weathering. Arsenic, often the most abundant minor constituent in pyrite, is a sensitive monitor of progressive pyrite oxidation in coal. To test the effect of pyrite composition and environmental parameters on the rate and extent of pyrite oxidation in coal, splits of five bituminous coal samples having differing amounts of pyrite and extents of As substitution in the pyrite, were exposed to a range of simulated weathering conditions over a period of 17 months. Samples investigated include a Springfield coal from Indiana (whole coal pyritic S = 2.13 wt.%; As in pyrite = detection limit (d.l.) to 0.06 wt.%), two Pittsburgh coal samples from West Virginia (pyritic S = 1.32-1.58 wt.%; As in pyrite = d.l. to 0.34 wt.%), and two samples from the Warrior Basin, Alabama (pyritic S = 0.26-0.27 wt.%; As in pyrite = d.l. to 2.72 wt.%). Samples were collected from active mine faces, and expected differences in the concentration of As in pyrite were confirmed by electron microprobe analysis. Experimental weathering conditions in test chambers were maintained as follows: (1) dry Ar atmosphere; (2) dry O2 atmosphere; (3) room atmosphere (relative humidity ∼20-60%); and (4) room atmosphere with samples wetted periodically with double-distilled water. Sample splits were removed after one month, nine months, and 17 months to monitor the extent of As and Fe oxidation using As X-ray absorption near-edge structure (XANES) spectroscopy and 57Fe Moessbauer spectroscopy, respectively. Arsenic XANES spectroscopy shows progressive oxidation of pyritic As to arsenate, with wetted samples showing the most rapid oxidation. 57Fe Moessbauer spectroscopy also shows a much greater proportion of Fe3+ forms (jarosite, Fe3+ sulfate, FeOOH) for samples stored under wet conditions, but much less difference among samples stored

  20. In situ57Fe Moessbauer Investigation of Solid-State Redox Reactions of Lithium Insertion Electrodes for Advanced Batteries

    A novel in situ electrochemical cell for 57Fe Moessbauer measurements was developed in order to clarify the mechanisms of solid-state redox reactions in lithium insertion materials containing iron. Our in situ Moessbauer technique was successfully applied to the determination as to which transition metal ion was a redox center in the insertion electrodes, such as LiFe0.5Mn1.5O4, LiFeTiO4, or LiFe0.25Ni0.75O2, for the lithium-ion batteries.

  1. Moessbauer spectroscopy study of interfaces for spintronics

    The submonolayer sensitivity and element-specificity of conversion electron Moessbauer spectroscopy, combined with the use of 57Fe enriched tracer layers, enable to carefully investigate thin films and interfaces at the atomic-scale. This paper reports on the main achievements we obtained so far in the study of structural, chemical, and magnetic properties of a variety of interfaces between oxides and Fe-based films having potential interest in the field of spintronics.

  2. Instrumentation for Moessbauer spectroscopy

    The indigenous efforts in instrumentation for Moessbauer spectroscopy are reviewed. After a brief recapitulation of early developments in this field, the current status is described. Instrumentation for Moessbauer spectroscopy involves various aspects such as, velocity transducer, preparation of the radioactive source in proper host matrix, gamma-ray detectors, electron detectors in the case of conversion electron Moessbauer spectroscopy, data acquisition system, temperature variation facility such as cryostats and furnaces, externally applied magnetic field, etc. While the review attempts to cover most of these aspects, the constituents of a basic modern Moessbauer spectrometer, viz. a constant accelerator Moessbauer drive, a top loading type liquid helium cryostat and an inexpensive microprocessor based data acquisition system are discussed in detail. Developments in personal computer based systems are also indicated. (author). 10 figs., 61 refs

  3. The external magnetic field dependence of RF splitting of 57Fe hyperfine lines. NMR + Moessbauer double resonance experiment

    We present the results of an experimental investigation of a RF splitting of 57Fe hyperfine lines of the regime of NMR and Moessbauer double resonance. The experiments have been performed as a function of RF field intensity and static magnetic field magnitude. The intensity of the RF components and the separation between them are extremely sensitive to the frequency and amplitude of the RF magnetic field. The RF splitting of hyperfine lines is inversely proportional to the strength of the static magnetic field. (orig.)

  4. {sup 57}Fe Moessbauer and X-ray characterisation of sandstones

    Mulaba-Bafubiandi, A. F. [University of Johannesburg, Mineral Processing and Technology Research Centre, Department of Metallurgy, School of Mining, Metallurgy and Chemical Engineering, Faculty of Engineering and The Built Environment (South Africa); Waanders, F. B., E-mail: frans.waanders@nwu.ac.za [North West University, School of Chemical and Minerals Engineering (South Africa)

    2013-04-15

    Sandstones from the Free State province in South Africa have been mined and processed mainly by small scale and artisanal miners in the rural areas. In the present investigation basic fire proof and water absorption tests, X-ray and {gamma}-ray based characterisation techniques were used to study the sandstones. The collected samples were grouped according to their apparent colour in day light conditions and the elemental analysis showed the presence of a high amount of oxygen (>52%) and silicon (>38%) with Mn, Al, Fe and Ca as major elements in proportions related to the colour distribution of the various sandstones. The uniaxial compressive stress was found to be the highest (56 MPa) for the greyish sandstone and the lowest (8 MPa) for the white sandstone sample, also associated with the lowest (Al+Fe)/Si value of 0.082. The humidity test showed that the 6 % water absorption was lower than the recommended ASTM value of 8 %. The sandstone samples were also subjected to various high temperatures to simulate possible fire conditions and it was found that the non alteration of the mineral species might be one of the reasons why the sandstones are regarded as the most refractory amongst the building materials typically used. Moessbauer spectroscopy revealed that iron is present in all the sandstones, mainly as Fe{sup 3 + } with the black sandstone showing an additional presence of 3 % Fe{sup 2 + } indicating that a higher iron content coupled to higher silicon content, contributes to an increase in the uniaxial compressive strength.

  5. Moessbauer NMR double resonance in 57Fe. Coupling between quadrupole split states

    In order to describe the interaction of a nucleus (in a static electric field gradient) with a radiation field, we have introduced the concept of ''dressed nucleus''. The eigenvalues of its Hamiltonian are calculated, which leads to expressions for the different energies of γ-rays produced by spontaneous emission. We have calculated these energies as well as their relative probabilities in the case of Ie=3/2--Ig=1/2- M1 transitions. We have shown that a Moessbauer spectrum using as a source an ensemble of ''dressed nuclei'' and a single line absorber consists of six lines: two lines of the original quadrupole doublet and four sidebands, each of them having the same intensity. (orig.)

  6. 57Fe Moessbauer investigation of oriented single-crystal and polycrystalline PbFe12O19

    57Fe Moessbauer spectra of PbFe12O19 have been obtained at 295 K on polycrystalline and single-crystal thin sections oriented with the c-axis parallel and perpendicular, respectively, to the γ-ray propagation direction. Due to the lower Neel temperature, the internal magnetic fields (Heff) in PbFe12O19 are lower than those in BaFe12O19 and SrFe12O19 but the systematics of the hyperfine interactions are similar to those in other hexaferrites. For example, the relative values of Heff exhibit the following sequence: 2b 1 2 and the isomer shifts (δ) exhibit the following ordering: 4f1 2. The large dynamic displacement of the 2b Fe3+ ion parallel to the c-axis is clearly demonstrated by the relative intensity of the 2b site for the two oriented single crystals, being negligible for the crystal perpendicular to the c-axis, and equal to its population fraction for the crystal parallel to the c-axis. The lower value for the electric quadrupole splitting of the 2b site is believed to be related to the larger dynamic displacements at this site compared to other hexaferrites

  7. Moessbauer Spectroscopy in Materials Science

    The publication in electronic form has been set up as proceedings of the conference dealing with applications of the Moessbauer spectroscopy in material science. Twenty-three abstracts and twenty-two presentations are included.

  8. Moessbauer spectroscopy with 191193Ir

    The contributions made by Ir Moessbauer spectroscopy to the determination of nuclear parameters, as well as applications in solid state physics and chemistry, are reviewed. In addition, a brief description of experimental techniques and source preparation procedures is given. (Auth.)

  9. Applications of transient Moessbauer spectroscopy

    Transient effects in Moessbauer spectroscopy were generated by sweeping the frequency or switching the phase of recoilless gamma radiation. From a sinusoidal frequency sweep a separation of source and absorber contributions to the experimental linewidth was obtained. With phase switching exceptionally large effects were observed. The experimental results were obtained mainly using the 67Zn resonance. (Auth.)

  10. Technological applications of Moessbauer spectroscopy

    A brief review is given of some recent industrial applications of Moessbauer spectroscopy. One of the most desirable futures of the Moessbauer effect is the feasibility of performing in situ measurements. Such measurements are extremely important especially in the upgrading of coal derived liquids. Such applications have been very successful in understanding the role of iron sulfides stoichiometries in direct coal liquefaction. The use of in situ techniques is invaluable in the investigation of the metal support interaction and their relation to carburization processes in Fischer-Tropsch reactions. Emphasis is placed in the use of a multiple technique approach to elucidate scientific problems of industrial importance. (Auth.)

  11. Structural and {sup 57}Fe Moessbauer study of EuCr{sub 1 - x}Fe{sub x}O{sub 3} nanocrystalline particles

    Widatallah, H. M., E-mail: hishammw@squ.edu.om; Al-Shahumi, T. M. H.; Gismelseed, A. M. [Sultan Qaboos University, Department of Physics (Oman); Klencsar, Z. [Hungarian Academy of Sciences, Chemical Research Institute (Hungary); Al-Rawas, A. D.; Al-Omari, I. A.; Elzain, M. E.; Yousif, A. A. [Sultan Qaboos University, Department of Physics (Oman); Pekala, M. [University of Warsaw, Chemistry Department (Poland)

    2012-03-15

    A structural and Moessbauer study of mechanosynthesized EuCr{sub 1 - x}Fe{sub x}O{sub 3} nanocrystalline particles ({approx}20-30 nm) is presented. The lattice parameters increase with increasing x-value leading to an increasingly distorted structure. The crystallite sizes range between 20 nm and 30 nm. Magnetic and {sup 57}Fe Moessbauer measurements show the samples with x < 0.7 to be paramagnetic and those with x {>=} 0.7 to be partially superparamagnetic at 298 K. The 78 K Moessbauer spectra of the samples with x = 0.3-1.0 are composed of well-resolved two sextets that are explicable in terms of the structural model that we recently have proposed for the EuCrO{sub 3} nanoparticles according to which the transition metal ions and Eu{sup 3 + } partly exchange their usual sites in the perovskite-related structure (Widatallah et al. J Phys D Appl Phys 44:265403, 2011). Consequently, the two sextets obtained at 78 K refer to Fe{sup 3 + } ions at the usual B-octahedral site and the A-dodecahedral site usually occupied by Eu{sup 3 + }.

  12. Maritime Antarctica soils studied by Moessbauer spectroscopy and other methods

    Soil samples from the King george Island, Antarctica, have been studied by 57 Fe Moessbauer spectroscopy, X-ray diffractometry, radiometry,neutron activation analysis and chemical analytical methods. X-ray diffractometry measurements have identified soils containing different volume ratios of quartz, feldspar, chlorite as well as hematite. The difference in the phase composition and in the iron distribution among the crystallographic sites of iron bearing minerals (chlorite, magnetite and hematite) of samples from two different depths was derived from the complex Moessbauer spectra. The differences in the mineral composition, iron distribution, concentration of water soluble salts, pH and radioactivity of certain radionuclides indicate the occurrence of chemical weathering of minerals. (author)

  13. Characterization of the firing conditions of archaeological Marajoara pottery by Moessbauer spectroscopy and X-ray diffraction

    Munayco, P., E-mail: mpablo@cbpf.br; Scorzelli, R. B. [Centro Brasileiro de Pesquisas Fisicas (Brazil)

    2013-08-15

    Here we report on a study of samples from fragments of Marajoara ceramics using {sup 57}Fe Moessbauer spectroscopy and XRD. The Moessbauer spectra were measured at room temperature (RT) and at liquid helium temperature (4.2 K). Despite a certain variability of the Moessbauer spectra, dominant features could be established, which allowed the samples to be classified into characteristic types (Moess-types) according to their Moessbauer patterns. The different Moess-types were defined on account of the presence and intensity or the absence of certain components, mainly in the RT spectra. The analysis is complemented by data obtained by X-ray diffraction.

  14. Magnetic-electronic properties of FeS and Fe7S8 studied by 57Fe Moessbauer and electrical measurements at high pressure and variable temperatures

    The effect of pressure on the magnetic and electronic properties of synthetic FeS and Fe7S8 has been investigated by using 57Fe Moessbauer and electrical resistance measurements on polycrystalline samples pressurized in miniature gem anvil cells up to a pressure of ∼12 GPa in the temperature range 300-5 K. FeS in the low-pressure phases (P∼7 GPa) adopts a magnetically quenched low-spin state and a non-metallic behaviour associated with the filled valence band. The non-metallic behaviour observed in all pressure phases is explained in terms of electron correlation between Fe:3d electrons. Ins. In contrast, Fe7S8 is magnetic-metallic below ∼ 5 GPa and diamagnetic-metallic above this pressure. The metallic behaviour is ascribed to hole conduction in the S:3p band, as inferred from the temperature dependence of the Moessbauer data. The collapse of band magnetism at ∼5 GPa in Fe7S8 may be due to pressure-induced band broadening, leading to a breakdown of the Stoner criterion. (author)

  15. Lattice dynamic studies from {sup 151}Eu-Moessbauer spectroscopy

    Katada, Motomi [Tokyo Metropolitan Univ., Hachioji (Japan). Faculty of Science

    1997-03-01

    New complexes {l_brace}(Eu(napy){sub 2}(H{sub 2}O){sub 3})(Fe(CN){sub 6})4H{sub 2}O{r_brace}{sub x}, bpy({l_brace}(Eu(bpy)(H{sub 2}O){sub 4})(Fe(CN){sub 6})1.5bpy4H{sub 2}O{r_brace}{sub x}) and ({l_brace}(Eu(phen){sub 2}(H{sub 2}O){sub 2})(Fe(CN){sub 6})2phen{r_brace}{sub x}) etc were synthesized using phenanthroline and bipyridine. Lattice dynamic behaviors of Eu and Fe atom in the complexes were investigated by Moessbauer spectroscopy. By {sup 151}Eu-Moessbauer spectrum and parameters of new complexes, bpy complex showed the largest quadrupole splitting value, indicating bad symmetry of Eu ligand in the environment. Molecular structure of napy, bpy and phen complex were shown. These complexes are consisted of Eu atom coordinated with ligand and water molecule, of which (Fe(CN){sub 6}){sup 3-} ion formed one dimentional polymer chain and naphthyridines formed stacking structure. New complexes were observed by {sup 57}Fe-Moessbauer spectroscopy, too. The quadrupole splitting values were very different each other, indicating change of symmetry of Fe atom in the environment and three valence low spin state of Fe in the complex. (S.Y.)

  16. Moessbauer Spectroscopy of Locally Inhomogeneous Systems

    The paper considers ways for obtaining information from Moessbauer spectra of locally inhomogeneous systems. The entire notion locally inhomogeneous system (LIS) is given a more precise definition applied to Moessbauer spectroscopy. There are considered factors that lead to local inhomogeneity of hyperfine interactions and its mechanisms. Application of LIS Moessbauer spectra processing and analysis methods are discussed. Ways for comprehensive utilization of various methods are described along with the role of a priori information at all processing stages.

  17. Moessbauer Spectroscopy study of Quimsachata Volcano materials

    It has been studied volcanic lava from Quimsachata Volcano in Pem. Moessbauer Spectroscopy, X-ray diffraction, electronic and optical microscopy allowed the identification of different mineralogical phases. (A.C.AS.)

  18. Processes in Geophysics Studied by Moessbauer Spectroscopy

    Helgason, Orn [University of Iceland, Science Institute (Iceland)

    2004-12-15

    Moessbauer spectroscopy has been appreciated in geoscience as a powerful tool to study magnetic and structural properties of a wide range of minerals and rocks. In this presentation the application of Moessbauer spectroscopy in different geophysical processes such as tracing the development of magma during volcanic eruptions and phase transitions of magnetic minerals due to thermal impact of dikes in earlier lava formation or hydrothermal alteration will be discussed.

  19. Applications of Moessbauer Spectroscopy in Industry

    The demand by industrial researchers to characterize commercial materials with high precision has seen the growth of many spectroscopic techniques in the broad area of applied materials science. Moessbauer spectroscopy is slowly moving into the industrial arena, due in part to the development of new and highly technological materials whose performance can only be optimized through complete analysis and evaluation down to the atomic level. The movement from the traditional research laboratory environment is assisted by the portability of the most recent instrumentation, including PC based data acquisition, miniature spectrometers, user friendly software for spectral analysis and the development of the scattering detectors for in-situ Moessbauer analysis. Scientific researchers are more often being sought to collaborate in industrial projects to solve problems of economic and social importance. An overview is presented on some of the industrial applications for which Moessbauer spectroscopy is being used today. Discussion includes some of the features important for close collaboration between the research scientist and industrial partners, as well as some of the challenges likely to be faced by the researcher in the endeavours to bring the Moessbauer methodology to the industrial environment. Corrosion research, and the need to fully understand the effect of environmental parameters on the performance of structural steels, is one area in which Moessbauer spectroscopy has become a required analytical technique. One example of a close liason between academia and industry and the use of Moessbauer spectroscopy to characterize and improve the quality of galvanneal steel sheet is presented.

  20. 57Fe Mössbauer spectroscopy and magnetic study of Al13Fe4

    Highlights: • We show that Mössbauer spectra of Al13Fe4 can be fitted well with three quadrupole doublets. • The shape of the in-field Mössbauer spectrum is well accounted for with five component subspectra. • The electronic density of states has a pseudogap around the Fermi energy. • We find that the Debye temperature of the compound studied is 383(3) K. - Abstract: The results of ab initio electronic structure and electric field gradient (EFG) calculations, and of X-ray diffraction, 57Fe Mössbauer spectroscopy, and magnetic studies of Al13Fe4 are reported. It is shown that Al13Fe4 crystallizes in the monoclinic space group C2/m, in which Fe atoms are located at five inequivalent crystallographic sites, with the lattice parameters a=15.503(2) Å, b=8.063(2) Å, c=12.464(2) Å, and β=107.71(2)°. We demonstrate that zero-field Mössbauer spectra can be decomposed into three quadrupole doublets. With the aid of the calculated EFG parameters we show that the first doublet results from one Fe site, the second doublet is due to two other Fe sites, and the third doublet originates from the last two Fe sites. We find that the shape of the Mössbauer spectrum of Al13Fe4 measured in an external magnetic field of 90 kOe can be accounted for with five component subspectra generated using the calculated EFG parameters at five inequivalent Fe sites. The quadrupole splittings corresponding to three component doublets are shown to increase with decreasing temperature and are well described by a T3/2 power-law relation. The Debye temperature of Al13Fe4 is found to be 383(3) K. We find a pseudogap in the density of states (DOS), with a width of ∼0.2 eV, that is centered 0.1 eV above the Fermi energy. The finite DOS at the Fermi energy confirms good metallicity of Al13Fe4. The 1/T-like dependence of the magnetic susceptibility shows that Al13Fe4 is a paramagnet

  1. Interactions between osmium atoms dissolved in iron observed by the 57Fe Mössbauer spectroscopy

    Konieczny Robert

    2015-03-01

    Full Text Available The room temperature 57Fe Mössbauer spectra for binary iron-based solid solutions Fe1−xOsx, with x in the range 0.01 ≤ x ≤ 0.05, were analyzed in terms of binding energy Eb between two Os atoms in the Fe-Os system. The extrapolated values of Eb for x = 0 were used for computation of enthalpy of solution of osmium in iron. The result was compared with that resulting from the cellular atomic model of alloys by Miedema. The comparison shows that our findings are in qualitative agreement with the Miedema's model predictions.

  2. Possibilities of Moessbauer spectroscopy for chemical analysis

    Full text: The Moessbauer spectroscopy technique belongs to few methods of defining the phase state or crystallographic sites of a substance. The Moessbauer spectra bear information on various hyperfine interactions, many of which are indirectly related to the chemical nature of the Moessbauer atom and its nearest environment. Determination of the parameters of hyperfine interactions that can be extracted from Moessbauer spectra and used for qualitative analysis is a routine task. In the present work, we studied the influence of various factors on experimental errors encountered in quantitatively defining the phase composition or site populations of the substance under study, such as the measurements geometry, Lamb-Moessbauer coefficients, absorber thickness, efficiency and dead time of the detection system and spectral line shape. The absolute f measurements were made using the 'black' absorber method. Moessbauer measurements were carried out with carefully controlled background intensities, since the accuracy of f evaluation directly depends on the measurement of the background. The influence of a non-uniformity of samples on the results of the quantitative analysis is discussed. The data analysis was divided into two parts: removal of instrumental artifacts by folding and baseline correction and deconvolution to extract the hyperfine parameters of individual local environments. In our approach, calibration graphs were drawn by measuring the spectra of a series of analogous samples having different known concentrations. For the same purpose, the internal standard method was also used. Experimental data are presented for phase analyses of different samples. (author)

  3. Applications of Moessbauer spectroscopy in cement studies

    In the last two decades Moessbauer spectrometer has been employed to investigate cement and its clinker. In this work some of these investigations are exhibited briefly hoping that this would facilitate further investigations. It has already been seen that Moessbauer spectroscopy gives good information about some vague points which were present before using this technique as a tool in cement studies such as clinker formation, iron solubility, the iron states in the different phases of clinker as well as the effect of hydration at different times on the states of iron cement pastes, methods for the quality control of the manufactured clinker, the evaluation of the degree of hydration and the compressive strength have been assessed. A concept about the Moessbauer spectroscopy is presented. (author)

  4. The polar mixed-valent lanthanum iron(II, III) sulfide La3Fe2-δS7: Synthesis, crystal and electronic structure, 57Fe Moessbauer spectra, magnetic susceptibility and electrical resistivity

    La3Fe2-δS7 (δ=0.042(6)) was synthesized through a reaction of the elements in a LiCl/KCl flux at 970 K, and its structure was determined by single-crystal X-ray diffraction. The compound crystallizes in the polar hexagonal space group P63 with a=10.1906(6), c=5.9543(4) A and Z=2, and adopts the Ce6Al10/3S14 structure type. The structure contains both octahedral and tetrahedral iron sites: one-dimensional rods of face-sharing FeS6 octahedra run along the 63 screw axis of the cell; FeS4 tetrahedra, all pointing in the same direction, are stacked along the threefold rotation axes. The iron-centered polyhedra are linked by lanthanum atoms, which are coordinated by [7+1] sulfur atoms in a bicapped trigonal prismatic arrangement. 57Fe Moessbauer spectroscopy confirms that FeIII and FeII cations occupy the tetrahedral and octahedral iron sites, respectively. Magnetic susceptibility data indicate an antiferromagnetic transition at TN∼155 K. Density functional band structure calculations within the local density approximation reveal two covalent Fe-S subsystems within the compound that mix only weakly. A large anisotropy is indicated by bands that disperse predominantly along the hexagonal axis. The electronic band structure suggests pseudo-one-dimensional metallic conductivity along the rods of face-sharing FeS6 octahedra. However, due to the defects on the FeII positions, La3Fe2-δS7 shows an activated conducting behavior. - Graphical Abstract: Rods of face-sharing [FeIIS6]-octahedra and [FeIIIS4]-tetrahedra, all pointing in the same direction, dominate the polar structure. Vacancies in the octahedral Fe positions downgrade one-dimensional metallic conductivity to an activated semi-conducting behavior.

  5. Carrier mobility of iron oxide nanoparticles supported on ferroelectrics studied by Moessbauer spectroscopy

    Okamoto, T., E-mail: TAKUMI_OKAMOTO@denso.co.jp [DENSO Corporation (Japan); Kano, J. [Okayama University, Graduate School of Natural Science and Technology (Japan); Nakamura, S. [Teikyo University, Department of Science and Engineering (Japan); Fuwa, A. [Waseda University, Faculty of Science and Engineering (Japan); Otoyama, T.; Nakazaki, Y. [Nano Cube Japan Co., Ltd. (Japan); Hashimoto, H.; Takada, J. [Okayama University, Graduate School of Natural Science and Technology (Japan); Ito, M. [DENSO Corporation (Japan); Ikeda, N. [Okayama University, Graduate School of Natural Science and Technology (Japan)

    2013-04-15

    {sup 57}Fe Moessbauer spectroscopy was performed on two types of Fe oxide nanoparticles supported on a typical ferroelectric, BaTiO3. It was found that the valence state of FeO nanoparticles changed to a mixed 2+/3+ state at high temperature where BaTiO{sub 3} shows paraelectric behaviour. We attribute this phenomenon to the fluctuation of electric dipoles which realizes carrier injection into the Fe oxides. This is the first report which discusses a dynamical valence state of transition metal oxides supported on ferroelectrics.

  6. Investigations of sulfide minerals with layered structure by Moessbauer spectroscopy methods

    Samples obtained as a result of the tochilinite synthesis process were investigated by 57Fe Moessbauer spectroscopy. Tochilinite, magnetite and troilite were obtained in investigated samples. The dependences of phase relative content on different content of Mg atoms in the initial mixture were received. It was found that Mg atoms stabilized tochilinite structure. It was shown that magnesium atom entering into tochilinite structure led to Fe atom redistribution in brucite-like layer. It was confirmed that in tochilinite structure equal number of sulfide and brucite-like layers conjugated.

  7. Tracking pyritic sulfur during the microwave-chemical desulfurization of coal using Moessbauer spectroscopy

    The transformations of pyrite in coal during the microwave-chemical treatment for desulfurization of coal were studied with Moessbauer spectroscopy of 57Fe. The results for phase analyses show that the selective dielectric heating by microwave energy can give rise to the thermal decomposition of pyrite FeS2 in coal to new phases, pyrrhotite Fe1-xS (0< x≤0.125) and troilite FeS which can be dissolved in dilute HCl solution. Therefore the microwave irradiation combined with pickling treatment will be an effective method of desulfurization of coal

  8. Metallosupramolecular coordination polyelectrolytes investigated by Moessbauer spectroscopy

    Metallosupramolecular coordination polyelectrolytes (MEPEs) based on rigid and flexible ditopic bis-terpyridine ligands and Fe(II) ions are investigated by Moessbauer spectroscopy. We demonstrate the influence of mechanical stress induced by grinding on the structure of MEPE as well as the ability of MEPE to self-repair through recrystallisation.

  9. Moessbauer spectroscopy study of a natural zeolite

    With the help of Moessbauer spectroscopy, it was established that iron in natural zeolites occupies positions in the aluminosilicate structure in place of aluminium; the positions of iron are octahedricals, and the valency is 3+; it was shown too, that the zeolite is geometrically stable to acid treatment, notwithstanding the formation of vacancies during acid treatments. (author)

  10. Spherical electrostatic electron spectrometer for Moessbauer spectroscopy

    Benczer-Koller, N.; Kolk, B.

    1977-01-01

    A high transmission spherical electrostatic electron spectrometer was constructed for combined Moessbauer and conversion electron spectroscopies. To date, a transmission of 7% and an energy resolution of 2.5% at 14 keV were achieved for a source of 1 cm diameter.

  11. Moessbauer spectroscopy in kaolin iron study

    In kaolin iron can be found in two distinct ways: First in solid solution replacing another element in the Kaolin structure. Second as oxides or oxide-hydroxide. The use of Moessbauer Spectroscopy allows to identify in which way iron is present and quantify its content in Kaolin. In this work Kaolin samples of two different sources were studied using this technique. (author)

  12. Moessbauer spectroscopy - applications of the Doppler principle

    Moessbauer spectroscopy is an experimental method based on the application of the Doppler principle in the velocity modulation system for variation of γ-ray energy. The object of observations is a resonating nucleus. From Moessbauer spectra one can gain information on the electronic and magnetic environment (based on hyperfine interactions) and on the vibrational states of atoms (based on the Debey-Waller factor). It is a typical microscopic method which has found applications in all disciplines of natural sciences as well as in medicine, art, archaeology and materials science. (author) 5 figs., 37 refs

  13. Surface analysis of mixed-conducting ferrite membranes by the conversion-electron Moessbauer spectroscopy

    Conversion-electron Moessbauer spectroscopy analysis of iron surface states in the dense ceramic membranes made of 57Fe-enriched SrFe0.7Al0.3O3-δ perovskite, shows no traces of reductive decomposition or carbide formation in the interfacial layers after operation under air/CH4 gradient at 1173 K, within the limits of experimental uncertainty. The predominant trivalent state of iron cations at the membrane permeate-side surface exposed to flowing dry methane provides evidence of the kinetic stabilization mechanism, which is only possible due to slow oxygen-exchange kinetics and enables long-term operation of the ferrite-based ceramic reactors for natural gas conversion. At the membrane feed-side surface exposed to air, the fractions of Fe4+ and Fe3+ are close to those in the powder equilibrated at atmospheric oxygen pressure, suggesting that the exchange limitations to oxygen transport are essentially localized at the partially reduced surface. - Graphical Abstract: Conversion-electron Moessbauer spectroscopy analysis of dense ceramic membranes made of 57Fe-enriched SrFe0.7Al0.3O3-δ perovskite, shows no reductive decomposition in thin interfacial layers after testing under air/CH4 gradient, enabling stable operation of the ferrite-based ceramic reactors for partial oxidation of methane. Highlights: → Conversion-electron Moessbauer spectroscopy is used for mixed-conducting membranes. → No decomposition is detected in the membrane surface layers under air/CH4 gradient. → Due to kinetic stabilization, Fe3+ states prevail at the surface exposed to methane. → Transmission Moessbauer spectra show perovskite decomposition on equlibration in CH4. → Ferrite-based ceramic reactors can stably operate under air/CH4 gradient.

  14. In situ characterisation of supported iron-iridium catalysts by iron-57 and iridium-193 Moessbauer spectroscopy

    Some silica-supported iron-iridium catalysts with different iron to iridium ratios and formed by the incipient wetness technique have been examined in situ by 57Fe and 193Ir Moessbauer spectroscopy following pretreatment in hydrogen. The results show that the reduction of the iron component is enhanced by the presence of iridium metal. The pretreated catalysts were evaluated for the hydrogenation of carbon monoxide at 2700C and 50 atmospheres pressure. The presence of iridium, which was shown by Moessbauer spectroscopy to result in the formation of reduced iron, iridium, and iron iridium alloy in the pretreated catalyst, was found to increase the catalytic activity and also influence selectivity. However, the systematic variation of the iridium content which was shown by Moessbauer spectroscopy to determine the exact phase composition of the pretreated catalysts, appeared to have little effect on catalytic performance. The 57Fe Moessbauer spectra recorded from all the used catalysts showed the formation of large and small particle ε'-Fe2.2C under the high pressure of the catalytic reaction. The results suggest that the formation of iron carbides on reduced iron, perhaps at the surface, and the adsorption of hydrogen on reduced iridium are important features of this catalytic system. (orig.)

  15. Transient Moessbauer spectroscopy: line shapes

    Transient effects in Moessbauer measurements when the recoilless gamma radiation is rapidly modulated, e.g., with the aid of mechanical motion is described. As in conventional experiments, the intensity transmitted through a resonance absorber is measured as a function of time, synchronized to the phase of the source motion. However, with fast modulation the intensity at time t depends on the history of Doppler velocity and the modulation is simplest to treat as phase modulation using a classical field description for the recoilless radiation. 5 refs., 3 figs. (L.I.)

  16. Characterization of Maghsail meteorite from Oman by Moessbauer spectroscopy, X-ray diffraction and petrographic microscopy

    The meteorite found at Maghsail (16 55 70 N-53 46 69 E) west of Salalah Oman, has been studied by 57Fe Moessbauer spectroscopy, X-diffractometry and petrographic microscopy. In the polished section the meteorite exhibits a porphyritic texture consisting of pyroxene and olivine phenocrysts in a fine to medium grained ground mass in addition to minor phases possibly skeletal chromite, troilite and minute amount of iron oxides. X-ray diffraction supports the existence of these compounds. The Moessbauer spectra of powdered material from the core of the rock at 298 K and 78 K exhibit a mixture of magnetic and paramagnetic components. The paramagnetic components are assigned to the silicate minerals olivine and pyroxene. On the other hand, the magnetic spectra reveal the presence of troilite and iron oxides. The petrographic analyses indicate that the iron oxides are terrestrial alteration products.

  17. Characterization of Maghsail meteorite from Oman by Moessbauer spectroscopy, X-ray diffraction and petrographic microscopy

    Al-Rawas, A. D., E-mail: arawas@squ.edu.om; Gismelseed, A. M. [College of Science, SQU, Department of Physics (Oman); Al-Kathiri, A. F. [Ministry of Commerce and Industry (Oman); Elzain, M. E.; Yousif, A. A. [College of Science, SQU, Department of Physics (Oman); Al-Kathiri, S. B. [Ministry of Commerce and Industry (Oman); Widatallah, H. M. [College of Science, SQU, Department of Physics (Oman); Abdalla, S. B. [College of Science, SQU, Department of Earth Sciences (Oman)

    2008-09-15

    The meteorite found at Maghsail (16 55 70 N-53 46 69 E) west of Salalah Oman, has been studied by {sup 57}Fe Moessbauer spectroscopy, X-diffractometry and petrographic microscopy. In the polished section the meteorite exhibits a porphyritic texture consisting of pyroxene and olivine phenocrysts in a fine to medium grained ground mass in addition to minor phases possibly skeletal chromite, troilite and minute amount of iron oxides. X-ray diffraction supports the existence of these compounds. The Moessbauer spectra of powdered material from the core of the rock at 298 K and 78 K exhibit a mixture of magnetic and paramagnetic components. The paramagnetic components are assigned to the silicate minerals olivine and pyroxene. On the other hand, the magnetic spectra reveal the presence of troilite and iron oxides. The petrographic analyses indicate that the iron oxides are terrestrial alteration products.

  18. Moessbauer spectroscopy in neptunium compounds

    Nakamoto, Tadahiro; Nakada, Masami; Masaki, Nobuyuki; Saeki, Masakatsu [Japan Atomic Energy Research Inst., Tokyo (Japan)

    1997-03-01

    Moessbauer effects are observable in seven elements of actinides from {sup 232}Th to {sup 247}Cm and Moesbauer spectra have been investigated mainly with {sup 237}Np and {sup 238}U for the reasons of availability and cost of materials. This report describes the fundamental characteristics of Moessbauer spectra of {sup 237}Np and the correlation between the isomer shift and the coordination number of Np(V) compounds. The isomer shifts of Np(V) compounds had a tendency to increase as an increase of coordination number and the isomer shifts of Np(V) compounds showed broad distribution as well as those of Np(VI) but {delta} values of the compounds with the same coordination number were distributed in a narrow range. The {delta} values of Np(VI) complexes with O{sub x} donor set suggest that the Np atom in its hydroxide (NpO{sub 2}(OH){center_dot}4H{sub 2}O)might have pentagonal bipyramidal structure and at least, pentagonal and hexagonal bipyramidal structures might coexist in its acetate and benzoate. Really, such coexistence has been demonstrated in its nitrate, (NpO{sub 2}){sub 2}(NO{sub 3}){sub 2}{center_dot}5H{sub 2}O. (M.N.)

  19. Moessbauer spectroscopy of laminar metallic systems

    Full text: Methods of ion and ion-plasma material modification are widely used to improve surface physicochemical properties of metal materials. For practical application of obtained with such methods laminar metal systems there should be formed a thermally stable non-uniform structure-phase depth distribution. In this connection there arises the need in systematic investigations of diffusion and phase formation processes in modified layers. Laminar metal systems belong to so-called locally inhomogeneous systems (LIS). LIS are characterized by change of environment and properties of same atoms from position to position. LIS are convenient model objects for investigations of material property inter-relations with its local characteristics, kinetics of diffusion processes, phase formation, crystallization and atomic ordering. Introducing direct changes into the character and rate of local inhomogeneity one can influence a wide range of useful physical and chemical properties. Moessbauer spectroscopy is one of the most effective methods for LIS investigations. Local character of obtained information combined with information on cooperative phenomena makes possible realization of investigations unfeasible with other methods. Moessbauer spectroscopy provides vast information on peculiarities of macro- and micro- states of matter even for substances with no regular structure. The paper describes methods for obtaining information from LIS Moessbauer spectra. Notion of local inhomogeneity applied to Moessbauer spectroscopy is made more accurate; possible reasons for its formation along with possible formation mechanisms are proposed; such notions as type and power of local inhomogeneity are introduced. The paper also considers methods for processing and analysis of LIS Moessbauer spectra with their classification and opportunities for combined utilization of various methods; role of a priori information at all stages of processing is analyzed. On example of iron

  20. Moessbauer spectroscopy of Fe-based nanomaterials

    There are two opinions concerning the effect of the nanosized grains on magnetic properties and Moessbauer spectra. One of them testifies that nanomaterials have a grain boundary phase (interface region) which decreases the specific saturation magnetization and leads to the additional sextet in the Moessbauer spectrum. The second one treats the changes in spectra by the impurities. In this work the results on a-Fe, Fe90Ge10 and Fe77,5Al22.5 nanocrystalline alloys are presented. The nanostructured (8 nm) powders of Fe, bcc disordered Fe90Ge10 and Fe77,5Al22.5 were produced by mechanical grinding and alloying. The samples were studied by X-ray diffraction, Moessbauer spectroscopy, magnetic measurements and then compared with microstructured ones. With the absence of contamination no changes have been found in the specific saturation magnetization, Curie temperature and hyperfine interaction parameters of the nanomaterials. No additional sextet in the Moessbauer spectra and peculiarities in the temperature dependences of a.c. magnetic susceptibility were found either. We have registered a slight lines broadening (∼ 20%) in Moessbauer spectrum of the nanocrystalline pure Fe. The broadening observed is explained by random in sign and in magnitude anisotropic contribution to the hyperfine magnetic field from the Fe atoms in the interfaces. The conclusion drawn is that the interface of the nanostructure (boundary and close-to-boundary distorted zones) of 1 nm width considerably have the same magnetic properties and hyperfine interaction parameters in comparison with those in the bulk.

  1. Moessbauer spectroscopy of locally inhomogeneous systems

    Substances with characteristic local inhomogeneities - with different from position to position neighborhood and properties of like atoms - gain recently increased scientific attention and wide practical application. We would call a system locally inhomogeneous if atoms in the system are in non-equivalent atomic locations and reveal different properties. Such systems are, first of all, variable composition phases, amorphous, multi-phase, admixture, defect and other systems. LIS are most convenient model objects for studies of structure, charge, and spin atomic states, interatomic interactions, relations between matter properties and its local characteristics as well as for studies of diffusion kinetics, phase formation, crystallization and atomic ordering; all that explains considerable scientific interest in such LIS. Such systems find their practical application due to wide spectrum of useful, and sometimes unique, properties that can be controlled varying character and degree of local inhomogeneity. Moessbauer spectroscopy is one of the most effective methods for investigation of LIS. Local character of obtained information combined with information on cooperative phenomena makes it possible to run investigations impossible for other methods. Moessbauer spectroscopy may provide with abundant information on peculiarities of macro- and microscopic state of matter including that for materials without regular structure. At the same time, analysis, processing and interpretation of Moessbauer spectra for LIS (that are sets of a large amount of partial spectra) face considerable difficulties. Development of computer technique is accompanied with development of mathematical methods used for obtaining physical information from experimental data. The methods make it possible to improve considerably, with some available a priori information, effectiveness of the research. Utilization of up-to-date mathematical methods in Moessbauer spectroscopy requires not only adaptation

  2. 57Fe Moessbauer Study of Localization and Valence Sate of Iron Ions in Granular Nanocomposites (FeCoZr)x(Al2O3)100-x for Spintronic Applications

    The influence of composition of the composite films, containing distributed fragmented components of amorphous metallic alloy CoFeZr and amorphous alumina with particles dimensions of 6-10 nm, on the Moessbauer spectra and hyperfine parameters was investigated. Moessbauer spectroscopy of the (Co0.45Fe0.45Zr0.10)X(Al2O3)1-X studied films with 30 at. % 55 %, and lack of the ferromagnetic state in the metallic nanoparticles

  3. Moessbauer spectroscopy as a tool in astrobiology

    Two miniaturized Moessbauer spectrometers are part of the Athena instrument package of the NASA Mars Exploration Rovers, Spirit and Opportunity. The primary objectives of their science investigation are to explore two sites on the surface of Mars where water may once have been present, and to assess past environmental conditions at those sites and their suitability for life. Aqueous minerals - jarosite at Meridiani Planum, Opportunity's landing site, and goethite in the Columbia Hills in Gusev Crater, Spirit's landing site - were identified by Moessbauer spectroscopy, thus providing in situ proof of water being present at those sites in the past. The formation of jarosite in particular puts strong constraints on environmental conditions during the time of formation and hence on the evaluation of potential habitability. On Earth Moessbauer spectroscopy was used to investigate microbially induced changes in Fe oxidation states and mineralogy at the Loihi deep sea mount, a hydrothermal vent system, which might serve as an analogue for potential habitats in the Martian subsurface and the sub-ice ocean of Jupiter's icy moon Europa.

  4. Trace cobalt speciation in bacteria and at enzymic active sites using emission Moessbauer spectroscopy

    Kamnev, A.A.; Antonyuk, L.P.; Smirnova, V.E.; Serebrennikova, O.B. [Laboratory of Biochemistry, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, Saratov (Russian Federation); Kulikov, L.A.; Perfiliev, Yu.D. [Laboratory of Nuclear Chemistry Techniques, Department of Radiochemistry, Faculty of Chemistry, Moscow State University (Russian Federation)

    2002-02-01

    {sup 57}Co emission Moessbauer spectroscopy (EMS) allows the chemical state of cobalt, as influenced by its coordination environment, to be monitored in biological samples at its physiological (trace) concentrations. To draw attention to EMS as a valuable tool for speciation of cobalt in biocomplexes, the process of cobalt(II) metabolism in cells of the plant growth-promoting rhizobacterium Azospirillum brasilense Sp245 was investigated using EMS of {sup 57}Co{sup II}-doped bacterial cells. EMS measurements also showed {sup 57}Co{sup II}-activated glutamine synthetase (GS, a key enzyme of nitrogen metabolism, isolated from this bacterium) to have two different cobalt(II) forms at its active sites, in agreement with data available on other bacterial GSs. Chemical after-effects following electron capture by the nucleus of the parent {sup 57}Co{sup II} during the {sup 57}Co{yields}{sup 57}Fe transition, which contribute to the formation of a stabilised daughter {sup 57}Fe{sup III} component along with the nucleogenic {sup 57}Fe{sup II} forms, are also briefly considered. (orig.)

  5. Iron oxides characterization by Moessbauer spectroscopy

    In this work rust development on low carbon wire surface after the conformation process at different temperatures was studied by Moessbauer spectroscopy. The characterization was made by determining the following spectral parameters; 1) Quadrupole splitting, 2) Isomer shift, and 3) Magnetic splitting. The area quantification determined the percentage amount of three different iron oxides. These iron oxides were: a) Wustite (Fe O), b) Hematite (Fe2O3), and c) Magnetite (Fe3O4) which were present in the rust studied. With the results it was possible to establish the best temperature to favor the development of each of these iron oxides. (Author)

  6. Implementation of the Electron conversion Moessbauer spectroscopy

    In the present work has been exposed the principles of the Conversion Moessbauer Electron Spectroscopy and its possibilities of application. Is also described the operation of the parallel plate avalanche detector made at the CEADEN starting from modifications done to the Gancedo's model and is exposed examples of the use of this detector in the characterization of corroded surfaces, with chemical cleaning and in samples of welded joints. The experiences obtained of this work were extended to the National Polytechnic Institute of Mexico where a similar detector, made in our center, was installed there

  7. Superparamagnetic properties of γ-Fe2O3 particles: Moessbauer spectroscopy and DC magnetic measurements

    When studying magnetic systems consisting of particles with sizes in the nanometer range, the principal problems is the nature of their magnetic state. At low temperatures they are typically micro-magnetic or spin-glass like and with increasing temperature they gradually go over to the superparamagnetic state. It is necessary to realize, however, that the temperature of transition to superparamagnetism strongly depends on the relevant time window which amounts to ∼10-7 s for Moessbauer spectroscopy of 57Fe and units of seconds for d.c. magnetic measurements. The particles in our powder samples of Fe oxide were shown by SEM to have sizes in the range of 10 nm. Their Moessbauer spectra (MS) were acquired in a Janis cryo-system in the temperature range 120-295 K. In contrast to XRD, where the phase composition could not be unambiguously resolved, MS at 120 K clearly indicated the absence of magnetite and presence of the maghemite phase. The magnetization curves were measured in the same temperature region in fields up to 5 T. In addition the temperature dependences of magnetic moments of Zero-Field-Cooled and Field-Cooled samples for various probe fields were analyzed. The derived distributions of blocking temperatures will be compared with our results from Moessbauer spectroscopy. (authors)

  8. 197Au Moessbauer study of gold ores, mattes, roaster products, and gold minerals

    The chemical state of gold in gold ores, mattes and roaster products has been studied by 197Au Moessbauer spectroscopy. Gold minerals were studied in order to provide reference data for the ore spectra. 57Fe Moessbauer spectroscopy was used to monitor the iron-compounds always present in gold ores and to follow their transformations caused by smelting and roasting. (orig.)

  9. Hyperfine structure of {sup 57}Fe in minerals from a manganese ore deposit

    Nascimento, C. K., E-mail: cassiuskn@yahoo.com.br [Universidade Federal de Minas Gerais, Departamento de Quimica (Brazil); Pereira, M. C. [Universidade Federal dos Vales do Jequitinhonha e Mucuri, Instituto de Ciencia e Tecnologia (Brazil); Cavalcante, L. C. D.; Lana, A. M.; Murad, E.; Braga, J. P. [Universidade Federal de Minas Gerais, Departamento de Quimica (Brazil); Fabris, J. D. [Universidade Federal dos Vales do Jequitinhonha e Mucuri, UFVJM (Brazil)

    2011-11-15

    Investigations based on {sup 57}Fe Moessbauer spectroscopy and powder X-ray diffraction report the existence of siderite in a manganese ore deposit in the city of Conselheiro Lafaiete, Minas Gerais, Brazil. Moessbauer parameters at 110 K indicated the isomorphous substitution of Fe{sup 2 + } in siderite structure by other cations such as Ca{sup 2 + } and Mg{sup 2 + }, resulting in the distortion of siderite structure. The proposed mechanism suggests the formation of siderite and it is consistent with the process of carbonate formation in reducing environments.

  10. Moessbauer investigations of itmid

    A sample of itmid available commercially was obtained and investigated using57 Fe Moessbauer spectroscopy, atomic absorption, X-ray fluorescence. The Moessbauer spectra showed the presence hematite (alpha-Fe2 O3), goethite (alpha-FeOOH), and a third phase which has a six-line spectrum with the following parameters : Isomer shift (gamma= 0.52 mm/s), magnetic field (H=290 kOe). After conducting a series of reduction and calcination to the itmid sample and with the aid of atomic absorption and X-ray fluorescence results the third phase was identified as the iron sulfide compound FeS. 3 figs., 3 tabs

  11. Moessbauer spectroscopy on the surface of mars. Why?

    A Moessbauer spectrometer is included in the preliminary payload of a rover to be placed on the surface of Mars in the Soviet to the planet in 1996. In connection with the American planetary program it has also been suggested to construct a Moessbauer spectrometer to be landed on Mars. The objective is to study the iron compounds of the Martian soil and rocks by backscattering Moessbauer spectroscopy. The paper describes the significance of the element iron in the study of the evolution of the planetary system and what we might expect to learn from Moessbauer spectroscopy of the surface materials of Mars. The study of Mars is expected to expand substantially in the coming decades, probably culminating with a manned flight to the planet. The international Moessbauer community may contribute significantly to the preparation of these events. (orig.)

  12. Moessbauer spectroscopy of metals from birth to death

    In today's metallurgy, precision techniques, such as X-ray and electron diffraction, electron microscopy, infrared spectroscopy and electron probe micro-analyzer, are being indispensably used, and, comparing to them, Moessbauer spectroscopy is not inferior at all in usefulness, convenience and cost benefit. Actually, however, it is not yet popular among the metallurgists probably because people believe that the Moessbauer effect is a difficult physics, radioactive sources are difficult to handle, and spectral analyses are complicated. These beliefs are in fact groundless and must be dissolved for further diffusion of this useful Moessbauer technique in metals and other industries.The present introductory talk intends to help people's better understanding and no anxiety for using the Moessbauer spectroscopy by showing how it can be applied to various problems of metals and alloys from their birth to the end, that is, from the study of minerals and ores before smelting to that of corrosion and other failures.Firstly, the principle of Moessbauer spectroscopy will be explained with simplest illustrations together with simple pictures of apparatuses including the high temperature furnace and the high pressure cell.In the second will be shown typical examples of Moessbauer patterns of magnetite, carbon steel and other alloys, with indications of how to analyze the seemingly complicated spectra. Some other examples will be shown with special apparatuses easy to measure. The usefulness and convenience of Moessbauer spectroscopy will be understood again from these examples. More examples will be on amorphous alloys and other advanced materials

  13. Moessbauer spectroscopy in studies of photosynthesis

    Photosynthesis is a process occurring in certain species of bacteria, algae and higher plants. It transforms solar energy into various forms of energy-rich organic molecules. Photosystem II (PSII) is the 'heart' of the photosynthetic apparatus because it delivers electrons and protons for further steps of the light-driven phases of photosynthesis. There are two enigmatic iron binding structures within the core of photosynthetic apparatus, which play an important role in the electron transfer within PSII. Many investigations focus on the determination of their function which is the key to the understanding of the molecular mechanism of the energy and electron transfer within PSII. Among many methods used in this research field, the Moessbauer spectroscopy is a unique one, which gives the possibility to study changes of the valence and spin states of those two iron sites and the dynamical properties of their protein matrix in the presence of various physiological and stress conditions.

  14. Seasonal variation of iron speciation in a pearl-raising bay sediment by Moessbauer spectroscopy

    Ago Bay in Mie Prefecture, central Japan, is world-famous for the site of Mikimoto pearl culture, but recently the production of pearls has considerably declined. Environmental deterioration of the bay is suspected of having caused the decline. The periodic investigation into iron speciation of the bay sediment by 57Fe Moessbauer spectroscopy revealed its high pyrite (FeS2) content from the surface to the 20-cm depth. The pyrite in the surface sediment decreased only in spring, three months after the dissolved oxygen in the bottom water was at maximum. Such oxygen-consuming material as pyrite accumulated through long-term biotic activity is a most-likely explanation for the prolonged environmental deterioration of the bay, which appears in the high chemical oxygen demand (COD) of the sediment. (author)

  15. Magnetic properties of RE{sub 10}TCd{sub 3} (RE = Ho, Er, Tm, Lu; T = Fe, Co, Ni, Ru) and {sup 57}Fe Moessbauer spectroscopic data of Y{sub 10}FeCd{sub 3}

    Niehaus, Oliver; Johnscher, Michael; Block, Theresa; Gerke, Birgit; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2016-02-01

    Fourteen X-ray-pure intermetallic compounds RE{sub 10}TCd{sub 3} (RE = Ho, Er, Tm, Lu; T = Fe, Co, Ni, Ru) and Y{sub 10}FeCd{sub 3} were obtained through high-frequency melting of the elements in sealed niobium tubes and subsequent annealing in a muffle furnace. They adopt the Er{sub 10}FeCd{sub 3} structure, a ternary ordered version of the Co{sub 2}Al{sub 5} type. Temperature-dependent magnetic susceptibility measurements show Pauli paramagnetism for the lutetium compounds Lu{sub 10}FeCd{sub 3}, Lu{sub 10}CoCd{sub 3}, and Lu{sub 10}RuCd{sub 3}. The RE{sub 10}TCd{sub 3} phases with holmium, erbium, and thulium show Curie-Weiss paramagnetism and the experimental magnetic moments match with the free ion values of RE{sup 3+}. All these compounds order antiferromagnetically. The highest Neel temperature was observed for the holmium compounds, e.g. 46.5 K for Ho{sub 10}RuCd{sub 3}. Some of the RE{sub 10}TCd{sub 3} phases show field-induced spin reorientations. A {sup 57}Fe Moessbauer spectrum of Y{sub 10}FeCd{sub 3} confirms the single crystallographic iron site.

  16. {sup 57}Fe Mössbauer spectroscopy and magnetic study of Al{sub 13}Fe{sub 4}

    Albedah, Mohammed A.; Nejadsattari, Farshad [Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5 (Canada); Stadnik, Zbigniew M., E-mail: stadnik@uottawa.ca [Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5 (Canada); Przewoźnik, Janusz [Solid State Physics Department, Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059 Kraków (Poland)

    2015-01-15

    Highlights: • We show that Mössbauer spectra of Al{sub 13}Fe{sub 4} can be fitted well with three quadrupole doublets. • The shape of the in-field Mössbauer spectrum is well accounted for with five component subspectra. • The electronic density of states has a pseudogap around the Fermi energy. • We find that the Debye temperature of the compound studied is 383(3) K. - Abstract: The results of ab initio electronic structure and electric field gradient (EFG) calculations, and of X-ray diffraction, {sup 57}Fe Mössbauer spectroscopy, and magnetic studies of Al{sub 13}Fe{sub 4} are reported. It is shown that Al{sub 13}Fe{sub 4} crystallizes in the monoclinic space group C2/m, in which Fe atoms are located at five inequivalent crystallographic sites, with the lattice parameters a=15.503(2) Å, b=8.063(2) Å, c=12.464(2) Å, and β=107.71(2)°. We demonstrate that zero-field Mössbauer spectra can be decomposed into three quadrupole doublets. With the aid of the calculated EFG parameters we show that the first doublet results from one Fe site, the second doublet is due to two other Fe sites, and the third doublet originates from the last two Fe sites. We find that the shape of the Mössbauer spectrum of Al{sub 13}Fe{sub 4} measured in an external magnetic field of 90 kOe can be accounted for with five component subspectra generated using the calculated EFG parameters at five inequivalent Fe sites. The quadrupole splittings corresponding to three component doublets are shown to increase with decreasing temperature and are well described by a T{sup 3/2} power-law relation. The Debye temperature of Al{sub 13}Fe{sub 4} is found to be 383(3) K. We find a pseudogap in the density of states (DOS), with a width of ∼0.2 eV, that is centered 0.1 eV above the Fermi energy. The finite DOS at the Fermi energy confirms good metallicity of Al{sub 13}Fe{sub 4}. The 1/T-like dependence of the magnetic susceptibility shows that Al{sub 13}Fe{sub 4} is a paramagnet.

  17. Moessbauer study of some Argentinian chlorites

    Three chlorite samples obtained from mining areas in Mendoza, Argentina, have been studied by wet chemical analysis, X-ray diffraction and 57Fe Moessbauer spectroscopy. The total Fe contents and the Fe2+/Fe3+ atomic ratio are used to characterize the samples and are discussed in connection to the likely genesis of the minerals. (orig.)

  18. Moessbauer study of some Argentinian chlorites

    Gregori, D.A. (Dept. de Geologia, Univ. Nacional del Sur, Bahia Blanca (Argentina)); Mercader, R.C. (Dept. de Fisica, Univ. Nacional de La Plata, La Plata (Argentina))

    1994-02-01

    Three chlorite samples obtained from mining areas in Mendoza, Argentina, have been studied by wet chemical analysis, X-ray diffraction and [sup 57]Fe Moessbauer spectroscopy. The total Fe contents and the Fe[sup 2+]/Fe[sup 3+] atomic ratio are used to characterize the samples and are discussed in connection to the likely genesis of the minerals. (orig.)

  19. Multiwire proportional chamber for Moessbauer spectroscopy: development and results

    A new Multiwere proportional Chamber designed for Moessbauer Spectroscopy is presented. This detector allows transmission backscattering experiments using either photons or electrons. The Moessbauer data acquisition system, partially developed for this work is described. A simple method for determining the frontier between true proportional and semi-proportional regions of operation in gaseous detectors is proposed. The study of the tertiary gas mixture He-Ar-CH4 leads to a straight forward way of energy calibration of the electron spectra. Moessbauer spectra using Fe-57 source are presented. In particular those obtained with backsattered electrons show the feasibility of depth selective analysis with gaseous proportional counters. (author)

  20. Application of 61Ni Moessbauer spectroscopy to chemical problems

    Using the possibility to produce 61Co sources at the MAinz Microtron, 61Ni Moessbauer spectroscopy was applied to different kinds of chemical problems. Measurements of isomer shifts and Vzz values in some common compounds and compounds with unusual chemical bonding for comparison with band structure calculations, measurement of 61Ni Moessbauer parameters in model compounds for hydrogenase and dehydrogenase with an active [NiS4] centre, and study of novel binary NiF3 compounds at helium temperature are presented

  1. Development of a highly efficient conversion electron Moessbauer spectroscopy (CEMS) detector for low temperature (xPb1-x)Te bilayers

    The 57Fe Moessbauer spectroscopy is a nuclear, non-destructive technique used for the investigation of structural, magnetic and hyperfine properties of several materials. It is a powerful tool in characterizing materials in physics, metallurgy, geology and biology field areas, especially magnetic materials, alloys and minerals containing Fe. Lately, the Conversion Electron Moessbauer Spectroscopy (CEMS) is widely used in making studies on ultra-thin magnetic films, as well as other nanostructured materials. In case of magnetic nanostructures, low temperature (LT) studies are especially important due to the possibility of dealing with superparamagnetic effects. In this work it was developed a CEMS measurement system for low temperatures (R) and an optical cryostat (Model SVT-400, Janis Research Co, USA), from which the project was originally conceived at the Applied Physics / Moessbauer spectroscopy Department from University of Duisburg-Essen, Germany. The LT-CEMS system was fully built, tested and successfully applied in a preliminary characterization of Fe/(EuxPb1-x)Te(111) bilayers with use of a 15 angstrom, 57 Fe probe layer, with reasonable results at sample temperatures as low as 8 K. (author)

  2. Application of Moessbauer Spectroscopy to the Study of Corrosion

    Corrosion research, and the need to fully understand the effects that environmental conditions have on the performance of structural steels, is one area in which Moessbauer spectroscopy has become a required analytical technique. This is in part due to the need to identify and quantify the nanophase iron oxides that form on and protect certain structural steels, and that are nearly transparent to most other spectroscopic techniques. A review is given of the most recent Moessbauer characterization of rusts that have formed on structural steels exposed to different environments. Moessbauer spectroscopy is playing an important role in a new corrosion program in the United States in which steel bridges, old and new, are being evaluated for corrosion problems that may reduce their serviceable lifetimes. Moessbauer spectroscopy has been used to characterize the corrosion products that form the protective patina on weathering steel, as well those that form in adverse environments in which the oxide coating is not adherent or protective to the steel. Moessbauer spectroscopy has also become an important analytical technique for investigating the corrosion products that have formed on archeological artifacts, and it is providing guidance to aid in the removal of the oxides necessary for their preservation.

  3. Chemical aspects of 237 Np Moessbauer spectroscopy

    The 237Np Moessbauer effect has been especially useful in studies of neptunium chemistry, by virtue of its excellent resolution and straightforward experimental techniques. Neptunium can have valences from +3 to +7, and a broad range of compounds can be prepared that are analogous to those of other actinide elements. Studies on neptunium compounds, for example, have a ready application to the analogous compounds of uranium and plutonium. The emphasis in this paper will be on the application of the 237Np Moessbauer effect to problems in neptunium chemistry

  4. Atomic short-range order in mechanically synthesized iron based Fe-Zn alloys studied by 57Fe Mössbauer spectroscopy

    Konieczny Robert

    2015-03-01

    Full Text Available Mechanical alloying method was applied to prepare nanocrystalline iron-based Fe1−xZnx solid solutions with x in the range 0.01 ≤ x ≤ 0.05. The structural properties of the materials were investigated with the Mössbauer spectroscopy by measuring the room temperature spectra of 57Fe for as-obtained and annealed samples. The spectra were analyzed in terms of parameters of their components related to unlike surroundings of the iron probes, determined by different numbers of zinc atoms existing in the neighborhood of iron atoms. The obtained results gave clear evidence that after annealing process, the distribution of impurity atoms in the first coordination spheres of 57Fe nuclei is not random and it cannot be described by binomial distribution. The estimated, positive values of the short-range order parameters suggest clustering tendencies of Zn atoms in the Fe-Zn alloys with low zinc concentration. The results were compared with corresponding data derived from Calphad calculation and resulting from the cellular atomic model of alloys by Miedema.

  5. Determination of electric field, gradient tensor parameters of copper sites in Bi2Sr2CaCu2O8 and YBaCu3O7 by Moessbauer spectroscopy

    By the method of the Moessbauer emission spectroscopy using 67Cu(67Zn) isotope parameters of electric field gradient tensor for the centers 67Zn2+ in lattices of high Tc superconductors YBa2Cu3O7 and Bi2Sr2CaCu2O8 are determined. Qualitative agreement between the calculated and experimentally obtained values of main component of electric field gradient tensor. Using the data obtained, analyses of the Moessbauer study results for the above-mentioned ceramics on 57Fe impurity atoms is carried out

  6. Study of low energy Ar+ ion irradiated 57Fe/Pt multilayers

    This paper reports a study on the effects of Ar+ ion irradiation in 57Fe/Pt multilayers having the structure Si (substrate)/[57Fe(19 A)/Pt(25 A)]x10. The as-deposited multilayers were irradiated with 90 keV Ar+ ions at a fluence of 2 x 1016 ions cm-2 at different temperatures. X-ray reflectivity, x-ray diffraction and conversion electron Moessbauer spectroscopy were used for the characterization of the irradiated samples. Using x-ray reflectivity it was observed that irradiation results in mixing across the interfaces and deterioration of the multilayer structure. The mixing results in the formation of fcc FePt phase and no L10 ordering is observed in the samples. The results are discussed in terms of recoil displacements induced, energy transfers from ions supporting the observations of Bernas et al, using kinetic Monto Carlo simulations

  7. Charge distribution in neptunium compounds calculated from moessbauer spectroscopy data

    Calculations of the 5f-orbitals population density in the neptunium compounds are carried out on the basis of experimental data, obtained by the Moessbauer spectroscopy method. Charge distribution in compounds Np(3), Np(4), Np(5), Np(6) and Np(7) is presented. Approach to studying the correlation between the δ indices and orbital population densities is proposed

  8. Moessbauer Spectroscopy of Iron Containing Vitamins and Dietary Supplements

    Moessbauer spectroscopy was used to study various industrial samples of vitamins containing ferrous fumarate and ferrous bisglycinate chelate (Ferrochel) and dietary supplements containing ferrous sulfate. The presence of small quantities of various ferric impurities was found. Two vitamins contained major iron compounds that did not correspond to ferrous fumarate and ferrous bisglycinate chelate.

  9. Italian money tested for forgery by moessbauer spectroscopy

    Italian money has been investigated by Moessbauer spectroscopy. The results indicated that the spectrum of a 10000 lire bank-note consisted of three magnetic sextets and two quadrupole doublets, the spectrum of a 5000 lire note consisted of two Zeeman sextets, but in the 'false' money there are two quadrupole doublets only

  10. Investigations of the hyperfine interactions in copper-oxide perovskites using (151)Eu and (57)Fe moessbauer spectroscopy. Doctoral thesis

    Linden, J.

    1994-12-31

    In 1986, superconductivity was discovered in a perovskite-type material at an unprecedentedly high temperature. As no satisfactory theory describing high-Tc superconductivity has been developed and since not all the perovskite phases exhibiting superconducting properties have been explored, the field is still the focus of active research. This work strives to promote the basic understanding of the high-Tc superconducting materials. It is suggested that the results obtained here are part of those boundary conditions that any successful theory of high-Tc superconductivity must take into account. This overview begins with a survey of the various phases studied in the work, followed by the theory behind the methods used to characterize the materials. Finally the experimental conditions and the results are presented.

  11. Thermal decomposition and reconstruction of CaFe-layered double hydroxide studied by X-ray diffractometry and 57Fe Mössbauer spectroscopy

    Bugris, Valéria; Ádok-Sipiczki, Mónika; Anitics, Tamás; Kuzmann, Ernő; Homonnay, Zoltán; Kukovecz, Ákos; Kónya, Zoltán; Sipos, Pál; Pálinkó, István

    2015-06-01

    In spite of numerous investigations on the various processes of the thermal decomposition and rehydration of layered double hydroxides (LDHs) by a variety sophisticated experimental means, many details are still unexplored and some contradictions are still unresolved. In this work, our efforts were focussed on clarifying the composition, structure and properties of thermally decomposed metaphases originating from CaFe-LDH, heat treated in the 373-973 K temperature range. The structure reconstruction ability of mixed metal oxide phases obtained after heat treatments was also investigated, mainly concentrating on the changes in the microenvironment of Fe(III), in the presence of controlled amount of water vapour (i.e., at different relative humidities). All samples were characterised by X-ray diffractometry, and the iron-containing phases were studied by 57Fe Mössbauer spectroscopy.

  12. Anelastic Relaxation Mechanisms Characterization by Moessbauer Spectroscopy

    Soberon Mobarak, Martin Jesus, E-mail: msoberon@sep.gob.mx [Secretaria de Educacion Publica (Mexico)

    2005-02-15

    Anelastic behavior of crystalline solids is generated by several microstructural processes. Its experimental study yields valuable information about materials, namely: modulus, dissipation mechanisms and activation enthalpies. However, conventional techniques to evaluate it are complicated, expensive, time consuming and not easily replicated. As a new approach, in this work a Moessbauer spectrum of an iron specimen is obtained with the specimen at repose being its parameters the 'base parameters'. After that, the same specimen is subjected to an alternated stress-relaxation cycle at frequency {omega}{sub 1} and a new Moessbauer spectrum is obtained under this excited condition; doing the same at several increasing frequencies {omega}{sub n} in order to scan a wide frequencies spectrum. The differences between the Moessbauer parameters obtained at each excitation frequency and the base parameters are plotted against frequency, yielding an 'anelastic spectrum' that reveals the different dissipation mechanisms involved, its characteristic frequency and activation energy. Results are in good agreement with the obtained with other techniques

  13. Emission Moessbauer spectroscopy of NiTi shape memory alloy

    The emission Moessbauer study on NiTi SMA (Shape Memory Alloy) is first reported. The 51.6 at% Ni-Ti alloy was provided by Shanghai Institute of steel and Iron Research. The emitter (also samples in this experiment) was produced by the nuclear reaction 58Ni(p,2p) 57Co in which a small amount of 58Ni was transformed to 57Co. The emitter Moessbauer spectra were measured after the sample was water quenched from 700 degree C for 30 min and aged at 500 degree C for 60 min and isochronal annealed in different temperature. Meantime the TEM observation and resistivity measure were also performed for the same material in the same heat treatment conditions. This work indicates that emission Moessbauer spectroscopy can be used to study the micro-mechanism of NiTi SMA

  14. Characterisation by Moessbauer Spectroscopy of the Forms of Iron in Sulfide-Rich Fulvic Acid Solutions

    Variations in the nature of the bonding between iron and fulvic acid as a function of pH in sulfide-rich solutions have been investigated by 57Fe Moessbauer spectroscopy. In all solutions iron was enriched to 95% in the 57Fe isotope and ratios of Fe : fulvic acid were maintained at 1 : 100 on a weight basis for all measurements. When the pH was decreased below 5.0, there was a progressive change in the composition of the spectra, which contained three distinct components that were similar to those seen in the absence of sulfide; i.e., a sextet from magnetically-dilute Fe(III) and doublets from Fe(II) and Fe(III). There was, however, a higher proportion of the iron as Fe(II) in the sulfide-containing solutions and this represented the only form of iron at very low pH. Establishment of equilibria was slow as evidenced by considerable hysteresis between the compositions of the solutions with decreasing and increasing pHs. On increasing the pH, sulfide prevented the formation of magnetically dilute Fe(III) species and instead, in the range 3.5-6.0, compounds were generated with parameters consistent with sulfur being coordinated to the iron. One had parameters similar to those of pyrite and hence probably contains disulfide (S22-) units, whilst a second, with poorly defined magnetic hyperfine splitting, may contain monosulfide (S2-) units, with structures related to either pyrrhotite (Fe1-xS) or greigite (Fe3S4). A third component probably corresponds to a mononuclear low spin Fe(II) complex, involving sulfur and fulvic acid in the iron coordination sphere. These species were oxygen-sensitive and decomposed to yield magnetically dilute Fe(III) complexes and Fe(III) oxyhydroxides on aeration of the solutions.

  15. Characterisation by Moessbauer Spectroscopy of the Forms of Iron in Sulfide-Rich Fulvic Acid Solutions

    Goodman, B. A., E-mail: bgoodm@scri.sari.ac.uk [Scottish Crop Research Institute, Invergowrie (United Kingdom); Cheshire, M. V. [Macaulay Land Use Research Institute, Craigiebuckler (United Kingdom)

    2002-09-15

    Variations in the nature of the bonding between iron and fulvic acid as a function of pH in sulfide-rich solutions have been investigated by {sup 57}Fe Moessbauer spectroscopy. In all solutions iron was enriched to 95% in the {sup 57}Fe isotope and ratios of Fe : fulvic acid were maintained at 1 : 100 on a weight basis for all measurements. When the pH was decreased below 5.0, there was a progressive change in the composition of the spectra, which contained three distinct components that were similar to those seen in the absence of sulfide; i.e., a sextet from magnetically-dilute Fe(III) and doublets from Fe(II) and Fe(III). There was, however, a higher proportion of the iron as Fe(II) in the sulfide-containing solutions and this represented the only form of iron at very low pH. Establishment of equilibria was slow as evidenced by considerable hysteresis between the compositions of the solutions with decreasing and increasing pHs. On increasing the pH, sulfide prevented the formation of magnetically dilute Fe(III) species and instead, in the range 3.5-6.0, compounds were generated with parameters consistent with sulfur being coordinated to the iron. One had parameters similar to those of pyrite and hence probably contains disulfide (S{sub 2}{sup 2-}) units, whilst a second, with poorly defined magnetic hyperfine splitting, may contain monosulfide (S{sup 2-}) units, with structures related to either pyrrhotite (Fe{sub 1-x}S) or greigite (Fe{sub 3}S{sub 4}). A third component probably corresponds to a mononuclear low spin Fe(II) complex, involving sulfur and fulvic acid in the iron coordination sphere. These species were oxygen-sensitive and decomposed to yield magnetically dilute Fe(III) complexes and Fe(III) oxyhydroxides on aeration of the solutions.

  16. Characterization of the corrosion products using Moessbauer and Raman Spectroscopy

    A presentation will be given of some of the currently used spectroscopic techniques for analyzing corroded steel structures. Moessbauer spectroscopic and Micro-Raman spectroscopic are two important analytical techniques for investigating the corrosion coatings which form on steels exposed in a diverse range of environments. Both methods are non-destructive and can be applied in-situ to study the corrosion in the laboratory or in the field where the structures themselves are located. The moessbauer and Raman spectroscopic techniques are complementary in providing details of the corrosion products within different spatial resolutions. Moessbauer and Raman spectroscopic is the only techniques which can uniquely identify all the iron oxides and measure the fraction of each in corrosion coatings. It can be used in scattering geometry to study the corrosion products as the remain attached to the substrate, or it can be used in transmission geometry to analyze coatings which have been removed or have flaked from the steel. Generally several square centimeters of coating are analyzed by Moessbauer spectroscopy which is regarded as a bulk analytical technique. Micro-Raman spectroscopy, on the other hand, allows identification of the corrosion products in the coating to about 2 micron spatial resolution. Although presently unable to measure the fraction of each oxide, Micro-Raman spectroscopy is able to identify the oxides to be mapped in three dimensions, across the surface of the coating, as well as through the coating thickness using metallographic cross-section analysis. (Author)

  17. Study of thermal stability of permanent magnets by the method of Moessbauer spectroscopy

    A method permitting identification of residual magnetization factor α, as applied to permanent magnets from barium ferrite BaFe12O19, is described. Formulas for indentification of factor α based on analysis of the Moessbauer spectra of 57Fe nuclei obtained in the temperature range of 120-300 K, where magnets from barium ferrite manifest special instability, are provided. The value of factor α obtained based on the Moessbauer spectra is 2 ·10-3 deg -1, which coincides with the value obtained based on magnetic measurements

  18. Determination of cis and trans Fe2+ populations in 2M1 muscovite by Moessbauer spectroscopy

    Specimens of muscovite from Siluro-Devonian Appalachian granites of the Gander zone in New Brunswick were studied by 57Fe Moessbauer spectroscopy, microprobe analysis and X-ray powder diffractometry. Chemical compositions, corresponding structural formulae and powder patterns indicate that they are dioctahedral true micas of 2M1 polytype. Moessbauer spectroscopy shows that these muscovites fall into two groups having distinct spectra, despite an absence of systematic differences in their chemical compositions, X-ray patterns, unit-cell parameters, and Fe3+/Fetotal ratios. In the first group, two distinct and well-resolved viFe2+ spectral contributions occur whereas, in the second group, a single but broader viFe2+ contribution occurs. All spectra from both groups have viFe3+ contributions. These observations are confirmed by quadrupole splitting distribution (QSD) analyses of the spectra. Spectra from the first group clearly show a bimodal distribution of quadrupole splittings for Fe2+, with a dominant contribution at ∼3.0 mm/s and a minor one at ∼2.1 mm/s. In the second group, the spectra show a broad unimodal distribution of QSDs for Fe2+. We attribute the 3.0 and 2.1 mm/s QSD components to Fe2+ in cis and trans octahedral sites, respectively. Muscovites from our second group may have Fe2+ in both cis and trans sites but these cannot be resolved, as is usually the case, for example, with trioctahedral micas. In group one, cis/trans populations provide measures of the degree of cation order and of the density of vacancies on the cis sites. Simple models based on average unit cell site dimensions are found not to hold. Local effects seem to dominate, with Fe2+ showing no systematic preference for cis or trans sites

  19. The Nature of Line Broadening in Thermally Detected 57FeFe NMR

    57FeFe with isotopic concentrations from 15 to 95% is studied using NMR thermally detected by nuclear orientation. Lines are found to be consistently homogeneous. The contrast with previous inhomogeneous 57FeFe lines from Moessbauer detected NMR is explained by differences in radio frequency field strength.

  20. Paramagnetic hyperfine interactions of iron in solid ammonia from Moessbauer spectroscopy

    Moessbauer studies on highly dilute 57Fe in solid ammonia are reported. The hyperfine parameters of the paramagnetic reaction product FeNH3 point to a nearly atomic configuration of iron [Ar]3d74s. The electronic spin relaxation slows down rapidly under application of an external magnetic field. The field dependence of the magnetic hyperfine patterns indicates a strong axial magnetic anisotropy. (author)

  1. Differences of the {sup 57}Fe hyperfine parameters in both oxyhemoglobin and spleen from normal human and patient with primary myelofibrosis

    Oshtrakh, M. I., E-mail: oshtrakh@mail.utnet.ru; Alenkina, I. V. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation); Vinogradov, A. V.; Konstantinova, T. S. [Ural State Medical Academy (Russian Federation); Semionkin, V. A. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation)

    2013-05-15

    Study of oxyhemoglobin in red blood cells and spleen tissues from normal human and patient with primary myelofibrosis was carried out using Moessbauer spectroscopy with a high velocity resolution. The {sup 57}Fe hyperfine parameters were evaluated and small variations in quadrupole splitting were revealed for both normal human and patient's oxyhemoglobin and both normal human and patient's spleen.

  2. A Moessbauer and NMR spectroscopy study of RFe12-xMx intermetallics

    Several members of the ThMn12 type compounds RFe12-xMx with RY, Gd, Er, Sm; M=V, Mo, Ti, W, Si were studied with 57Fe Moessbauer spectroscopy. For GdFe10Mo2 and YFe10V2 NMR spectra at 4.2 K were also taken. The spectra were analyzed by taking into account the preferential distribution of the M atoms over the 3 crystallographic sites available for both Fe and M atoms in the ThMn12 lattice. A binominal distribution was used for calculating the probability of the possible nearest neighbor configurations of the Fe atoms, leading to fits with up to 4 separate subspectra for each of the 3 crystallographic sites 8i, 8j, and 8f which provided a consistent description of the experimental data. A spin reorientation transition was found for ErFe10V2 in the temperature range 4.2 K - 77 K. (orig.)

  3. Application of Moessbauer spectroscopy in investigating Egyptian archaeology

    This article summarizes the results of applications of the Moessbauer spectroscopy to investigate Ancient Egyptian pottery from the periods: Ancient Egyptian (3200-525 B.C.), Greek-Roman (320 B.C.-640 A.C.) and Early Islamic (800-1000 A.C.). Many objective informations deduced about: provinance, manufacturing techniques for different domestic purposes, civilization transfer between the Arab countries, methods of colouration and applying decorating glazes, and finally dating of ancient pottery. (orig.)

  4. Characterization of Egyptian coal from Sinai using Moessbauer spectroscopy

    The presence of iron bearing minerals in coal makes the Moessbauer Spectroscopy (MS) extremely useful for characterization of coals from different localities. In this paper the MS has been applied to characterize Egyptian coal from Sinai (Maghara). The chemical analysis of this coal is given. The MS results showed that pyritic sulphur (pyrite and marcasite) is the only bearing mineral in Egyptian coal. A review is given for the iron bearing minerals in coals from different countries measured by MS. (author)

  5. Structure and 57Fe conversion electron M(o)ssbauer spectroscopy study of Mn-Zn ferrite nanocrystal thin films by electroless plating in aqueous solution

    SUN JianRong; WANG XueWen; LIU JinHong; WANG JianBo; LI FaShen

    2008-01-01

    Mn1-xZnxFe2O4 thin films with various Zn contents and of different thickness were synthesized on glass substrates directly by electroless plating in aqueous solution at 90℃ without heat treatment. The Mn-Zn ferrite films have a single spinel phase structure and well-crystallized columnar grains growing per-pendicularly to the substrates. The results of conversion electron 57Fe Mossbauer spectroscopy (CEMS) indicate that the cation distribution of Mn-xZnxFe2O4 ferrite nanocrystal thin films fabricated by elec-troless plating is different from the bulk materials' and a great quantity of Fe3+ ions are still present on A sites for x>0.5. When the Zn content of the films increases, Fe3+ ions in the films transfer from A sites to B sites and the hyperfine magnetic field reduces, suggesting that Zn2+ has strong chemical affinity towards the A sites. On the other side, with the increase of the thickness of the films, Fe3+ ions, at B sites in the spinel structure, increase and the array of magnetic moments no longer lies in the thin film plane completely. At x=0.5, Hc and Ms of Mn1-xZnxFe2O4 thin films show a minimum of 3.7 kA/m and a maximum of 419.6 kA/m, respectively.

  6. Gas flow counter conversion electron Moessbauer spectroscopy (GFC-CEMS)

    Conversion Electron Moessbauer Spectroscopy (CEMS) is well established technique to study surface properties of materials. However non availability of commercial experimental set up and complexity of operational parameters have been restricting the working experimental groups with in the country and abroad. In this paper we have presented the development work for the design of Gas Flow Counter (GFC), e.g. convenient sample mount, grounding, steady flow rate adjustment and minimum He-losses so that the detector operation and installation becomes convenient and dependable. The basic design is modified e.g. large volume to maintain steady gas flow, sample mount close to central wire and O-ring fitted flange. The CEMS spectra are recorded using conventional Moessbauer drive and 57Co source. The calibrated spectrum shows a detection efficiency of about 20% for natural iron and steel foil. The CEMS spectrum for FeTi bulk and transmission Moessbauer Spectroscopy (TMS) spectrum of FeTi thin film deposited by vacuum evaporation on thin glass substrate were recorded to test the performance of GFC-CEMS. (author)

  7. Moessbauer spectroscopy: Methodology and some applications to magnetic materials

    The development of a new computer program for analysis of Moessbauer spectra that allows the user to make a detailed simulation of a measured spectrum is described. The program includes several novel computational algorithms as well as extensive treatment of experimental side effects. Data collection instrumentation has been improved by the development of computer based data acquisition units. Replacing traditional multichannel analyzers, these computer controlled units provide increased flexibility, improved capacity and ease of data handling. The systems designed range from a simple Apple II interface, to a high performance self contained computer controlled unit. The computerized spectrometers feature two independent channels, allowing for acquisition of the spectrum of interest and of a simultaneous calibration spectra, as well as software controlled frequency of operation. Moessbauer spectroscopy is applied to amorphous Fe based alloys to study the correlations among hyperfine interactions, and to study the crystallization behaviour of these alloys. Special attention has been payed to the quadrupole interaction in the amorphous phases. Careful data analysis, making use of the above mentioned program, is used in an attempt to determine the complex magnetic structures found in various iron phosphides. The usefulness of the Ni-61 isotope for Moessbauer spectroscopy has been investigated. (author)

  8. Moessbauer spectroscopy in Egyptian and Qatari steel industry

    This paper gives an example of applying the Moessbauer Spectroscopy (MS) in steel industry in both Egypt and Qatar. The author carried out the measurements at the Moessbauer laboratories in Al-Azhar University and in Qatar University. Measurements were carried out on the raw materials and the products. It was possible to check the characteristics of the products at each stage and also the efficiency of its production. The mechanism of formation could be followed. The analysis of M spectra of plain carbon steel provides information on the different phases, reveals the effect of quenching, shows the effect of the interstitial carbon atoms and their movement during tempering. Order disorder transformation, solid solubility limits and texture of materials are mentioned. (author)

  9. Corrosion of steam generator pipelines analysed using Moessbauer spectroscopy

    The variability of the properties and the composition of the corrosion products of the stainless CrNi and mild steels in dependence on the conditions (temperature, acidity, etc.) is of such range that, in practice, it is impossible to determine the properties of the corrosion products for an actual case from the theoretical data only. Since the decontamination processes for the materials of the water-cooled reactor (WWER-440) secondary circuits are in the progress of development, it is necessary to draw the needed information by the measurement and analysis of the real specimens [Cohen, L., 1980. Application of Moessbauer Spectroscopy, vol. II. Academic Press, NY, USA]. The corrosion layers were separated by scraping the rust off the surface and the powder samples were studied by transmission Moessbauer spectroscopy. It should be noted that the gamma spectroscopic measurements give no evidence of the presence of low-energy gamma radiation emitted from the samples. The scrapped specimen powder was homogenised (using the 50 μm sieve) and fixed into the special holder. The 57Co in Rh matrix was used as the radioactive Moessbauer source. Measured spectra were fitted using program NORMOS SITE. According to the results obtained from Moessbauer spectra, it is possible to establish that the main component of secondary circuit's corrosion products is magnetite Fe3O4. Next components are hematite α-Fe2O3 and hydro-oxide akagenite β-FeOOH, which is characterised by significant paramagnetic doublet in the middle of spectra. The sextets corresponding to base materials (martenzite and austenite steels) were identified in all measured spectra

  10. The method of Moessbauer conversion spectroscopy. Moessbauer measurements at 180W and 182W

    In the Moessbauer conversion spectroscopy the detection of the Moessbauer absorption is carried out by watching the conversion electrons afterwards emitted. In spite of the higher experimental efforts, the method is a real alternative to the usual transmission experiment. In a series of Mb-measurements at the E2-transitions of the Os-, Hf-, and W-isotopes, the criteria developed for the applicability of the MBC could be ascertained. The two W-isotopes 180W and 182W tested in this study are located at the beginning of the transition of deformed nuclei to spherical ones. Deviations from the simple rotation model should be perceptible in the size of the electromagnetic moments and in the transition probabilities of the excited nuclear states. For the first excited rotational states, the proportion of the quadrupole moments can be determined with the help of Mb-measurements. The result does not show any deviations from the predictions of the rotational model. Further information about the structure of rotational states can be gained from Mb-isomeric shifts. In this essay the isomeric shift of the first rotational state in 182W was determined for several joints. Limiting values for the negative Δ 2> are given with an electron density calibration based on relativistic Hartree-Fock-calculations. (orig./WBU)

  11. The Moessbauer Spectroscopy Studies of Cementite Precipitations during Continuous Heating from As-Quenched State of High Carbon Cr-Mn-Mo Steel

    This work complements the knowledge concerning the kinetics of cementite precipitation during tempering. Investigations were performed on 120MnCrMoV8-6-4-2 steel. The samples of investigated steel were austenitized at the temperature of 900oC and quenched in oil. Then four of five samples were tempered. Tempering consisted of heating the samples up to chosen temperatures at the heating rate of 0.05oC/s and fast cooling after reaching desired temperature. This work presents the results of investigations performed carried out using the Moessbauer spectroscopy technique and their interpretation concerning cementite nucleation and growth during tempering. The values of hyperfine magnetic field on 57Fe atomic nuclei, determined for the third component of the Moessbauer spectrum as regards to its intensity, indicate that these are the components coming from ferromagnetic carbides. Big differences in hyperfine magnetic fields coming from Fe atoms existing in the structure of carbides, measured on samples heated up to the temperatures of 80oC and 210oC, in comparison with values for 57Fe atoms precipitated from carbides during heating up to the temperature of 350oC and 470oC, allow to state that these are the carbides of different crystal structure. The influence of hardened steel heating temperature on cementite precipitation was determined. The Moessbauer spectroscopy was applied not only for magnetic hyperfine field studies, but also to analyze the values of quadrupole splitting and isomeric shift, which resulted in significant conclusions concerning the changes in cementite precipitations morphology, chemical composition and the level of stresses being present in this research. (authors)

  12. Moessbauer study of defect trapping at 57Co in cold worked aluminium

    Point defects induced by cold work of Al at various temperatures between 4.2 K and 80 K were trapped at 57Co/57Fe atoms and studied by Moessbauer spectroscopy. No free migration of interstitials was observed, whereas enhanced and free diffusion of vacancies, respectively was found at 100 K and 200 K. (author)

  13. Moessbauer spectroscopy study of iron corrosion underneath painting system

    The effect of pigments on the development of corrosion products between the painting system and metal surface when exposed to marine environments has been discussed. The pigments studied were: red mud zinc chromate, zinc chromate, red oxide zinc phosphate, manganese phosphate barium chromate and basic lead silico chromate. Moessbauer spectroscopy revealed that the upper rust layer in all the cases consisted of γ-Fe2O3, γ-FeOOH and α-FeOOH. The lower rust layer immediately in contact with the metal surface consisted of an asymmetrical doublet due to γ-FeOOH. (Auth.)

  14. USB based multi-channel scaler for Moessbauer spectroscopy

    This paper presents a new high-performance Multi-Channel Scaler (MCS) system developed in Electronics Division, BARC. It enables the nuclear pulse counting system to record the input counting rate as a function of time, as required in certain experiments. It is based on a high-density FPGA chip designed using VHDL, and other state of art components. It offers USB bus connectivity with a host computer. With an external amplifier, an HV supply and a drive unit, this Multi-Channel Scaler system can be used for Moessbauer spectroscopy applications. (author)

  15. Coatings and Films analyzed and optimized by Moessbauer Spectroscopy

    Thin Films, multilayers and coatings are playing a steadily increasing role for most advanced technical applications and the development of new materials. For the improvement of corrosion, friction and wear properties of machine and tool surfaces, carbides and nitrides are especially interesting. Here we present the effects of pulsed laser irradiation of iron in methane atmosphere and their analysis by Moessbauer spectroscopy. The dependence of the phase formation and the resulting properties are given in relation to the laser treatment parameters, such as number of laser shots and reactive gas pressure. For example, the irradiation of pure iron in methane atmosphere at low pressures or low number of laser pulses results in the formation of an amorphous carbon surface layer and hexagonal FexC, which is more and more transformed into Fe3C cementite when increasing the number of pulses or the gas pressure. It will be demonstrated that Moessbauer spectroscopy is well suited to analyze the processing and to give valuable hints for its optimization

  16. Moessbauer study of the structure of Fe - zircon system

    Iron-doped silicate (zircon), prepared by a ceramic method with the addition of LiF as mineralizer, was analyzed by X-ray powder diffraction (XRD) and 57Fe Moessbauer spectroscopy to obtain information on the solid solution formation. The results of X-ray diffraction and Moessbauer spectroscopy have shown that only a small fraction of iron, about 1.5 mol%, is incorporated in the zircon structure as paramagnetic Fe3+ species while the remaining Fe3+ cations form magnetic α-Fe2O3 particles which are trapped within the zircon matrix. (author)

  17. 57Fe-ion implantation in pulse laser deposited La0.75Ca0.25MnO3 films: Conversion electron Mössbauer spectroscopy and X-ray diffraction studies

    U D Lanke; J Prabhjyot Pal

    2000-02-01

    Oriented La0.75Ca0.25MnO3 (LCMO) films have been deposited by pulsed laser deposition (PLD) method on (100) LaAlO3 substrates. Ion-beam technique is used to introduce a very low concentration of 57Fe+ in LCMO film. The deposited films were subjected to 100 keV 57Fe+ implantation with different fluences at room temperature. The main motivation of this work was to study the influence of implantation on the transport mechanism in materials exhibiting colossal magnetoresistance (CMR) property. It is observed that Fe implantation drastically affects the structural and magneto-transport properties. The samples were characterized using the X-ray diffraction (XRD) technique, conversion electron Mössbauer spectroscopy (CEMS) and resistance temperature (–) measurements.

  18. Moessbauer spectroscopy study on the effect of infrared and gamma radiation on the structure of minerals. Part of a coordinated programme on development of methods for application of Moessbauer spectroscopy in mineralogy, soil sciences and the study of ceramics

    A number of fundamental and applied problems were studied by Moessbauer spectroscopy. (a) The observation of Moessbauer spectra in iron silacate deerite with respect to the structure of this mineral was interpreted by charge transfer between iron ions, and correlated with thermally activated electron delocalisation. (b) The studies of local coals showed the suitability of Moessbauer spectroscopy in control of the desulpherisation process. (c) A simple method to use Moessbauer measurement to determine the obstructions in water pipes was developed

  19. Comparative Study of Human Liver Ferritin and Chicken Liver by Moessbauer Spectroscopy. Preliminary Results

    A comparative study of normal human liver ferritin and livers from normal chicken and chicken with Marek disease was made by Moessbauer spectroscopy. Small differences of quadrupole splitting and isomer shift were found for human liver ferritin and chicken liver. Moessbauer parameters for liver from normal chicken and chicken with Marek disease were the same.

  20. Comparative Study of Human Liver Ferritin and Chicken Liver by Moessbauer Spectroscopy. Preliminary Results

    Oshtrakh, M. I. [Ural State Technical University - UPI, Division of Applied Biophysics, Faculty of Physical Techniques and Devices for Quality Control (Russian Federation); Milder, O. B.; Semionkin, V. A. [Ural State Technical University - UPI, Faculty of Experimental Physics (Russian Federation); Prokopenko, P. G. [Russian State Medical University, Faculty of Biochemistry (Russian Federation); Malakheeva, L. I. [Simbio Holding, Science Consultation Department (Russian Federation)

    2004-12-15

    A comparative study of normal human liver ferritin and livers from normal chicken and chicken with Marek disease was made by Moessbauer spectroscopy. Small differences of quadrupole splitting and isomer shift were found for human liver ferritin and chicken liver. Moessbauer parameters for liver from normal chicken and chicken with Marek disease were the same.

  1. In-situ Moessbauer spectroscopy with MIMOS II

    Fleischer, Iris, E-mail: fleischi@uni-mainz.de; Klingelhoefer, Goestar [Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg University of Mainz (Germany); Morris, Richard V. [NASA Johnson Space Center (United States); Schroeder, Christian [University of Bayreuth and University of Tuebingen (Germany); Rodionov, Daniel [Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg University of Mainz (Germany); Souza, Paulo A. de [Tasmanian ICT Centre (Australia); Collaboration: MIMOS II Team

    2012-03-15

    The miniaturized Moessbauer spectrometer MIMOS II was developed for the exploration of planetary surfaces. Two MIMOS II instruments were successfully deployed on the martian surface as payload elements of the NASA Mars Exploration Rover (MER) mission and have returned data since landing in January 2004. Moessbauer spectroscopy has made significant contributions to the success of the MER mission, in particular identification of iron-bearing minerals formed through aqueous weathering processes. As a field-portable instrument and with backscattering geometry, MIMOS II provides an opportunity for non-destructive in-situ investigations for a range of applications. For example, the instrument has been used for analyses of archaeological artifacts, for air pollution studies and for in-field monitoring of green rust formation. A MER-type MIMOS II instrument is part of the payload of the Russian Phobos-Grunt mission, scheduled for launch in November 2011, with the aim of exploring the composition of the martian moon Phobos. An advanced version of the instrument, MIMOS IIA, that incorporates capability for elemental analyses, is currently under development.

  2. Transition to collapsed tetragonal phase in CaFe2As2 single crystals as seen by 57Fe Mossbauer spectroscopy

    Bud'ko, Sergey L.; Ma, Xiaoming; Tomic, Milan; Ran, Sheng; Valenti, Roser; Canfield, Paul C.

    2015-01-01

    Temperature dependent measurements of 57Fe Mossbauer spectra on CaFe2As2 single crystals in the tetragonal and collapsed tetragonal phases are reported. Clear features in the temperature dependencies of the isomer shift, relative spectra area and quadrupole splitting are observed at the transition from the tetragonal to the collapsed tetragonal phase. From the temperature dependent isomer shift and spectral area data, an average stiffening of the phonon modes in the collapsed tetragonal phase...

  3. Study on the magnetic behavior of In-doped nickel chromite by using Moessbauer spectroscopy

    Hyun, Sung Wook; Kim, Chul Sung [Kookmin University, Seoul (Korea, Republic of); Park, Seung Iel [Sukwon Co. Ltd., Gumi (Korea, Republic of); Oh, Young Jei [Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    2011-02-15

    NiCr{sub 1.9-x} {sup 57}Fe{sub 0.1}In{sub x}O{sub 4} (x = 0.0, 0.1, 0.3, and 0.5) was prepared by using a sol-gel method. The crystal structure at room temperature was determined to be a normal cubic spinel with space group Fd3m. An analysis of the x-ray diffraction patterns was performed using a Rietveld refinement method while the Bragg R{sub B} and R{sub F} factors were below 5%. The magnetic Neel temperature decreased from 150 K to 77 K with increasing In concentration, which was confirmed by zero-field-cooled (ZFC) magnetization at applied fields under 100 Oe and by Moessbauer spectra measured at various temperatures. Magnetic hysteresis loops of the samples at 77 K showed drastically increasing magnetization and decreasing coercivity with increasing In concentration. The Moessbauer spectra of the samples were measured at various temperatures ranging from 4.2 to 295 K. The isomer shift value showed that the charge states of the iron ions are ferric. The Moessbauer spectra showed two magnetic phases with two different magnetic spin direction sites for the Cr{sup 3+} ion state. Moessbauer spectra below 77 K showed 6 sharp absorption lines and the linewidth became broader with increasing temperature, which indicates a Jahn-Teller distortion and relaxation.

  4. Nuclear gamma resonance absorption (Moessbauer) spectroscopy as an archaeometric technique to assess chemical states of iron in a Tupiguarani ceramic artifact from Corinto, Minas Gerais, Brazil

    Floresta, D.L.; Ardisson, J.D., E-mail: denise.floresta@ifmg.edu.br, E-mail: jdr@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Fagundes, M.; Fabris, J.D., E-mail: marcelo.fagundes@ufvjm.edu.br, E-mail: jdfabris@ufmg.edu.br [Universidade Federal dos Vales do Jequitinhonha e Mucuri (LAEP/UFVJM), Diamantina, MG (Brazil). Lab. de Arqueologia e Estudos da Paisagem

    2013-07-01

    Archaeological ceramics of Tupiguarani Tradition are found in many parts throughout the Brazilian territory and have many similarities. Fragments of Tupiguarani pottery found in the archaeological site known as Beltrao, in the municipality of Corinto, state of Minas Gerais, were identified and collected by researchers of the LAEP/UFVJM, in Diamantina, also in Minas Gerais. A selected fragment of about 15 mm-thick, with a color gradation across the ceramic wall ranging from red, on one side, grayish in the middle and orange on the opposite side, was transversely cut and a series of subsamples of powdered materials were collected from different depths across the wall, in layer segments of ∼3 mm, from the orange side. These powdered subsamples were analyzed with X-ray fluorescence and diffraction spectroscopy and {sup 57}Fe Moessbauer spectroscopy at room temperature (298 K) and at 80 K. According to the XRF results, the elementary composition does not clearly vary with the depth in the sample. The powder XRD analysis revealed the occurrence mainly of quartz and muscovite. Results of {sup 57}Fe Moessbauer spectroscopy reveal that hematite is the magnetically ordered phase. An Fe{sup 2+} component appears for the grayish subsample. According to these results, the red subsample seems to be the external part of the pottery, representing the side that had direct contact with fire used to burn the precursor clay in air for this primitive ceramics preparation. The grayish middle layer is probably due to burning clay mixed with some ashes containing residual carbon, under milder temperature than on the external . (author)

  5. Determination of cis and trans Fe{sup 2+} populations in 2M{sub 1} muscovite by Moessbauer spectroscopy

    Shabani, Amir A.T. [University of Ottawa, Department of Earth Sciences (Canada); Rancourt, Denis G. [University of Ottawa, Department of Physics (Canada); Lalonde, Andre E. [University of Ottawa, Department of Earth Sciences (Canada)

    1998-12-15

    Specimens of muscovite from Siluro-Devonian Appalachian granites of the Gander zone in New Brunswick were studied by {sup 57}Fe Moessbauer spectroscopy, microprobe analysis and X-ray powder diffractometry. Chemical compositions, corresponding structural formulae and powder patterns indicate that they are dioctahedral true micas of 2M{sub 1} polytype. Moessbauer spectroscopy shows that these muscovites fall into two groups having distinct spectra, despite an absence of systematic differences in their chemical compositions, X-ray patterns, unit-cell parameters, and Fe{sup 3+}/Fe{sub total} ratios. In the first group, two distinct and well-resolved {sup vi}Fe{sup 2+} spectral contributions occur whereas, in the second group, a single but broader {sup vi}Fe{sup 2+} contribution occurs. All spectra from both groups have {sup vi}Fe{sup 3+} contributions. These observations are confirmed by quadrupole splitting distribution (QSD) analyses of the spectra. Spectra from the first group clearly show a bimodal distribution of quadrupole splittings for Fe{sup 2+}, with a dominant contribution at {approx}3.0 mm/s and a minor one at {approx}2.1 mm/s. In the second group, the spectra show a broad unimodal distribution of QSDs for Fe{sup 2+}. We attribute the 3.0 and 2.1 mm/s QSD components to Fe{sup 2+} in cis and trans octahedral sites, respectively. Muscovites from our second group may have Fe{sup 2+} in both cis and trans sites but these cannot be resolved, as is usually the case, for example, with trioctahedral micas. In group one, cis/trans populations provide measures of the degree of cation order and of the density of vacancies on the cis sites. Simple models based on average unit cell site dimensions are found not to hold. Local effects seem to dominate, with Fe{sup 2+} showing no systematic preference for cis or trans sites.

  6. Development of a highly efficient conversion electron Moessbauer spectroscopy (CEMS) detector for low temperature (<20 K) measurements and tests on Fe / (Eu{sub x}Pb{sub 1-x})Te bilayers; Desenvolvimento de um detector de alta eficiencia para espectroscopia Moessbauer de eletrons de conversao (CEMS) a baixas temperaturas (<20K) e testes em bicamadas Fe / (Eu{sub x}Pb{sub 1-x})Te

    Pombo, Carlos Jose da Silva Matos

    2006-07-01

    The {sup 57}Fe Moessbauer spectroscopy is a nuclear, non-destructive technique used for the investigation of structural, magnetic and hyperfine properties of several materials. It is a powerful tool in characterizing materials in physics, metallurgy, geology and biology field areas, especially magnetic materials, alloys and minerals containing Fe. Lately, the Conversion Electron Moessbauer Spectroscopy (CEMS) is widely used in making studies on ultra-thin magnetic films, as well as other nanostructured materials. In case of magnetic nanostructures, low temperature (LT) studies are especially important due to the possibility of dealing with superparamagnetic effects. In this work it was developed a CEMS measurement system for low temperatures (<20 K) based on a solid-state electron multiplier (Channeltron{sup R}) and an optical cryostat (Model SVT-400, Janis Research Co, USA), from which the project was originally conceived at the Applied Physics / Moessbauer spectroscopy Department from University of Duisburg-Essen, Germany. The LT-CEMS system was fully built, tested and successfully applied in a preliminary characterization of Fe/(Eu{sub x}Pb{sub 1-x})Te(111) bilayers with use of a 15 angstrom, {sup 57} Fe probe layer, with reasonable results at sample temperatures as low as 8 K. (author)

  7. Surface analysis in steel nitrides by using Moessbauer spectroscopy

    The formation of iron nitride layer at low temperatures, 600-700 K, by Moessbauer spectroscopy is studied. These layers were obtained basically through two different processes: ion nitriding and ammonia gas nitriding. A preliminary study about post-discharge nitriding was made using discharge in hollow cathode as well as microwave excitation. The assembly of these chambers is also described. The analysis of the nitrided samples was done by CEMS and CXMS, aided by optical microscopy, and the CEMS and CXMS detectors were constructed by ourselves. We also made a brief study about these detectors, testing as acetone as the mixture 80% He+10% C H4 as detection gases for the use of CEMS. The surface analysis of the samples showed that in the ammonia gas process nitriding the nitrided layer starts by the superficial formation of an iron nitride rich nitrogen. By thermal evolution this nitride promotes the diffusion of nitrogen and the formation of other more stable nitrides. (author)

  8. Magnetic interactions in water based ferrofluids studied by Moessbauer spectroscopy

    Kuncser, V [National Institute for Physics of Materials, PO Box MG 7, 77125, Bucharest-Magurele (Romania); Schinteie, G [National Institute for Physics of Materials, PO Box MG 7, 77125, Bucharest-Magurele (Romania); Sahoo, B [Fachbereich Physik, Universitaet Duisburg-Essen Lotharstrasse 65, D-47048, Duisburg (Germany); Keune, W [Fachbereich Physik, Universitaet Duisburg-Essen Lotharstrasse 65, D-47048, Duisburg (Germany); Bica, D [Romanian-Academy-Timisoara Branch, Center for Advanced and Fundamental Technical Research, Mihai Viteazal Nr. 23, 300223, Timisoara (Romania); Vekas, L [Romanian-Academy-Timisoara Branch, Center for Advanced and Fundamental Technical Research, Mihai Viteazal Nr. 23, 300223, Timisoara (Romania); Filoti, G [National Institute for Physics of Materials, PO Box MG 7, 77125, Bucharest-Magurele (Romania)

    2007-01-10

    Various samples of ferrofluids consisting of colloidal suspensions of surfacted cobalt ferrite or magnetite nanoparticles in water were studied by x-ray diffraction and temperature dependent Moessbauer spectroscopy. Information about the particle mean size, the size dispersion and the effective magnetic anisotropy energy was obtained for each sample. The results are consistent with the formation of a magnetic dead layer at the particle surface, whose thickness depends on the surfactant-ferrite combination. The magnetic relaxation processes are faster in the colloidal suspensions of magnetite particles as compared with the suspensions of cobalt ferrite particles. The type of the surfactant also influences the magnetic relaxation behaviour, and hence the macroscopic properties of the ferrofluid at ambient temperature.

  9. Pottery from a Chimu Workshop Studied by Moessbauer Spectroscopy

    Ceramic finds from a pottery workshop in the Lambayeque valley were studied by neutron activation analysis, Moessbauer spectroscopy and X-ray diffraction in an attempt to assess an advanced division of labour on the North Coast of Peru during the Chimu period (AD 1350-1460). The study suggests that the material was predominantly fired in a reducing environment with partial reoxidation at the end of the firing cycles, although firing in an oxidising atmosphere has taken place occasionally. The observed variation of firing conditions is characteristic for the use of pit kilns. The results of the archaeometric studies confirm the stylistic studies and show that pottery was no status symbol and far less important as a carrier of Chimu style than metal artefacts.

  10. The Moessbauer spectroscopy in the characterization of atmospheric corrosion products

    A study of corrosion products on mild steel formed after 1 and 5 years exposure in two industrial coastal weathering stations in the Bay from Matanzas City, Cuba, has been carried out. Structural analysis was conducted using mainly transmission Moessbauer Spectroscopy and the X-ray diffraction as complementary technique. The main phases found in the specimen exposed to high chloride containing environment were: lepidocrocite (γ- FeOOH), goethite (α- FeOOH) and magnetite concentration was the lowest, the phases found were γ- FeOOH and α- FeOOH, and the phase transformation proposed was γ- FeOOh -> α- Fe-OOH. In this station were found also amorphous corrosion products. There amorphous phases could be responsible for the lowest levels of corrosion on steel in this station

  11. Characterization of Argentine Loess and Paleosols by Moessbauer Spectroscopy

    We have used Moessbauer spectroscopy to investigate iron-bearing mineral samples of loess and paleosols from a geologic section at La Plata, Argentina, 34 deg. 54' 14'' S and 58 deg. 2' W. Hematite is by far the dominant iron-bearing magnetic component in initial loess and paleosol samples. The samples were also subjected to magnetic separation. The magnetically enriched loess fractions show a remarkable increase in the content of magnetite. The enhancement of non-magnetic Fe3+ and a decrease of Fe2+ mineral phases in the paleosol layer seem to be a consequence of the process of pedogenesis which also caused a dissolution of magnetic iron oxides by weathering. The increase of magnetite in the silt fraction suggests that the wind could have been the main carrier of magnetic minerals, causing the major differences in the magnetic parameters between loess and paleosols in the Argentine loess plateau

  12. Characterization of oxide catalysts by in situ Moessbauer spectroscopy

    Chemical and structural information as obtained by Moessbauer spectroscopy when applied on the study of the catalysts under controlled temperature and pressure of the sample environment or under conditions close to the reaction ones is reviewed. Several cells for these in situ or operando measurements, respectively, are described: working at high and/or low temperature, under vacuum or rather high pressure, in a static atmosphere or in a flow, in gas or liquid phase, in the presence of magnetic fields or by applying the electric field. Examples of catalytic reactions being studied in such in situ cells are given, focusing on the oxide catalysts either crystalline or amorphous or on the oxide supported catalysts. The advantages of in situ measurements were noticed, especially for unraveling the reaction mechanism. (authors)

  13. Corrosion study of heat exchanger tubes in pressurized water cooled nuclear reactors by conversion electron Moessbauer spectroscopy

    Nuclear energy production tends to return into the focus of interest because of the constantly increasing energy need of the world and the green house effect problems of the strongest competitor oil or gas based power plants. In addition to the construction of new nuclear power plants, lifetime extension of the existing ones is the most cost effective investment in the energy business. However, feasibility and safety issues become very important at this point, and corrosion of the construction materials should be carefully investigated before decision on a potential lifetime extension of a reactor. 57Fe-Conversion Electron Moessbauer Spectroscopy (CEMS) is a sensitive tool to analyze the phase composition of corrosion products on the surface of stainless steel. The upper ∼300 nm can be investigated due to the penetration range of conversion electrons. The corrosion state of heat exchanger tubes from the four reactor units of the Paks Nuclear Power Plant, Hungary, were analyzed by several methods including CEMS. The primary circuit side of the tubes was studied on selected samples cut out from the heat exchangers during regular maintenance. Cr- and Ni-substituted magnetite, sometimes hematite, amorphous Fe-oxides/oxyhydroxides as well as the signal of bulk austenitic steel of the tubes were detected. The level of Cr- and Ni-substitution in the magnetite phase could be estimated from the Moessbauer spectra. Correlation between earlier decontamination cycles and the corrosion state of the heat exchangers was sought. In combination with other methods, a hybrid structure of the surface oxide layer of several microns was established. It is suggested that previous AP-CITROX decontamination cycles can be responsible for this structure which makes the oxide layer mobile. This mobility may be responsible for unwanted corrosion product transport into the reactor vessel by the primary coolant.

  14. Application of Moessbauer spectroscopy to the study of neptunium adsorbed on deep-sea sediments

    A Neptunium Moessbauer spectrometer (the first in Great Britain) was constructed and the Moessbauer spectra of NpAl Laves phase alloy obtained. Neptunium was sorbed onto a calcareous deep-sea sediment from sea water, using a successive-loading technique. Sorption appeared to be by an equilibrium reaction, and because of the low solubility of neptunium in seawater, this meant that the maximum loading that could be achieved was 8mg237Np/g sediment. This proved to be an adequate concentration for Moessbauer measurements and a Moessbauer spectrum was obtained. This showed that most of the neptunium was in exchange sites and not present as precipitates of neptunium compounds. It was probably in the 4+ state indicating that reduction had occurred during sorption. This work has demonstrated that Moessbauer Spectroscopy has great potential as an aid to understanding the mechanism of actinide sorption in natural systems. (author)

  15. Comparative study of iron oxide nanoparticles as prepared and dispersed in copaiba oil using Moessbauer spectroscopy with low and high velocity resolution

    Full text: Development of biocompatible magnetic fluids is one of the interesting topics in biomedical research. Typical magnetic fluids consist of iron-containing magnetic nanoparticles. Therefore, 57Fe Moessbauer spectroscopy can be used for their characterization. Iron oxide nanoparticles dispersed in biocompatible Copaiba oil may be developed as magnetic fluids for biomedical aims. In this case it is interesting to analyze the effect of Copaiba oil molecules on magnetic features of nanoparticles. Iron oxides nanoparticles were synthesized by co-precipitation of a heated mixture of ferrous and ferric chloride aqueous solutions with concentrated ammonia (25 % v.v.), under vigorous stirring. Addition of hydrochloric acid after precipitation of nanoparticles and repeated washing produced a stable sol at pH2. Copaiba oil dispersed in cyclohexane was then added to the as-prepared sol under stirring. The resulting suspension was dried to remove out the organic solvent whereas the precipitated sample was collected. The obtained samples were characterized using X-ray diffraction, TEM and HRTEM. X-ray diffraction patterns were usual for magnetite and maghemite or their mixture. TEM analysis demonstrated uniform nanoparticles with a diameter of 8 nm. Moessbauer spectra of iron oxide nanoparticles as prepared and dispersed in Copaiba oil were measured using two different spectrometers: Wissel spectrometer with a low velocity resolution (512 channels) for measurements at 295 and 21 K and automated precision Moessbauer spectrometric system with a high velocity resolution (4096 channels) for measurements at 295 and 90 K. Moessbauer spectra of iron oxide nanoparticles, as-prepared and dispersed in Copaiba oil, measured at corresponding temperatures using both spectrometers demonstrated some differences which may be a result of the effect of Copaiba oil molecules. The fitting of all measured spectra demonstrated that usual models used for fitting Moessbauer spectra of magnetite

  16. Comparative study of iron oxide nanoparticles as prepared and dispersed in copaiba oil using Moessbauer spectroscopy with low and high velocity resolution

    Oshtrakh, M.I., E-mail: oshtrakh@mail.utnet.ru [Faculty of Physical Techniques and Devices for Quality Control, Ural Federal University, Ekaterinburg (Russian Federation); Sepelak, V. [Institute of Nanotechnology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen (Germany); Rodriguez, A.F.R. [Universidade Federal do Acre, Rio Branco, AC (Brazil); Semionkina, V.A.; Ushakov, M.V. [Faculty of Physical Techniques and Devices for Quality Control, Ural Federal University, Ekaterinburg (Russian Federation); Faculty of Experimental Physics, Ural Federal University, Ekaterinburg (Russian Federation); Santos, J.G.; Silveira, L.B.; Marmolejo, E.M. [Fundacao Universidade Federal de Rondonia, Departamento de Fisica, Ji-Parana, RO (Brazil); Souza-Parisef, M. de; Morais, P.C. [Universidade de Brasilia, Instituto de Fisica, Nucleo de Fisica Aplicada, Brasilia, DF (Brazil)

    2011-07-01

    Full text: Development of biocompatible magnetic fluids is one of the interesting topics in biomedical research. Typical magnetic fluids consist of iron-containing magnetic nanoparticles. Therefore, {sup 57}Fe Moessbauer spectroscopy can be used for their characterization. Iron oxide nanoparticles dispersed in biocompatible Copaiba oil may be developed as magnetic fluids for biomedical aims. In this case it is interesting to analyze the effect of Copaiba oil molecules on magnetic features of nanoparticles. Iron oxides nanoparticles were synthesized by co-precipitation of a heated mixture of ferrous and ferric chloride aqueous solutions with concentrated ammonia (25 % v.v.), under vigorous stirring. Addition of hydrochloric acid after precipitation of nanoparticles and repeated washing produced a stable sol at pH2. Copaiba oil dispersed in cyclohexane was then added to the as-prepared sol under stirring. The resulting suspension was dried to remove out the organic solvent whereas the precipitated sample was collected. The obtained samples were characterized using X-ray diffraction, TEM and HRTEM. X-ray diffraction patterns were usual for magnetite and maghemite or their mixture. TEM analysis demonstrated uniform nanoparticles with a diameter of 8 nm. Moessbauer spectra of iron oxide nanoparticles as prepared and dispersed in Copaiba oil were measured using two different spectrometers: Wissel spectrometer with a low velocity resolution (512 channels) for measurements at 295 and 21 K and automated precision Moessbauer spectrometric system with a high velocity resolution (4096 channels) for measurements at 295 and 90 K. Moessbauer spectra of iron oxide nanoparticles, as-prepared and dispersed in Copaiba oil, measured at corresponding temperatures using both spectrometers demonstrated some differences which may be a result of the effect of Copaiba oil molecules. The fitting of all measured spectra demonstrated that usual models used for fitting Moessbauer spectra of

  17. Moessbauer spectroscopy on the reaction center of Rhodopseudomonas viridis

    Proteins called 'reaction centers' (RC) can be isolated from many photosynthetic bacteria. They have one non-heme iron in a quinone acceptor region. The RC of Rhodopseudomonas viridis contains an additional tightly bound tetra-heme cytochrome c subunit. The electronic configuration of both cytochrome and the non-heme iron has been studied in the crystallized protein by Moessbauer spectroscopy at different redox potentials, pH-values, and with an addition of o-phenanthroline. At high potentials (Eh=+500 mV) all heme irons are in the low spin Fe3+-state, and at low potential (Eh=150 mV) they are low spin Fe2+ with the same Moessbauer parameters for all hemes independent of pH. Redox titrations change the relative area of the reduced and oxidized states in agreement with other methods. The non-heme iron shows a high spin Fe2+ configuration independent of Eh and pH with parameters comparable to those of Rhodopseudomonas sphaeroides. Surprisingly, there is strong evidence for another non-heme iron species in part of the molecules with a Fe2+ low spin configuration. Incubation with o-phenanthroline decreases the relative Fe2+ hs-area and increases the contribution of Fe2+ ls-area. Above 210 K the mean square displacement, 2>, of the RC-crystals increases more than linearly with temperature. This may be correlated with the increase of the electron transfer rate and indicates that intramolecular mobility influences the functional activity of a protein. (orig.)

  18. Electric field gradient at 57Fe in scandium and systematics of the electric field gradient at impurities in transition-metal hosts

    The electric field gradient (EFG) at 57Fe probe atoms in hcp transition-metal scandium is measured using Moessbauer spectroscopy, with 57Fe as a dilute impurity in pure scandium metal. The quadrupole splitting obtained is 0.26(2) mm/s and the corresponding EFG is 1.3(1) x 1017 V/cm2 at the probe site in scandium. The ratio eq/sup el//eq/sup ion/ is in fairly good agreement with the universal correlation proposed by Raghavan et al. The results are compared with the theoretical value of the EFG calculated using the conduction-electron charge-shift model. Also, a systematic scheme, which can be used to determine eq/sup el/ and the sign of EFG in transition-metal hosts, is proposed

  19. The big and little of fifty years of Moessbauer spectroscopy at Argonne

    Using radioactive materials obtained by chance, a turntable employing gears from Heidelberg's mechanical toy shops, and other minimal equipment available in post World War II Germany, in 1959 Rudolf Moessbauer confirmed his suspicion that his graduate research had yielded ground-breaking results. He published his conclusion: an atomic nucleus in a crystal undergoes negligible recoil when it emits a low energy gamma ray and provides the entire energy to the gamma ray. In the beginning Moessbauer's news might have been dismissed. As Argonne nuclear physicist Gilbert Perlow noted: ''Everybody knew that nuclei were supposed to recoil when emitting gamma rays--people made those measurements every day''. If any such effect existed, why had no one noticed it before? The notion that some nuclei would not recoil was ''completely crazy'', in the words of the eminent University of Illinois condensed matter physicist Frederich Seitz. Intrigued, however, nuclear physicists as well as condensed matter (or solid state) physicists in various locations--but particularly at the Atomic Energy Research Establishment at Harwell in Britain and at Argonne and Los Alamos in the U.S.--found themselves pondering the Moessbauer spectra with its nuclear and solid state properties starting in late 1959. After an exciting year during which Moessbauer's ideas were confirmed and extended, the physics community concluded that Moessbauer was right. Moessbauer won the Nobel Prize for his work in 1961. In the 1960s and 1970s Argonne physicists produced an increasingly clear picture of the properties of matter using the spectroscopy ushered in by Moessbauer. The scale of this traditional Moessbauer spectroscopy, which required a radioactive source and other simple equipment, began quite modestly by Argonne standards. For example Argonne hosted traditional Moessbauer spectroscopy research using mostly existing equipment in the early days and equipment that cost $100,000 by the 1970s alongside work at

  20. Failure of the classical field model of Moessbauer spectroscopy

    The conventional classical treatment of the field emitted by a Moessbauer nucleus predicts an enhanced counting rate in a two-detector coincidence scheme, whereas quantum electrodynamics does not. Our experiment agrees with QED

  1. Proceedings of the 1. National Meeting of Moessbauer Spectroscopy

    Several works, both theoretical and experimental, on Moessbauer effect which have been done by Brazilian physical groups are presented in this meeting. The historical evolution of this field in Brazil is also approached. (L.C.)

  2. Transition to collapsed tetragonal phase in CaFe2As2 single crystals as seen by 57Fe Mössbauer spectroscopy

    Bud'ko, Sergey L.; Ma, Xiaoming; Tomić, Milan; Ran, Sheng; Valentí, Roser; Canfield, Paul C.

    2016-01-01

    Temperature dependent measurements of 57Fe Mössbauer spectra on CaFe2As2 single crystals in the tetragonal and collapsed tetragonal phases are reported. Clear features in the temperature dependencies of the isomer shift, relative spectra area, and quadrupole splitting are observed at the transition from the tetragonal to the collapsed tetragonal phase. From the temperature dependent isomer shift and spectral area data, an average stiffening of the phonon modes in the collapsed tetragonal phase is inferred. The quadrupole splitting increases by ˜25 % on cooling from room temperature to ˜100 K in the tetragonal phase and is only weakly temperature dependent at low temperatures in the collapsed tetragonal phase, in agreement with the anisotropic thermal expansion in this material. In order to gain microscopic insight about these measurements, we perform ab initio density functional theory calculations of the electric field gradient and the electron density of CaFe2As2 in both phases. By comparing the experimental data with the calculations we are able to fully characterize the crystal structure of the samples in the collapsed-tetragonal phase through determination of the As z coordinate. Based on the obtained temperature dependent structural data we are able to propose charge saturation of the Fe-As bond region as the mechanism behind the stabilization of the collapsed-tetragonal phase at ambient pressure.

  3. Moessbauer analysis of crystallization processes in iron-soda-lime-silicate glasses

    57Fe Moessbauer spectroscopy was used to observe the crystallization process in glasses with composition denoted by [0.50SiO2, 0.45Na2O, 0.05CaO]100-x(Fe2O3)x with x equal to 4, 10 and 16 mol%. It is shown that Moessbauer spectroscopy is a very suitable technique for detecting and checking the very early stages of crystallite formation in amorphous materials. The crystallization process was observed and qualitatively analysed by means of classical volume nucleation theory

  4. Moessbauer spectroscopy with high velocity resolution. New possibilities of chemical analysis in material science and biomedical research

    An improvement in velocity resolution of Moessbauer spectroscopy permitted us to carry out a more detailed study of iron chemical state in various iron-containing compounds in a wide range of research. New possibilities of Moessbauer spectroscopy with high velocity resolution were shown in the studies of meteorites, nanocomposites, pharmaceuticals and biological subjects. (author)

  5. Identification of Spinel Iron Oxide Nanoparticles by 57Fe NMR

    SangGap Lee

    2011-12-01

    Full Text Available We have synthesized and studied monodisperse iron oxide nanoparticles of smaller than 10 nm to identify between the two spinel phases, magnetite and maghemite. It is shown that 57Fe NMR spectroscopy is a promising tool for distinguishing between the two phases.

  6. Speciation of triphenyltin compounds using Moessbauer spectroscopy. Final report

    Eng, G.

    1993-11-01

    Organotin compounds have been used widely as the active agent in antifouling marine paints. Organotin compounds, i.e., tributyltin compounds (TBTs) and triphenyltin compounds (TPTs) have been found to be effective in preventing the unwanted attachment and development of aquatic organisms such as barnacles, sea grass and hydroids on ships, hulls and underwater surfaces. However, these organotin compounds have been found to be toxic to non-targeted marine species as well. While speciation of tributyltins in environmental water systems has received much attention in the literature, little information concerning the speciation of triphenyltins is found. Therefore, it would be important to study the fate of TPTs in the aquatic environment, particularly in sediments, both oxic and anoxic, in order to obtain speciation data. Since marine estuaries consist of areas with varying salinity and pH, it is important to investigate the speciation of these compounds under varying salinity conditions. In addition, evaluation of the speciation of these compounds as a function of pH would give an insight into how these compounds might interact with sediments in waters where industrial chemical run-offs can affect the pH of the estuarine environment. Finally, since organotins are present in both salt and fresh water environments, the speciation of the organotins in seawater and distilled water should also be studied. Moessbauer spectroscopy would provide a preferred method to study the speciation of triphenyltins as they leach from marine paints into the aquatic environment. Compounds used in this study are those triphenyltin compounds that are commonly incorporated into marine paints such as triphenyltin fluoride (TPTF), triphenyltin acetate (TPTOAc), triphenyltin chloride (TPTCl) and triphenyltin hydroxide (TPTOH).

  7. Electronic structure of the unique [4Fe-3S] cluster in O2-tolerant hydrogenases characterized by 57Fe Mossbauer and EPR spectroscopy.

    Pandelia, Maria-Eirini; Bykov, Dmytro; Izsak, Robert; Infossi, Pascale; Giudici-Orticoni, Marie-Thérèse; Bill, Eckhard; Neese, Frank; Lubitz, Wolfgang

    2013-01-01

    Iron-sulfur clusters are ubiquitous electron transfer cofactors in hydrogenases. Their types and redox properties are important for H(2) catalysis, but, recently, their role in a protection mechanism against oxidative inactivation has also been recognized for a [4Fe-3S] cluster in O(2)-tolerant group 1 [NiFe] hydrogenases. This cluster, which is uniquely coordinated by six cysteines, is situated in the proximity of the catalytic [NiFe] site and exhibits unusual redox versatility. The [4Fe-3S] cluster in hydrogenase (Hase) I from Aquifex aeolicus performs two redox transitions within a very small potential range, forming a superoxidized state above +200 mV vs. standard hydrogen electrode (SHE). Crystallographic data has revealed that this state is stabilized by the coordination of one of the iron atoms to a backbone nitrogen. Thus, the proximal [4Fe-3S] cluster undergoes redox-dependent changes to serve multiple purposes beyond classical electron transfer. In this paper, we present field-dependent (57)Fe-Mössbauer and EPR data for Hase I, which, in conjunction with spectroscopically calibrated density functional theory (DFT) calculations, reveal the distribution of Fe valences and spin-coupling schemes for the iron-sulfur clusters. The data demonstrate that the electronic structure of the [4Fe-3S] core in its three oxidation states closely resembles that of corresponding conventional [4Fe-4S] cubanes, albeit with distinct differences for some individual iron sites. The medial and distal iron-sulfur clusters have similar electronic properties as the corresponding cofactors in standard hydrogenases, although their redox potentials are higher. PMID:23267108

  8. Study of iron exchanged zeolites by Moessbauer effect and electron spin resonance spectroscopy

    Crystalline iron exchanged NaY zeolites, prepared from aqueous solutions and calcined at atmospheric conditions, have been studied and characterized by XRD, Moessbauer and EPR spectroscopies and TGA analysis. Three iron sites are clearly distinguished from Moessbauer and EPR measurements. Firstly, characteristic Moessbauer and EPR spectra may arise from framework sites, suggesting that Fe has substituted Al. It is also found that their spectroscopic signals are not intensity affected by thermal treatments. Secondly, a Moessbauer doublet which may arise from octahedral sites in the large cavity of the zeolite, shows however, that this doublet and its EPR signal are intensity temperature affected. An additional line broadening is observed on the low velocity line of this doublet, Thirdly, characteristic Moessbauer and EPR signals, which are also intensity temperature dependent have been associated to accluded material, where the Moessbauer doublet presents the line broadening effect before mentioned. Such line broadening effect may be due to perturbing signals from iron ions in tetrahedral sites. Finally, it has been observed that during calcination of the FeY zeolites, the three characteristic EPR signals for the three iron sites, do not increase at the expenses of the other. A result that may suggest a strong bonding between Fe-site of the Y zeolite, irrespective of the iron source. (Author)

  9. The 57Fe hyperfine interactions in the iron bearing phases in different fragments of Chelyabinsk LL5 meteorite: a comparative study using Mössbauer spectroscopy with a high velocity resolution

    A comparative study of the 57Fe hyperfine interactions in iron bearing phases of Chelyabinsk LL5 ordinary chondrite fragments with different lithology was carried out using Mössbauer spectroscopy with a high velocity resolution. The obtained values of hyperfine parameters for the same iron bearing phases in different fragments demonstrated small variations. These differences were related to small variations in the Fe local microenvironments in both M1 and M2 sites in olivine and pyroxene, to deviation from stoichiometry in troilite with increase in Fe vacancies and to differences in Ni concentrations in α-Fe(Ni, Co) and γ-Fe(Ni, Co) phases in the metal grains. The obtained differences may indicate a breccia structure of Chelyabinsk LL5 ordinary chondrite

  10. Fe-implanted 6H-SiC: Direct evidence of Fe{sub 3}Si nanoparticles observed by atom probe tomography and {sup 57}Fe Mössbauer spectroscopy

    Diallo, M. L.; Fnidiki, A., E-mail: abdeslem.fnidiki@univ-rouen.fr; Lardé, R.; Cuvilly, F.; Blum, I. [Groupe de Physique des Matériaux, Université et INSA de Rouen - UMR CNRS 6634 - Normandie Université. F-76801 Saint Etienne du Rouvray (France); Lechevallier, L. [Groupe de Physique des Matériaux, Université et INSA de Rouen - UMR CNRS 6634 - Normandie Université. F-76801 Saint Etienne du Rouvray (France); Département de GEII, Université de Cergy-Pontoise, rue d' Eragny, Neuville sur Oise, 95031 Cergy-Pontoise (France); Debelle, A.; Thomé, L. [Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), CNRS-IN2P3-Univ. Paris-Sud 11, Bât. 108, 91405 Orsay (France); Viret, M. [Service de Physique de l' Etat Condensé (DSM/IRAMIS/SPEC), UMR 3680 CNRS, Bât. 772, Orme des Merisiers, CEA Saclay 91191 Gif sur Yvette (France); Marteau, M.; Eyidi, D.; Declémy, A. [Institut PPRIME, UPR 3346 CNRS, Université de Poitiers, ENSMA, SP2MI, téléport 2, 11 Bvd M. et P. Curie 86962 Futuroscope, Chasseneuil (France)

    2015-05-14

    In order to understand ferromagnetic ordering in SiC-based diluted magnetic semiconductors, Fe-implanted 6H-SiC subsequently annealed was studied by Atom Probe Tomography, {sup 57}Fe Mössbauer spectroscopy and SQUID magnetometry. Thanks to its 3D imaging capabilities at the atomic scale, Atom Probe Tomography appears as the most suitable technique to investigate the Fe distribution in the 6H-SiC host semiconductor and to evidence secondary phases. This study definitely evidences the formation of Fe{sub 3}Si nano-sized clusters after annealing. These clusters are unambiguously responsible for the main part of the magnetic properties observed in the annealed samples.

  11. Iron-zirconium oxide catalysts for the hydrogenation of carbon monoxide: In situ studies by iron-57 Moessbauer spectroscopy

    Some unsupported iron-zirconium oxide catalysts have been prepared by the calcination in air of precipitates containing 15 mole% iron. The catalyst formed at 5000C was shown by powder X-ray diffraction to consist of a non-equilibriated solid solution of iron(III) in a tetragonal or cubic zirconium dioxide structure whereas the catalyst formed at 10000C was found to contain a zirconium-doped α-iron(III) oxide, or a magnetically ordered iron-zirconium oxide, in combination with an iron-containing monoclinic polymorph of zirconium dioxide. The 57Fe Moessbauer spectra recorded in situ following the pretreatment of the solids in nitrogen, carbon monoxide and hydrogen showed that little change is induced in the catalysts under such conditions. The 57Fe Moessbauer spectra also showed that the pretreated catalysts were unchanged by exposure to a 1:1 mixture of carbon monoxide and hydrogen at 2700C and 1 atmosphere pressure but were partially converted to iron carbide when used for the hydrogenation of carbon monoxide at 3300C and at 20 atmospheres pressure. The hydrocarbon product distribution showed Schulz-Flory α-values of 0.73 to 0.76 which were higher than the α-values obtained from pure iron catalysts which had been prepared and pretreated in a similar fashion. The 57Fe Moessbauer spectra and the results of the catalytic evaluation may be associated with an interaction between zirconium(IV) and the electron-rich atoms of the reactant carbon monoxide. (orig.)

  12. Moessbauer and infrared spectroscopy as a diagnostic tool for the characterization of ferric tannates

    Jaen, Juan A., E-mail: jjaen@ancon.up.ac.p [Universidad de Panama, Depto. de Quimica Fisica, CITEN, Lab. No. 105, Edificio de Laboratorios Cientificos-VIP (Panama); Navarro, Cesar [Universidad de Panama, Escuela de Quimica, Facultad de Ciencias Naturales, Exactas y Tecnologia (Panama)

    2009-07-15

    Fourier transform infrared spectroscopy and Moessbauer spectroscopy are use for the characterization and qualitative analysis of hydrolysable and condensed tannates. The two classes of tannates may be differentiated from the characteristic IR pattern. Moessbauer proof that a mixture of mono- and bis-type ferric tannate complexes, and an iron(II)-tannin complex are obtained from the interaction of hydrolysable tannins (tannic acid and chestnut tannin) and condensed tannins (mimosa and quebracho) with a ferric nitrate solution. At pH 7, a partially hydrolyzed ferric tannate complex was also obtained.

  13. Moessbauer and infrared spectroscopy as a diagnostic tool for the characterization of ferric tannates

    Fourier transform infrared spectroscopy and Moessbauer spectroscopy are use for the characterization and qualitative analysis of hydrolysable and condensed tannates. The two classes of tannates may be differentiated from the characteristic IR pattern. Moessbauer proof that a mixture of mono- and bis-type ferric tannate complexes, and an iron(II)-tannin complex are obtained from the interaction of hydrolysable tannins (tannic acid and chestnut tannin) and condensed tannins (mimosa and quebracho) with a ferric nitrate solution. At pH 7, a partially hydrolyzed ferric tannate complex was also obtained.

  14. Atmospheric Corrosion on Steel Studied by Conversion Electron Moessbauer Spectroscopy

    In order to investigate initial products on steel by atmospheric corrosion, conversion electron Moessbauer measurements were carried out at temperatures between 15 K and room temperature. From the results obtained at low temperatures, it was found that the corrosion products on steel consisted of ferrihydrite.

  15. Study of chicken liver and spleen by Moessbauer spectroscopy

    A preliminary study of purified normal human liver ferritin, normal chicken liver and spleen tissues in lyophilized form showed differences in room temperature Moessbauer hyperfine parameters. An additional study of liver and spleen tissues with lower iron content from chicken with lymphoid leukemia indicated small differences between the quadrupole splittings in these samples compared with those in normal tissues.

  16. Application of Moessbauer spectroscopy to study archaeological Egyptian pottery

    Moessbauer spectra have been used as ''fingerprints'' in obtaining information an ancient Egyptian pottery and in fine art. An empirical relation has been found that connects the natural radiation dose with the intensity ratio of the two non-magnetic central peaks. It was suggested that this relation be used for dating ancient pottery. 8 refs, 13 figs, 2 tabs

  17. Moessbauer study of natural iron-oxide complexes

    Typical Fe-oxide complex assemblage in rock samples taken from Lake Victoria Goldfield in Tanzania was studied using Moessbauer spectroscopy between room temperature and 4.2 K. The room temperature Moessbauer spectrum of a typical rock sample from the region is a mixture of two-line patterns and a six-line pattern. At 200 K the two-line pattern starts to develop into a rather asymmetric, broad width six-line pattern which at 4.2 K has hyperfine field, B82, of about 50 T, δ = -0.20 mm/s and δ= 0.24 mm/s. The analysis of the 57Fe-Moessbauer spectra shows that the rock sample is composed of hexagonal pyrrhotite, amphibole silicate and α-FeOOH. Details of the characterisation of the phases of the Fe-oxide complex, α-FeOOH is the basis of the report

  18. Systematic study of mechanical deformation on Fe3AlxSi1-x powders by Moessbauer spectroscopy

    The Moessbauer technique has been used to measure hyperfine magnetic fields, isomer shifts and relative areas of 57Fe atoms located at various sites in Fe3AlxSi1-x series with x = 0, 0.3, 0.5, 0.7. Four samples were crushed; then they were annealed for 10 h at 1,023 K and cooled down at 3o/min in order to recover the DO3 stable phase. Moessbauer studies revealed that annealed samples have a DO3 structure, whereas deformed samples are partially disordered, with both ordered DO3 and disordered A2 structures, even though X-rays measurements do not show superstructure peaks. The amount of disordered structure decreases with Si content.

  19. Moessbauer study of iron uptake in cucumber root

    57Fe Moessbauer spectroscopy was used to study the uptake and distribution of iron in the root of cucumber plants grown in iron-deficient modified Hoagland nutrient solution and put into iron-containing solution with 10 μM Fe citrate enriched with 57Fe (90%) only before harvesting. The Moessbauer spectra of the frozen roots exhibited two Fe3+ components with typical average Moessbauer parameters of δ = 0.5 mm s-1, Δ = 0.46 mm s-1 and δ = 0.5 mm s-1, Δ = 1.2 mm s-1 at 78 K and the presence of an Fe2+ doublet, assigned to the ferrous hexaaqua complex. This finding gives a direct evidence for the existence of Fe2+ ions produced via root-associated reduction according to the mechanism proposed for iron uptake for dicotyledonous plants. Monotonous changes in the relative content of the components were found with the time period of iron supply. The Moessbauer results are interpreted in terms of iron uptake and transport through the cell wall and membranes.

  20. The big and little of fifty years of Moessbauer spectroscopy at Argonne.

    Westfall, C.

    2005-09-20

    Using radioactive materials obtained by chance, a turntable employing gears from Heidelberg's mechanical toy shops, and other minimal equipment available in post World War II Germany, in 1959 Rudolf Moessbauer confirmed his suspicion that his graduate research had yielded ground-breaking results. He published his conclusion: an atomic nucleus in a crystal undergoes negligible recoil when it emits a low energy gamma ray and provides the entire energy to the gamma ray. In the beginning Moessbauer's news might have been dismissed. As Argonne nuclear physicist Gilbert Perlow noted: ''Everybody knew that nuclei were supposed to recoil when emitting gamma rays--people made those measurements every day''. If any such effect existed, why had no one noticed it before? The notion that some nuclei would not recoil was ''completely crazy'', in the words of the eminent University of Illinois condensed matter physicist Frederich Seitz. Intrigued, however, nuclear physicists as well as condensed matter (or solid state) physicists in various locations--but particularly at the Atomic Energy Research Establishment at Harwell in Britain and at Argonne and Los Alamos in the U.S.--found themselves pondering the Moessbauer spectra with its nuclear and solid state properties starting in late 1959. After an exciting year during which Moessbauer's ideas were confirmed and extended, the physics community concluded that Moessbauer was right. Moessbauer won the Nobel Prize for his work in 1961. In the 1960s and 1970s Argonne physicists produced an increasingly clear picture of the properties of matter using the spectroscopy ushered in by Moessbauer. The scale of this traditional Moessbauer spectroscopy, which required a radioactive source and other simple equipment, began quite modestly by Argonne standards. For example Argonne hosted traditional Moessbauer spectroscopy research using mostly existing equipment in the early days and

  1. Moessbauer Spectroscopic Study of a Mural Painting from Morgadal Grande, Mexico

    Kuno, A.; Matsuo, M. [University of Tokyo, Graduate School of Arts and Sciences (Japan); Soto, A. Pascual [Universidad Nacional Autonoma de Mexico, Instituto de Investigaciones Esteticas (Mexico); Tsukamoto, K. [Escuela Nacional de Antropologia e Historia (Mexico)

    2004-12-15

    In this study, {sup 57}Fe Moessbauer spectroscopy has been applied to fragments of a mural painting excavated at Morgadal Grande, Mexico, to characterize the pigments used. A sextet attributable to hematite ({alpha}-Fe{sub 2}O{sub 3}) was clearly detected in the red fragments. The spectra of orange fragments showed a doublet attributable to paramagnetic high-spin Fe{sup 3+}, which presumably originates from goethite ({alpha}-FeOOH) exhibiting superparamagnetic relaxation due to its small particle size. The blue fragments contained little iron. The scattered X-ray Moessbauer spectra revealed that the thickness of the pigments was larger than 20 {mu}m.

  2. Moessbauer Spectroscopic Study of a Mural Painting from Morgadal Grande, Mexico

    In this study, 57Fe Moessbauer spectroscopy has been applied to fragments of a mural painting excavated at Morgadal Grande, Mexico, to characterize the pigments used. A sextet attributable to hematite (α-Fe2O3) was clearly detected in the red fragments. The spectra of orange fragments showed a doublet attributable to paramagnetic high-spin Fe3+, which presumably originates from goethite (α-FeOOH) exhibiting superparamagnetic relaxation due to its small particle size. The blue fragments contained little iron. The scattered X-ray Moessbauer spectra revealed that the thickness of the pigments was larger than 20 μm.

  3. Magnetite nanoparticles as-prepared and dispersed in Copaiba oil: study using magnetic measurements and Moessbauer spectroscopy

    Oshtrakh, Michael I., E-mail: oshtrakh@gmail.com; Ushakov, Mikhail V. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation); Semenova, Anna S.; Kellerman, Dina G. [Institute of Solid State Chemistry, Ural Branch, Russian Academy of Sciences (Russian Federation); Sepelak, Vladimir [Institute of Nanotechnology, Karlsruhe Institute of Technology (Germany); Rodriguez, Alfonso F. R. [Universidade Federal do Acre (Brazil); Semionkin, Vladimir A. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation); Morais, Paulo C. [Universidade de Brasilia, Instituto de Fisica, Nucleo de Fisica Aplicada (Brazil)

    2013-04-15

    Study of magnetite nanoparticles, as-prepared and dispersed in Copaiba oil as magnetic fluid, by means of magnetic measurement and Moessbauer spectroscopy at various temperatures demonstrated differences in the saturation magnetization and Moessbauer hyperfine parameters which were related to the interactions of Copaiba oil polar molecules with iron cations on magnetite nanoparticle's surface.

  4. Use of Moessbauer spectroscopy to determine the effect of salinity on the speciation of triorganotins in Anacostia River sediments

    Eng, George; Song Xueqing [University of the District of Columbia, Department of Chemistry and Physics and Agricultural Experimental Station (United States); May, Leopold, E-mail: may@cua.edu [Catholic University of America, Department of Chemistry (United States)

    2006-06-15

    The speciation of several tributyltin and triphenyltin compounds under varying salinity conditions (0, 20, 40 and 60%) was studied by Moessbauer spectroscopy in both anaerobic and aerobic Anacostia River sediments. The Moessbauer spectral parameters of the spiked sediments indicated that changes in the salinity did not affect the speciation of the tin compounds in either aerobic or anaerobic sediments.

  5. Research field development ou iron-sulfur proteins by the Moessbauer spectroscopy and EPR

    A research line on iron sulfides (chemical and structurally seemed with the iron-sulfur proteins), implanted and developed at CBPF-Brazil, using the same theoretical and experimental models used in the development of the research field on iron-sulfur proteins is reported. The techniques used are Moessbauer spectroscopy and EPR. (L.C.)

  6. Moessbauer spectroscopy phase analysis of the products of oxidative leaching of pyrrhotite

    Using Moessbauer spectroscopy, Fe3O4, γ-Fe2O3 and α-Fe2O3 were found to be the main products of autoclave oxidative leaching of pyrrhotite concentrates, and not hydroxides as suggested earlier. The samples of pulp (solid:liquid ratio 1:1) were investigated without any preliminary treatment. (T.I.)

  7. Moessbauer conversion spectroscopy measurements at 182 W and 145 Pm

    Taking advantage of the constancy in counting-rate of a Moessbauer-conversion spectrometer a relatively high effect could be obtained and it was possible to determine the electronic isotopic-shift in other, not enriched, compounds of 182W. The negative sign of the mean quadratic charge radius, Δ2>, found by Wagner in a transmission-experiment, could be reproduced. In the Moessbauer-conversion-spectrometer only a very small amount of absorber-material is necessary, so that radioactive isotopes not existing in nature can be measured. The resonance-absorption of the 61 keV-transition in 145Pm was observed for the first time. The lifetime of the 61 keV level was extracted from the line width and leads to a value Tsub(1/2) = (1.0 + 0.4/-0.2)ns. (orig./WBU)

  8. Determination of Spin State in Dinuclear Iron(II) Coordination Compounds Using Applied Field Moessbauer Spectroscopy

    So far there has been no direct method to determine the spin state of molecules in dinuclear iron(II) compounds. The molecular fractions of high spin (HS) and low spin (LS) species have been deduced from magnetic susceptibility and zero field Moessbauer spectroscopy data irrespective of whether they belong to LS-LS, LS-HS and HS-HS pairs. However, the distinction of pairs becomes possible if Moessbauer measurements are carried out in an external magnetic field. The proposed method opens new possibilities in the study of spin crossover phenomena in dinuclear compounds.

  9. Fermi level dependence of Moessbauer spectroscopic components corresponding to iron interstitials and their clusters in silicon

    57Fe deposited p- and n-type float-zone Si are studied by high temperature Moessbauer spectroscopy. After the deposition the spectra obtained at room temperature indicate that 57Fe atoms are migrating already, and forming the components due to interstitial, substitutional Fe and other clusters in Si. A measurement, i.e., simultaneously an annealing at 1273 K for about 10 days leads further to the diffusion of 57Fe atoms into a deeper part of the matrix. The spectra depend not only on the dopants and their concentrations, but also on temperature. This Fermi level dependence will provide us information on the charge states of each Fe component in Si matrix, and therefore their energy levels

  10. Moessbauer and XRD investigations of layered double hydroxides (LDHs) with varying Mg/Fe ratios

    Sipiczki, Monika [University of Szeged, Department of Inorganic and Analytical Chemistry (Hungary); Kuzmann, Erno, E-mail: kuzmann@ludens.elte.hu; Homonnay, Zoltan [Eoetvoes Lorand University, Institute of Chemistry (Hungary); Megyeri, Jozsef [Centre for Energy Research, Hungarian Academy of Sciences (Hungary); Kovacs, Krisztina [Eoetvoes Lorand University, Institute of Chemistry (Hungary); Palinko, Istvan [University of Szeged, Department of Organic Chemistry (Hungary); Sipos, Pal [University of Szeged, Department of Inorganic and Analytical Chemistry (Hungary)

    2013-04-15

    The effects of the Mg(II)/Fe(III) ratio on the structure and Fe microenvironments in MgFe LDH substances were investigated. The LDHs were prepared by the co-precipitation method with Mg(II)/Fe(III) ratios from 2:1 to 6:1. The materials were characterized by {sup 57}Fe Moessbauer spectroscopy and powder X-ray diffractometry. The {sup 57}Fe Moessbauer spectra exhibited asymmetric doublet corresponding to high-spin Fe(III) microenvironments in all LDH structure. It was found that the quadrupole splitting decreased with increasing Mg(II)/Fe(III)ratio reflecting change in the electric field gradient due to the incorporation of different amounts of iron into the Mg-containing layers.

  11. Moessbauer spectroscopy of the nano-dimensional powders of composites Fe-C and its compact received under high temperatures and pressure up to 5.0 GPa

    Nano dimensional encapsulated by carbon powders of Fe were obtained by mechan o-chemical reaction method. Using the apparatus of synthesis under high pressures (p ∼5.0 GPa) and temperatures from these powders containing diamond carbon modification and iron carbide Fe3C magnetic composites were received. Moessbauer study showed that initial material at T1 contains α-Fe and the carbide Fe3C. The analysis of obtained Moessbauer spectra 57Fe in Fe-C matrix let to see at T1, T5 the presence of a small quantity of the intermediate carbides which one can see at T2, T3, T4. The Moessbauer spectrum at T5 contains the pronounced Zeeman hyperfine 57Fe splitting in carbide Fe3C and the singlet with the isomeric shift δ1.3 mm/s. At the T1, T2, T3, T4 temperatures the Moessbauer study is more informative than X-ray analysis. The well correlation between the Moessbauer study, X-ray diffractions and temperature specific magnetization dependences study is observed

  12. Moessbauer spectroscopy with a high velocity resolution: advances in biomedical, pharmaceutical, cosmochemical and nano technological research

    Oshtrakha, M.I., E-mail: oshtrakh@mail.utnet.ru [Faculty of Physical Techniques and Devices for Quality Control, Ural Federal University, Ekaterinburg (Russian Federation); Semionkina, V.A. [Faculty of Experimental Physics, Ural Federal University, Ekaterinburg (Russian Federation)

    2011-07-01

    Full text: Velocity resolution is a term denoted the smallest velocity step (2V/2{sup n}) in velocity driving system of Moessbauer spectrometer and velocity step for the one point in Moessbauer spectrum. Velocity resolution coefficient 1/2{sup n} in velocity driving system is constant and velocity resolution value depends on velocity range (2V) only while velocity resolution in Moessbauer spectrum may be the same or less. Moessbauer spectroscopy with a high velocity resolution is a new method to measure precision high quality spectra. It is well known that one of the main parts of Moessbauer spectrometer is velocity driving system. Usual spectrometers are used sinusoidal or triangular velocity reference signal and 256 or 512 channels to form velocity signal. Such velocity driving system provides spectra measurement with a low velocity resolution (2{sup n}=256 or 512 channels) with possibility to decrease measurement time and reach needed signal/noise ratio by spectra folding on the direct and reverse motion. However, these driving systems do not provide a low systematic error for velocity signal while folding increases integral velocity error due to different velocity errors on the direct and reverse motions. These problems can be neglected if a high precision is not required for spectra measurement. Nevertheless, further development of Moessbauer spectroscopy may be related to increase in precision and quality of spectra measurement with less instrumental (systematic) velocity error and to increase in velocity resolution for both spectrometer and spectrum. A new velocity driving system was developed for Moessbauer spectrometer SM- 2201. This system uses saw-tooth shape velocity reference signal and 2{sup n}=4096 channels to form velocity signal. On the basis of SM-2201 and liquid nitrogen cryostat with moving absorber and temperature variation in the range of 295-85 K a new automated precision Moessbauer spectrometric system with a high velocity resolution was

  13. Thermodynamic Properties of $^{56,57}$Fe

    Algin, E; Guttormsen, M; Larsen, A C; Mitchell, G E; Rekstad, J; Schiller, A; Siem, S; Voinov, A

    2008-01-01

    Nuclear level densities for $^{56,57}$Fe have been extracted from the primary $\\gamma$-ray spectra using ($^3$He,$^3$He$^{\\prime}\\gamma$) and ($^3$He,$\\alpha \\gamma$) reactions. Nuclear thermodynamic properties for $^{56}$Fe and $^{57}$Fe are investigated using the experimental level densities. These properties include entropy, Helmholtz free energy, caloric curves, chemical potential, and heat capacity. In particular, the breaking of Cooper pairs and single-quasiparticle entropy are discussed and shown to be important concepts for describing nuclear level density. Microscopic model calculations are performed for level densities of $^{56,57}$Fe. The experimental and calculated level densities are compared. The average number of broken Cooper pairs and the parity distribution are extracted as a function of excitation energy for $^{56,57}$Fe from the model calculations.

  14. Study of the roasting of pyrite minerals by Moessbauer spectroscopy

    Kinetics of the roasting process of pyrite minerals are studied by observing Moessbauer spectra and X-ray diffraction of pyrite minerals roasted at (610 +- 5) 0C for time periods t = 0.0, 0.5, 1.0, 2.0, 5.0, 15.0, 30.0, and 60.0 minutes. These studies indicate an optimum time period (t) for an efficient transformation of pyrite into the magnetic oxides α-Fe2O3 and γFe2O3. (author)

  15. Moessbauer spectroscopy description of limonite from Taraco, in the Huancane Province of the Puno Region, Peru

    Bustamante, A., E-mail: abustamanted@unmsm.edu.pe [San Marcos National University, School of Physical Sciences (Peru); Cabrera, J.; Garcia, V.; Urday, E. [Saint Augustine National University in Arequipa, Electron Microscopy Center (Peru); Abdu, Y. A.; Scorzelli, R. B. [Centro Brasileiro de Pesquisas Fisicas (Brazil)

    2005-11-15

    Natural iron oxides are very common in nature and are the main components of many minerals, rocks and soils. There are a great variety of these minerals in Peru, especially in the Andes region. The mineral studied was extracted from the Taraco District in the Huancane Province of the Puno Region. The extracted sample is a yellowish mineral with very small particles which is called limonite. X-ray diffraction indicates the presence of goethite as the principal mineralogical phase and quartz as the secondary phase. The {sup 57}Fe Moessbauer spectra at room temperature show broadened spectra that were fitted using a distribution model. The most probable field of the magnetic component is 21T, corresponding to the presence of small particles of goethite, confirmed by the 4.2 K spectrum. MS of the calcinated sample in air at 900 deg. C show the presence of two hematite sextets, one related to bulk particles and another to surface particles. Chemical analysis using Scanning Electron Microscopy and Energy Dispersive X-ray Spectrometer indicates that O and Fe are the major components; other elements such as Al, Si, Mg and Ca are also present.

  16. Moessbauer spectroscopy description of limonite from Taraco, in the Huancane Province of the Puno Region, Peru

    Natural iron oxides are very common in nature and are the main components of many minerals, rocks and soils. There are a great variety of these minerals in Peru, especially in the Andes region. The mineral studied was extracted from the Taraco District in the Huancane Province of the Puno Region. The extracted sample is a yellowish mineral with very small particles which is called limonite. X-ray diffraction indicates the presence of goethite as the principal mineralogical phase and quartz as the secondary phase. The 57Fe Moessbauer spectra at room temperature show broadened spectra that were fitted using a distribution model. The most probable field of the magnetic component is 21T, corresponding to the presence of small particles of goethite, confirmed by the 4.2 K spectrum. MS of the calcinated sample in air at 900 deg. C show the presence of two hematite sextets, one related to bulk particles and another to surface particles. Chemical analysis using Scanning Electron Microscopy and Energy Dispersive X-ray Spectrometer indicates that O and Fe are the major components; other elements such as Al, Si, Mg and Ca are also present.

  17. Investigation of iron-containing complexes of deoxyribonucleic acid nucleosides by Moessbauer spectroscopy

    DNA and nucleoside complexes with ferric and ferrous ions were investigated for the concentration of iron ions, ionic strength, temperature, and the nature and spatial configuration of neighbouring atoms of the iron ions in the complexes. Moessbauer spectroscopy was used. The Moessbauer measurements were conducted on lyophilized samples at room temperature (300 K) and on frozen solutions at liquid nitrogen temperature (77 K). Quadrupole splitting was found in all spectra obtained by a Pd(Co) source, with the exception of thymidine, thus indicating that the formation of complexes had not affected the oxidation state of iron ions. A decrease in isomer shift and an increase in quadrupole splitting were found in all spectra obtained by an iron(III) chloride source as well as in all spectra obtained by an iron chloride tetrahydrate source. UV irradiation of the samples prior to the Moessbauer measurements was found to have no effect on the Moessbauer spectra but to result in changes in the oxidation state of iron ions, mainly their valency and the ferrous/ferric ion ratio. The results are shown in a table and in graphs. (L.O.)

  18. Early Pottery Making in Northern Coastal Peru. Part I: Moessbauer Study of Clays

    We report on an investigation of several ancient clays which were used for pottery making in northern coastal Peru at a kiln site from the Formative period (ca. 2000-800 BC) in the Poma Canal and at a Middle Sican pottery workshop in use between ca. AD 950 and 1050 at Huaca Sialupe in the lower La Leche valley. Neutron activation analysis, 57Fe Moessbauer spectroscopy and X-ray diffraction were used for the characterisation of the clays. The changes that occur in iron-bearing compounds in the clays depending on the kiln atmosphere and on the maximum firing temperature were studied by Moessbauer spectroscopy and X-ray diffraction. Laboratory firing series under varying controlled conditions were performed to obtain a basic understanding of the different reactions taking place in the clays during firing. The results can be used as models in the interpretation of the Moessbauer spectra observed in ancient ceramics from the same context.

  19. Early Pottery Making in Northern Coastal Peru. Part I: Moessbauer Study of Clays

    Shimada, I. [Southern Illinois University (United States); Haeusler, W.; Hutzelmann, T.; Wagner, U. [Technische Universitaet Muenchen, Physik-Department E15 (Germany)

    2003-09-15

    We report on an investigation of several ancient clays which were used for pottery making in northern coastal Peru at a kiln site from the Formative period (ca. 2000-800 BC) in the Poma Canal and at a Middle Sican pottery workshop in use between ca. AD 950 and 1050 at Huaca Sialupe in the lower La Leche valley. Neutron activation analysis, {sup 57}Fe Moessbauer spectroscopy and X-ray diffraction were used for the characterisation of the clays. The changes that occur in iron-bearing compounds in the clays depending on the kiln atmosphere and on the maximum firing temperature were studied by Moessbauer spectroscopy and X-ray diffraction. Laboratory firing series under varying controlled conditions were performed to obtain a basic understanding of the different reactions taking place in the clays during firing. The results can be used as models in the interpretation of the Moessbauer spectra observed in ancient ceramics from the same context.

  20. Studies by X-ray diffraction and Moessbauer spectroscopy of ceramics from the Nasca culture

    We have studied a set of ceramic fragments from Nasca culture (Ica - Peru) by X-ray diffraction and Moessbauer spectroscopy to obtain information on the technology used in their preparation. The results suggest that the firing temperature of Nasca pottery was between 700 oC and 900 oC. Because the studied fragments comes from a museum, and no from excavation, thermoluminescence and optical stimulated luminescence was applied to verify the authenticity of the pieces. (orig.)

  1. XII International conference Moessbauer spectroscopy and its applications. Collection of materials

    The collection contains materials of XII International conference Moessbauer spectroscopy and its applications (ICMSA-2012). Materials are presented in the sections: Solid-state physics and magnetism; Surface structure of thin films, multilayered and nanosized systems; New materials and intense effects on a substance (thermal, radiation, deformation, etc.); Applications in biology and medicine; Chemistry, catalysis, structure and interaction; Geology and mineralogy; Synchrotron radiation and gamma optics; New experimental methods and techniques

  2. Cryogenic resonance-electron Moessbauer spectroscopy with a helium-filled proportional counter

    As studied in our previous works,a proportional counter filled with pure helium gas works well at low temperatures near 4.2 K. The helium-filled proportional counter (HFPC) provides us with method to detect nuclear radiations at low temperatures. A typical application of this counter is resonance-electron Moessbauer spectroscopy (REMS) at low temperatures (<∼30 K). In this article some examples of REMS measurements with HFPC are given. (author)

  3. Dynamics of biomoleculars studied by Rayleigh scattering of Moessbauer radiation and Moessbauer spectroscopy

    This paper reports on dynamics of biomoleculars, proteins and DNA that plays a role in the supply and the regulation their functional activity, for example, like transducers of oxygen, like enzymes, in photosynthesis and so on. The Mossbauer spectroscopy (MS) and especially Rayleigh Scattering of Mossbauer Radiation (RSMR) permit to obtain the quantitative data on dimensions and times of complex hierarchy of motion in biopolymers and to create correspondent functional models. The scheme of RSMR includes Mossbauer source 57Co, the scatterer---biopolymer, the detector and Mossbauer analyzer (Black absorber---or one-line absorber), that situated before and after the scatterer on definite angle -2θ

  4. Study of iron ore in Wadi Shatti by using Moessbauer spectroscopy

    Several techniques such as Moessbauer spectroscopy, x-ray diffraction, and chemical analysis were used to identify the iron phases present in iron ore from Wadi Shatti. Three representative samples from different locations were selected. X-ray result of sample A shows that siderite is the main phase. magnetite, silicate and iron sulphide exist in small amounts. Moessbauer spectroscopy at room temperature shows the presence of all the above mentioned phases. X-ray result of sample B shows a large amount of titanium and iron phosphate, and magnetite and silicate. These constituents of sample B, except titanium were detected by Moessbauer spectroscopy. X-ray result of sample c shows that the main phases are goethite, siderite and silicate, and small amount og magnetite. The Moessbauer results showed the sam x-ray results except magnetite. The goethite, which appears as four sextets with hyperfine fields of 37.5, 36.5, 34.12 and 30.45 tesla, respectively, is the major phase. Iron compounds in the samples were converted to the element Fe after reduction in hydrogen gas for 5.5 hrs. at a temperature of 550 degree centigrade except a small portion of silicates. A calcination process for 72 hrs at 500 degree centigrade leads to faster reduction of iron ore samples to the elemental form of iron α-ironwhich in turn contained less impurities (which was attributed to silicates) than direct reduction of the samples. Comparing these results with an iron ore sample from the region of East Awinat Mountains in Libya will be very useful to industry, in order to make a decision to get benefit of this huge resource of iron ore. Indeed present results confirmed the complexity of Wadi Shatti samples but it is not impossible, with more effort is needed, to become useful resource. (author)

  5. 119Sn Moessbauer spectroscopy of tin containing float glass

    According to the production process of float glasses tin is used as a common refining agent. Since the surface quality of the glass strongly depends on the local distribution of Sn-redox states, the influence of process parameters on Sn2+/Sn4+ ratios and the assignment to their structural role in the glass network is extremely helpful. Therefore, glass compositions based on SiO2-Al2O3-B2O3-CaO-SnO2 were molten with additions of 0,1, 0,3 and 0,5 wt% SnO2. All samples were tempered for 7 days at 1400 C in N2 and N2-air mixtures with controlled pO2-values of 10-2 and 10-5 bar, respectively. Hyperfine parameters for the tin nucleus in different structural units and their oxidation states were calculated from 119Sn Moessbauer spectra, using theoretical simulations of electron densities and electric field gradients with the Wien2k software. Finally, the thermochemical impact of oxygen on the structure of Sn-bearing glasses is discussed

  6. Mineral identification in Colombian coals using Moessbauer spectroscopy and X-ray diffraction

    Fajardo, M. [Universidad del Valle, A.A, Departamento de Fisica (Colombia); Mojica, J. [Instituto Nacional de Investigaciones en Geociencia, Mineria y Quimica (INGEOMINAS) (Colombia); Barraza, J. [Universidad del Valle, A.A, Departamento de Procesos Quimicos, Facultad de Ingenieria (Colombia); Perez Alcazar, G.A.; Tabares, J.A. [Universidad del Valle, A.A, Departamento de Fisica (Colombia)

    1999-11-15

    Minerals were identified in three Colombian coal samples from the Southwest of the country using Moessbauer spectroscopy and X-ray diffraction. Original and sink separated coal fractions of specific gravity 1.40 and 1.60 with particle size less than 600 {mu}m were used in the study. Using Moessbauer spectroscopy, the minerals identified in the original coal samples were pyrite jarosite, ankerite, illite and ferrous sulfate, whereas by means of X-ray diffraction, minerals identified were kaolinite, quartz, pyrite, and jarosite. Differences in mineral composition were found in the original and sink separated fractions using both techniques. Moessbauer spectra show that the mineral phases in low concentrations such as illite, ankerite and ferrous sulfate do not always appear in the spectra of sink coals, despite of those minerals occurring in the original coal, due to the fact that they are associated with the organic matter and not liberated in the grinding process. X-ray results show that the peak intensity grows as the specific gravity is increased indicating that the density separation method could be an effective process to clean coal.

  7. Fe mineralogy of rocks from the Vredefort impact structure investigated with Moessbauer spectroscopy

    The Vredefort impact structure in South Africa is the largest and oldest remnant impact structure on Earth. Observations from above the crater reveal lower than average magnetic field intensities, but the rocks in the crater have been shown to possess much higher magnetic intensities than the regional average that varies on a centimeter scale. Various mechanisms, including the presence of single domain magnetite structures, have been proposed for this anomaly. Moessbauer spectroscopy has been applied to study the Fe-mineralogy of samples from near the centre of the Vredefort crater. Transmission Moessbauer measurements on bulk and microtomics sections of samples showed that the magnetic minerals were magnetite and hematite, and we suggest that oxidation of olivine during the impact is responsible for the magnetic properties of the rocks.

  8. Characterization of mineral phases of agricultural soil samples of Colombian coffee using Moessbauer spectroscopy and X-ray diffraction

    Rodriguez, Humberto Bustos, E-mail: hbustos@ut.edu.co; Lozano, Dagoberto Oyola; Martinez, Yebrayl Antonio Rojas; Pinilla, Marlene Rivera [Universidad del Tolima, Grupo Ciencia de Materiales y Tecnologia en Plasma (Colombia); Alcazar, German Antonio Perez [Universidad del Valle, Grupo Metalurgia Fisica y Teoria de las Transiciones de Fase (Colombia)

    2012-03-15

    Soil chemical analysis, X-ray diffraction (XRD) and Moessbauer spectrometry (MS) of {sup 57}Fe were used to characterize mineral phases of samples taken from the productive layer (horizon A) of agricultural coffee soil from Tolima (Colombia). Chemical analysis shows the chemical and textural parameters of samples from two different regions of Tolima, i.e., Ibague and Santa Isabel. By XRD phases like illite (I), andesine (A) and quartz (Q) in both samples were identified. The quantity of these phases is different for the two samples. The MS spectra taken at room temperature were adjusted by using five doublets, three of them associated to Fe{sup + 3} type sites and the other two to Fe{sup + 2} type sites. According to their isomer shift and quadrupole splitting the presence of phases like illite (detected by DRX), nontronite and biotite (not detected by XRD) can be postulated.

  9. Moessbauer and X-ray investigation of clay minerals originated from Libya

    57Fe transmission Moessbauer spectroscopy and X-ray diffractometry were used to study clay mineral samples originated from two different regions (Um-arrazm and Alkawasim) of Libya in order to get information about their mineralogical composition to assess their potential for use in the Libyan oil industry. In the samples originated from Un-arrazm calcite, akaganeite and nontronite while in the samples originated from Alkawasim quartz, akaganeite, montmorillonite, kaolinite, illite, mica and hematite were identified with different ratios by using diffraction method. The differences in the phase composition of iron-containing phases of samples from different localities have reflected in the complex Moessbauer spectra at both 300 K and 80 K. For the samples originated from Um-arrazm the Moessbauer parameters of subspectra were identified as nontronite and akaganeite. (author)

  10. Moessbauer investigation of iron uptake in wheat

    Kovacs, K., E-mail: kkriszti@bolyai.elte.hu [Eoetvoes Lorand University, Laboratory of Nuclear Chemistry, Institute of Chemistry (Hungary); Kuzmann, E. [Hungarian Academy of Sciences, Laboratory of Nuclear Chemistry, Chemical Research Center (Hungary); Fodor, F.; Cseh, E. [Eoetvoes Lorand University, Department of Plant Physiology (Hungary); Homonnay, Z.; Vertes, A. [Eoetvoes Lorand University, Laboratory of Nuclear Chemistry, Institute of Chemistry (Hungary)

    2008-07-15

    Iron uptake and distribution in wheat roots were studied with {sup 57}Fe Moessbauer spectroscopy. Plants were grown both in iron sufficient and in iron deficient nutrient solutions. Moessbauer spectra of the frozen iron sufficient roots exhibited three iron(III) components with the typical average Moessbauer parameters of {delta} = 0.50 mm s{sup -1}, {Delta} = 0.43 mm s{sup -1}, {delta} = 0.50 mm s{sup -1}, {Delta} = 0.75 mm s{sup -1} and {delta} = 0.50 mm s{sup -1}, {Delta} = 1.20 mm s{sup -1} at 80 K. These doublets are very similar to those obtained earlier for cucumber [0], which allows us to suppose that iron is stored in a very similar way in different plants. No ferrous iron could be identified in any case, not even in the iron deficient roots, which confirms the mechanism proposed for iron uptake in the graminaceous plants.

  11. Study on the spin crossover transition and glass transition for Fe(II) complex film, [Fe(II)(H-triazole){sub 3}]-Nafion, by means of Moessbauer spectroscopy

    Nakamoto, Akio; Kamebuchi, Hajime, E-mail: cc106909@mail.ecc.u-tokyo.ac.jp [University of Tokyo, Graduate School of Arts and Sciences (Japan); Enomoto, Masaya [Tokyo University of Science, Department of Chemistry, Faculty of Science Division I (Japan); Kojima, Norimichi [University of Tokyo, Graduate School of Arts and Sciences (Japan)

    2012-03-15

    [Fe(II)(H-trz){sub 3}]-Nafion (trz = triazole) is a transparent spin crossover complex film, where the spin crossover transition between the low-spin (S = 0) and the high-spin (S = 2) states takes place between 225 K and 300 K. In this film, two doublets corresponding to the low-spin and high-spin states were observed in the {sup 57}Fe Moessbauer spectra, reflecting the spin crossover transition. From the analysis of {sup 57}Fe Moessbauer spectra, the Debye temperatures of the low-spin and high-spin sites were estimated at 185 K and 176 K, respectively, in the temperature range between 10 K and 150 K. In this film, the total intensity of the Moessbauer spectra corresponding to the low-spin and high-spin sites drastically decreases above 200 K, reflecting the glass transition of Nafion, where the lattice vibration of [Fe(H-trz){sub 3}]{sub n}{sup 2n+} is softened just as in solution due to micro-Brown motion of the segment of Nafion polymer membrane.

  12. Computer processing of Moessbauer spectrum data

    Computer processing was adopted to pick up significant signals from the undefined Moessbauer spectra. A program, by which smoothing and curve fitting was made possible, was devised and applied to the analysis of the Moessbauer spectra of 57Fe enriched iron and other specimens. Although this processing sometimes distorted the absorption peaks, it was quite effective for elimination of noise and finding of exact positions of absorption peaks. Availability of the processing was demonstrated by several examples obtained for 57Fe enriched iron, natural iron, calcined ferric oxyhydroxides, red mud residue and its calcined product. (auth.)

  13. Anisotropy energy distribution determined by Moessbauer spectroscopy in a metallic glass

    The distribution of frozen-in magnetic anisotropy in as-quenched Fe73.5Si13.5Cu1Nb3B9 amorphous melt-spun ribbons was studied by Moessbauer effect spectroscopy, using the temperature-dependent magnetoelastic effect produced on the metallic glass by 1 μm Al coatings. Al coatings were deposited by RF sputtering at T∼350 K on both sides of the amorphous ribbons. Estimated magnetic anisotropy values were below 1 kJ/m3, with preeminence of anisotropy energy densities lower than 300 J/m3

  14. Moessbauer spectroscopy and magnetic studies of orientated textured Fe3O4 ferrofluid

    Nano scale magnetite based ferrofluid is synthesized by chemical co pre cipitation technique and stabilized with oleic acid. Magnetization and viscosity measurements were used to optimize for texturing purpose. The freeze-textured ferrofluid in two configurations, namely, (1) field texture system (FTS) and (2) zero field texture system (ZTS) are investigated by magnetization measurements at 298 K and Moessbauer spectroscopy measurements at 77 and 298 K. These results are analysed on the basis of the contributions from collective superparamagnetic reversal and the strength of the inter particle interactions.

  15. Moessbauer spectroscopy and magnetization of ordered arrays of ultrathin FePt nanodisks with perpendicular magnetisation

    Ellrich, J., E-mail: jens.ellrich@grenzebach.com; Kruk, R., E-mail: robert.kruk@kit.edu; Brand, R. A., E-mail: richard.brand@kit.edu; Hahn, H., E-mail: horst.hahn@kit.edu [Karlsruhe Institute of Technology, Institute for Nanotechnology (Germany); Huetten, A., E-mail: huetten@physik.uni-bielefeld.de [Bielefeld University, Department of Physics, Physics of Nanostructures (Germany); Lei, Y., E-mail: yong.lei@tu-ilmenau.de [Technische Universitaet Ilmenau, Fachgebiet 3D-Nanostrukturierung Institut fuer Physik and IMN (Germany)

    2012-05-15

    The purpose of this communication is to show that arrays of FePt with perpendicular anisotropy can be studied using energy-selective conversion electron Moessbauer spectroscopy. Magnetic nanostructures have been in the focus of technology and science for many years. One of the economically and comparably scientifically most demanding application of these structures is in storage devices such as hard-disks and MRAMs. The FePt nanodisks presented here show a combination of material and magnetic properties which enable the fabrication of highly ordered nanostructures.

  16. Magnetic properties of GdNiSn studied by 155Gd Moessbauer spectroscopy

    The magnetic and electronic properties of the GdNiSn compound have been studied by the 155Gd Moessbauer spectroscopy. The alignment of the electric field gradient axes system has been determined at the Gd site. The possible magnetic structures have been proposed in the whole range of temperatures below the Neel temperature. In the proposed magnetic structures the Gd magnetic moments are either collinear and lie in the crystallographic ab-plane (cb-plane) or noncollinear and deviate for 54(2) deg. from the crystallographic b-axis

  17. Conversion electron Moessbauer spectroscopy of plasma immersion ion implanted H13 tool steel

    Conversion electron Moessbauer spectroscopy (CEMS) has been used to investigate nitride formation in AISI-H13 tool steel after treatment by plasma immersion ion implantation (PI3) at 350 C. With only slight variation in the plasma conditions, it is possible to influence the kinetics of nitride precipitation so as to obtain nitrogen concentrations that range from those associated with ε-Fe2N through ε-Fe3N to γ'-Fe4N. The CEMS results enable a more definite identification of the nitrides than that obtained by glancing-angle X-ray diffraction and nuclear reaction analysis alone. (orig.)

  18. Analysis of iron state in some Argentinian soils by dissolution methods and Moessbauer spectroscopy

    Bahia Blanca (Argentina) soils, in particular entisols, are studied by Moessbauer spectroscopy. X-ray diffraction and scanning electron microscopy are used to characterize the samples. Samples were treated with different chemical iron extraction methods, in order to determine relative Feo and Fed fractions. The Feo/Fed ratios are obtained and the relative effect of iron extraction treatment on spectra components are determined. In addition, the effect of extraction procedures, dithionite-citrate-bicarbonate and oxalate, in the residual soil fraction are analyzed. (orig.)

  19. Moessbauer spectroscopy in disordered magnetic systems: Clustering effects in AuFe reentrant ferromagnet

    Basic properties of magnetic reentrant systems are reported. The results obtained with Moessbauer Spectroscopy, are briefly reviewed and critically discussed. Particular emphasis is placed on the case of Au1-xFex (x>15%) reentrant ferromagnet. In the light of our experiments under external field, a model is proposed, describing the microscopic structure as an assembly of small weakly coupled superparamagnetic clusters. We believe that this short scale effect is not in disagreement with the existence of large ferromagnetic domains (≅50μ) recently observed by electron transmission microscopy on similar reentrant alloys by Senoussi et al. (orig.)

  20. Moessbauer spectroscopy, electron microscopy and electron diffraction studies of small particle magnetic systems: Identification of disease specific haemosiderins

    Moessbauer spectroscopy has shown that the iron-containing cores of the biological iron storage material haemosiderin produced under normal and various pathological conditions are significantly different in their magnetic properties. The differences have been correlated with information on the particle size, morphology, crystallinity and mineral form of the haemosiderin cores obtained by complementary electron microscopy and electron diffraction studies. These results have important implications for the use of Moessbauer spectroscopy in determining the properties of small particle magnetic systems and also considerable relevance for the improved understanding and treatment of iron overload disease. (orig.)

  1. Improvement of depth selective electron Moessbauer spectroscopy for investigations of locally heterogenous nanosystems

    Full text: Active use of Moessbauer spectroscopy in various investigations including study of properties of locally heterogeneous systems stipulates continuous improvements of instrumental and methodical base. There has been developed a nondestructive method of depth selective conversion electron Moessbauer spectroscopy (DS CEMS) for obtaining of Moessbauer information from subsurface locally heterogeneous systems with depth resolution about several nm. Precise investigations by this method at a combined installation electron spectrometer - nuclear gamma resonance spectrometer are of special interest. Quality of such investigations first of all depends upon the possibilities of the electron spectrometer. There were found stipulated by the electron spectrometer conditions of achievement of the depth resolution close to physical nanolimit. There was achieved evident success in development of DS CEMS method at high-effective magnetic sector electron spectrometer with double focusing equipped with large area non-equipotential electron source (a sample under investigation) of and with the position-sensitive detector of electrons, which is similar to the detector. The present spectrometer satisfies the conditions found above. It allows also to work with low-energy electrons up to 500 eV including Auger electrons and electrons of true secondary emission. Thickness about several nm with the depth resolution about tenths of nm is studied in the last case at rather high efficiency of measurements. The main aspects of use of internal conversion electrons, Auger electrons and secondary electrons accompanying decay of Moessbauer levels of different nuclei in the method of depth selective electron Moessbauer spectroscopy (DS EMS) were considered. There were recommended optimal variants for use of either that type of electron irradiation and their combinations for a number of solved problems. The electron spectrometer with a sample at a boundary of the magnetic gap corresponds to

  2. Magnetic behaviour in the semiconducting and superconducting regions of 57 Fe-doped La2-xSrxCuO4-δ

    From Moessbauer and resistivity measurements on 57Fe-doped La2-xSrxCuO4-δ samples, we have determined the phase diagram of the system for 0 0.15, a Fe-induced spin-glass state is observed. Recent data on oriented powder samples are discussed

  3. Sorption-induced reversible oxidation of Fe(2) at the smectite/water interface under strictly anoxic conditions. A Moessbauer spectroscopy study

    Previous studies of Fe(II) sorption onto montmorillonite have been performed with the mineral extracted from the MX80 bentonite. These studies have shown that Fe(II) can be sorbed onto clay minerals in cation exchange position. The affinity of montmorillonite for Fe(II) and Ca(II) is identical. Fe(II) may also be specifically adsorbed onto montmorillonite clay edges. Moessbauer spectroscopy confirmed the high affinity of clay surfaces for Fe(II) sorption and showed that this sorption is mainly due to a two step mechanism: Fe(II) specific adsorption, followed by oxidation of the Fe(II) sorbed. The identification of the oxidizing agent was prohibited due to the complex chemistry of the natural MX80 montmorillonite. Thus, synthetic iron-free montmorillonite was used (chemical formula: Ca0.3 (A1.4Mg0.6) (Si4) O10(OH)2 ). 57Fe(II) sorption experiments were conducted in a N2 atmosphere gloves-box, in strictly anoxic conditions. Solid samples were synthesized in order to confirm the clay high affinity for Fe(II), in absence of structural oxidant, and to have a better comprehension of the sorption mechanism. Moessbauer spectra were recorded for each sample. Whereas no Fe(III) is detected in solution as pH was increased and then, a significant amount of surface sorbed Fe(III) was found to be reversibly produced, which amounts for 0-3% of total Fe in the pre-sorption edge acid region, up to 7% of total Fe when all Fe is sorbed in the neutral to alkaline pH range. From pH ≅ 2 to pH ≅ 7, a sorption edge plateau is observed. In this plateau, the sorbed-Fe(III)/sorbed-Fe ratio increases with pH, up to 45% at pH 7. Moessbauer spectra comparison with ferrous hydroxide, synthesized in the same redox conditions at higher pH, show that this oxidation can not be due to the trace amounts Oz in the suspension. The Moessbauer spectra components of both Fe(II) and Fe(III) appears as paramagnetic doublets: iron has not been polymerized, but is present as cations. This result shows that

  4. Characterization of a Copper mineral from Rio Grande do Sul (RS, Brazil) by Moessbauer spectroscopy and chemical analysis

    A sample from a copper-based mineral is analysed by Moessbauer spectroscopy. The results are compared with those form X-ray diffraction and microscopic analyses. A graphic correlation between the areas in the chalcopyrite spectra and the copper contents determined by chemical analysis is also made. (C.L.B.)

  5. Moessbauer spectroscopy of 151Eu and 153Eu. Applications to structural chemistry and electronic properties of rare-earth compounds

    The decrease of the 151Eu isomer shift on hydrogenation of a dilute EuPd alloy (2.5at% Eu) is discussed in term of the volume effect on the charge density at the nucleus. It is shown from 153Eu Moessbauer spectroscopy in rare earth titanates that a vibrational anisotropy lead to the observation of a Goldanskii-Karyagin effect

  6. Isothermal defect annealing in semiconductors investigated by time-delayed Moessbauer spectroscopy: application to ZnO

    The theory for so-called Time-Delayed-Measurements is outlined. This method allows for isothermal annealing studies in emission Moessbauer spectroscopy utilizing radioactive beams. The usefulness of this method is illustrated by the example of the annealing of a magnetic defect in ZnO.

  7. Efficiency analysis of clearance of two types of exogenous iron from the rat brain by Moessbauer spectroscopy

    Polikarpov, D. M., E-mail: polikarpov.imp@gmail.com; Cherepanov, V. M.; Gabbasov, R. R. [National Research Centre, ' Kurchatov Institute' (Russian Federation); Chuev, M. A.; Mischenko, I. N. [Russian Academy of Sciences, Russian Institute of Physics and Technology (Russian Federation); Korshunov, V. A. [Russian Academy of Sciences, Institute of Higher Nervous Activity and Neurophysiology (Russian Federation); Panchenko, V. Y. [National Research Centre, ' Kurchatov Institute' (Russian Federation)

    2013-04-15

    Fe{sub 3}O{sub 4} based ferrofluid was injected transcranially in the ventricle of the rat brain. At 3 months after the injection the rat was sacrificed and the brain was investigated by Moessbauer spectroscopy and histological Perls Prussian blue method. Joint analysis of histological and Moessbauer data confirms that superparamagnetic nanoparticles Fe{sub 3}O{sub 4}, which constituted about 91 % of the iron of the ferrofluid, were cleared from the brain, while the concomitant chemical compound containing ferric ion in the high-spin state, remains intact.

  8. Analysis of iron storage proteins in chicken liver and spleen tissues in comparison with human liver ferritin by Moessbauer spectroscopy

    Characterization of iron storage proteins in liver and spleen from normal chicken and chicken with lymphoid leukemia in comparison with human liver ferritin were considered by Moessbauer spectroscopy (preliminary results). Small differences in Moessbauer hyperfine parameters for both normal and lymphoid leukemia chicken liver and spleen were observed. The value of quadrupole splitting for human liver ferritin was higher than those for chicken tissues. A decrease of iron content in lymphoid leukemia chicken tissues was also found, however, the reason of this fact (pathology or feeding) was not clear yet. (author)

  9. Moessbauer spectroscopy of R2Fe14B and related compounds

    The Moessbauer Spectroscopy (MBS) has been widely used in the last 4 years for the study of the recently discovered ternary compounds R2F14B where R means Y, Th or a rare earth element. The strong interest for this class of intermetallics arose drastically after the discovery of the exceptional properties of Nd2Fe14 as an ideal material for permanent magnet applications. The newest results about hyperfine fields BHF, quadrupole splitting EQ and isomer shifts I.S. at the 6 crystallographically different Fe sites and at the 2 R sites in the R2F14B and their impact on the understanding of the local magnetic moments and magnetocrystalline anisotropy will be reviewed. In the case of RFe12-xMx compounds where M = V, Ti, Si, Mo, W, Cr, complex Moessbauer spectra were obtained because of the presence of 3 crystallographically inequivalent Fe sites and the presence of differents amounts of the M component on one or more of these sites. (orig.)

  10. Degradation of passive layers of iron studied by conversion electron Moessbauer spectroscopy

    Integral electron Moessbauer spectroscopy (ICEMS) and additionally some electrochemical methods were used to characterize the passivation process of iron (low carbon steel) in sulfate, sulfate + sulfite (a possible model solution of acid rain) solutions and in phosphate buffer. The phase compositions and thicknesses of the passive layers formed due to the electrochemical polarizations were analyzed in dependence on the duration of the anodic passivations and on the pH of the used electrolytes. The passive layer, as determined from the Moessbauer spectra, consists mainly of γ-FeOOH, however in sulfite containing sulfate aqueous solution at pH 3.5 Fe2C and despite ex-situ circumstances FeSO4 x H2O was detected after the shortest polarization time. The film thickness, which was found to grow nearly with polarization time in pure sulfate solution and in phosphate buffer, reached a maximum of 60-100 nm (depending on pH) in sulfate +sulfite solution after a passivation time of about 4 hours. It has been proved, that HSO3- ion, which is contained by acid rain, initiate pit formation under acid conditions and so enforces the corrosion of iron. The experimental results furthermore suggest, that not the whole oxidic layer is responsible for the passivity but only a very thin intermediate layer formed between an inner oxide layer of a cubic structure and the rhombic oxide (γ-FeOOH) cover. (author) 7 refs.; 7 figs.; 2 tabs

  11. Moessbauer study of spin structure transformation from an incommensurate to a commensurate state

    Choi, Kang Ryong; Park, Seung-Iel; Kim, Sam Jin; Kim, Chul Sung, E-mail: cskim@phys.kookmin.ac.kr [Kookmin University, Departmentt of Physics (Korea, Republic of)

    2009-01-15

    We present crystallographic and magnetic properties of NiCr{sub 1.98}{sup 57}Fe{sub 0.02}O{sub 4} by using X-ray diffractometry (XRD), vibrating sample magnetometry (VSM), and Moessbauer spectroscopy. The lattice constants a{sub 0} were determined to be 8.318 A. The ferrimagnetic Neel temperature (T{sub N}) for NiCr{sub 1.98}{sup 57}Fe{sub 0.02}O{sub 4} is determined to be 90 K. The Moessbauer absorption spectra for all chromites at 4.2 K show two well developed sextets superposed with small difference of hyperfine fields (H{sub hf}) caused by Cr{sup 3+} ions in two different magnetic sites. The values of the isomer shifts show that the charge states of Fe are Fe{sup 3+} for all temperature range. Ni-chromites Moessbauer spectra below T{sub N} present aline broadening due to a Jahn-Teller distortion and show that spin structure behavior of Cr ions change from an incommensurate to a commensurate state.

  12. Monitoring iron carbide production from iron ore by quantitative Moessbauer spectroscopy

    The process of converting iron ore (principally Fe2O3 or Fe3O4) into iron carbide (Fe3C) to be used as feedstock for steel-making yields complex mixtures of several iron containing compounds as a function of processing conditions. In addition to the above compounds (hematite, magnetite and cementite), the mixtures typically contain wustite (FeO) and metallic iron (Fe). Moessbauer spectroscopy has been developed into a quantitative analytical method for monitoring the degree of conversion to carbide from samples periodically extracted from a fluidized bed reactor type of pilot plant. Emphasis has been placed on standardizing and simplifying the analysis procedure for routine use in an industrial environment. (orig.)

  13. A fast microprocessor controlled data acquisition system for high resolution Moessbauer spectroscopy

    We describe a microprocessor controlled data acquisition system designed for Moessbauer spectroscopy which operates in both pulse height analysis and multichannel scaling with high counting rate (> 20 MHz) and resolution (up to 8192 channels per spectrum). The apparatus makes use of two counters and of a double memory block. It is thus possible to obtain a minimum channel-advance dead-time lower than 50 nsec and a minimum dwell-time of 1 μsec. The accumulated data are transferred to a microcomputer for storage and analysis from one of the two blocks while the other continues the acquisition process. The system is totally programmable, and all the acquisition parameters can be easily selected in a wide range. (orig.)

  14. Investigation the Effect of Nb Additions on Sm2Fe17 Materials by Moessbauer Spectroscopy

    A technique for producing Sm2Fe17 from cast ingots without the presence of free iron(αFe) has been investigated by Moessbauer Spectroscopy. This technique involves the additions of between 4 and 5 at % Nb to the melt. The dendrites iron was replaced by paramagnetic Nb Fe-2 phase. However the additions of higher than 4 at % Nb, gives arise the presence of paramagnetic NbFe2 phase at the expense of Sm2Fe17. Therefore the optimum addition to produce ingot without α-Fe, with small amount of paramagnetic NbFe2 phase and high amount of Sm2Fe17 phase is 4 at % Nb

  15. Speciation of 241Am molecular compounds through 237Np Moessbauer and 241Am XPS spectroscopy

    Light actinides (U to Am) can be found in several oxidation states from (II) to (VII) in the molecular form or in the condensed matter state. The large variety of oxidation states is usually attributed to the contribution of the 5f states to the valence orbitals. For the heavier actinides, for which the 5f electrons are non bonding, the actinides become rare-earth like with a smaller number of oxidation states (II and III). However it is still not understood what really decides on the stability of a given oxidation state, and how it is depending on the chemical environment (coordination sphere, nature of the counter-anion, etc). This work shows how Moessbauer spectroscopy and 4f photoelectron spectroscopy (XPS) can contribute to progress in the understanding of the electronic structure of the actinide, especially for Am compounds Moessbauer reverse experiments were undertaken to show in what manner the electronic structure of the Am is preserved during the decay process (oxidation state stability). The result of XPS measurements shows that it is possible to correlate the 4f binding energy of the Am to the charge at the actinide core. The obtained results are somewhat surprising. The formal oxidation state (V) is 'less oxidised' than expected. Some Am(III) have less electron density (that means are more ionic) than americyl (V) hydroxide or carbonate. The reason for these surprisingly results comes from the 'Am=O' multiple bond system which reduces dramatically the charge at the actinide by a pi-donation mechanism. The evolution of the 4f binding energy of the Am species does not follow the oxidation state order. Theoretical DFT calculation were done on Am(V) compounds for qualitative electronic modeling. (authors)

  16. Local electric field properties in K2ZnCl4 studied by magnetic resonance and Moessbauer spectroscopy

    The local electric properties at K and Zn sites in the normal, incommensurate and commensurate phases of K2ZnCl4, as derived from a numerical computation of the lattice contribution to the electric potential V(r), electric field intensity E(r) and electric field gradient tensor Vαβ(r) are reported. The numerical data obtained at each cation position were correlated with the experimental 39 K NMR, Cu2+ EPR and 57 Fe Moessbauer results in pure and doped K2ZnCl4. The electric field gradient (efg) of the K+, Cu2+ and Fe3+ ions is directly related to the crystal field parameter. By this comparison, on computations done in the ionic fractional charge and relaxed lattice approximations the insertion of probe-species of ion and copper ions be on off-centre Zn sites is proposed. The 39 K-efg-tensor calculation of the incommensurate phase fit well the NMR data reported recently. (authors)

  17. Chemical-mineralogical characterization and Moessbauer spectroscopy of aquamarine from Pedra Azul, Northeast of Minas Gerais

    Aquamarines from three pegmatites located the vicinities of the Pedra Azul city, Minas Gerais state, were investigated in terms of chemical composition, physical properties and Moessbauer spectroscopy. The small lenticular pegmatite bodies are usually less than 5 m wide and exhibit a conspicuous mineralogical and textural zoning. The last thermal event in these pegmatites, determined by K-Ar method in muscovite, is of Neo proterozoic age, coincident with the late stages of the Brasiliano tectono- metamorphic cycle. Chemical analyses showed that sodium is the alkali with higher contents in the aquamarines, thus enabling their classification as sodic beryls. In zoned samples there is an increase of Fe as well as Mn from center to border, while no systematic variation could be detected for other elements. The specific gravity of 2.72 to 2.80 g/cm3 is higher than the values determined for samples from other pegmatites of Minas Gerais. The refraction indices are ne=1.569 - 1.579 and NW= 1.573 - 1.581 and the birefringence varies from 0.002 to 0.008. The refraction indices increase with the Be O content. The color of aquamarines varies from medium to light blue, sometimes greenish blue. Moessbauer spectra obtained at room temperature and at 80 K show that Fe2+ is the main chromophore-ion and suggest that the iron is present in octahedral sites as well as in the structural channels. Moessbauer spectra also indicate that the incorporation of Fe3+ may cause a shift from deep blue to light blue colors. Based on their aquamarine composition the pegmatites were classified as barren, poor in rare alkalis (Li, Rb, Cs) and therefore little differentiated. The relatively simple mineralogy and the lack of lithium minerals such as lepidolite and spodumene confirm this classification. Thus, the composition of beryl can be used as a tracer for the prospection of pegmatites with different degrees of differentiation and consequently with different types of mineralization. (author)

  18. Application of Moessbauer spectroscopy to the study of tannins inhibition of iron and steel corrosion

    Jaen, Juan A., E-mail: jjaen@ancon.up.ac.pa [Universidad de Panama, CITEN, Depto. de Quimica Fisica (Panama); Obaldia, J. De; Rodriguez, M. V. [Universidad de Panama, Escuela de Quimica, Facultad de Ciencias Naturales, Exactas y Tecnologia (Panama)

    2011-11-15

    The inhibitory effect of tannins was investigated using, among others, potentiodynamic polarizations and Moessbauer spectroscopy. These techniques confirmed that the nature, pH and concentration of tannic solution are of upmost importance in the inhibitory properties of the solutions. It is observed that at low tannin concentration or pH, both, hydrolizable and condensed tannins, effectively inhibit iron corrosion, due to the redox properties of tannins. At pH Almost-Equal-To 0, Moessbauer spectra of the frozen aqueous solutions of iron(III) with the tannin solutions showed that iron is in the form of a monomeric species [Fe(H{sub 2}O){sub 6}]{sup 3 + }, without coordination with the functional hydroxyl groups of the tannins. The suspended material consisted of amorphous ferric oxide and oxyhydroxides, though with quebracho tannin partly resulted in complex formation and in an iron (II) species from a redox process. Other tannins, such as chestnut hydrolysable tannins, do not complex iron at this low pH. Tannins react at high concentrations or pH (3 and 5) to form insoluble blue-black amorphous complexes of mono-and bis-type tannate complexes, with a relative amount of the bis-ferric tannate generally increasing with pH. Some Fe{sup 2 + } in the form of hydrated polymeric ferrous tannate could be obtained. At pH 7, a partially hydrolyzed ferric tannate complex was also formed. The latter two phases do not provide corrosion protection. Tannin solutions at natural pH react with electrodeposited iron films (approx. 6 {mu}m) to obtain products consisting only on the catecholate mono-complex of ferric tannate. Some aspects of the mechanism of tannins protection against corrosion are discussed.

  19. Mineralogy of the clay fraction of soils from the moray cusco archaeological site: a study by energy dispersive X-ray fluorescence, X-ray diffractometry and Moessbauer spectroscopy

    Ceron Loayza, Maria L., E-mail: malucelo@hotmail.com; Bravo Cabrejos, Jorge A.; Mejia Santillan, Mirian E. [Universidad Nacional Mayor de San Marcos, Laboratorio de Analisis de Suelos, Laboratorio de Espectroscopia Moessbauer, Facultad de Ciencias Fisicas (Peru)

    2011-11-15

    The purpose of this work is to report the advances in the elemental and structural characterization of the clay fraction of soils from the terraces of the Moray Archaeological site, located 38 km north of the city of Cusco, Cusco Region. One sample was collected from each of the twelve terraces of this site and its clay fraction was separated by sedimentation. Previously the pH of the raw samples was measured resulting that all of the samples were from alkaline to strongly alkaline. Energy dispersive X-ray fluorescence (EDXRF) was used for the elemental characterization, and X-ray diffractometry (XRD) and transmission Moessbauer spectroscopy (TMS), using the {gamma} 14.4 keV nuclear resonance transition in {sup 57}Fe, were used for the structural characterization of the clays and clay minerals present in each sample. The EDXRF analyses of all the samples show the presence of relatively high concentrations of sulfur in some of the samples and relatively high concentrations of calcium in all of the samples, which may be related to the high alkalinity of the samples. By XRD it is observed the presence of quartz, calcite, gypsum, cronstedtite, 2:1 phyllosilicates, and iron oxides. The mineralogical analysis of Fe by TMS shows that it is present in the form of hematite and occupying Fe{sup 2 + } and Fe{sup 3 + } sites in phyllosilicates, cronstedtite, and other minerals not yet identified.

  20. The Moessbauer spectroscopy studies of matrix changes during continuous heating from as-quenched state of high carbon tool steel

    This work presents the results of investigations carried out using Moessbauer spectroscopy technique, and their interpretation concerning ferrite or martensite matrix and its changes during tempering. The changes in the matrix are brought about by the stress relaxation, retained austenite transformation, nucleation and solubility of ε carbides as well as cementite nucleation and growth. This research was conducted on a new high-carbon alloy 120MnCrMoV8-6-4-2 steel, which was designed by the Phase Transformations Research Group, AGH UST, in 1998. Moessbauer spectroscopy was applied not only for magnetic hyperfine field studies, but also for analysis of the values of quadrupole splitting and isomeric shift, what resulted in significant conclusions concerning the changes in matrix chemical composition, microstructure, and the level of stresses being present in it.

  1. The Moessbauer spectroscopy studies of matrix changes during continuous heating from as-quenched state of high carbon tool steel

    Krawczyk, Janusz, E-mail: jkrawczy@ruczaj.pl; Bala, Piotr [AGH University of Science and Technology, Faculty of Metals Engineering and Industrial Computer Science (Poland); Hanc, Aneta [Institute of Materials Science, University of Silesia (Poland)

    2009-04-15

    This work presents the results of investigations carried out using Moessbauer spectroscopy technique, and their interpretation concerning ferrite or martensite matrix and its changes during tempering. The changes in the matrix are brought about by the stress relaxation, retained austenite transformation, nucleation and solubility of {epsilon} carbides as well as cementite nucleation and growth. This research was conducted on a new high-carbon alloy 120MnCrMoV8-6-4-2 steel, which was designed by the Phase Transformations Research Group, AGH UST, in 1998. Moessbauer spectroscopy was applied not only for magnetic hyperfine field studies, but also for analysis of the values of quadrupole splitting and isomeric shift, what resulted in significant conclusions concerning the changes in matrix chemical composition, microstructure, and the level of stresses being present in it.

  2. The moessbauer spectroscopy study of an ancient bronze mirror without sampling

    The Moessbauer spectra of 119Sn for a bronze mirror of the Han Dynasty are described. A method of measuring Moessbauer spectrum without sampling is established. For the sake of contrast, both the spectra of transmission and of γ-ray scattering were measured. The results show that on the surface of the bronze mirror tin is in the state of Sn4+ oxide

  3. Concentration-dependent site occupancy in europium-doped Y2WO6 as studied by 151Eu Moessbauer spectroscopy

    151Eu Moessbauer spectroscopy is used to investigate the phosphor Ysub(2-x)Eusub(x)WO6. The interpretation of the spectra is based on the existence of three non-equivalent yttrium sites on which Eu can be substituted. Small differences in the covalency for the three sites can explain the different isomer shifts. It is shown that the relative occupancy of one of the sites strongly depends of the europium content. (author)

  4. Interaction of N2+ and N+ ions with α-Fe nanoparticles in copper film studied by Moessbauer spectroscopy

    The interaction of N2+, N+ ions with α-Fe nanoparticles in copper film has been studied by Moessbauer spectroscopy. The results showed that there was obviously non-liner effect in N2+ ion implantation. In the present study, the processes of thermodynamics for collision and after collision of N2+ and N+ ions with α-Fe nanoparticles have also been investigated

  5. Investigation of the kinetics of internal oxidation of Cu-Fe-alloys with the help of Moessbauer spectroscopy

    Homogeneous and supersaturated Cu Fe mixed crystals are oxidated at an oxygen partial pressure which lies below the decomposition pressure of the copper oxides. With the help of Moessbauer spectroscopy, it is possible to track the kinetics of each iron state during internal oxidation. Corrosion products are magnetite, wuestite, and delafossite. The appearance of these compounds depends on the composition of the mixed crystal, the oxidation temperature and the oxidation time. (orig.)

  6. Study of solid-state reaction in Fe/Zr layer systems by 97Fe Moessbauer spectroscopy

    The paper examines, under UHV conditions, vapour-deposited, polycrystalline Fe/Zr multiple layers after heat treatment ex situ and in situ by means of the Moessbauer spectroscopy. It shows that, as a consequence of solid-state reaction, an amorphous Fe-Zr-phase is formed. From the Moessbauer spectra the mean Fe concentration of the amorphous phase was determined. In contrast to that no amorphization was observed after heat treatment under similar conditions at a polycrystalline Fe layer which had been vapour-deposited on a surface-physically relatively clean and orderly Zr(0001) monocrystal surface, instead the formation of the crystalline intermetallic compound FeZr3 was observed. The result proves that grain boundaries of the polycrystalline Zr layers at the Fe/Zr interface act as nucleation on centers for the amorphous Fe-Zr phase. (orig.)

  7. Design and construction of an electromechanical velocity modulator for Moessbauer spectroscopy

    Velasquez, A. A., E-mail: avelas26@eafit.edu.co; Carmona, A. [Universidad EAFIT, Grupo de Electromagnetismo Aplicado (Colombia); Velasquez, D.; Angel, L. [Universidad EAFIT, Grupo de Optica Aplicada (Colombia)

    2011-11-15

    In this paper we report the design, construction and characterization of an electromechanical velocity modulator for application in Moessbauer spectroscopy. The modulator was constructed with copper coils, Neodymium magnets, steel cores and polymeric membranes. The magnetic field in the driving and velocity sensing stages was analyzed by the finite element method, which showed a linear relation between the magnetic field in the region of motion of both coils and the position of the coils within the steel cores. The results obtained by computational simulation allowed us to optimize geometries and dimensions of the elements of the system. The modulator presented its first resonance frequency at 16.7 Hz, this value was in good agreement with that predicted by a second order model, which showed a resonant frequency of 16.8 Hz. The linearity of the velocity signal of the modulator was analyzed through an optical method, based on a Michelson-Morley interferometer, in which the modulator moved one of the mirrors. Results showed a satisfactory linearity of the velocity signal obtained in the sensing coil, whose correlation with a straight line was around 0.99987 for a triangular reference waveform.

  8. Characterization of a mechanochemically activated titanium-hematite mixture: Moessbauer spectroscopy study

    Cristobal, A.A. [Division Ceramicos - INTEMA, Universidad Nacional de Mar del Plata - CONICET, Av. J.B.Justo 4302, B7608FDQ Mar del Plata (Argentina); Ramos, C.P., E-mail: ciramos@cnea.gov.a [GIyA - CAC - CNEA, Av. Gral. Paz 1499, 1650 San Martin, Bs. As. (Argentina); CONICET (Argentina); Botta, P. [Division Ceramicos - INTEMA, Universidad Nacional de Mar del Plata - CONICET, Av. J.B.Justo 4302, B7608FDQ Mar del Plata (Argentina); Aglietti, E.F. [Centro de Tecnologia de Recursos Minerales y Ceramica - CETMIC, CONICET- CIC, Camino Parque Centenario y 506, B1897ZCA M.B.Gonnet (Argentina); Saragovi, C. [GIyA - CAC - CNEA, Av. Gral. Paz 1499, 1650 San Martin, Bs. As. (Argentina); Porto, J.M. [Division Ceramicos - INTEMA, Universidad Nacional de Mar del Plata - CONICET, Av. J.B.Justo 4302, B7608FDQ Mar del Plata (Argentina)

    2009-10-01

    Mechanochemical processes involving reactions between metals and crystalline oxides are of interest because of their potential technological applications in structural, magnetic or electric materials. In addition they can contribute to the understanding of the natural occurring processes that lead to the formation of minerals and soils. The controlled studies of how the distribution of cations in the titanomagnetites takes place can help toward building a model for the nature of their magnetism and, since they are the primary carriers of rock and soil magnetism, are therefore intensively investigated in many experimental and theoretical studies. In behalf of a better comprehension of the thermal, physical-chemical, magnetic and hyperfine behavior, we have considered a titanium and hematite mixture, with molar ratio Ti:Fe{sub 2}O{sub 3} of 1:2, mechanochemically activated during different activation times. We have studied the development of new phases by X-ray diffraction, scanning electron microscopy and Moessbauer spectroscopy. The evolution from the starting materials affected by different milling times and subsequent annealing shows that Ti reduces the Fe ions in the Fe{sub 2}O{sub 3} lattice, partly to Fe{sup 2+} and partly to metallic Fe.

  9. Moessbauer spectroscopy of corrosion products of mild steel due to microbiologically influenced corrosion

    Corrosion products of mild steel exposed to four different cultures of sulfur reducing bacteria (SRB) grown in a synthetic medium have been studied by transmission Moessbauer spectroscopy (TMS). Cultures of SRB studied are two hydrogenase positive strains, Desulfovibrio desulfuricans (DD) and Desulfovibrio vulgaris (DV) and two hydrogenase negative strains Desulfotomaculum orientis (DO) and Desulfotomaculum nigrificans (DN). The corrosion products generated on the coupons as well as in the broth were studied. In all the cases, the corrosion products removed from coupons showed the presence of green rust 2 (GR2), ferrous sulfides, γ-FeOOH and superparamagnetic (SPM) α-FeOOH in different proportions. The corrosion products from the broth showed a symmetrical central doublet, which indicates the presence of γ-FeOOH and SPM α-FeOOH along with ferrous sulfides. The corrosion products from coupons suspended in sewage water also showed the presence of GR 2 and ferrous sulfides together with oxyhydroxides. FTIR spectrum supports the presence of these phases in corrosion products. The formation of GR 2 on coupons seems to be the first step for the SRB induced corrosion. The corrosion rate has been found in the order of DO > DN > DV > DD. (author)

  10. A Moessbauer spectroscopy and magnetometry study of magnetic multilayers and oxides

    Bland, J

    2002-01-01

    A study of the magnetic properties of thin films, multilayers and oxides has been performed using Moessbauer spectroscopy and SQUID magnetometry. The systems studied are DyFe sub 2 , HoFe sub 2 and YFe sub 2 cubic Laves Phase thin films, DyFe sub 2 /Dy and DyFe sub 2 /YFe sub 2 multilayers; Ce/Fe and U/Fe multilayers; and iron oxide powders and thin films. CEMS results at room temperature show a low symmetry magnetic easy axis for all of the Laves Phase samples studied. Analysis of the dipolar and contact hyperfine fields show that this axis is close to the [2-bar41] and [3-bar51] directions but cannot be fully determined. The spin moments lie out of plane in all samples by approximately 22 deg, indicating a significant magneto-elastic anisotropy. 2.5 kG inplane applied field measurements indicate a much larger magnitude of magnetocrystalline anisotropy in the DyFe sub 2 system than in the YFe sub 2 system. In the DyFe sub 2 /YFe sub 2 multilayer samples the anisotropy is dominated by the dysprosium single-io...

  11. Speciation and transformations of cobalt(II) in bacterial cells using emission (57Co) Moessbauer spectroscopy

    Complete text of publication follows. The 57Co emission variant of Moessbauer spectroscopy (EMS), despite its solitary applications in biology owing to intrinsic methodological difficulties (Yu.D. Perfiliev, A.A. Kamnev, Moessbauer Effect Ref. and Data J., 30 (2007) 121-122; A.A. Kamnev, J. Mol. Struct., 744-747 (2005) 161-167), is highly sensitive and informative. The parameters of 57Co emission spectra provide chemical speciation data for the 57Co cation (chemical state, coordination environment and symmetry, etc.), as well as quantitative information on its distribution between different cation-binding sites in complicated biosystems (A.A. Kamnev, in 'Metal Ions in Biology and Medicine', Vol. 10, John Libbey Eurotext, Paris (2008), pp. 522-527). 57Co EMS can be successfully applied for monitoring 57Co2+ interactions with microbial cells, including its metabolic transformations (A.A. Kamnev et al., Anal. Chim. Acta, 573-574 (2006) 445-452). Comparative studies in rapidly frozen aqueous suspensions of live and dead cells of the ubiquitous phytostimulating soil bacterium Azospirillum brasilense have shown similarities in the chemical species formed upon purely chemical interaction of 57Co2+ traces with dead cell biomass and those formed upon primary rapid steps (2 min) of 57Co2+ sorption by the surface of live cells. For live cells, however, the parameters of 57Co emission spectra were found to change within an hour, which reflected ongoing metabolic transformations of the cation. The data obtained are in good agreement with the recently discovered involvement of Co2+ in reactions with labile [Fe-S] clusters during their de novo biosynthesis or repair in E. coli (C. Ranquet et al., J. Biol. Chem., 282 (2007) 30442-30451), presenting the molecular basis for Co2+ toxicity, besides Co2+-induced oxidative stress. The results obtained show that 57Co EMS can provide unique information both for speciation bioanalysis and for the monitoring of radionuclide bioleaching and

  12. Applications of Moessbauer spectroscopy in the study of minerals: some recent trends

    Three examples of mineralogy studies in which Moessbauer spectrsocopy is playing a determinant role: magnetic order in silicates, biomineralization of iron by bacteria and order-disorder transitions in Fe-Ni alloys in meteorites are discussed. (L.C.)

  13. Extraterrestrial Moessbauer Spectroscopy: More than Three Years of Mars Exploration and Developments for Future Missions

    Schroeder, Christian; Klingelhoefer, Goestar; Morris, Richard V.; Rodionov, Daniel S.; Fleischer, Iris; Blumers, Mathias

    2007-01-01

    The NASA Mars Exploration Rovers (MER), Spirit and Opportunity, landed on the Red Planet in January 2004. Both rovers are equipped with a miniaturized Moessbauer spectrometer MIMOS II. Designed for a three months mission, both rovers and both Moessbauer instruments are still working after more than three years of exploring the Martian surface. At the beginning of the mission, with a landed intensity of the Moessbauer source of 150 mCi, a 30 minute touch and go measurement produced scientifically valuable data while a good quality Moessbauer spectrum was obtained after approximately eight hours. Now, after about five halflives of the sources have passed, Moessbauer integrations are routinely planned to last approx.48 hours. Because of this and other age-related hardware degradations of the two rover systems, measurements now occur less frequently, but are still of outstanding quality and scientific importance. Summarizing important Moessbauer results, Spirit has traversed the plains from her landing site in Gusev crater and is now, for the greater part of the mission, investigating the stratigraphically older Columbia Hills. Olivine in rocks and soils in the plains suggests that physical rather than chemical processes are currently active.

  14. Moessbauer effect technique in mineral science

    A survey is presented of literature devoted to the application of the Moessbauer effect in practical work. Significant problems are pointed to of applying Moessbauer spectroscopy in specific fields. An extensive list of references is annexed. (L.O.)

  15. 57Fe Mössbauer probe of spin crossover thin films on a bio-membrane

    An illustrious complex [Fe(ptz)6](BF4)2 (ptz = 1-propyl-tetrazole) (1) which was produced in the form of submicron crystals and thin film on Allium cepa membrane was probed by 57Fe Mossbauer spectroscopy in order to follow its intrinsic spin crossover. In addition to a weak signal that corresponds to neat SCO compound significant amount of other iron compounds are found that could have morphed from 1 due to specific host-guest interaction on the lipid-bilayer of bio-membrane. Further complimentary information about biogenic role of membrane, was obtained from variable temperature Mossbauer spectroscopy on a ∼5% enriched [57Fe(H2O)6](BF4)2 salt on this membrane.

  16. Recoil-free gamma resonant absorption in 57 Fe nuclei in the presence of strong microwave field

    The growing interest paid to the multiphoton nuclear transitions in the last twenty years is due in part to the promising applications of these phenomena in the nuclear spectroscopy. The exciting possibility to compensate the nuclear recoil by the intense beams of photons of corresponding frequency was noted since 1975 and the absorption cross section of the multiphoton process was evaluated in some particular cases. In this paper a test of the multiphoton model is performed in an experiment of recoil-free 14.14 keV γ-ray resonant absorption in a thin absorber of potassium trioxalatoferrate exposed to a pulsed 1 Mw microwave field with the frequency of 3 GHz, the pulse width of 1 μs and the pulse train frequency of 222 Hz. The single line absorber, enriched in 57 Fe, in powder form, was uniformly pasted by silicon grease on a teflon support making an angle of 45 angle toward the reciprocally perpendicular direction of the γ beam and guided field propagation. The absorption spectra were recorded by a 1 μs linear gate, using a conventional constant acceleration Moessbauer transmission spectrometer and a moving 57 Co (Cu) γ source. Two velocity scales of 30 cm/s and of 10 mm/s were used to looking for the first order sidebands corresponding to the 3 GHz and to examine the microwave perturbation of the parent resonance. A careful computer analysis has shown a clear decrease of the area ratio for the un-shifted line without a sensitive change in the Γ value of the half linewidth. Any acoustic or strange rf effects were avoided by the proper choice of the absorber. Also, any possible thermal effect was eliminated by supplementary temperature dependence measurements on the sample. Thus, a multiphoton nature can be attributed to the observed microwave perturbation. (authors)

  17. Improving the empirical model for plasma nitrided AISI 316L corrosion resistance based on Moessbauer spectroscopy

    Campos, M.; Souza, S. D. de [Universidade Federal de Sao Carlos, Departamento de Fisica (Brazil); Souza, S. de [Instituto de Pesquisas Energeticas e Nucleares, Centro de Ciencia e Tecnologia de Materiais (Brazil); Olzon-Dionysio, M., E-mail: dmod@df.ufscar.br [Universidade Federal de Sao Carlos, Departamento de Fisica (Brazil)

    2011-11-15

    Traditional plasma nitriding treatments using temperatures ranging from approximately 650 to 730 K can improve wear, corrosion resistance and surface hardness on stainless steels. The nitrided layer consists of some iron nitrides: the cubic {gamma}{sup Prime} phase (Fe{sub 4}N), the hexagonal phase {epsilon} (Fe{sub 2 - 3}N) and a nitrogen supersatured solid phase {gamma}{sub N}. An empirical model is proposed to explain the corrosion resistance of AISI 316L and ASTM F138 nitrided samples based on Moessbauer Spectroscopy results: the larger the ratio between {epsilon} and {gamma}{sup Prime} phase fractions of the sample, the better its resistance corrosion is. In this work, this model is examined using some new results of AISI 316L samples, nitrided under the same previous conditions of gas composition and temperature, but at different pressure, for 3, 4 and 5 h. The sample nitrided for 4 h, whose value for {epsilon}/{gamma}{sup Prime} is maximum (= 0.73), shows a slightly better response than the other two samples, nitrided for 5 and 3 h ({epsilon}/{gamma}{sup Prime} = 0.72 and 0.59, respectively). Moreover, these samples show very similar behavior. Therefore, this set of samples was not suitable to test the empirical model. However, the comparison between the present results of potentiodynamic polarization curves and those obtained previously at 4 and 4.5 torr, could indicated that the corrosion resistance of the sample which only presents the {gamma}{sub N} phase was the worst of them. Moreover, the empirical model seems not to be ready to explain the response to corrosion and it should be improved including the {gamma}{sub N} phase.

  18. Moessbauer effect: a dual method for myriad applications

    This essay summarises the author's admittedly partial thoughts on the applications of the Moessbauer effect. After a short overview of the history of Moessbauer effect and Moessbauer spectroscopy, we focus on recent difficulties of the applications of the method. These emerge from the complexity of Moessbauer spectroscopy, which is now extensively used by experts of other fields. Finally the plan of setting up a Web-based Encyclopaedia of Moessbauer Spectroscopy is put forward.

  19. Systematic study of hyperfine fields in Rh2 Y Z type Heusler alloys with 119 Sn impurity using Moessbauer spectroscopy

    The magnetic hyperfine fields in the Heusler alloys Rh2 Mn .98 Ge Sn 02, Rh2 Mn Ge.98 Sn.02, Rh2 Mn Pb .98 Sn .02 and Rh2 Mn Sn has been studied by 119 Sn Moessbauer spectroscopy at 293 K, 77 K, 4.2 K and 293 K with applied external magnetic field. The results show that when one compare the magnetic hyperfine fields systematic with the Heusler alloys X2 Mn Z (X = Co, Ni, Cu, Pd, and Z = s p metal), this systematic is similar to the Co alloys, although can not explained by the currents models for the Heusler alloys. (author)

  20. Investigations of the atomic structure of amorphous ytterbium-alloys by Moessbauer spectroscopy

    Atomic-scale structures of the amorphous alloys Yb80X20 (X = Cu, Ag, Au, Pd, Bi) have been investigated with a 174Yb-Moessbauer source. The distribution of the quadrupole splitting parameters obtained from the analysis of the Moessbauer spectra was compared with the theoretical function for a charge distribution corresponding to dense random packing (DRP) of ions. The atomic structure deduced from the distribution of splitting parameters was consistent with the DRP-model in the amorphous alloys Yb80Cu20, Yb80Ag20, Yb80Au20, Yb80Pd20. In contrast the Moessbauer spectrum of the amorphous alloy Yb80Bi20 showed clear evidence of short range order. This is presumably due to the tendency of bismuth to form covalent bondings. (orig./GSCH)

  1. Moessbauer spectroscopy of Mg(0.9)Fe(0.1)SiO3 perovskite

    Jeanloz, Raymond; O'Neill, Bridget; Pasternak, Moshe P.; Taylor, R. D.; Bohlen, Steven R.

    1992-01-01

    Ambient pressure Moessbauer spectra of Mg(0.9)Fe-57(0.1)SiO3 perovskite synthesized at pressure-temperature conditions of about 50 GPa and 1700 K show that the iron is entirely high-spin Fe(2+) and appears to be primarily located in the octahedral site within the crystal structure. We observe broad Moessbauer lines, suggesting a distribution of electric-field gradients caused by disorder associated with the Fe ions. Also, the perovskite exhibits magnetic ordering at temperatures lower than 5 K, implying that there is a magnetic contribution to the absolute ('third-law') entropy of this phase.

  2. In-situ Moessbauer Spectroscopy with MIMOS II at Rio Tinto, Spain

    Fleischer, I; Klingelhoefer, G; Wehrheim, S; Ebert, S; Panthoefer, M; Blumers, M; Schmanke, D; Maul, J; Schroeder, C [Institut fuer Anorganische und analytische Chemie, Johannes-Gutenberg-Universitaet Mainz, Staudinger Weg 9, 55128 Mainz (Germany); Rull, F, E-mail: fleischi@uni-mainz.d [Unidad Asociada UVA-CSIC, al Centro de AstrobiologIa, Universidad de Valladolid, 47006-Valladolid (Spain)

    2010-03-01

    The Rio Tinto, located in southwest Spain, exhibits a nearly constant, acidic pH-value along its course. Due to the formation of sulfate minerals, Rio Tinto is considered a potential analogue site for sulfate-rich regions on Mars, in particular at the landing site of the Mars Exploration Rover Opportunity, where the ferric sulfate mineral jarosite was identified with Opportunity's Moessbauer spectrometer. Primary and secondary mineralogy was investigated in situ with portable Raman and Moessbauer spectrometers at four different Rio Tinto sampling sites. The two techniques analyse different sample portions due to their specific field of view and sampling depth and provide complementary mineralogical information.

  3. The Moessbauer Spectroscopy Studies of ε to Cementite Carbides Transformation during Isothermal Heating from As-Quenched State of High Carbon Tool Steel

    This work presents results of investigations using the Moessbauer spectroscopy technique and their interpretation concerning transformation of ε to cementite carbides during tempering in relation to the previously conducted dilatometric, microscopic and mechanical investigations. Investigations were performed on 120MnCrMoV8-6-4-2 steel. The influence of the tempering time on nucleation and solubility of ε carbides, and on cementite nucleation and growth, was determined. The analysis of phase transformations during various periods of tempering using the Moessbauer spectroscopy technique made possible to reveal fine details connected with the processes. (authors)

  4. Soils from the Jabal Al-Akhdar region of North East Libya: Characterisation of the iron using chemical methods and Moessbauer spectroscopy

    Soils from North East Libya have been investigated by X-ray diffraction, chemical analysis and Moessbauer spectroscopy. Quartz, kaolinite and illite were the main components identified by XRD in all specimens. Total and poorly ordered iron oxides were estimated using dithionite-citrate-bicarbonate (DCB) and oxalate extraction methods, respectively; in all cases, the oxalate-extractable iron represents a relatively minor fraction. Moessbauer spectroscopy showed the presence of substantial quantities of haematite and goethite, both in microcrystalline forms, but there was no systematic relationship between the relative proportions of these phases and the geographical origins of the soils

  5. A Moessbauer study on some low-dimensional magnetic compounds

    The author investigates the crystal field effects and magnetic behaviour of some low-dimensional systems which show ratio's of interchain to intrachain interactions of about 10-3. This behaviour is studied from a microscopic point of view by measuring the hyperfine interaction between the electronic system and the nuclear system of 57Fe by means of the Moessbauer effect. (Auth.)

  6. Limits of applicability of the classical field concept in Moessbauer spectroscopy

    We show that the classical model widely employed for the field radiated by an excited Moessbauer nucleus predicts an enhanced rate of coincidences for two detectors. This contradicts our experiment. We discuss the limits of applicability of the classical field concept for various experimental conditions. (orig.)

  7. X-ray diffraction and Moessbauer spectroscopy of high energy ball-milled α-Fe2O3/TiO2 composite powders

    α-Fe2O3/TiO2 Composite powders have been prepared by high energy ball-milling for different times. The composites were studied using Moessbauer Spectroscopy (MS) and X-ray diffraction (XRD). The patterns of XRD show broadening in the diffraction peaks, indicating a decrease in the particle size of the composites with milling time. Also, the XRD patterns show an evolving new structural phase correlated with an evolving Titanium ferrite species with milling time. Moessbauer Spectroscopy shows the evolving titanium ferrite species characterized by a quadrupole doublet at the expense of the α-Fe2O3 represented by the magnetic sextet. The doublet corresponding to the Ti-ferrite phase dominates the Moessbauer spectra at long milling time (greater than 100 h of milling).

  8. Ultra-soft magnetic properties and correlated phase analysis by 57Fe Mössbauer spectroscopy of Fe74Cu0.8Nb2.7Si15.5B7 alloy

    Manjura Hoque, S.; Liba, S. I.; Anirban, A.; Choudhury, Shamima; Akhter, Shireen

    2016-02-01

    A detailed study of magnetic softness has been performed on FINEMENT type of ribbons by investigating the BH loop with maximum applied field of 960 A/m. The ribbon with the composition of Fe74Cu0.8Nb2.7Si15.5B7 was synthesized by rapid solidification technique and the compositions volume fraction was controlled by changing the annealing condition. Detail phase analysis was performed through X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Vibrating sample magnetometer (VSM) and Mössbauer spectroscopy in order to correlate the ultrasoft magnetic properties with the volume fraction of amorphous and α-Fe(Si) soft nano composites. Bright (BF) and dark field (DF) image with selective area diffraction (SAD) patterns by the transmission electron microscopy (TEM) of the sample annealed for the optimized annealed condition at 853 K for 3 min reveals nanocrystals with an average size between 10-15 nm possessing the bcc structure which matches with the grain size revealed by the X-ray diffraction. Kinetics of crystallization of α-Fe(Si) phases has been determined by DSC curves. Extremely small coercivity of 30.9 A/m and core loss of 2.5 W/Kg for the sample annealed at 853 K for 3 min was found. Similar values for other crystalline conditions were determined by using BH loop tracer with a maximum applied field of around 960 A/m. Mössbauer spectroscopy was used to determine chemical shift, hyperfine field distribution (HFD), and peak width of different phases. The volume fractions of the relative amount of amorphous and crystalline phases are also determined by Mössbauer spectroscopy. High saturation magnetization along with ultrasoft magnetic properties exhibits very high potentials technological applications.

  9. Ultra-soft magnetic properties and correlated phase analysis by 57Fe Mössbauer spectroscopy of Fe74Cu0.8Nb2.7Si15.5B7 alloy

    S. Manjura Hoque

    2016-02-01

    Full Text Available A detailed study of magnetic softness has been performed on FINEMENT type of ribbons by investigating the BH loop with maximum applied field of 960 A/m. The ribbon with the composition of Fe74Cu0.8Nb2.7Si15.5B7 was synthesized by rapid solidification technique and the compositions volume fraction was controlled by changing the annealing condition. Detail phase analysis was performed through X-ray diffraction (XRD, Differential scanning calorimetry (DSC, Vibrating sample magnetometer (VSM and Mössbauer spectroscopy in order to correlate the ultrasoft magnetic properties with the volume fraction of amorphous and α-Fe(Si soft nano composites. Bright (BF and dark field (DF image with selective area diffraction (SAD patterns by the transmission electron microscopy (TEM of the sample annealed for the optimized annealed condition at 853 K for 3 min reveals nanocrystals with an average size between 10-15 nm possessing the bcc structure which matches with the grain size revealed by the X-ray diffraction. Kinetics of crystallization of α-Fe(Si phases has been determined by DSC curves. Extremely small coercivity of 30.9 A/m and core loss of 2.5 W/Kg for the sample annealed at 853 K for 3 min was found. Similar values for other crystalline conditions were determined by using BH loop tracer with a maximum applied field of around 960 A/m. Mössbauer spectroscopy was used to determine chemical shift, hyperfine field distribution (HFD, and peak width of different phases. The volume fractions of the relative amount of amorphous and crystalline phases are also determined by Mössbauer spectroscopy. High saturation magnetization along with ultrasoft magnetic properties exhibits very high potentials technological applications.

  10. Moessbauer investigations of natural and synthetic tochilinite and velleriite

    Samples of natural and synthetic tochilinites and valleriites were investigated by Moessbauer spectroscopy methods. Subjects of the investigations were samples obtained as a result of tochilinite synthesis process under different conditions (temperature of a synthesis and Fe/Mg ratio in the initial mixture), natural tochilinites, natural and synthetic valleriites. Both the extraction of hyperfine parameter distribution function and model fitting were used for processing and an analysis of Moessbauer spectra. The relative contents of obtained phases as functions of Mg atom relative content in the initial mixture were received. It was exhibited that magnesium stabilized the tochilinite structure at the synthesis temperature equal to 160 grad C, this stabilization at higher temperature was not observed. It was shown that Mg atoms at entering into the tochilinite structure preferred to replace the Fe atoms from one of two nonequivalent positions in brucite-like layer. Besides it was confirmed that in synthetic tochilinite structure the equal number of sulfide and brucite-like layers conjugated. As a result of the comparison of synthetic tochilinite with natural one it was established that iron ions were absented in natural tochilinite brucite-like layer. Parameters of hyperfine interactions were determined for valleriite and crystal chemical identification of 57Fe subspectra were carried out. (authors)

  11. Studies on the metal-nucleotide (Co-5'IMP, Co-5'GMP) interaction via Moessbauer emission spectroscopy and magnetic susceptibility measurements

    By means of 57Co Moessbauer emission spectroscopy and magnetic susceptibility measurements, the local symmetries and electronic structure of the Co(II) ions in the Co-5'IMP and Co-5'GMP complexes in the hydrated and dehydrated forms have been determined. (Auth.)

  12. Doppler shift attenuation measurements on 57Fe and 57Co

    Lifetime measurements by the Doppler shift attenuation method for levels in the nuclei 57Fe and 57Co, populated via the reactions 55Mn(α, pnγ)57Fe and 55Mn(α, 2nγ)57Co, respectively, are reported. The relative γ-ray intensities and the branching ratios for levels in the two nuclei are also presented. In 57Fe, mean lifetime values of tau = (0.20 +-0.09) ps and (0.26 +- 0.10) ps are obtained for the levels at 1007.0 keV and 1356.8 keV, respectively, for which no lifetime information existed previously and values of tau = 0.08 +- 0.03, 0.54sub(-0.15)sup(+0.30) and (0.16 +- 0.06) ps are determined for the levels at 2355.7, 3269.1 and 6185.6 keV, respectively, for which only the limits of lifetimes were reported earlier. For the 2455.2 keV level in 57Fe a lower limit of 2 ps is obtained for its mean life. In 57Co lifetimes of eight levels with Jsup(π) -/2 have been measured and compared with the earlier reported values. The results of lifetime measurements and reduced transition probabilities for both the nuclei are discussed and compared with the available shell model calculations

  13. Moessbauer spectroscopy on Mars: goethite in the Columbia Hills at Gusev crater

    In January 2004 the USA space agency NASA landed two rovers on the surface of Mars, both carrying the Mainz Moessbauer spectrometer MIMOS II. The instrument on the Mars-Exploration-Rover (MER) Spirit analyzed soils and rocks on the plains and in the Columbia Hills of Gusev crater landing site on Mars. The surface material in the plains have an olivine basaltic signature [1, 5] suggesting physical rather than chemical weathering processes present in the plains. The Moessbauer signature for the Columbia Hills surface material is very different ranging from nearly unaltered material to highly altered material. Some of the rocks, in particular a rock named Clovis, contain a significant amount of the Fe oxyhydroxide goethite, α-FeOOH, which is mineralogical evidence for aqueous processes because it is formed only under aqueous conditions. In this paper we describe the analysis of these data using hyperfine field distributions (HFD) and discuss the results in comparison to terrestrial analogues.

  14. 2D-correlation analysis applied to in situ and operando Moessbauer spectroscopy

    Aldon, Laurent; Perea, Alexis [ICGM/AIME (UMR 5253 CNRS), CC 15-02, Universite Montpellier II, Place E. Bataillon, 34095 Montpellier Cedex 5 (France)

    2011-02-01

    In this paper we propose a new way for Moessbauer data treatment when numerous experimental spectra are recorded in operando conditions depending on a perturbation. In our example, the perturbation is the Li amount extracted from a positive electrode material LiFe{sub 0.75}Mn{sub 0.25}PO{sub 4}. In other cases perturbation could be the recording temperature, the pressure or kinetic parameter or even time for isothermal experiments. From analysis of both synchronous and asynchronous 2D-correlation spectra, we can focus our attention on the intensity variations at some specific positions deduced from cross-peaks. This analytical method is very powerful when overlap between absorption lines is observed. This is typically the case when Fe{sup 2+}/Fe{sup 3+} contributions are simultaneously present in a Moessbauer spectrum at lower velocities. (author)

  15. Coatings and weathering rinds at Gusev crater, Mars, investigated by depth selective Moessbauer spectroscopy

    The miniaturised Moessbauer spectrometer (MIMOS II) is part of the scientific payload of the two Mars Exploration Rovers, 'Spirit' and 'Opportunity' (Klingelhoefer et al., J Geophys Res 108(E12), 2003). MIMOS II can obtain 14.4 keV γ-ray spectra and 6.4 keV X-ray spectra simultaneously in backscattering geometry. Comparing 6.4 keV and 14.4 keV spectra yields depth selective information about a sample and allows for the detection and characterization of thin coatings or weathering rinds. Laboratory measurements and a Monte Carlo simulation were used to study the influence of coatings of varying thickness and composition on backscattering Moessbauer spectra. The thickness of thin surface layers on natural samples can be estimated by comparing measured and the corresponding simulated spectra.

  16. Conversion electron Moessbauer spectroscopy with very low energy (0 to 15 eV) electrons

    A very intensive peak of low energy electrons (≤15 eV) appears in the electron energy spectrum, measured by a high transmission magnetic spectrometer, if a negative voltage of more than about 20 volts is applied to the Moessbauer absorber. The MB-spectrum of enriched stainless steel, recorded with these electrons, shows a high resonance effect of about 700% with countrates of 103 sec-1, compared to 750% and 60 sec-1 at the K-edge. Two processes seem to be responsible with characteristic attenuation length of about 40 A and about 400 A. We conclude, that part of these electrons are produced directly by Moessbauer absorption and conversion, resulting in low energy Auger electron emission, showing a high surface sensitivity as well. (orig.)

  17. Thermal treatment of the Fe78Si9B13 alloy in it amorphous phase studied by means of Moessbauer spectroscopy

    The magnetic and microhardness changes, dependents of the temperature that occur in the Fe78Si9B13 alloy in it amorphous state were studied by means of the Moessbauer spectroscopy and Vickers microhardness. According to the Moessbauer parameters and in particular that of the hyperfine magnetic field, this it changes according to the changes of the microhardness; i.e. if the microhardness increases, the hyperfine magnetic field increases. The registered increment of hardness in the amorphous state of this alloy should be considered as anomalous, according to the prediction of the Hall-Petch equation, the one that relates negative slopes with grain sizes every time but small. (Author)

  18. Electronic and structural properties of some ternary neptunium(VII) oxides from 237Np Moessbauer spectroscopy

    The 60 kev Moessbauer resonance of 237Np has been measured in some complex oxides of heptavalent neptunium. The nature of bonding and the molecular symmetry are discussed on the basis of the isomer shift and quadrupole coupling constant data. The molecular character of the compounds is evidenced by the low Debye temperatures and the strong bond covalency. The quadrupole coupling constant is temperature independent; this reveals the absence of any non-bonding states of f electrons. (authors)

  19. Investigation of gadolinium alloys and intermetallic compounds by the Moessbauer spectroscopy method

    The resonance absorption of the gamma quanta by 155Gd nuclei was utilized to determine the hyperfine parameters for the alloys of gadolinium with scandium and yttrium and for intermetallic compounds of gadolinium with iron, cobalt and nickel. In all cases, values of hyperfine magnetic fields, electric field gradients and isomer shifts of the Moessbauer line were obtained. Moreover, in some cases, the angle between the direction of the hyperfine field and the main axis of the electric field gradient was determined. (author)

  20. Human nigral and liver iron - comparison by Moessbauer spectroscopy, electron microscopy and ELISA

    The properties of iron present in human liver and human substantia nigra (SN) were compared. Moessbauer measurements have shown that iron is present in similar concentrations in SN and in the liver, mainly as ferritin-like iron. The size of the iron cores of ferritin, as obtained from electron microscopy, is much smaller in SN (3.6 ± 0.4 nm) than in liver (5.7 ± 0.5 nm). The small size in SN is in agreement with the low blocking temperature (about 10 K), determined by temperature dependent Moessbauer studies on whole tissues. ELISA studies have shown differences between SN and liver in the structures of the protein shells of ferritin. The H/L ratio (concentration of heavy to light chains) in liver is 0.40 ± 0.02, while in SN it is 4.3 ± 0.3. Another possible iron binding compound in SN is neuromelanin (NM). Moessbauer studies of neuromelanin, isolated from 22 SNs, demonstrated that this iron is superparamagnetic. The blocking temperature found for this neuromelanin iron is however much higher than that for ferritin.

  1. The metallurgic furnaces at the Curamba Inca site (Peru): a study by Moessbauer spectroscopy and X-ray diffractometry

    The Inca site at Curamba is located in the Province of Apurimac in the southern highlands of Peru where, according to some historians, several thousand furnaces used for ore smelting were found. For this work, four samples of burned soil were gathered from these furnaces and classified as Curamba1, Curamba2, Curamba3, and Curamba4, and studied using transmission Moessbauer spectroscopy (TMS) and X-ray diffractometry (XRD). The mineralogical composition of the samples was determined by XRD and the structural sites in the minerals occupied by iron cations were characterized by TMS. Moreover, an attempt was made to determine the maximum temperature reached in these furnaces using the refiring technique of the samples in an oxidizing environment and monitoring the structural modifications at the iron sites by changes in the Moessbauer hyperfine parameters. The TMS results of Curamba2 show that the maximum temperature reached in this furnace was about 900 deg. C, in agreement with the mineralogical composition found by XRD. In the case of Curamba1 and Curamba4 the maximum temperature estimated was about 400 deg. C.

  2. Moessbauer and EPR Study of Reaction Intermediates of Cytochrome P450

    We present a complementary Moessbauer and EPR study on reaction intermediates of substrate-free and substrate-bound cytochrome P450cam from Pseudomonas putida prepared by the freeze-quench method from 57Fe-labeled P450cam using peroxy acetic acid as oxidizing agent. When reacting the substrate-free P450cam for 8 ms reaction time the reaction mixture consists of ∼85% of ferric low-spin iron (Fe(III)) with g-factors and hyperfine parameters of the starting material; the remaining ∼15% are identified as ferryl iron (Fe(IV); SFe=1) by its Moessbauer signature. Parallel to the ferryl iron a tyrosine radical (Srad=1/2) is formed. The two paramagnetic species are not exchange-coupled; however, they are close enough to significantly influence the (EPR) relaxation behavior of the radical spin. In the case of substrate-bound P450cam only trace amounts of the tyrosine radical are formed within 8 ms (<3%); within the accuracy of Moessbauer spectroscopy (5%) iron(IV) can not be detected. The results point to Tyr-96, which is hydrogen-bonded to the substrate camphor, as the candidate for the observed tyrosine radical.

  3. Iron valency in minerals of xenoliths and redox state of the upper mantle (by Moessbauer spectroscopy data)

    The subjects of the research were mantle xenoliths from Cenozoic alkaline basalts in the Baikalian-Mongolian region. The Moessbauer spectroscopy was used to study iron valence in mineral structures. The mineral compositions were analyzed by microprobe technique. The values of ΔlgfO2 for xenoliths is vary: DP: -0.9- (-1.7); TD: -0.9-(-1.8); VP: -0.1-(-0.8); BA: -0.1-(-0.8). p - T equilibrium conditions of mineral association in xenoliths correspond to graphite stability field, ΔlgfO2 values evidence of predominance of CO2 and H2O in the mantle fluid. The heterogeneity in redox state corresponds to thermal heterogeneity. The deduced equation allows estimating the value of oxygen fugacity only the data of chemistry and φSp.

  4. Moessbauer Spectroscopy, Dilatometry and Neutron Diffraction Detection of the ε-Phase Fraction in Fe-Mn Shape Memory Alloys

    The results of a Moessbauer spectroscopy (MS) and a neutron diffraction (ND) study carried out on a set of Fe-Mn alloys quenched from high temperatures are reported. Upon quenching the high temperature stable phase FCC (γ) together with metastably retained HCP-(ε) phase are formed. The lattice parameters obtained using ND are in excellent agreement with previous results of the literature. The phase fractions obtained from MS are coincident, within experimental errors, with those extracted from ND, with exception of the case of an alloy with the lowest Mn content (16.8 at.% Mn). That situation can be associated with the occurrence of a high density of stacking faults (SF) in the γ phase or to the presence of a paramagnetic γ phase. ε phase fractions obtained from MS and ND decrease smoothly with Mn content but are always larger than the values reported in literature resulting from dilatometry.

  5. Conversion electron Moessbauer spectroscopy of epitaxial Co2Cr0.6Fe0.4Al thin films

    Heusler half-metals are promising for spintronic applications. Epitaxial thin films of the exemplar compound Co2Cr0.6Fe0.4Al (CCFA) were investigated using conversion electron Moessbauer spectroscopy to clarify the factors influencing the spin polarization. CCFA films were deposited by rf magnetron sputtering on MgO substrates with and without an Fe buffer layer. Annealing improves their crystallographic order, causes the diffusion of Fe atoms from the Fe buffer layer into the CCFA, and favors the Co-Fe disorder. The listed factors are possible reasons for the increase and subsequent reduction of the tunneling magnetoresistance in CCFA thin films observable across the annealing temperature range

  6. Speciation of {sup 241}Am molecular compounds through {sup 237}Np Moessbauer and {sup 241}Am XPS spectroscopy

    Fouchard, S.; Gouder, T.; Colineau, E.; Wastin, F.; Rebizant, J.; Simoni, E.; Guillaumont, D.; Meyer, D

    2004-07-01

    Light actinides (U to Am) can be found in several oxidation states from (II) to (VII) in the molecular form or in the condensed matter state. The large variety of oxidation states is usually attributed to the contribution of the 5f states to the valence orbitals. For the heavier actinides, for which the 5f electrons are non bonding, the actinides become rare-earth like with a smaller number of oxidation states (II and III). However it is still not understood what really decides on the stability of a given oxidation state, and how it is depending on the chemical environment (coordination sphere, nature of the counter-anion, etc). This work shows how Moessbauer spectroscopy and 4f photoelectron spectroscopy (XPS) can contribute to progress in the understanding of the electronic structure of the actinide, especially for Am compounds Moessbauer reverse experiments were undertaken to show in what manner the electronic structure of the Am is preserved during the decay process (oxidation state stability). The result of XPS measurements shows that it is possible to correlate the 4f binding energy of the Am to the charge at the actinide core. The obtained results are somewhat surprising. The formal oxidation state (V) is 'less oxidised' than expected. Some Am(III) have less electron density (that means are more ionic) than americyl (V) hydroxide or carbonate. The reason for these surprisingly results comes from the 'Am=O' multiple bond system which reduces dramatically the charge at the actinide by a pi-donation mechanism. The evolution of the 4f binding energy of the Am species does not follow the oxidation state order. Theoretical DFT calculation were done on Am(V) compounds for qualitative electronic modeling. (authors)

  7. Moessbauer spectroscopy for characterizing biodegradation of magnetic nanoparticles in a living organism

    Mischenko, Ilya Nikitich, E-mail: IlyaMischenko@rambler.ru; Chuev, Michail Alexandrovich; Cherepanov, Valeriy Mihailovich; Polikarpov, Michail Alexeevich [National Research Centre ' Kurchatov Institute' (Russian Federation)

    2012-03-15

    We have developed a model for describing nanoparticles magnetic dynamics. This allows us to fit self-consistently the wide set of the experimental data, particularly, the evolution of Moessbauer spectral shape with temperature and external magnetic field as well as the magnetization curves for nanoparticles injected into mice. Thus, we reliably evaluate changes in characteristics of the nanoparticles and their chemical transformation to ferritin-like forms in mouse's organs as a function of time after injection of nanoparticles. Actually, the approach allows one to quantitatively characterize biodegradation and biotransformation of magnetic particles in a body.

  8. Maghemite in basalt studied by Moessbauer spectroscopy in external magnetic field

    In the present study, we investigate the feasibility of detecting and determining the presence of maghemite in rock samples, by obtaining Moessbauer spectra in an external magnetic field of 1.6 T at room temperature. The interaction of the external magnetic field and the magnetic moments of the sublattices will induce differential shifts in the peak positions. By this method, we can assign some lower limit of the amount of maghemite in the sample. The results are compared with a model for a mixture of maghemite and stoichiometric magnetite. (orig.)

  9. Microwave absorption and 57Fe Mössbauer properties of Ni-Ti doped barium hexaferrite

    The impact of doping the Fe component of barium hexaferrite with Ni0.5Ti0.5 is investigated using x-ray powder diffraction, 57Fe Mössbauer spectroscopy and microwave network analysis. The dopant ions exhibit a preference for the 2b, 4f2 and 12k-sites and the unit cell volume is observed to decrease. The ferromagnetic resonance frequency is reduced by about 11.5 GHz for each additional dopant ion per formula unit

  10. Spin density wave in (Fe{sub x}V{sub 3-x})S{sub 4} and the coexistence of normal and condensate states: A Moessbauer study

    Embaid, B.P., E-mail: pembaid@fisica.ciens.ucv.ve [Laboratorio de Magnetismo, Escuela de Fisica, Universidad Central de Venezuela, Apartado 47586, Los Chaguaramos, Caracas 1041-A (Venezuela, Bolivarian Republic of); Gonzalez-Jimenez, F. [Laboratorio de Magnetismo, Escuela de Fisica, Universidad Central de Venezuela, Apartado 47586, Los Chaguaramos, Caracas 1041-A (Venezuela, Bolivarian Republic of)

    2013-03-15

    Iron-vanadium sulfides of the monoclinic system Fe{sub x}V{sub 3-x}S{sub 4} (1.0{<=}x{<=}2.0) have been investigated by {sup 57}Fe Moessbauer Spectroscopy in the temperature range 30-300 K. Incommensurate spin density waves (SDW) have been found in this system. An alternative treatment of the spectra allows a direct measurement of the temperature evolution of condensate density of the SDW state which follows the Maki-Virosztek formula. For composition (x=1.0) the SDW condensate is unpinned while for compositions (x>1.0) the SDW condensate is pinned. Possible causes of the pinning-unpinning SDW will be discussed. - Highlights: Black-Right-Pointing-Pointer Fe{sub x}V{sub 3-x}S{sub 4}(1.0{<=}x{<=}2.0) system was investigated by {sup 57}Fe Moessbauer Spectroscopy. Black-Right-Pointing-Pointer Incommensurate spin density wave (SDW) has been found in this system. Black-Right-Pointing-Pointer We report the temperature evolution of the condensate density of SDW state. Black-Right-Pointing-Pointer For composition (x=1.0) the SDW is unpinned while for (x>1.0) is pinned.

  11. Moessbauer investigations on pyrrhotite

    An experimental study of the vacancy distribution in pyrrhotite (Fe/sub 1-x/S) is presented. Seven samples from various deposits in India are investigated using Moessbauer spectroscopy, X-ray diffraction, and thermo-magnetic analysis techniques and a partially ordered and partially random vacancy distribution model for intermediate pyrrhotite is discussed. (author)

  12. EPR and (57)Fe ENDOR investigation of 2Fe ferredoxins from Aquifex aeolicus.

    Cutsail, George E; Doan, Peter E; Hoffman, Brian M; Meyer, Jacques; Telser, Joshua

    2012-12-01

    We have employed EPR and a set of recently developed electron nuclear double resonance (ENDOR) spectroscopies to characterize a suite of [2Fe-2S] ferredoxin clusters from Aquifex aeolicus (Aae Fd1, Fd4, and Fd5). Antiferromagnetic coupling between the Fe(II), S = 2, and Fe(III), S = 5/2, sites of the [2Fe-2S](+) cluster in these proteins creates an S = 1/2 ground state. A complete discussion of the spin-Hamiltonian contributions to g includes new symmetry arguments along with references to related FeS model compounds and their symmetry and EPR properties. Complete (57)Fe hyperfine coupling (hfc) tensors for each iron, with respective orientations relative to g, have been determined by the use of "stochastic" continuous wave and/or "random hopped" pulsed ENDOR, with the relative utility of the two approaches being emphasized. The reported hyperfine tensors include absolute signs determined by a modified pulsed ENDOR saturation and recovery (PESTRE) technique, RD-PESTRE-a post-processing protocol of the "raw data" that comprises an ENDOR spectrum. The (57)Fe hyperfine tensor components found by ENDOR are nicely consistent with those previously found by Mössbauer spectroscopy, while accurate tensor orientations are unique to the ENDOR approach. These measurements demonstrate the capabilities of the newly developed methods. The high-precision hfc tensors serve as a benchmark for this class of FeS proteins, while the variation in the (57)Fe hfc tensors as a function of symmetry in these small FeS clusters provides a reference for higher-nuclearity FeS clusters, such as those found in nitrogenase. PMID:22872138

  13. Determination of the Lamb-Moessbauer factors of LiFePO4 and FePO4 for electrochemical in situ and operando measurements in Li-ion batteries

    57Fe Moessbauer spectroscopy is a powerful tool to investigate redox reactions during in electrochemical lithium insertion/extraction processes. Electrochemical oxidation of LiFeIIPO4 (triphylite) in Li-ion batteries results in FeIIIPO4 (heterosite). LiFePO4 was synthesized by solid state reaction at 800 deg. C under Ar flow from Li2CO3, FeC2O4.2H2O and NH4H2PO4 precursors in stoichiometric composition. FePO4 was prepared from chemical oxidation of LiFePO4 using bromine as oxidative agent. For both materials a complete 57Fe Moessbauer study as a function of the temperature has been carried out. The Debye temperatures are found to be θM=336 K for LiFePO4 and θM=359 K for FePO4, leading to Lamb-Moessbauer factors f300K=0.73 and 0.77, respectively. These data will be useful for a precise estimation of the relative amounts of each species in a mixture. - Graphical abstract: Relative amount of FePO4 obtained by Moessbauer and electrochemical data. We have corrected Moessbauer spectral intensities with our f factor of both LiFePO4 and FePO4. Open (filled) squares correspond to values obtained during charging (discharging) process. The dashed line, given as a guideline for the eye, corresponds to the ideal case were amounts deduced from different experimental measurements are equal.

  14. {sup 119}Sn Moessbauer spectroscopy in the heavy - fermion ferrimagnet UCu{sub 5}Sn

    Latka, K [Marian Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland); Kruk, R [Institute of Nanotechnology, Forschungszentrum Karlsruhe GmbH, PO Box 3640, D-76021 Karlsruhe (Germany); Kmiec, R [Henryk Niewodniczanski Institute of Physics, Radzikowskiego 152, 31-342 Krakow (Poland); Troc, R; Tran, V H, E-mail: uflatka@cyf-kr.edu.p [Wlodzimierz Trzebiatowski Institute of Low Temperature and Structure Research Polish Academy of Sciences, PO Box 937, 50-950 Wroclaw (Poland)

    2010-03-01

    {sup 119}Sn Moessbauer studies of UCu{sub 5}Sn compound have been performed in a wide temperature range between 4.2 K and 78 K. Magnetic hyperfine split spectra observed below T=54 K indicate the onset of magnetic ordering. The temperature dependence of the average transferred effective magnetic hyperfine field at the tin site can be surprisingly well fitted using the Brillouin function for S = 1/2. A rather small distribution of magnetic hyperfine fields {delta}{sub H} obtained from the fitting procedure is in favour with the assumption that atomic mixing between Cu and Sn position can be neglected. The value of {theta} = 10(2){sup 0} shows that the direction of the effective magnetic hyperfine field H{sub eff} is close to the c-axis being in accord with the uranium magnetic moment direction.

  15. 119Sn Moessbauer spectroscopy in the heavy - fermion ferrimagnet UCu5Sn

    119Sn Moessbauer studies of UCu5Sn compound have been performed in a wide temperature range between 4.2 K and 78 K. Magnetic hyperfine split spectra observed below T=54 K indicate the onset of magnetic ordering. The temperature dependence of the average transferred effective magnetic hyperfine field eff> at the tin site can be surprisingly well fitted using the Brillouin function for S = 1/2. A rather small distribution of magnetic hyperfine fields δH obtained from the fitting procedure is in favour with the assumption that atomic mixing between Cu and Sn position can be neglected. The value of θ = 10(2)0 shows that the direction of the effective magnetic hyperfine field Heff is close to the c-axis being in accord with the uranium magnetic moment direction.

  16. 119Sn Moessbauer spectroscopy in the magnetically diluted Heusler-type systems

    119Sn Moessbauer investigations of the ferromagnetically diluted Nisub(2)Mnsub(x)Bsub(1-x)Sn(B=Ti, V) and Pdsub(2)Mnsub(x)Vsub(1-x)Sn Heusler-type systems have been performed and the results are reviewed and discussed. It has been found that distributions of the transferred hyperfine magnetic field as seen by a tin nucleus are very sensitive for a type of the local magnetic interaction in these simple ferromagnets, especially when studied versus the sample temperature. This sensitivity allows to reach some conclusions about the coupling mechanism between localised manganese magnetic moments. Namely, it is concluded that the interaction beyond the second neighbour shell is practically irrelevant for the magnetic ordering process. This very fact means that the free electron approach to the calculation of exchange integrals can not be applied for these particular systems. (Author)

  17. Site populations analysis of the Sm2(Co,Fe)17 alloys using Moessbauer spectroscopy

    Moessbauer measurements were carried out at room temperature for Sm2(Co1-x Fex)17 alloys with x=0,1 to 0,6 and Sm2(Co0.9-v Fev Cu0.08 Zr0.02)8.35, with v=0.23 to 0.27. All samples were characterized by x-ray diffraction. They showed rhombohedral structure of Th2 Zn17 type (R 3-bar m), where Fe atoms occupy four crystallographic sites. All spectra showed magnetic splitting and a high complexity resulting from the superposition of four Fe sites. Hyperfine parameters and site populations were obtained by least-squares fitting of the spectra. (author)

  18. A study of the electric hyperfine interaction at 57Fe in Na3Fe(CN)6.2H2O using polarized recoilless gamma radiation

    Polarimetric Moessbauer measurements have been carried out to determine the electric hyperfine hamiltonian for the 14.4 keV excited state of an 57Fe nucleus in monoclinic Na3Fe(CN)6.2H2O. The experiments were made with a single crystal sample using polarized gamma rays emitted from a magnetized source. The data were analyzed using a density matrix formalism and taking into account the change in polarization of the radiation inside the absorber of finite thickness. The quadrupole interaction is nonaxial with eta = 0.52(9) and the main principal axis of the electric field gradient lies in the ac-plane. (Auth.)

  19. Conversion electron Moessbauer spectroscopy study of r.f. sputtered Cd0.95 Fe0.05 Ie thin films

    Conversion electron Moessbauer spectroscopy (CEMS) studies have been performed on Cd0.95 Fe0.05 Te films grown by r.f. sputtering on quartz and silicon substrates. the CEMS spectra show the presencce of Fe2+ and Fe3+ in the films. It was studied the dependence of the population of both ions on substrate temperature, annealing temperature and substrate type. (Author)

  20. Moessbauer spectroscopy and x-ray fluorescence study of ancient pottery from the New Kingdom excavated at Mit-Rahina (Memphis)

    Ancient pottery sherds from excavations at Mit Rahina Region from the New Kingdom were studied by Moessbauer and x-ray fluorescence spectroscopy. Based on the data the provenance of the clay used for the production of each type of these potteries and the manufacturing technology were determined. A group of potteries was found which had been imported from the neighbouring region. (author) 8 refs.; 7 figs.; 2 tabs

  1. Moessbauer spectroscopy and X-ray diffraction analyses of clayey samples used as ceramic sourcing materials, in Peru

    Quille, Ruben, E-mail: quilleruben@gmail.com; Bustamante, Angel [San Marcos National University, Laboratory of Ceramics and Nanomaterials, Faculty of Physical Sciences (Peru); Palomino, Ybar [National University of San Cristobal de Huamanga, Experimental Center of Ceramics (Peru)

    2011-11-15

    The ceramic industry is an important area of economic activity in the Ayacucho Region, in particular in the District of Quinua. As a consequence, there is a huge demand for clay to produce ceramic pastes in that region. This paper reports on results concerning the mineralogical characterization of four clayey samples, which were collected MAA and SPQA from the area Pampa de La Quinua with geographic coordinates 13 Degree-Sign 02 Prime 49 Double-Prime S 74 Degree-Sign 08 Prime 03 Double-Prime W, CE1M and CE2M from the Quinua locality 13 Degree-Sign 03 Prime 07 Double-Prime S 74 Degree-Sign 08 Prime 31 Double-Prime W, both in the District of Quinua, Province of Huamanga, Ayacucho, Peru. The chemical and mineralogical characterization of these samples was carried out with powder X-ray diffraction detecting quartz, albite, montmorillonite, kaolinite and glauconite mineral phases, Moessbauer spectroscopy detected iron in kaolinite, glauconite and montmorillonite minerals. Chemical analysis was performed through scanning electron microscopy and energy dispersive X-ray spectroscopy. Data obtained from the combination of these techniques provided relevant information about the morphology, chemical composition, and the mineralogy of samples.

  2. 57Fe NMR study of nitrided Ce2 Fe17

    The 57 Fe NMR of Ce2 Fe17 Nx (x=0-1.5) was measured in the ordered magnetic state at 4.2 K. For x = 0, resonances coming from all Fe sites have been identified in the 30 - 45 MHz range. With nitrogenation, new lines appear in the range 37 - 54 MHz. Every nitrogenated sample shows three sets of lines, arising from regions where Ce atoms have 0, 2, and 3 nitrogen atoms as near neighbors. (author). 5 refs., 1 fig

  3. Moessbauer and XRD study of pulse plated Fe-P and Fe-Ni thin layers

    Miko, Annamaria [Bay Zoltan Institute for Material Science (Hungary); Kuzmann, Erno, E-mail: kuzmann@para.chem.elte.hu [Eoetvoes Lorand University, Research Group for Nuclear Methods in Structural Chemistry, Hungarian Academy of Sciences, Department of Nuclear Chemistry (Hungary); Lakatos-Varsanyi, Magda [Bay Zoltan Institute for Material Science (Hungary); Kakay, Attila [Research Institute for Solid State Physics and Optics (Hungary); Nagy, Ferenc [Eoetvoes Lorand University, Research Group for Nuclear Methods in Structural Chemistry, Hungarian Academy of Sciences, Department of Nuclear Chemistry (Hungary); Varga, Lajos Karoly [Research Institute for Solid State Physics and Optics (Hungary)

    2005-09-15

    {sup 57}Fe conversion electron Moessbauer spectroscopy, X-ray diffraction, electrochemical and magnetic measurements were used to study pulse electroplated Fe-P and Ni-Fe coatings. XRD and {sup 57}Fe CEMS measurements revealed the amorphous character of the novel pulse plated Fe-P alloys. CEM spectra indicated significant differences in the short range order and in the magnetic anisotropy between the Fe-P deposits pulse plated at medium long deposition time (t{sub on} = 2 ms), with short relaxation time (t{sub off} = 9 ms) and low current density (I{sub p} = 0.05 Acm{sup -2}) or at short deposition time (t{sub on} = 1 ms) with long relaxation time (t{sub off} = 250 ms) and high current density (I{sub p} = 1.0 Acm{sup -2}). The broad peaks centred around the fcc reflections in XRD of the pulse plated Ni-22 wt.% Fe deposit reflected a microcrystalline Ni-Fe alloy with a very fine, 5-8 nm, grain size. The CEM spectrum of the pulse plated Ni-22 wt.% Fe coating corresponded to a highly disordered solid solution alloy containing a minute amount of ferrihydrite. Extreme favourable soft magnetic properties were observed with these Ni-Fe and Fe-P pulse plated thin layers.

  4. Voigt-based methods for arbitrary-shape static hyperfine parameter distributions in Moessbauer spectroscopy

    Rancourt, D.G.; Ping, J.Y. (Ottawa-Carleton Inst. for Physics, Ottawa Univ., Ontario (Canada))

    1991-05-01

    We introduce a powerful approach for obtaining arbitrary-shape static hyperfine parameter distributions from thickness corrected Moessbauer spectra. The distributions are taken to be sums of Gaussian components and the corresponding spectra are shown analytically to be sums of Voigt lines. Three cases are worked out in detail for distributions of: (1) center shifts, (2) quadrupole splittings with linear coupling to center shifts, and (3) hyperfine fields with linear couplings to center shifts and quadrupole splittings. The domain of validity of our method is described, with particular attention given to recognizing the presence of dynamic effects. An application of hyperfine field distributions to the spectra of Fe-Ni alloys is given. In all cases, convergence is rapid and unambiguous with only two or three Gaussian components being needed for ideal fits. Adding more components does not destabilize the solution but only results in the same distribution and the same value sof all the parameters being obtained. Problems occurring with other methods are eliminated by design - given the intrinsic suitability of an expansion in terms of Gaussians. (orig.).

  5. The influence of ruthenium on the magnetic properties of gamma-Fe sub 2 O sub 3 (maghemite) studied by Moessbauer spectroscopy

    Helgason, O; Berry, F J; Mosselmans, F

    2003-01-01

    Ruthenium-doped gamma-Fe sub 2 O sub 3 has been synthesized and examined by x-ray powder diffraction, XANES, EXAFS and by sup 5 sup 7 Fe Moessbauer spectroscopy. Ruthenium K-edge x-ray absorption spectroscopy shows that ruthenium adopts a fully occupied octahedral site in the spinel related gamma-Fe sub 2 O sub 3 structure as Ru sup 4 sup +. The sup 5 sup 7 Fe Moessbauer spectra recorded in the presence of a longitudinal magnetic field of 6 T confirmed the octahedral coordination of the tetravalent ions and canting angles for the Fe sup 3 sup + ions were determined as 24 deg. for those in octahedral sites and 33 deg. for those in tetrahedral sites. The sup 5 sup 7 Fe Moessbauer spectra recorded in situ from ruthenium-doped gamma-Fe sub 2 O sub 3 showed parameters typical of maghemite up to 600 K but with a magnetic hyperfine field distribution suggesting an inhomogeneous distribution of ruthenium within particles of varied size around about 15 nm. At 700 K a phase transition from gamma-Fe sub 2 O sub 3 to alp...

  6. Research by Moessbauer and infrared spectroscopy of films of polyacrylonitrile doped with FeCl2 and FeCl3

    The heating effect on films of polyacrylonitrile and doping of the ions Fe(II) and Fe (III) may reveal important aspects of the use of this polymer in the search for new materials. This paper was done the doping of the films of PAN with ions Fe(II) and Fe (III), with thermo heating is range of 60 a 90 deg C e de 90 a 170 deg C through the alkaline and acid hydrolysis of the CN groups used spectroscopy of FTIR and Moessbauer techniques to evaluate the structural changes results of doping process this polymer. The results showed that the FTIR spectral have a strong interaction of the ions Fe(II) and Fe (III) with PAN and confirmed by Moessbauer data. (author)

  7. 57Fe hyperfine interaction parameters and selected magnetic properties of high purity MFe12O19 (M = Sr, Ba)

    Much of the confusion regarding the 57Fe Moessbauer spectroscopic hyperfine parameters of SrFe12O19 and BaFe12O19 at 300 K has been removed by means of an interlaboratory investigation of well-characterized samples prepared from high purity starting materials. In contrast to previous investigations, the contributions of each of the five Fe sublattices to the Moessbauer spectrum are discernible at 300 K and five components are necessary for an adequate fit of the data. The relative magnitudes of the hyperfine fields, Hn, and isomer shifts, δ, are as follows: for SrFe12O19 and BaFe12O19: Hn(2b)n(12k)n(4f1)n(2a)n(4f2), for SrFe12O19 δ(4f1)≤δ(2b)2), and for BaFe12O19 δ(2b)1)2)<δ(2a). The above assignment is based on considerations of both magnetic and crystal/chemical structures. The high purity starting materials seem to have appreciable influences on both hyperfine interaction parameters and bulk magnetic properties as observed by others for spinel and garnet ferrites. (orig.)

  8. 121Sb Moessbauer spectroscopy of antimony (V) chloro fluorides SbClsub(5-x)Fsub(x)

    121Sb Moessbauer spectra of a number of compounds of the series SbClsub(5-x)Fsub(x) were measured. The variations of isomer shift and quadrupole coupling are discussed in terms of the molecular geometry

  9. Moessbauer study on the deformed surface of high-manganese steel

    Conversion electron, X-ray backscattering and conventional transmission 57Fe Moessbauer measurements have been performed to investigate the origin of the remarkable work hardening at the surface of a high-manganese steel which is called Hadfield steel. Moessbauer results show that α' martensite has no relation to work hardening. From the comparison of conversion electron to X-ray backscattering spectra, the occurrence of decarbonization is suggested at the surface. The transmission Moessbauer spectrum at 20 K for deformed specimen shows the existence of ε martensite which could be related to the work hardening of Hadfield steel. (orig.)

  10. Moessbauer studies of the pseudo-binary intermetallic compounds Gd(Al sub(x) Fe sub(1-x))2

    The series of psedudo-binary intermetallic compounds Gd(Al sub(x) Fe sub(1-x))2 has been studies by Moessbauer spectroscopy in the concentration region where it crystallizes in the cubic system. The experimental spectra are complex and have been analysed in terms of seven configurations, corresponding to 0,1,2...6 Fe neighbours. In the region rich in Fe (0.25 >= x >= 0.05) the spectrum associated to six Fe neighbours shows a constant magnetic hyperfine (hf) field, and a decreasing electric quadrupole interaction. In the region rich in Al (0.75 >= x >= 0.90) the computer analysis is more difficult; in this range the 57Fe hf field which corresponds to the most probable configuration (zero Fe neighbours), shows a change in spin. Estimates of the s and d contributions to the hf field are made at the different concentrations. (Author)

  11. Moessbauer effect study of ancient Egyptian pottery

    Moessbauer spectroscopy was used in examining ancient Egyptian pottery. From the values of Moessbauer parameters and the differences for the individual samples, conclusions could be drawn as to the temperature of baking and the kind of clay used in various archaeological periods. (A.K.)

  12. Moessbauer spectroscopic analysis of ancient Egyptian pottery

    Ten pieces of Egyptian pottery ware and eleven silt samples collected at Hierakonopolis (Nile River, Egypt) were studied by Moessbauer spectroscopy. Three Nile silt samples and three pottery sherds were test fired and refired in an oxidized atmosphere up to 11000C. Changes of the Moessbauer parameters depend upon the firing temperatures as well as the firing atmosphere. (Auth.)

  13. Moessbauer study of (Bi,Pb)-2223 superconductors irradiated with 86Kr ions

    57Fe Moessbauer spectroscopy was used to study the effects of heavy ion irradiation on (Bi0.93Pb0.17)Sr1.9Ca2.05(Cu1.02Fe0.01)3Oy superconductors. The Moessbauer spectra of the irradiated superconductor showed significant changes in the subspectra belonging to different Cu microenvironments into which Fe ions were substituted. The relative occurrence of Fe occupying the square pyramidal fivefold oxygen coordinated Cu sites decreased while Fe3+ substituting the square planar fourfold oxygen coordinated Cu sites increased upon bombardment by 246 MeV 86Kr8+ ions. This observation was interpreted on the basis of partial replacement of the apical oxygen atoms in the square pyramids surrounding one of the Cu sites. Such oxygen vacancies create additional square planar coordination sites for Cu. These results also support the covalent character of Cu-O bonds in the superconducting layer as well as the ionic character of bond of apical oxygen to Cu. (author)

  14. Moessbauer investigation of characteristic distribution of iron oxides in sediments from the Antarctica

    Sediments from the Admirally Bay, King George Island, Antarctica, were investigated by 57Fe Moessbauer spectroscopy, X-ray diffractometry, and radiometry. Quartz, feldspar, chlorite, calcite, dolomite, mica, kaolinite, hematite and magnetite were identified as constituent minerals in the sediment samples. The phase composition and the iron distribution among the crystallographic sites of iron-bearing minerals (silicates, magnetite and hematite) of samples from different location have been derived from the complex Moessbauer spectra. At different locations sediments has significant characteristic differences in the mineral composition, in the iron distribution among the crystallographic site of silicates, and in the specific radioactivity of Cs radionuclides. These results indicate differences in the rock formation and alteration by the sediments in this maritime part of Antarctica. There is a much higher amount of iron oxides in the sediments from south part of the geological fault across the Admirally Bay than in the north part. This can be associated with much more alteration in the rocks in the south part compared to the northern one. This finding can contribute to the question of the history of the formation and alteration of volcanic rocks in the border of Antarctica. (author)

  15. The elementary concentration and the behavior of the iron in Cuban agricultural soils by means of the Neutron activation Analysis and Moessbauer Spectroscopy

    Representative samples from Cuban agricultural soils, which have been benefited with industrial waste are studied by means of the methods of the Analysis for Instrumental Neutronic Activation and Moessbauer Spectroscopy. The elemental contents of Na, K, Ca, Fe, Cr, etc. are determined, and the influence of the industrial waste in the elemental concentrations is valued. The behavior of the iron is studied, like one of the important elements in several processes of development of the plants. The oxidation and coordination states of the Fe in soils are studied

  16. Chemical-mineralogical characterization and Moessbauer spectroscopy of aquamarine from Pedra Azul, Northeast of Minas Gerais; Caracterizacao quimico-mineralogica e espectroscopia Moessbauer de agua-marinha da regiao de Pedra Azul, nordeste de Minas Gerais

    Viana, Rubia Ribeiro; Jordt-Evangelista, Hanna [Ouro Preto Univ., MG (Brazil). Escola de Minas. Dept. de Geologia]. E-mail: rubia@degeo.ufop.br; hanna@degeo.ufop.br; Costa, Geraldo Magela da [Ouro Preto Univ., MG (Brazil). Dept. de Quimica]. E-mail: magela@iceb.ufop.br

    2001-03-01

    Aquamarines from three pegmatites located the vicinities of the Pedra Azul city, Minas Gerais state, were investigated in terms of chemical composition, physical properties and Moessbauer spectroscopy. The small lenticular pegmatite bodies are usually less than 5 m wide and exhibit a conspicuous mineralogical and textural zoning. The last thermal event in these pegmatites, determined by K-Ar method in muscovite, is of Neo proterozoic age, coincident with the late stages of the Brasiliano tectono- metamorphic cycle. Chemical analyses showed that sodium is the alkali with higher contents in the aquamarines, thus enabling their classification as sodic beryls. In zoned samples there is an increase of Fe as well as Mn from center to border, while no systematic variation could be detected for other elements. The specific gravity of 2.72 to 2.80 g/cm{sup 3} is higher than the values determined for samples from other pegmatites of Minas Gerais. The refraction indices are ne=1.569 - 1.579 and NW= 1.573 - 1.581 and the birefringence varies from 0.002 to 0.008. The refraction indices increase with the Be O content. The color of aquamarines varies from medium to light blue, sometimes greenish blue. Moessbauer spectra obtained at room temperature and at 80 K show that Fe{sup 2+} is the main chromophore-ion and suggest that the iron is present in octahedral sites as well as in the structural channels. Moessbauer spectra also indicate that the incorporation of Fe{sup 3+} may cause a shift from deep blue to light blue colors. Based on their aquamarine composition the pegmatites were classified as barren, poor in rare alkalis (Li, Rb, Cs) and therefore little differentiated. The relatively simple mineralogy and the lack of lithium minerals such as lepidolite and spodumene confirm this classification. Thus, the composition of beryl can be used as a tracer for the prospection of pegmatites with different degrees of differentiation and consequently with different types of

  17. Moessbauer spectrometers

    The recent advances in Moessbauer spectrometers, their parameters and electronic circuits are reviewed. The transfer functions of two mathematical models of electromechanical transducers (with discrete and continuously distributed parameters) are given. The problems of drive and pick-up parts optimisation are discussed. The electronic circuits for reference triangle wave generators with reduced nonlinearity are described. The influence of the positive and negative corrections of the Moessbauer spectrometer feedback loop on the error-signal is discussed. A flow chart for adaptive minimization of the error-signal is presented. In addition a special drive system using piezoelements with an appropriate digital sinusoidal generator is also included. A flow chart of the system for data acquisition is shown. (author)

  18. Moessbauer spectrometers

    The recent advances in Moessbauer spectrometers, their parameters and electronic circuits are reviewed. The transfer functions of two mathematical models of electromechanical transducers (with discrete and continuously distributed parameters) are given. The problem of optimization of the drive and pick-up parts is discussed. The electronic circuits for reference triangle wave generators with reduced nonlinearity are described. A Moessbauer spectrometer with both positive and negative corrections in the feedback loop is described. The influence of these corrections on the error-signal is discussed. A flow chart for adaptive minimization of the error-signal is presented. In addition a special drive system using piezo elements with an appropriate digital sinusoidal generator is also included. A flow chart of the system using PC for data accumulation is shown. (author)

  19. A 57Fe Mössbauer study of magnetocaloric Fe doped MnCoGe

    MnCoGe-based compounds are of interest with respect to the magnetocaloric effect due to a martensitic phase transition from the low-temperature orthorhombic phase to the high-temperature hexagonal phase. A key feature is that the transition temperature can be readily tuned to obtain a magneto-structural transition. Fe is an effective substitute for Mn or Co to stabilize the hexagonal phase at low temperature. Here we present initial 57Fe Mössbauer spectroscopy measurements on (Mn 0.96Fe 0.04)CoGe and Mn(Co 0.96Fe 0.04)Ge samples doped with 0.5 wt % 57Fe. The martensitic transition temperatures were determined to be 239 K and 304 K with transition full widths at half maximum of 44 K and 39 K respectively as determined from x-ray diffraction experiments over the temperature range 10–310 K. The magnetic properties were studied over the temperature range 5–300 K and a magneto-structural transition found in Mn(Co 0.96Fe 0.04)Ge. Analysis of the 20 K Mössbauer spectra reveals that the Fe atoms are distributed on both the Mn and Co sites and tend to prefer to occupy the Co site in both the (Mn 0.96Fe 0.04)CoGe and Mn(Co 0.96Fe 0.04)Ge samples. The hyperfine fields determined for Fe atoms on the Mn and Co sites at 20 K in the ferromagnetic orthorhombic phases are Bhf−Mn= 16.4(4) T and Bhf−Co= 21.1(4) T

  20. Isotope-periodic multilayer method for short self-diffusion paths - a comparative neutron and synchrotron Moessbauer reflectometric study of FePd alloys

    FePt, FePd, CoPt, and CoPd in equilibrium exhibit the L10 structure with high perpendicular magnetic anisotropy making them attractive candidates for high-density magnetic recording. Magnetic properties of these films depend on the distribution and orientation of the L10 fraction controlled by diffusion on atomic scale. Epitaxial isotope-periodic natFePd/57FePd alloy films were prepared by molecular beam epitaxy and heat treated at 5000C for various retention times. Isotope-sensitive non-destructive methods, neutron reflectometry and synchrotron Moessbauer reflectometry were applied to follow very short diffusion paths normal to the film plane. Squared diffusion lengths and diffusion profiles were obtained from the fitting of experimental reflectivity curves for each annealing treatment steps. The somewhat different diffusion lengths obtained for the neutron and synchrotronMoessbauer reflectograms of the same samples are explained by the larger footprint of the sample in the neutron experiment for which interface inhomogeneities are to be averaged. Diffusion in the microscopically different local environments were modelled by piecewise constant diffusion coefficients in the regions identified as different species by conversion electron Moessbauer spectroscopy.

  1. Moessbauer spectroscopy and X-ray fluorescence analysis in studies for determinate the sources of several prehispanic objects

    A study by the Moessbauer effect and X-ray fluorescence analysis of the mexican prehispanic ceramic specimens is presented. Several iron compounds of the ceramics are determined, the different iron compounds indicate different sources of the clays, and different forms of ovens used with them, this compounds are identified by the differents oxidation states of the magnetic iron Fe3+, Fe2+. (author)

  2. 197Au Moessbauer spectroscopy; hyperfine interactions and dynamical behaviour of gold in molecular crystals and small particles

    The investigations described in this thesis are concerned with the Moessbauer effect in 197Au. The energy of the nuclear transitions is rather high (77 keV) and consequently the Moessbauer fraction is appreciable only at very low temperatures. Furthermore, the parent nucleus (197Pt) has a half life of 18 hrs and sources can be used for a few days only. Nevertheless this investigation has been undertaken because, once available, the technique can be readily applied to all gold-containing substances in order to study the hyperfine interactions which contain a lot of information on the chemical environment of the Moessbauer nucleus. These hyperfine effects on gold cannot be measured by other techniques like Electron Spin Resonance (ESR) or Nuclear Magnetic Resonance (NMR), except in a few special cases. Further, the source of 197Au in Pt exhibits the natural linewidth, not broadened by small hyperfine effects, in contrast with iron and tin sources. This makes it less complicated to determine absolute Moessbauer fractions

  3. Application of Moessbauer spectroscopy in studies of thermal fatigue of ceramic materials. Part of a coordinated programme on development of methods for the application of Moessbauer spectroscopy in mineralogy, soil sciences and ceramics

    Moessbauer measurements have been carried out on powder samples of pseudobrookite (Fe2TiO5) which is known to exhibit extensive microcracking due to its highly anisotropic thermal expansion. The samples were subjected to temperature cycling treatment either at high (30 to 450 C) or low (-130 to 120 C) temperature range. It was observed that the crystal lattice vibrations are changing in response to the thermal fatigue treatment applied. Measurements of isomer shift and Moessbauer spectral areas allows to determine the characteristic Debye temperature which depends on the type of temperature treatment used, the findings are in qualitative agreement with the existence of a critical grain size for the microcracking of Fe2TiO5 as found in elastic modules and flexural strength measurements

  4. Relation between Moessbauer spectroscopy and geometrical frustration factors in MCr1.9857Fe0.02O4 (M=Co,Zn)

    In order to elucidate the role of Cr ions in MCr2O4 (M=Co,Zn) exhibiting geometrically frustration and multiferroic property, we have substituted a small amount of Fe ions for Cr sites and investigated the magnetic behavior of Fe ions with Moessbauer spectroscopy. The crystal structure was found to be single-phase cubic spinel with space group of Fd3m. The lattice constants a0 and the internal structural parameter (x) of the oxygen were determined to be 8.340, 8.331 A and 0.261 and 0.260, respectively. The Moessbauer absorption spectra at 4.2 K show that the well-developed two sextets are superposed with small difference of hyperfine fields(Hhf). The hyperfine fields of CoCr1.9857Fe0.02O4 and ZnCr1.9857F 0.02O4 were determined to be 490∝480 kOe and 460∝450 kOe, respectively. Isomer shift values (δ) of the two sextets are found to be 0.33∝0.35 mm/s relative to those of Fe metal, which are consistent with the high spin Fe3+ charge state. From the results of Moessbauer measurement, it is suggested that Cr3+ ions have two different magnetic sites, and there is a correlation between hyperfine fields and degree of magnetic geometrical frustration. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Hyperfine interactions by Moessbauer effect

    Moessbauer spectroscopy has been used to investigate hyperfine interactions in materials endowed with complex electromagnetic crystallographic structures. Such structures (Me3B7O13X boracite-type systems, for instance), equally interesting from both scientific and applications viewpoint, are drawing a special attention lately on account of their being examined by means of increasingly refined experimental techniques. In view of the wide prospects of using these materials in various practical fields, this thesis counts among the studies aiming to ameliorate the methods of processing and determining the Moessbauer spectra parameters, characterized by complex hyperfine interactions, as well as among the studies of electric, magnetic and crystallographic investigation of the Moessbauer nucleus neighbourhood, in boracite-type structures. (author)

  6. Magnetic properties of UTSn compounds (T=Co, Rh, Ir, Ru) studied by 119Sn Moessbauer spectroscopy

    Detailed 119Sn Moessbauer studies were performed on the ferromagnetic uranium intermetallic compounds UTSn (T=Co, Rh, Ir, Ru) both above and below their Curie temperatures. The analysis of the experimental results allowed to determine the direction of magnetization which coincides with the crystallographic c axis for all these compounds as well as to define the orientations of the principal axes of the electric field gradient tensor with respect to the crystallographic axes. For UCoSn, URhSn, and UIrSn, the Vyy component is parallel to the c axis while in the case of URuSn, the Vzz component is parallel to this axis. The Moessbauer spectra taken at higher temperatures demonstrate a considerable distribution of magnitudes of the transferred magnetic hyperfine fields as well as a coexistence of magnetic and nonmagnetic contributions close to the Curie temperatures. copyright 1997 The American Physical Society

  7. Moessbauer characterisation of Fe-polygalacturonate as a medicine for human anaemia: the effect of iron concentration

    57Fe Moessbauer spectroscopy was used to study the effect of iron concentration on the oxidation state and microenvironments of iron in Fe-polygalacturonate compounds prepared by a novel method from pectin. The iron concentration of the coordination compounds was determined by inductively coupled plasma optical emission spectrometry analysis. The Moessbauer spectra of the studied compounds could be decomposed into three markedly different quadrupole doublets referring to three microenvironments. Two of these have ferrous and one has ferric oxidation state. In the applied concentration range the relative occurrence of the ferric component was found to increase considerably with iron concentration. At the same time, with increasing iron concentration the relative occurrence characteristic of the three components showed saturation behaviour up to the iron concentration at which for each pair of galacturonic acid units there is on average one iron atom in the system, which iron concentration value is interpreted as to be related to the complete fill up of certain iron complexation sites of the polygalacturonate chains.

  8. Magnetic fluid: Comparative study of nanosized Fe3O4 and Fe3O4 suspended in Copaiba oil using Moessbauer spectroscopy with a high velocity resolution

    Comparative study of nanosized magnetite and magnetite suspended in Copaiba oil (biocompatible magnetic fluid) was made using Moessbauer spectroscopy with a high velocity resolution (spectra were measured in 4096 channels). The better fit of room temperature spectra was done using 15 sextets and 1 doublet employing different parameters while spectra measured at 90 K were better fitted using 15 sextets with different parameters. These component numbers were related to multi-domain structure and non-stoichiometry of magnetite. Observed differences of magnetic hyperfine fields and relative areas of spectral components for nanosized Fe3O4 and Fe3O4 suspended in Copaiba oil may be related to the effect of surface interactions of Fe3O4 and polar molecules of Copaiba oil.

  9. Disentanglement of static and dynamic magnetism in itinerant AFe4X2 systems studied by muon spin relaxation and Moessbauer spectroscopy

    The AFe4X2 (A=Y,Lu,Zr; X=Ge,Si) family of transition metal tetrels has shown to be a promising candidate for studying the change of the electronic ground state under chemical substitution. Within the ZrFe4Si2-type structure (P42/mnm), the iron atoms are arranged in chains of edge-linked tetrahedral. Their structure is prone for reduced dimensionality or frustration and is thus expected to lead to emergent phenomena near a quantum critical point. In this talk, we give an overview of our recent experimental findings from Muon Spin Relaxation and Moessbauer Spectroscopy experiments for a variety of AFe4X2. We focus on the ZrFe4Si2 compound, where we observe electronic spin fluctuations already at 100 K whereas long-range magnetic order sets in only below 10 K.

  10. Magnetic anisotropy and spin fluctuations in the paramagnetic dimer [Fe(OMe)(dpm)2]2: Moessbauer spectroscopy and ab initio calculations

    The magnetic anisotropy and the spin fluctuations of the paramagnetic molecule [Fe(OMe)(dpm)2]2 are analyzed by means of Moessbauer spectroscopy in the temperature range [7.6-33] K. Spectra in the presence of a 5 T magnetic field directed along the γ rays were collected, by using a sample of pseudo-single crystal prepared by oriented grains. From the fits of the spectra, the hyperfine parameters are determined. Fits give also the value and direction of the magnetic anisotropy, referred to the electric field gradient (EFG) principal axes. The latter, together with the EFG components, were evaluated by means of ROHF ab initio calculations. Lastly, the rate of the spin transitions in function of T is discussed

  11. Characterization of the Carancas-Puno meteorite by energy dispersive X-ray fluorescence, X-ray diffractometry and transmission Moessbauer spectroscopy

    Ceron Loayza, Maria L., E-mail: malucelo@hotmail.com; Bravo Cabrejos, Jorge A. [Universidad Nacional Mayor de San Marcos, Laboratorio de Analisis de Suelos, Facultad de Ciencias Fisicas (Peru)

    2011-11-15

    We report the results of the study of a meteorite that impacted an inhabited zone on 15 September 2007 in the neighborhood of the town of Carancas, Puno Region, about 1,300 km south of Lima. The analysis carried out by energy dispersive X-ray fluorescence, X-ray diffractometry and transmission Moessbauer spectroscopy (at room temperature and at 4.2 K), reveal the presence in the meteorite sample of magnetic sites assigned to taenite (Fe,Ni) and troilite (Fe,S) phases, and of two paramagnetic doublets assigned to Fe{sup 2 + }, one associated with olivine and the other to pyroxene. In accord with these results, this meteorite is classified as a type IV chondrite meteorite.

  12. YPdSn and YPd{sub 2}Sn: Structure, {sup 89}Y solid state NMR and {sup 119}Sn Moessbauer spectroscopy

    Hoeting, Christoph [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, Corrensstrasse 30, D-48149 Muenster (Germany); Eckert, Hellmut [Institut fuer Physikalische Chemie, Universitaet Muenster, Corrensstrasse 30, D-48149 Muenster (Germany); Langer, Thorsten; Schellenberg, Inga [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, Corrensstrasse 30, D-48149 Muenster (Germany); Poettgen, Rainer, E-mail: pottgen@uni-muenster.de [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, Corrensstrasse 30, D-48149 Muenster (Germany)

    2012-06-15

    The stannides YPdSn and YPd{sub 2}Sn were synthesized by high-frequency melting of the elements in sealed tantalum tubes. Both structures were refined on the basis of single crystal X-ray diffractometer data: TiNiSi type, Pnma, a=715.4(1), b=458.8(1), c=789.1(1) pm, wR2=0.0461, 510 F{sup 2} values, 20 variables for YPdSn and MnCu{sub 2}Al type, Fm3 Macron m, a=671.44(8), wR2=0.0740, 55 F{sup 2} values, 5 parameters for YPd{sub 2}Sn. The yttrium atoms in the new stannide YPdSn are coordinated by two tilted Pd{sub 3}Sn{sub 3} hexagons (ordered AlB{sub 2} superstructure). In the Heusler phase YPd{sub 2}Sn each yttrium atom has octahedral tin coordination and additionally eight palladium neighbors. The cubic site symmetry of yttrium is reflected in the {sup 119}Sn Moessbauer spectrum which shows no quadrupole splitting. In contrast, YPdSn shows a single signal at {delta}=1.82(1) mm/s subjected to quadrupole splitting of {Delta}E{sub Q}=0.93(1) mm/s. Both compounds have been characterized by high-resolution {sup 89}Y solid state NMR spectroscopy, which indicates the presence of strong Knight shifts. The spectrum of YPd{sub 2}Sn is characterized by an unusually large linewidth, suggesting the presence of a Knight shift distribution reflecting local disordering effects. The range of {sup 89}Y Knight shifts of several binary and ternary intermetallic yttrium compounds is briefly discussed. - Graphical abstract: YPdSn and YPd{sub 2}Sn: Structure, {sup 89}Y solid state NMR and {sup 119}Sn Moessbauer spectroscopy. Highlights: Black-Right-Pointing-Pointer Synthesis and structure of ternary stannides YPdSn and YPd{sub 2}Sn. Black-Right-Pointing-Pointer {sup 119}Sn Moessbauer spectroscopic investigation of YPdSn and YPd{sub 2}Sn. Black-Right-Pointing-Pointer {sup 89}Y solid state NMR of intermetallics.

  13. Moessbauer spectroscopy study of a mineral sample from Oshno Hill, District of Chavin de Pariarca, Huanuco Region, Peru

    The analysis by X-ray diffraction of a mining sample collected from Oshno hill, which is located in the District of Chavin de Pariarca, Huamalies Province, Huanuco, Peru, indicates the presence of lepidocrocite (γ-FeOOH) and goethite (α-FeOOH). The room temperature Moessbauer spectrum (MS) doublet with broad lines displays hyperfine parameters corresponding to the presence of particles of iron hydroxides smaller than 100 A in a superparamagnetic regime. The measurement of a MS at 4.2 K allowed confirming the presence of goethite and lepidocrocite (with average magnetic fields of 49.21 T and 44.59 T, respectively).

  14. Study of excess Fe metal in the lunar fines by magnetic separation, Moessbauer spectroscopy, and microscopic examination.

    Housley, R. M.; Grant, R. W.; Abdel-Gawad, M.

    1972-01-01

    A simple and convenient method of making quantitative magnetic separations has been applied to the lunar fines. The fractions obtained form groups containing distinctively different particle types; thus, it appears that magnetic separation in itself many be a useful way of characterizing lunar fines. Moessbauer studies of fines 10084 show that the metal cannot contain more than about 1.5% Ni, implying that by far the bulk of the metal results from reduction rather than from direct meteoritic addition. Microscopic examination of magnetic separates from 15101 fines suggests that reduction of Fe accompanies every major impact event on the moon.

  15. Magnetic properties and Moessbauer studies of Gd1-xSrxFeO3-y (x=0.25, 0.75)

    Perovskite Gd1-xSrxFeO3-y (x=0.25 and 0.75) powders have been studied by X-ray diffraction, Mohr's salt analysis, vibrating sample magnetometer, and Moessbauer spectroscopy. X-ray diffraction patterns show that their crystal structures are orthorhombic for x=0.25 and cubic for x=0.75. 57Fe Moessbauer spectra of the Gd1-xSrxFeO3-y have been taken at various temperatures ranging from 4.2 to 850 K. It is found that Neel temperatures for x=0.25 and 0.75 are 685 and 270 K, respectively. Moessbauer spectra of Gd0.75Sr0.25FeO3-y powders have been taken at various temperatures ranging from 13 to 620 K. The Neel temperature decreases with the increase of the Sr concentration, which suggests that the superexchange interaction for Gd-Fe-O-Fe is stronger than that for Sr-Fe-O-Fe. Moessbauer spectrum at 13 K consists of magnetic sextet components arising from different charge states of iron ions. In the orthorhombic phases (x=0.25), the charge states coexist Fe3+ and Fe4+(high spin) and the charge states coexist Fe3+ and Fe4+(low and high spin) in the cubic phases (x=0.75). Magnetic susceptibility measurements by using a vibrating sample magnetometer show that Gd1-xSrxFeO3-y behavior is weak-ferromagnetic due to canted spin for x=0.75 and antiferromagnet for x=0.25

  16. Deconvolution of Moessbauer spectra using Voigt functions; Deconvolucion de espectros Moessbauer empleando funciones Voigt

    Flores Ll, H.J

    1990-08-15

    The form of the resonance line in Moessbauer spectroscopy is a form of Lorentzian line, but this form of line it enlarges due to several effects: finite thickness of the absorber, instrumental instability, diffusion of Co{sup 57} in crystals and fluctuations in the environment of the emitting nucleus. To take into account this effects it has been used as form of line in Moessbauer spectroscopy the Voigt function that is the convolution of a Lorentzian and a Gaussian. (Author)

  17. Substitution effects in M-type hexaferrite powders investigated by Moessbauer spectrometry

    Significant improvements of the magnetic properties of M-type hexaferrites (SrFe12O19) can be achieved through partial substitutions with a rare-earth element and a transition metal. From this point of view, 57Fe Moessbauer spectrometry is a very powerful tool to determine the location of the substituted elements. We discuss here the effects on the Moessbauer spectrum of the substitution of a rare earth ion (Sm3+, Nd3+ or La3+) in the Sr2+ site, and the substitution of a metal ion (Co2+ or Zn2+) in the Fe3+ sites

  18. A Moessbauer-effect study of autopsied lung tissue of asbestos workers

    A 57Fe Moessbauer-effect study of autopsied lung tissue from Canadian asbestos mine workers is presented. The spectra typically show large quantities of iron storage protein. This exhibits a quadrupole-split doublet at room temperature and both a doublet and a Zeeman-split sextet at 4.2 K, due to a distribution of particle sizes. A comparison is made with Moessbauer spectra of lung tissue from an individual not occupationally exposed to respirable asbestos, and with spectra of respirable chrysotile asbestos taken from Canadian mines. (author)

  19. The Moessbauer investigation in iron nitride/expanded graphite

    We successfully prepared the composites possessed high magnetic properties and shielding effectiveness (SE) in RF band with the methods of loading iron nitride nanoparticles on expanded graphite (EG) by the gaseous reduction and nitridation. XRD measurement shows that the ferric phases changed in different nitridation temperature. The phase components of nanoparticles were analyzed in detail by the measurement of 57Fe Moessbauer spectra. The result shows that as the temperature increased, the Fe particles were gradually nitride until completely before 400℃ and the γ'-Fe4N was gradually converted to ε-FexN (2

  20. An efficient Electron Re-emission Moessbauer (ERM) spectrometer

    The design, fabrication and evaluation of an integral Electron Re-emission Moessbauer (ERM) spectrometer, optimized for 57Fe experiments, is described. The percentage effect obtained with an unenriched stainless steel scatterer is 35 to 61% depending upon pulse height selection. The value obtained in the integral mode is 40%. This is at least four times larger than the corresponding value obtained with a commercial system (Ranger Instr. Inc.) and also better than all systems, except one, reported in the literature so far. (author)

  1. Moessbauer hydperfine fields in RBa2(Cu0.97FeO.O3)3O7-x [R = Y, Pr, Er

    Room temperature 57Fe Moessbauer spectra of RBa2 (Cu0.97FeO.O3)3O7-x [R=Y, Pr, Er] were obtained from samples with varying x. A magnetically-split hyperfine field spectrum was observed for the most oxygen-deficient Y sample, for all the Pr samples, and for none of the Er samples

  2. 57Fe NMR study of amorphous and rapidly quenched crystalline Fe-B alloys

    Pokatilov, V. S.

    2009-01-01

    Amorphous and crystalline Fe-B alloys (5-25 at % B) were studied using pulsed 57Fe nuclear magneticr esonance at 4.2 K. The alloy samples were prepared from a mixture of the 57Fe and 10B isotopes by rapid quenching from the melt. In the microcrystalline Fe-(5-12 at %) B alloys, the resonance frequencies were measured for local states of 57Fe nuclei in the tetragonal and orthorhombic Fe3B phases and also in α-Fe. The resonance frequencies characteristic of 57Fe nuclei in α-Fe crystallites with substitutional impurity boron atoms in the nearest neighborhood were also revealed. In the resonance frequency distribution P( f) in the amorphous Fe-(18-25) at % B alloys, there are frequencies corresponding to local Fe atom states with short-range order of the tetragonal and orthorhombic Fe3B phases. As the boron content decreases below 18 at %, the P( f) distributions are shifted to higher frequencies corresponding to 57Fe NMR for atoms exhibiting a short-range order of the α-Fe type. The local magnetic structure of the amorphous Fe-B alloys is also considered.

  3. Moessbauer studies of impactites from Huamalies province in Huanuco Region

    This report is about the X-ray diffraction and Moessbauer studies of three impactite samples denominated PMe-8, PMe-9 and PMe-11 from Huamalies Province in Huanuco Region, Peru. When terrestrial rocks are submitted to pressures higher than 60 GP, the majority is completely melted, forming a kind of glass called impactites. X-ray diffraction indicates the presence of quartz as the principal mineralogical phase in all samples. The 57Fe Moessbauer spectra at room temperature of samples PMe-8 and PMe-9 show broadened spectra that were fitted using a distribution model. The most probable field of the magnetic component is 34 T, corresponding to the presence of small particles of goethite, confirmed by the 4.2 K spectrum. For the sample PMe-11, the MS showed the presence of well crystallized hematite.

  4. Moessbauer studies of impactites from Huamalies province in Huanuco Region

    Bustamante, A., E-mail: abustamanted@unmsm.edu.pe; Espinoza, S. [San Marcos University, Faculty of Physical Sciences (Peru); Morales, G. [Museo de Historia Natural(Museum of Natural History) (Peru); Scorzelli, R. B. [Centro Brasileiro de Pesquisas Fisicas (Brazilian Center for Research in Physics) (Brazil)

    2005-11-15

    This report is about the X-ray diffraction and Moessbauer studies of three impactite samples denominated PMe-8, PMe-9 and PMe-11 from Huamalies Province in Huanuco Region, Peru. When terrestrial rocks are submitted to pressures higher than 60 GP, the majority is completely melted, forming a kind of glass called impactites. X-ray diffraction indicates the presence of quartz as the principal mineralogical phase in all samples. The {sup 57}Fe Moessbauer spectra at room temperature of samples PMe-8 and PMe-9 show broadened spectra that were fitted using a distribution model. The most probable field of the magnetic component is 34 T, corresponding to the presence of small particles of goethite, confirmed by the 4.2 K spectrum. For the sample PMe-11, the MS showed the presence of well crystallized hematite.

  5. A complex fitting program of Moessbauer transmission spectra

    A complex fitting program (MIMI) used to analyse Moessbauer spectrometry data is presented. It was written in FORTRAN 4 (F) and run on IBM 370/135 at the Institute of Atomic Physics, Bucharest. The program requires a 72 K memory. MIMI is able to analyse spectra with a maximum number of 512 spectral data points and 64 parameters in any combination of lines (magnetic and electric hyperfine interactions, or singular (lines) without restrictions in overlapping. The mathematical model and some typical convergence problems were presented in details. Then a flow-chart, the input data specifications and short descriptions of the main program and all of the subroutines are presented. Finally, a test run on a 57Fe Moessbauer spectrum is given for an Y6Fe3 intermetallic compound. (author)

  6. Influence of a thermochromic anion on the spin crossover of iron(II) trinuclear complexes probed by Moessbauer spectroscopy

    The insertion of thermochromic anions (1 and 2) into triazole based iron(II) trinuclear spin crossover complexes [FeII3(hyetrz)6(H2O)6](1 or 2)4Cl2 paves the way to a large panel of multifunctional materials. In addition to a gradual thermo-induced spin conversion of the central metal ion on cooling below room temperature, an unexpected split of the Moessbauer signal of the external iron(II) ions as well as pronounced relaxation phenomenon for the central HS iron(II) ion was discovered. This phenomenon is suggested to be induced by the tautomeric equilibrium between enol and keto forms of the anion.

  7. Fe(II-III) Hydroxysalt Green Rusts; from Corrosion to Mineralogy and Abiotic to Biotic Reactions by Moessbauer Spectroscopy

    Fe(II)-Fe(III) hydroxysalts commonly called green rusts are layered double hydroxides of formula [FeII(1-x)FeIIIx(OH)2]x+.[(x/n)An-.(m/n)H2O]x- constituted of brucite-like layers containing Fe cations in the centres of OH- octahedrons and interlayers, which anions and water molecules belong to. They play a key role in corrosion and environmental sciences as well as mineralogy since they are, on the one hand, intermediate products between Fe(II) and Fe(III) states and, on the other hand, can be the major iron-bearing mineral in hydromorphic gley soils. Their crystal structure, Moessbauer spectra, methods of synthesis, abiotic as well as biotic, and some applications are presented here.

  8. Influence of a thermochromic anion on the spin crossover of iron(II) trinuclear complexes probed by Moessbauer spectroscopy

    Robert, Francois; Naik, Anil D; Garcia, Yann, E-mail: yann.garcia@uclouvain.b [Institut de la Matiere Condensee et des Nanosciences, Universite Catholique de Louvain, Place L. Pasteur 1, 1348 Louvain-la-Neuve (Belgium)

    2010-03-01

    The insertion of thermochromic anions (1 and 2) into triazole based iron(II) trinuclear spin crossover complexes [Fe{sup II}{sub 3}(hyetrz){sub 6}(H{sub 2}O){sub 6}](1 or 2){sub 4}Cl{sub 2} paves the way to a large panel of multifunctional materials. In addition to a gradual thermo-induced spin conversion of the central metal ion on cooling below room temperature, an unexpected split of the Moessbauer signal of the external iron(II) ions as well as pronounced relaxation phenomenon for the central HS iron(II) ion was discovered. This phenomenon is suggested to be induced by the tautomeric equilibrium between enol and keto forms of the anion.

  9. Comparative study of the iron cores in human liver ferritin, its pharmaceutical models and ferritin in chicken liver and spleen tissues using Moessbauer spectroscopy with a high velocity resolution

    Full text: Application of the Moessbauer spectroscopy with a high velocity resolution (4096 channels) for a study of iron-containing biological species is of great interest. Improving the velocity resolution allows to reveal small variations in the electronic structure of iron, and to obtain hyperfine parameters with smaller instrumental (systematic) errors in comparison with measurements performed in 512 channels or less. It also allows a more reliable fitting of complex Moessbauer spectra. In the present study the Moessbauer spectroscopy with the high velocity resolution was used for a comparative analysis of ferritin and its pharmaceutically important models as well as iron storage proteins in a chicken liver and a spleen. The ferritin, an iron storage protein, consists of a nanosized polynuclear iron core formed by a ferrihydrite surrounded by a protein shell. Iron-polysaccharide complexes contain β-FeOOH iron cores coated with various polysaccharides. The Moessbauer spectra of the ferritin and commercial products Imferon, MaltoferR and Ferrum Lek as well as those of the chicken liver and spleen tissues were measured with the high velocity resolution at 295 and 90 K. They were fitted using two models: (1) with a homogeneous iron core (an approximation using one quadrupole doublet), and (2) with a heterogeneous iron core (an approximation using several quadrupole doublets). The model (1) can be used as the first approximation fit to visualize small variations in the hyperfine parameters. Using this model, differences in the Moessbauer hyperfine parameters were obtained in both 295 and 90 K Moessbauer spectra. However, this model was considered as a rough approximation because the measured Moessbauer spectra had non-Lorentzian line shapes. Therefore, the spectra of the ferritin, Imferon, MaltoferR and Ferrum Lek as well as those of the liver and spleen tissues were fitted again using the model (2) in which a different number of the quadrupole doublets was

  10. Moessbauer Study of Sedimentary Rocks from King George Island, Antarctica

    The separation of continents at the periphery of Antarctica occurred about 180 ma ago due to volcanic activity. Geological faults can be very important in the study of geological occurrences. Such geological faults occur across the Admiralty Bay, King George Island, and have been studied in detail previously. Controversial statements were given in earlier works, based on conventional geological investigations, as to whether altered 'Jurassic' and unaltered Tertiary rocks were separated by a major fault which goes across the Admiralty Bay, or whether there is no difference in the alteration of the rocks located at either side of the fault. The aim of our work is to investigate rock samples from the Admiralty Bay of King George Island, Antarctica, from different locations on both sides of the geological fault. For these investigations 57Fe Moessbauer spectroscopy and X-ray diffractometry were used. We have found that the phase composition, and the iron distribution among the crystallographic sites of iron-bearing minerals, are characteristic of the location of the rock samples from the Admiralty Bay of King George Island. There is a much higher amount of iron oxides in the rocks from the south part of the geological fault than in the north part. The differences in the mineral composition and iron distribution showed that the rocks in the southern part of the geological fault of King George Island are significantly altered compared to the rocks in the northern part. Our present results support and complement well the results obtained earlier on soils from King George Island.

  11. Electric field gradient at 57Fe in scandium and systematics of the electric field gradient at impurities in transition-metal hosts

    Nair, N. V.; Nair, K. Vijayakumaran

    1986-05-01

    The electric field gradient (EFG) at 57Fe probe atoms in hcp transition-metal scandium is measured using Mössbauer spectroscopy, with 57Fe as a dilute impurity in pure scandium metal. The quadrupole splitting obtained is 0.26(2) mm/s and the corresponding EFG is 1.3(1)×1017 V/cm2 at the probe site in scandium. The ratio eqel/eqion is in fairly good agreement with the universal correlation proposed by Raghavan et al. The results are compared with the theoretical value of the EFG calculated using the conduction-electron charge-shift model. Also, a systematic scheme, which can be used to determine eqel and the sign of EFG in transition-metal hosts, is proposed.

  12. OSSM2008 Polish Moessbauer Community Meeting: Program, Abstracts and List of Participants

    The Polish Moessbauer Community Meeting - OSSM2008 has been organized by Polish scientists using the Moessbauer spectroscopy in their research. Main subjects of the meeting are investigations of modern materials electronic structure by means of Moessbauer effect (ME), using ME in biological test of tissue diseases and ME investigation of physical properties of different steels

  13. Moessbauer spectroscopic studies of haemosiderins from different sources

    Moessbauer spectra obtained from the haemosiderin isolated from iron-overloaded horse and reindeer spleen and liver show superparamagnetic behaviour with a much lower transition temperature than haemosiderin from iron-overloaded human spleen. These data clearly indicate the existence of different forms of haemosiderin, which are primarily distinguishable by Moessbauer spectroscopy. (orig.)

  14. Characterization of Zn-bearing chlorite by Moessbauer and infrared spectroscopy - occurrence associated to the Pb-Zn-Ag deposits of Canoas, PR, Brazil

    In order to provide new insights on mineralogical aspects of geochemical mapping/natural processes related to the chlorite formation (e.g. crystallochemistry and mechanisms of formation of these materials, which has been applied in different studies of environmental profiles), we investigated chlorite samples associated to the Pb-Zn-Ag sulfide ore from Canoas 1 deposit (Vale do Ribeira, state of Parana, Brazil). By means of Moessbauer (MS) and infrared (IV) spectroscopy, we addressed some issues as those related to the chloritization processes, as well as how Zn would be incorporated into its crystalline structure. Results carried out by ME and IV spectroscopy clearly pointed out for a chlorite occurrence, which in fact incorporates Zn into its structure and also alters the structural patterns for this mineral. Moreover, ME data sets indicated the presence of Fe which is located only in octahedral sites, in trans-configuration, and the Zn emplacement by the chloritization process also occurs in the brucite layer. (author)

  15. Thermal treatment of the Fe78 Si9 B13 alloy and the analysis of it magnetic properties through Moessbauer spectroscopy and Positronium annihilation

    The present work is divided in five chapters. In the first one a general vision of the amorphous alloys is given from antecedents, structure, obtaining methods, properties and problems that at the moment, focusing us in a certain moment to the iron base alloys and the anomalous problem of hardness that it presents the alloy Fe78Si9B13 like previously mention us. The second chapter tries on the basic theory of the techniques of Moessbauer spectroscopy and Positron Annihilation spectroscopy, used for the characterization of our alloy as well as the complementary technique of X-ray diffraction (XRD) to observe that the amorphous phase was even studying. The third chapter describes the experimental conditions that were used to study the alloy Fe78Si9B13 in each one of their thermal treatments. In the fourth chapter the obtained results and their discussion are presented. In the fifth chapter the conclusions to which were arrived after analyzing the results are presented. (Author)

  16. Mineralogy, 57Fe Mössbauer spectra and magnetization of chalcolithic pottery

    Keller, R.; Masch, L.; Pohl, J.; Schmidbauer, E.

    2005-06-01

    Three chalcolithic pottery sherds, paint removed from the surface of each sherd, and an unheated red pigment (Tell-Halaf culture, Turkey) were analysed within the frame of archaeometric studies using mineralogical methods, 57Fe Mössbauer spectroscopy, magnetization and rotational hysteresis data. From mineralogical results, the individual minerals forming the cores of the sherds were determined. It was found that the sherds are lime-rich. High temperature X-ray analysis on comparable Ca-rich material showed that the established composition is consistent with a firing temperature of 750-950°C. Apart from the pigment, each Mössbauer spectrum of Fe-bearing components consists of dominating paramagnetic doublets, arising mostly from silicate phases, and of a six-line pattern with reduced intensity, due to ferri- and/or antiferromagnetic Fe-oxide phases. For three samples, an Fe3+ silicate component of the spectra is clearly dominating, which points to oxidizing conditions during firing. For the others Fe2+ and Fe3+ components occur in about equal intensities. For the pigment, the magnetic sextet is of similar intensity to the Fe3+ silicate component. From magnetic analysis of ferrimagnetic phases it follows that a low percentage of particles of solid solutions γ-Fe2O3 Fe3O4 exist, probably in part ≤0.1 μm in diameter. The ferrimagnetic particles of at least one paint are probably covered by a thin layer of hematite as found from rotational hysteresis data. An attempt is made to draw conclusions from the experimental results, regarding the firing conditions of the sherds and paints.

  17. The {sup 57}Fe hyperfine interactions in iron storage proteins in liver and spleen tissues from normal human and two patients with mantle cell lymphoma and acute myeloid leukemia: a Mössbauer effect study

    Oshtrakh, M. I., E-mail: oshtrakh@gmail.com; Alenkina, I. V. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation); Vinogradov, A. V.; Konstantinova, T. S. [Ural State Medical University (Russian Federation); Semionkin, V. A. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation)

    2015-04-15

    Study of human spleen and liver tissues from healthy persons and two patients with mantle cell lymphoma and acute myeloid leukemia was carried out using Mössbauer spectroscopy with a high velocity resolution. Small variations in the {sup 57}Fe hyperfine parameters for normal and patient’s tissues were detected and related to small variations in the {sup 57}Fe local microenvironment in ferrihydrite cores. The differences in the relative parts of more crystalline and more amorphous core regions were also supposed for iron storage proteins in normal and patients’ spleen and liver tissues.

  18. The 57Fe hyperfine interactions in iron storage proteins in liver and spleen tissues from normal human and two patients with mantle cell lymphoma and acute myeloid leukemia: a Mössbauer effect study

    Study of human spleen and liver tissues from healthy persons and two patients with mantle cell lymphoma and acute myeloid leukemia was carried out using Mössbauer spectroscopy with a high velocity resolution. Small variations in the 57Fe hyperfine parameters for normal and patient’s tissues were detected and related to small variations in the 57Fe local microenvironment in ferrihydrite cores. The differences in the relative parts of more crystalline and more amorphous core regions were also supposed for iron storage proteins in normal and patients’ spleen and liver tissues

  19. Structural, electrical, magnetic and {sup 57}Fe Mössbauer study of polycrystalline multiferroic DyFeO{sub 3}

    Reddy, S. Shravan Kumar; Raju, N. [Department of Physics, Osmania University, Hyderabad 500007, Telangana (India); Reddy, Ch. Gopal, E-mail: ch_gopalreddy@yahoo.com [Department of Physics, University College of Engineering, Osmania University, Hyderabad 500007, Telangana (India); Reddy, P. Yadagiri; Reddy, K. Rama [Department of Physics, Osmania University, Hyderabad 500007, Telangana (India); Reddy, V. Raghavendra [UGC DAE Consortium for Scientific Research, University campus, Khandwa Road, Indore, Madhya Pradesh 452001 (India)

    2015-12-15

    Structural, Raman spectroscopy, leakage current density, temperature dependent magnetization and Mössbauer measurements of polycrystalline DyFeO{sub 3} (DFO) prepared through sol–gel route are reported in this paper. Phase purity and structure of the prepared sample is confirmed from x-ray diffraction and Raman spectroscopy measurements. The room temperature leakage current density (J–E) measurements indicate that Ohmic contribution and space charge limited conduction are the dominating mechanisms at low and high applied electric fields respectively. Signatures of Fe{sup 3+} spin reorientation transition (T{sub SR}) and the antiferromagnetic ordering of Dy{sup 3+} ions are observed from the temperature dependent (10–350 K) magnetization data. The M–H data measured at 2 K shows the field induced metamagnetic transition. Internal hyperfine field obtained from temperature dependent (5–300 K) {sup 57}Fe Mössbauer measurements is observed to decrease below the T{sub SR} and further found to increase till 5 K indicating the contribution of Dy{sup 3+} magnetic ordering on the hyperfine field of Fe nucleus. - Highlights: • This paper analyses structural, electrical and magnetic properties of polycrystalline multiferroic DyFeO{sub 3} sample prepared through sol–gel route. • Signatures of Fe{sup 3+} spin reorientation transition and the antiferromagnetic ordering of Dy{sup 3+} ions are observed from the temperature dependent (10-350 K) magnetization data. • From the temperature dependent {sup 57}Fe Mössbauer measurements contribution of Dy{sup 3+} magnetic ordering on the hyperfine field of Fe nucleus is observed. • Ohmic and space charge limited conduction mechanisms are found to be dominating at low and high applied electric fields respectively in DyFeO{sub 3}.

  20. Effects of the iron content and redox state on the structure of sodium borosilicate glasses: A Raman, Moessbauer and boron K-edge XANES spectroscopy study

    The structure of iron-bearing sodium borosilicate glasses with up to 10 mol% FeO has been investigated in the range 0.15 ≤ Fe3+/SFe ≤ 0.95. According to Moessbauer spectroscopy, Fe3+ and Fe2+ are mainly in tetrahedral and octahedral coordination, respectively, although other coordination states exist for both cations. From XANES experiments, we conclude that increasing Fe content and varying redox states have only a minor effect on the relative proportions of BO3 and BO4 units. In Raman spectra, a decrease of the proportion of BO4 species present in danburite-like units (Na2O.B2O3.2SiO2) is found upon increasing iron content and oxidizing state. Whereas the insensitivity of the overall boron speciation to iron content and redox state points to weak interactions between boron and iron, the changes affecting BO4 species do indicate a more subtle interplay between Fe3+ and the other tetrahedrally coordinated cations (Si,B) because of the competition between tetrahedral Fe3+ and B3+ for charge compensation by Na+. (authors)

  1. After Effects of the 57Co(EC)57Fe-Reaction in some Cobalt and Iron Complexes

    Siekierska, K. F.; Fenger, Jørgen Folkvard; Olsen, J.

    Mössbauer emission spectra of iron and cobalt complexes, doped or labelled with 57Co, demonstrate that the 57Co(EC)57Fe reaction can have significant chemical effects, although the probability of displacement of the nascent57Fe is very low. Measurements on specifically 57Co-labelled [Co(bipy)3][Co...

  2. Kinetic study of the thermal transformation of limonite to hematite by X-ray diffraction, {mu}-Raman and Moessbauer spectroscopy

    Palacios, P. R., E-mail: roggerpr@gmail.com; Bustamante, Angel [Universidad Nacional Mayor de San Marcos, Laboratorio de Ceramicos y Nanomateriales, Facultad de Ciencias Fisicas (Peru); Romero-Gomez, P.; Gonzalez, J. C. [Instituto de Ciencia de Materiales de Sevilla - CSIC - Univ. Sevilla, Grupo de Investigacion de Superficies, Intercaras y Laminas Delgadas (Spain)

    2011-11-15

    A kinetic study about the phase limonite (FeO(OH)-nH{sub 2}O) was performed through X-ray diffraction, {mu}-Raman spectroscopy and Moessbauer spectroscopy. The oxide powder sample was extracted from Taraco district, Huancane province of Puno (Peru). X-ray diffraction identified the phase goethite as the main mineralogical component, and then the sample was subjected to in-situ heat treatment in the temperature range: 100 to 500 Degree-Sign C in oxidizing (air) and inert (nitrogen) atmospheres. The goethite phase remains stable in this range: room temperature to 200 Degree-Sign C. Between 200 Degree-Sign C to 250 Degree-Sign C there is a phase transition: {alpha}-Fe{sup 3 + }O(OH) {yields} {alpha}-Fe{sub 2}O{sub 3}, i.e., from goethite to hematite phase, taking as evidence the evolution of the diffraction profiles. At 200 Degree-Sign C spectra shows the start of broadened magnetic component and it was adjusted through of a magnetic distribution giving a mean field of 38.6T and a relative area of 52.9%, which is a characteristic of goethite. Also, it is noticed the presence of a small amount of hematite with a mean field of 49.0T linked with a superparamagnetic broadened doublet of relative area of 47.1% where the domains of the particles have sizes smaller than 100 A and it is evidence the superparamagnetic limit; i.e., the superparamagnetic effect tends toward a distribution of magnetic fields. Moreover, the Raman spectra of the in-situ thermal treatment, support the transition at 290 Degree-Sign C through the transformation of characteristic bands of goethite to hematite phase at the frequency range from 200 to 1,800 cm{sup - 1}.

  3. An equipment for Moessbauer radiation scattering

    The relative complexity of the equipment required to perform Rayleigh scattering of Moessbauer radiation experiments, as opposed to the more common transmission and backscattering forms of Moessbauer spectroscopy, is a barrier to the routine use of this technique. The block diagram of the equipment is presented. A goniometer, similar to those used in X-ray precision diffractometer, realizes the measuring geometry. On the goniometer there are mounted the electromagnetic vibrator with the Moessbauer source, a scatterer sample, a nuclear resonance absorber and a detector. The incident and the scattered beams are collimated by lead collimators with constant vertical divergence and variable horizontal divergences. The sample and the source can be moved independently and in (θ, 2θ) manner by a stepping motor which realizes at least 0.01 angle/step sample rotation. Nuclear instruments i.e., a driving unit, a digital function generator, a high voltage supply, a spectroscopy amplifier and a single channel analyzer complete the system. A personal computer controls the orientation of the sample, the Doppler movement and realizes the acquisition of the pulse height spectra and Moessbauer spectra by means of three new cards. The sample orientation is realized by the stepping motor card which controls the power supply current feeding delivery for the phases of the stepping motor. A standard multichannel analyzer card with 4K channel resolution and fixed dead time provides the pulse height spectra acquisition. In order to register Moessbauer spectra and to deliver 'address advance' and 'start' signals for the function generator, we designed a Moessbauer card. It consists of a programmable counter with three 16 bit counters. A quartz oscillator controls the counter which works as a timer and generates channel dwell time adjustable by the soft in the range 50 μs - 32 ms. After each channel dwell time, generated by the timer, the number of acquired pulses during it is read and

  4. Moessbauer spectroscopic study on glaze of pottery

    Iron-barium glaze was prepared from commercially available materials for ceramic arts and from chemical reagents, and investigated by means of Moessbauer spectroscopy and an electron probe micro analyzer (EPMA). Moessbauer spectra showed a doublet of paramagnetic high-spin Fe(II) and Fe(III) incorporated into aluminosilicate, and the magnetically-split hyperfine structures of hematite and magnetite, depending on the iron content and firing conditions. The EPMA indicated striped patterns on the secondary electron images, and the fluorescent X-ray analysis proved that the patterns are due to the heterogeneous distribution of elements in the glaze. (orig.)

  5. Moessbauer gamma echo

    By applying stepwise phase modulation of recoilless gamma radiation in a coincidence experiment, constructive interference is produced in transmission geometry between the source and the absorber fields. The resulting regenerated decay signal is called a gamma echo. Here it is demonstrated that during the decay of the 14.4 keV state of 57Fe multiple echo signals can be generated. (orig.)

  6. Microscopic Study of Nuclear Level Densities and Thermal Properties in 56,57Fe

    2007-01-01

    We calculate level densities for 56,57 Fe nuclei using BCS hamiltonian with inclusion of pairing interaction.The results of calculations show that the step structure observed experimentally has been supported by microscopic theory. Also the S-shaped energy and entropy as function of temperature have been obtained in theoretical calculations.Structures in the curves are interpreted as fingerprints of breaking Cooper pairs and quenching of pairing correlations.

  7. Level Densities and Radiative Strength Functions in 56FE and 57FE

    Tavukcu, E

    2002-12-10

    Understanding nuclear level densities and radiative strength functions is important for pure and applied nuclear physics. Recently, the Oslo Cyclotron Group has developed an experimental method to extract level densities and radiative strength functions simultaneously from the primary {gamma} rays after a light-ion reaction. A primary {gamma}-ray spectrum represents the {gamma}-decay probability distribution. The Oslo method is based on the Axel-Brink hypothesis, according to which the primary {gamma}-ray spectrum is proportional to the product of the level density at the final energy and the radiative strength function. The level density and the radiative strength function are fit to the experimental primary {gamma}-ray spectra, and then normalized to known data. The method works well for heavy nuclei. The present measurements extend the Oslo method to the lighter mass nuclei {sup 56}Fe and {sup 57}Fe. The experimental level densities in {sup 56}Fe and {sup 57}Fe reveal step structure. This step structure is a signature for nucleon pair breaking. The predicted pairing gap parameter is in good agreement with the step corresponding to the first pair breaking. Thermodynamic quantities for {sup 56}Fe and {sup 57}Fe are derived within the microcanonical and canonical ensembles using the experimental level densities. Energy-temperature relations are considered using caloric curves and probability density functions. The differences between the thermodynamics of small and large systems are emphasized. The experimental heat capacities are compared with the recent theoretical calculations obtained in the Shell Model Monte Carlo method. Radiative strength functions in {sup 56}Fe and {sup 57}Fe have surprisingly high values at low {gamma}-ray energies. This behavior has not been observed for heavy nuclei, but has been observed in other light- and medium-mass nuclei. The origin of this low {gamma}-ray energy effect remains unknown.

  8. Impact of 57Fe on neutron penetration in thick sodium-iron shields

    The latest release of the VITAMIN-E multigroup cross-section library contains two different versions of neutron cross sections for natural iron, one based on ENDF/B-V MOD-1, and the other on MOD-3. The isotope 57Fe has four inelastic-scattering levels below 846 keV, the energy of the first excited state in 56Fe. The importance of the new cross sections was investigated by using both VITAMIN-E versions of the iron cross sections in S8P3 174 group ANISN calculations for two Na-Fe shield configurations. In neutron penetration calculations through thick steel regions, 57Fe can be 10 times more important than is indicated by its isotopic abundance in natural iron. The 14.4-keV inelastic level of 57Fe is sufficiently important that it may be worthwhile to perform a measurement of this cross section to validate the ENDF/B-V MOD-3 value, which was obtained from nuclear model calculations. Shielding analyses were done with iron cross sections predating ENDF/B-V MOD-3 should be reviewed and may need to be revised

  9. Ultra-soft magnetic properties and correlated phase analysis by {sup 57}Fe Mössbauer spectroscopy of Fe{sub 74}Cu{sub 0.8}Nb{sub 2.7}Si{sub 15.5}B{sub 7} alloy

    Manjura Hoque, S.; Liba, S. I.; Akhter, Shireen [Materials Science Division, Atomic Energy Centre, Dhaka 1217 (Bangladesh); Anirban, A. [Semiconductor Physics Group, University of Cambridge (United Kingdom); Choudhury, Shamima [Department of Physics, University of Dhaka, Dhaka 1217 (Bangladesh)

    2016-02-15

    A detailed study of magnetic softness has been performed on FINEMENT type of ribbons by investigating the BH loop with maximum applied field of 960 A/m. The ribbon with the composition of Fe{sub 74}Cu{sub 0.8}Nb{sub 2.7}Si{sub 15.5}B{sub 7} was synthesized by rapid solidification technique and the compositions volume fraction was controlled by changing the annealing condition. Detail phase analysis was performed through X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Vibrating sample magnetometer (VSM) and Mössbauer spectroscopy in order to correlate the ultrasoft magnetic properties with the volume fraction of amorphous and α-Fe(Si) soft nano composites. Bright (BF) and dark field (DF) image with selective area diffraction (SAD) patterns by the transmission electron microscopy (TEM) of the sample annealed for the optimized annealed condition at 853 K for 3 min reveals nanocrystals with an average size between 10-15 nm possessing the bcc structure which matches with the grain size revealed by the X-ray diffraction. Kinetics of crystallization of α-Fe(Si) phases has been determined by DSC curves. Extremely small coercivity of 30.9 A/m and core loss of 2.5 W/Kg for the sample annealed at 853 K for 3 min was found. Similar values for other crystalline conditions were determined by using BH loop tracer with a maximum applied field of around 960 A/m. Mössbauer spectroscopy was used to determine chemical shift, hyperfine field distribution (HFD), and peak width of different phases. The volume fractions of the relative amount of amorphous and crystalline phases are also determined by Mössbauer spectroscopy. High saturation magnetization along with ultrasoft magnetic properties exhibits very high potentials technological applications.

  10. Studies on structure and covalence effects on hyperfine interactions of AFeO sub(2) and BFeS sub(2) compounds by Moessbauer spectroscopy (A= Na, Cu, Ag, B= K, Rb, Cs, Na)

    The compounds AFeO sub(2) and BFeS sub(2) (A = Na, Cu, Ag, B = K, Rb, Cs, Na) were investigated by Moessbauer spectroscopy. The spectra were registered at temperature range from 4.2 sup(0) to 300 sup(0)K and magnetic transitions were observed determining correspondent temperatures by variation of hyperfine field. The electric field gradient of these compounds and perovskite type compounds (Pb sub(1-x) - Ba sub(x)) Zr O sub(3) were calculated and experimental part were determined by perturbed angular correlation, taking in account the effects of covalence, crystal lattice parameters and dipolar contributions. (M.C.K.)

  11. A Moessbauer study of hemoglobin in paroxysmal nocturnal hemoglobinuria

    The 57Fe Moessbauer spectra of concentrated hemoglobin (Hb) of normal subjects and six patients with Paroxysmal Nocturnal Hemoglobinuria (PNH) were studied at 300deg K and 77 K. PNH is a very rate autoimmune hematological disease. The possibility of structural alterations of Hb induced by, or as part of the altered PNH-red cell membrane was the objective of this study. The Moessbauer parameters of the Hb of the normal subjects, both at 300 K and at 77 K, are identical to values previously reported. The PNH-Hb spectra show clear differences. They are wider and more asymmetric. At 77 K, an extra doublet grows in with an isomer shift of 0.425 mm/sec. and a quadrupolar splitting of 1.951 mm/sec. The other two doublets have δ's and ΔQ's slightly, but significantly, different from the corresponding values for normal Hb. These results are rationalized in terms of a population of Hb molecules with structures varying very slightly in a narrow range. The spread in structures manifests itself in a wider and more asymmetric Moessbauer spectrum. (orig.)

  12. Study of the dehydration process of melanterite under heat treatment and gamma irradiation effects using Moessbauer spectroscopy and thermal analysis measurements

    Thermal analysis measurements were performed on melanterite, FeS O4. 7 H2 O, with low heating rate at the dehydration temperature range from 340 degree k up to 420 degree K. These measurements showed different decomposition mechanism after gamma irradiation. Moessbauer effect (M E) measurements were carried out on heated melanterite. The change of the values of the Moessbauer parameters indicated the appearance of different hydrates of ferrous sulfate. The activation energy for dehydration was calculated before and after gamma irradiation. A correlation between the irradiation dose and the corresponding thermal energy required for water dehydration is proposed. 6 figs., 1 tab

  13. Bonding and Moessbauer Isomer Shifts in (Hg,Pb)—1223 Cuprate

    高发明; 田永君; 谌岩; 李东春; 董海峰; 张思远

    2003-01-01

    By using the chemical bond theory of dielectric description,the chemical bond parameters of(Hg,Pb)-1223 were calculated.The results show that the(Ba,Sr)-O and Ca-0 types of bond have higher ionic character,while the Cu-O and(Hg,Pb)-0 types of bond have more covalent character.Moessbauer isomer shifts of 57Fe and 119Sn doped in(Hg,Pb)-1223 were calculated by using the chemical environmental factor,he,defined by covalency and electronic polarizability.Four valence state tin and three valence iron sites were identified in 57Fe and 119Sn doped(Hg,Pb)-1223 superconductor.It can be concluded that all of the Fe atoms substitute the Cu at square planar Cu(1) site,Whereas Sn prefers to substitute the square pyramidal Cu(2) site.

  14. Formation of iron-57 divalent cation (57Fe2+) in Mössbauer sources of potassium trisoxalatoferrate(III)

    Fenger, Jes; Siekierska, K. E.; Maddock, A. G.

    The 57Co(electron capture)57Fe process taking place in 57Co-doped crystals of K3Fe III (C2O4)3,3H2O and K3Fe III (C2O4)3 produces some divalent 57Fe II . The reduced species may be Fe(C2O4)2 2–, which has previously been observed in γ-irradiated potassium trisoxalatoferrate(III).......The 57Co(electron capture)57Fe process taking place in 57Co-doped crystals of K3Fe III (C2O4)3,3H2O and K3Fe III (C2O4)3 produces some divalent 57Fe II . The reduced species may be Fe(C2O4)2 2–, which has previously been observed in γ-irradiated potassium trisoxalatoferrate(III)....

  15. Moessbauer studies on kapoeta meteorite

    Moessbauer spectroscopy in the temperature range (20 - 300 deg kelvin) has been carried out on a old fall Sudanese meteorite; Kapoeta. The first chapter covers the general background of meteorites, the second one the theoretical basis of Moessbauer Effect Spectroscopy (MES), whereas the third chapter the experimental set-up and the data processing. Experimental results obtained are collected in chapter four. The results obtained for the spectra of the scanned temperature range showed paramagnetic doublets, which were assigned to Fe2+ in pyroxene sites. The temperature dependence of the spectra ruled out the presence of olivine and assigned the orthopyroxene to the sites M1 and M2. The lattice dynamical parameters of the two sites were investigated on both temperature dependence of the isomer shift and the area under the resonance curve. the effective masses of the two sites were found to be 69.8 and 72.2 a.m.u. which are nearly equal whereas the Debye temperature were found to be 496.9 and 38.1 kelvin which are almost overlapping within the experimental errors. (Author)

  16. Mechanically - induced disorder in CaFe2As2: a 57Fe Mössbauer study

    Ma, Xiaoming; Ran, Sheng; Canfield, Paul C.; Bud'Ko, Sergey L.

    57 Fe Mössbauer spectroscopy was used to study an extremely pressure and strain sensitive compound, CaFe2As2, with different degrees of strain introduced by grinding and annealing. At the base temperature, in the antiferromagnetic/orthorhombic phase, compared to a sharp sextet Mössbauer spectrum of single crystal CaFe2As2, which is taken as an un-strained sample, an obviously broadened sextet and an extra doublet were observed for ground CaFe2As2 powders with different degrees of strain. The Mössbauer results suggest that the magnetic phase transition of CaFe2As2 can be inhomogeneously suppressed by the grinding induced strain to such an extent that the antiferromagnetic order in parts of the grains forming the powdered sample remain absent all the way down to 4.6 K. However, strain has almost no effect on the temperature dependent hyperfine magnetic field in the grains with magnetic order. The quadrupole shift in the magnetic phase approachs zero with increasing degrees of strain, indicating that the strain reduces the average lattice asymmetry at Fe atom position. Supported by US DOE under the Contract No. DE-AC02-07CH11358 and by the China Scholarship Council.

  17. Moessbauer Studies on the Quasibinary System FeTe1.45-TiTe1.45

    In this work the synthesis, powder XRD and Moessbauer studies of the quasibinary system FeTe1.45-TiTe1.45 were carried out. A series of nonstoichiometric tellurides FexTi1-xTe1.45 (x=0.1,0.2,...,1.0) was synthesized by the direct reaction from elements at 850oC. The Moessbauer results are in the good accordance with the XRD data. Behaviors lattice parameters and 57Fe Moessbauer parameters from composition of the tellurides allow to make some conclusions about their compensation mechanism for nonstoichiometry (CMN). For both FexTi1-xTe1.45, and nonstoichiometric Ti3Te4 CMN comes from the formation of Te-Te bonds at the constant metal valence. On the whole, in system titanium-tellurium CMN could be different and depends on the interval of composition.

  18. Moessbauer study of dissimilatory reduction of iron contained in glauconite by alkaliphilic bacteria

    Chistyakova, Nataliya I., E-mail: nchistyakova@yandex.ru; Rusakov, Vyacheslav S.; Shapkin, Alexey A. [M.V. Lomonosov Moscow State University, Faculty of Physics (Russian Federation); Zhilina, Tatyana N.; Zavarzina, Darya G. [Russian Academy of Sciences, Winogradsky Institute of Microbiology (Russian Federation)

    2012-03-15

    {sup 57}Fe Moessbauer investigations of glauconite and new solid phases formed during the process of the bacterial growth in alkaline environment were carried out at room temperature, 78 K and 4.8 K. The magnetically ordered phase formed during bioleaching of glauconite by G. ferrihydriticus in pure culture or in combination with Cl. alkalicellulosi represented as a mixture of off-stoichiometric magnetite and maghemite. In case of combined binary bacterium culture growth the relative content of magnetically ordered phase was more than for the G. ferrihydriticus growth.

  19. Fe1+ transient charge state in ZnS : 57Co Moessbauer sources

    ZnS:57Co Moessbauer sources emit below 255 K a line attributed to Fe1+ ions in addition to the main Fe2+ spectrum. Above this temperature the Fe1+ charge state is either no longer generated, or more probably its life time becomes shorter than the nuclear life time of 57Fe (14.4 KeV). Down to 100 K the Fe1+ contribution is present as a single line, and at lower temperatures this line broadens and splits into a doublet with large line widths. (Author)

  20. Moessbauer study of 3d-ion-substituted YBa2(Cu, Fe, M)3Osub(7-δ), M=V, Mn

    57Fe Moessbauer investigations at 300 K have been carried out on V, Mn substituted YBa2Cu3Osub(7-δ) system. Preliminary studies show that for small concentration of V (4%), Fe occupies preferentially the Cu(1) site whereas for the same concentration of Mn, Fe prefers the Cu(2) site. It is suggested that for low concentrations V has a preference for Cu(2) site in the 1-2-3 lattice. (author). 6 refs., 1 tab., 1 fig

  1. Moessbauer hydperfine fields in RBa sub 2 (Cu sub 0. 97 Fe sub O. O3 ) sub 3 O sub 7-x (R = Y, Pr, Er)

    Rubinstein, M.; Harford, M.Z. (Naval Research Lab., Washington, DC (US)); Swartzendruber, L.J.; Bennett, L.H. (National Bureau of Standards, Gaithersburg, MD (US))

    1988-12-01

    Room temperature {sup 57}Fe Moessbauer spectra of RBa{sub 2} (Cu{sub 0.97}Fe{sub O.O3}){sub 3}O{sub 7-x} (R=Y, Pr, Er) were obtained from samples with varying x. A magnetically-split hyperfine field spectrum was observed for the most oxygen-deficient Y sample, for all the Pr samples, and for none of the Er samples.

  2. Moessbauer-Fresnel zone plate as nuclear monochromator

    Zone plates currently used in x-ray optics derive their focusing power from (a spatial variation of) the electronic refractive index -- that is, from the collective effect of electronic x-ray-scattering amplitudes. Nuclei also scatter x rays, and resonant nuclear-scattering amplitudes, particularly those associated with Moessbauer fluorescence, can dominate the refractive index for x-rays whose energies are very near the nuclear-resonance energy. A zone plate whose Fresnel zones are filled alternately with 57Fe and 56Fe (57Fe has a nuclear resonance of natural width Γ = 4.8 nano-eV at 14.413 keV; 56Fe has no such resonance) has a resonant focusing efficiency; it focuses only those x-rays whose energies are within several Γ of resonance. When followed by an absorbing screen with a small pinhole, such a zone plate can function as a synchrotron-radiation monochromator with an energy resolution of a few parts in 1012. The energy-dependent focusing efficiency and the resulting time-dependent response of a resonant zone plate are discussed

  3. Feasibility test: Mossbauer spectroscopy of High Chart State of 57-Fe

    Yap, Ian

    2016-01-01

    This report focuses on the feasibility to conduct an experiment on measuring the isomer shift of high charge state of Fe. (The rest of the abstract is found in the document, as it is difficult to convert mathtype in docx. into Latex)

  4. Electronic and magnetic properties of metal diiodides MI2 (M=V, Cr, Mn, Fe, Co, Ni and Cd) from 129I Moessbauer spectroscopy

    The hyperfine interaction parameters at the iodine site in various metal diiodides (M=Cr, V, Mn, Fe, Co, Ni, Cd) were measured using the 27.8keV Moessbauer transition in 129I. Charge densities in the valence orbitals are deduced from an interpretation of isomer shift and quadrupole constant values. Magnetic hyperfine interactions transferred at the originally diamagnetic iodine ion in the magnetically ordered phases of the compounds allow one to determine the unpaired spin densities in the valence orbitals. Information relating to the magnetic structures are obtained from the number and intensities of magnetically nonequivalent sites and from the relative orientation between the transferred field and the electric field gradient axes. The Moessbauer spectra of 129Xe impurities created by β- decay of 129I in the NiI2 lattice reveal the absence of bonding of xenon atoms in this matrix

  5. The nature of point defects produced by cold working of metals studied with Moessbauer spectroscopy and perturbed γ-γ angular correlation

    The authors report on the production of point defects by cold working of Al, Cu, Ag, Pt and Au doped with the Moessbauer impurity 57Co. In the experiments no mobile interstitials were observed, while regarding vacancies the defect patterns are similar to those found after quenching and irradiation. The same observations for these hosts were made in recent experiments in which the PAC probe 111In was used. (Auth.)

  6. Long-range order in nanocrystalline Fe73.5Cu1Nb3Si13.5B9 studied by Moessbauer spectroscopy and x-ray diffraction

    Ferromagnetic nanocrystalline alloys prepared by crystallization from amorphous precursors are of high technical relevance for applications as soft-magnets. The most important representative of this class of materials is the soft-magnetic nanocrystalline alloy Fe73.5Cu1Nb3Si13.5B9 (VITROPERM, FINEMET). The present combined study of Moessbauer spectroscopy and x-ray diffraction aims at an understanding of the atomistic processes underlying the formation of the B2- and D03-order of the Fe3Si-type nanocrystallites during crystallization. From the Moessbauer spectra, which were fitted with the programme RECOIL taking into account hyperfine parameter distributions and correlations of the parameters, the silicon concentration and degree of long-range order of the nanocrystallites in dependence of isothermal annealing at 550 oC in could be determined. These data nicely fit with the B2- and D03-orderig as determined by x-ray diffraction. A comparison with recent tracer diffusion studies indicates that the kinetics of the ordering process is controlled by the slow Si self-diffusion in the Fe3Si-type nanocrystallites of Fe73.5Cu1Nb3Si13.5B9. (author)

  7. Substitution effects in M-type hexaferrite powders investigated by Moessbauer spectrometry

    Lechevallier, L. [Groupe de Physique des Materiaux, UMR CNRS 6634, Universite de Rouen, Site Universitaire du Madrillet, Avenue de l' Universite-BP 12, 76801 Saint Etienne du Rouvray Cedex (France)]. E-mail: luc.lechevallier@univ-rouen.fr; Le Breton, J.M. [Groupe de Physique des Materiaux, UMR CNRS 6634, Universite de Rouen, Site Universitaire du Madrillet, Avenue de l' Universite-BP 12, 76801 Saint Etienne du Rouvray Cedex (France)

    2005-04-15

    Significant improvements of the magnetic properties of M-type hexaferrites (SrFe{sub 12}O{sub 19}) can be achieved through partial substitutions with a rare-earth element and a transition metal. From this point of view, {sup 57}Fe Moessbauer spectrometry is a very powerful tool to determine the location of the substituted elements. We discuss here the effects on the Moessbauer spectrum of the substitution of a rare earth ion (Sm{sup 3+}, Nd{sup 3+} or La{sup 3+}) in the Sr{sup 2+} site, and the substitution of a metal ion (Co{sup 2+} or Zn{sup 2+}) in the Fe{sup 3+} sites.

  8. Moessbauer spectroscopic studies of Fe-20 wt.% Cr ball milled alloy

    Interesting differences were noticed in the alloying process during ball milling of Fe-10 wt.% Cr and Fe-20 wt.% Cr alloys by 57Fe Moessbauer spectroscopic studies. In both cases, there is almost no diffusion of Fe in Cr or vice versa up to 20 h of milling time. As the powders are milled for another 20 h substantive changes occur in the Moessbauer spectra showing atomic level mixing. But the two compositions behave differently with respect to alloying. Fe-20 wt.% Cr sample does not differ much in the hyperfine field distribution as it is milled from 40 to 100 h. On the other hand, the hyperfine field distribution keeps on changing with milling time for Fe-10 wt.% Cr sample even up to 100 h of milling. The average crystallite size is found to be 7.5 nm for Fe-10 wt.% Cr and 6.5 nm in Fe-20 wt.% Cr after milling.

  9. Moessbauer study of cobalt and iron in the cyanobacterium (blue green alga)

    Moessbauer emission and absorption studies have been performed on cobalt and iron in the cyanobacterium (blue-green alga). The Moessbauer spectrum of the cyanobacterium cultivated with 57Co is decomposed into two doublets. The parameters of the major doublet are in good agreement with those of cyanocobalamin (vitamin B12) labeled with 57Co. The other minor doublet has parameters close to those of Fe(II) coordinated with six nitrogen atoms. These suggest that cobalt is used for the biosynthesis of vitamin B12 or its analogs in the cyanobacterium. The spectra of the cyanobacterium grown with 57Fe show that iron is in the high-spin trivalent state and possibly in the form of ferritin, iron storage protein. (orig.)

  10. Biosynthesis, isolation and characterization of {sup 57}Fe-enriched Phaseolus vulgaris ferritin after heterologous expression in Escherichia coli

    Hoppler, Matthias [ETH Zurich, Laboratory of Human Nutrition, Zurich (Switzerland); Meile, Leo [ETH Zurich, Laboratory of Food Biotechnology, Zurich (Switzerland); Walczyk, Thomas [National University of Singapore, Department of Chemistry and Department of Biochemistry, Singapore (Singapore)

    2008-01-15

    Ferritin is the major iron storage protein in the biosphere. Iron stores of an organism are commonly assessed by measuring the concentration of the protein shell of the molecule in fluids and tissues. The amount of ferritin-bound iron, the more desirable information, still remains inaccessible owing to the lack of suitable techniques. Iron saturation of ferritin is highly variable, with a maximum capacity of 4,500 iron atoms per molecule. This study describes the direct isotopic labeling of a complex metalloprotein in vivo by biosynthesis, in order to measure ferritin-bound iron by isotope dilution mass spectrometry. [{sup 57}Fe]ferritin was produced by cloning and overexpressing the Phaseolus vulgaris ferritin gene pfe in Escherichia coli in the presence of {sup 57}FeCl{sub 2}. Recombinant ferritin was purified in a fully assembled form and contained approximately 1,000 iron atoms per molecule at an isotopic enrichment of more than 95% {sup 57}Fe. We did not find any evidence of species conversion of the isotopic label for at least 5 months of storage at -20 C. Transfer efficiency of enriched iron into [{sup 57}Fe]ferritin of 20% was sufficient to be economically feasible. Negligible amounts of non-ferritin-bound iron in the purified [{sup 57}Fe]ferritin solution allows for use of this spike for quantification of ferritin-bound iron by isotope dilution mass spectrometry. (orig.)

  11. A computer controlled Moessbauer spectrometer

    This paper describes a computer controlled data acquisition system for Moessbauer spectroscopy. In addition to reporting the fundamental ideas behind, and the construction of the system, this paper intends to serve as a manual for the user. The main unit is the 'Mark-VII' multiscaler/function generator, constructed as a double width NIM-unit. For the control of this unit we use an Apple IIe++ microcomputer equipped with a specially designed interface 'Kart-7'. The information supplied here should, however, be sufficient to interface other suitable microcomputers to the Mark-VII unit. The Kart-7 interface is described in this paper together with some details concerning its programming. The system is controlled by a program called 'HIN-5', which is also described in some detail. The manual section gives the details of how to start up and operate the spectrometer. (author)

  12. Large low-energy $M1$ strength for $^{56,57}$Fe within the nuclear shell model

    Brown, B. Alex; Larsen, A.C.

    2014-01-01

    A strong enhancement at low $\\gamma$-ray energies has recently been discovered in the $\\gamma$-ray strength function of $^{56,57}$Fe. In this work, we have for the first time obtained theoretical $\\gamma$ decay spectra for states up to $\\approx 8$ MeV in excitation for $^{56,57}$Fe. We find large $B(M1)$ values for low $\\gamma$-ray energies that provide an explanation for the experimental observations. The role of mixed $E2$ transitions for the low-energy enhancement is addressed theoreticall...

  13. Calculation of hyperfine magnetic fields at the nuclei of 57Fe in iron orthovanadate by SCF Xα-DV method

    Fermi-contact contributions to hyperfine magnetic fields on 57Fe nuclei in iron orthovanadate were calculated in approximation of self-consistent field, using local density functional and Xα-method of descrete variation. It is shown that at temperatures below 12K FC of HFMF on 57Fe nuclei in FeVO4 structure depends on the number of ligand atoms, entering the first coordination sphere of iron atoms. Decrease of coordination number leads to growth of covalency share in chemical binding of the central Fe3+ atom with ligand atoms

  14. Magnetic fluid: Comparative study of nanosized Fe{sub 3}O{sub 4} and Fe{sub 3}O{sub 4} suspended in Copaiba oil using Moessbauer spectroscopy with a high velocity resolution

    Oshtrakh, M I; Semionkin, V A; Milder, O B; Ushakov, M V [Faculty of Physical Techniques and Devices for Quality Control, Ural State Technical University - UPI, Ekaterinburg, 620002 (Russian Federation); Rodriguez, A F R [Universidade Federal do Acre, Rio Branco AC 79900-000 (Brazil); Santos, J G; Silveira, L B; Marmolejo, E M [Fundacao Universidade Federal de Rondonia, Departamento de Fisica, Ji-Parana RO 78961-970 (Brazil); Souza-Parise, M de; Morais, P C, E-mail: oshtrakh@mail.utnet.r [Universidade de Brasilia, Instituto de Fisica, Nucleo de Fisica Aplicada, BrasIlia DF 70910-900 (Brazil)

    2010-03-01

    Comparative study of nanosized magnetite and magnetite suspended in Copaiba oil (biocompatible magnetic fluid) was made using Moessbauer spectroscopy with a high velocity resolution (spectra were measured in 4096 channels). The better fit of room temperature spectra was done using 15 sextets and 1 doublet employing different parameters while spectra measured at 90 K were better fitted using 15 sextets with different parameters. These component numbers were related to multi-domain structure and non-stoichiometry of magnetite. Observed differences of magnetic hyperfine fields and relative areas of spectral components for nanosized Fe{sub 3}O{sub 4} and Fe{sub 3}O{sub 4} suspended in Copaiba oil may be related to the effect of surface interactions of Fe{sub 3}O{sub 4} and polar molecules of Copaiba oil.

  15. Synthesis, magnetic properties and Moessbauer spectroscopy for the pyrochlore family Bi{sub 2}BB Prime O{sub 7} with B=Cr and Fe and B Prime =Nb, Ta and Sb

    Blanco, Maria C. [INFIQC (CONICET), Dpto. de Fisicoquimica, Fac. de Ciencias Quimicas, U.N.C., Cordoba (X5000HUA) (Argentina); Franco, Diego G. [INFIQC (CONICET), Dpto. de Fisicoquimica, Fac. de Ciencias Quimicas, U.N.C., Cordoba (X5000HUA) (Argentina); Centro Atomico Bariloche - CNEA, Av. E. Bustillo 9500, S.C. de Bariloche (8500), R.N. (Argentina); Jalit, Yamile; Pannunzio Miner, Elisa V. [INFIQC (CONICET), Dpto. de Fisicoquimica, Fac. de Ciencias Quimicas, U.N.C., Cordoba (X5000HUA) (Argentina); Berndt, Graciele; Paesano, Andrea [Departamento de Fisica, Universidade Estadual de Maringa, Parana (Brazil); Nieva, Gladys [Centro Atomico Bariloche - CNEA, Av. E. Bustillo 9500, S.C. de Bariloche (8500), R.N. (Argentina); Carbonio, Raul E., E-mail: carbonio@mail.fcq.unc.edu.ar [INFIQC (CONICET), Dpto. de Fisicoquimica, Fac. de Ciencias Quimicas, U.N.C., Cordoba (X5000HUA) (Argentina)

    2012-08-15

    The samples Bi{sub 2}BB Prime O{sub 7}, with B=Cr and Fe and B Prime =Nb, Ta and Sb were prepared by solid state method. The crystallographic structure was investigated on the basis of X-ray powder diffraction data. Rietveld refinements show that the crystal structure is cubic, space group Fd-3m. The Bi{sup 3+} cation on the eight-coordinate pyrochlore A-site shows displacive disorder, as a consequence of its lone pair electron configuration. There is also a considerable A-site disorder shown by Rietveld Analysis and confirmed in the case of the iron containing samples with Moessbauer spectroscopy. The magnetic measurements show paramagnetic behavior at all temperatures for the Cr oxides. The Fe pyrochlores show antiferromagnetic order around 10 K.

  16. Multiple superhyperfine fields in a {DyFe2Dy} coordination cluster revealed using bulk susceptibility and (57)Fe Mössbauer studies.

    Peng, Yan; Mereacre, Valeriu; Anson, Christopher E; Powell, Annie K

    2016-08-01

    A [DyFeDy(μ3-OH)2(pmide)2(p-Me-PhCO2)6] coordination cluster, where pmideH2 = N-(2-pyridylmethyl)iminodiethanol, has been synthesized and the magnetic properties studied. The dc magnetic measurements reveal dominant antiferromagnetic interactions between the metal centres. The ac measurements reveal zero-field quantum tunnelling of the magnetisation (QTM) which can be understood, but not adequately modelled, in terms of at least three relaxation processes when appropriate static (dc) fields are applied. To investigate this further, (57)Fe Mössbauer spectroscopy was used and well-resolved nuclear hyperfine structures could be observed, showing that on the Mössbauer time scale, without applied field or else with very small applied fields, the iron nuclei experience three or more superhyperfine fields arising from the slow magnetisation reversal of the strongly polarized fields of the Dy(III) ions. PMID:27424877

  17. Moessbauer study of hemoglobin of diabetes

    The hemoglobins from normal adults (Gly-Hb 5%), people infected with diabetes (Gly-Hb 10%) and serious diabetics (Gly-Hb 15%) were investigated by Moessbauer spectroscopy at liquid nitrogen temperature. All the experimental spectra of hemoglobin are composed of three doublets corresponding to oxy-hemoglobin (Oxy-Hb), deoxy-hemoglobin (Deoxy-Hb) and low-spin hemo-chrome (Ls-Hemo) respectively. It is found that Oxy-Hb is decreasing but Deoxy-hb increasing for diabetes. Experimental results also indicate that the line-width of Moessbauer spectra of Oxy-Hb for diabetics is narrower than that for normal adults, showing that while Fe on Oxy-Hb exists in pile-up of some similar states for normal adults, but it becomes in single state for serious diabetes

  18. Moessbauer firing study of Lishan clay

    Lishan clay has been characterized by Moessbauer spectroscopy, X-ray diffraction, X-ray fluorescence, neutron activation, thermal and chemical analysis. It is proved that Lishan clay is the material used for making the terra-cotta warriors and horses of Qin Dynasty. Firing testing of clay was carried out in various conditions. The transformations induced by firing of clay were characterized by Moessbauer spectra. The data on quadrupole splittings of Fe3+ or Fe2+ ions, and on nonmagnetic component distributions at different firing temperatures, may lead to valuable informations on the manufacture of ancient pottery. The sintering temperature for the treea-cotta warriors and horses of Qin Dynasty was thus evaluated to be 950-1030 deg C

  19. Moessbauer studies on Al-Co ferrites

    Moessbauer spectroscopy studies have been performed on the spinel CoAlxFe2-xO4 (.2≤x≤1.7) in the temperature range 77-750 K using either a liquid nitrogen bath cryostat or a furnace. The samples are magnetic at 77 K giving spectra that have magnetic sextets coexisting with a central line which increases in population with the Al-content indicating relaxation effects. The data shows that Al possesses no preference to either tetrahedral or octahedral sites of the ferrite over the whole range of concentration. The Moessbauer hyperfine interaction parameters and magnetic transition temperatures were determined. As expected the hyperfine field and Curie temperature decrease when the Al-content increases. (orig.)

  20. Characterization of Zn-bearing chlorite by Moessbauer and infrared spectroscopy - occurrence associated to the Pb-Zn-Ag deposits of Canoas, PR, Brazil; Caracterizacao de clorita portadora de Zn por espectroscopia Moessbauer e espectroscopia infravermelho - uma ocorrencia associada ao deposito de Pb-Zn-Ag de Canoas, PR, Brasil

    Imbernon, Rosely Aparecida Liguori [Universidade de Sao Paulo (EACH/USP), SP (Brazil). Escola de Artes, Ciencias e Humanidades; Blot, Alain [Institut de Recherche pour le Developpement (IRD), Paris (France); Pereira, Vitor Paulo [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Inst. de Geociencias; Franco, Daniel Ribeiro, E-mail: imbernon@usp.br, E-mail: brotalain@free.fr, E-mail: vitor.pereira@ufrgs.br, E-mail: drfranco@on.br [Observatorio Nacional do Brasil (COGE/ON), Rio de Janeiro, RJ (Brazil). Coordenacao de Geofisica

    2011-06-15

    In order to provide new insights on mineralogical aspects of geochemical mapping/natural processes related to the chlorite formation (e.g. crystallochemistry and mechanisms of formation of these materials, which has been applied in different studies of environmental profiles), we investigated chlorite samples associated to the Pb-Zn-Ag sulfide ore from Canoas 1 deposit (Vale do Ribeira, state of Parana, Brazil). By means of Moessbauer (MS) and infrared (IV) spectroscopy, we addressed some issues as those related to the chloritization processes, as well as how Zn would be incorporated into its crystalline structure. Results carried out by ME and IV spectroscopy clearly pointed out for a chlorite occurrence, which in fact incorporates Zn into its structure and also alters the structural patterns for this mineral. Moreover, ME data sets indicated the presence of Fe which is located only in octahedral sites, in trans-configuration, and the Zn emplacement by the chloritization process also occurs in the brucite layer. (author)

  1. Thermal treatment of the Fe{sub 78} Si{sub 9} B{sub 13} alloy and the analysis of it magnetic properties through Moessbauer spectroscopy and Positronium annihilation; Tratamiento termico de la aleacion Fe{sub 78} Si{sub 9} B{sub 13} y el analisis de sus propiedades magneticas mediante Espectroscopia de Moessbauer y Aniquilacion de positronio

    Lopez M, A

    2005-07-01

    The present work is divided in five chapters. In the first one a general vision of the amorphous alloys is given from antecedents, structure, obtaining methods, properties and problems that at the moment, focusing us in a certain moment to the iron base alloys and the anomalous problem of hardness that it presents the alloy Fe{sub 78}Si{sub 9}B{sub 13} like previously mention us. The second chapter tries on the basic theory of the techniques of Moessbauer spectroscopy and Positron Annihilation spectroscopy, used for the characterization of our alloy as well as the complementary technique of X-ray diffraction (XRD) to observe that the amorphous phase was even studying. The third chapter describes the experimental conditions that were used to study the alloy Fe{sub 78}Si{sub 9}B{sub 13} in each one of their thermal treatments. In the fourth chapter the obtained results and their discussion are presented. In the fifth chapter the conclusions to which were arrived after analyzing the results are presented. (Author)

  2. Moessbauer study of the effect of oxygen stoichiometry on the high T/sub c/ superconductor Y1Ba2(Cu/sub 0.97/Fe/sub 0.03/)3O/sub 7-x/

    The Moessbauer effect of oxygen-depleted YBa2Cu3O/sub 7-x/ and PrBa2Cu3O/sub 7-x/ doped with 3% 57Fe has been investigated at room temperature. A manifold of quadrupole-split spectra has been found, whose parameters are in general agreement with those found by other workers. In addition, the Moessbauer spectra show that a fraction of the Fe sites develop magnetic order at room temperature when the oxygen content is reduced. It is demonstrated that the observed asymmetries in the Moessbauer spectra can be the result of a preferential alignment of the platelike crystallites that arises during the normal sample preparation process. The tendency to bond with the oxygen atoms is presumed to be responsible for the discreteness of the Moessbauer spectra as a function of oxygen depletion

  3. Moessbauer studies of malaria

    Moessbauer studies of rat and human erythrocytes infected by malarial parasites have been carried out. Different parameters of the pigment iron were obtained in human and rat infected red blood cells. No difference was found between the parameters obtained in rat erythrocytes infected by drug sensitive and drug resistant strains of P. berghei, both before and after the treatment with chloroquine. The pigment was shown to contain a trivalent, high spin iron compound, which is different from hematin. (Auth.)

  4. Moessbauer spectroscopic studies on spintronics-related materials

    Moessbauer spectroscopy is a powerful experimental tool for the investigations on local electronic and vibrational properties of solids. On the other hand, the recently developing field of 'spintronics', where spins of conduction electrons play a key role for transport phenomena, is requiring to control the size and physical properties of materials in nanoscales. Using Moessbauer spectroscopy it becomes possible to investigate local magnetism and electron-spin polarization of materials, while can be important information for further development of spintronics. In this article, Moessbauer spectroscopic studies on spintronics-related materials in the early stage after the discovery of giant magnetoresistance effect are outlined briefly, and then recent studies on Heusler-alloy-based layered structures are introduced topically. (author)

  5. Moessbauer effect study of the diagenesis on the southern Brazilian Triassic paleoherpetofauna

    Moessbauer spectroscopy is applied to identify the iron contents of bony elements of southern Brazilian Triassic reptile remains, and the question of the paragenetic mineral assemblage is discussed. (orig.)

  6. A Moessbauer study of the thermal behaviour of iron(III) benzoate

    The thermal behaviour of three different iron(III) benzoate complexes was investigated by Moessbauer spectroscopy, conventional thermal analysis and infrared spectroscopy. Each of the complexes had six benzoate ligands within the first coordination sphere. Their Moessbauer spectra showed only quadrupole pattern, characteristic of high-spin iron(III). When the complexes were heated in air, two new iron(III) benzoate complexes were obtained, having five and four benzoate ligands within the first coordination sphere. The Moessbauer spectra of these new complexes showed two distinct quadrupole petterns with relative concentration close to 2:1, which could be related to the nonequivalence of the three iron ions in the molecule. (author)

  7. Moessbauer effect of the origin of the colour in the ancient Egyptian black ware

    Samples of ancient Egyptian pottery, Roman pottery and modern pottery were examined by Moessbauer spectroscopy, infrared spectroscopy and x-ray diffraction with the aim of establishing the origin of the black colour of the Egyptian pottery. The Moessbauer spectra and the values of isomer shift and quadrupole splitting were used to decide on the presence of magnetic or non-magnetic ferrous or ferricions. (A.K.)

  8. Moessbauer study of function of magnesium in iron oxide catalysts

    YangJie-Xin; MaoLian-Sheng; 等

    1997-01-01

    Moessbauer spectroscopy has been utilized for studying the action of Mg element in iron oxide catalysts used for the dehydrogenation of ethylbenzene to sytrene.The experimental results show that the presence of opportune amount of Mg can enhance the stability and dispersion of catalysts,i.e.Mg is an sueful structure promoter in this kind of catalysts.

  9. Moessbauer study of rock paintings from Minas Gerais (Brazil)

    Four samples of a wall containing rock paintings have been studied by Moessbauer spectroscopy in combination with optical microscopy analysis and X-ray diffraction. Hematite and goethite were identified as the pigments responsible for the colors and the mineral tinsleyite, as the principal component of a light pink layer that is present in some parts of the wall. (orig.)

  10. Moessbauer transition dynamics in conditions of strong excitation of nuclear spins

    Sadykov, E.K.; Isavnin, A.G.; Skvortsov, A.I

    1997-05-15

    The state of the art Moessbauer spectroscopy has made unquestionable advance possible in the solid microstructure study. Apart from that application of the Moessbauer effect, another domain of investigations has been outlined since the outset, in the sixties, wherein the properties of gamma-radiation interaction with resonant nuclei in a recoilless mode are stressed. There were these recoilless processes that enabled to distinguish the gamma-radiation of natural width, and greatly encouraged the arising of traditional optics problems in the gamma range. The subject of interest in this article deals as well with the Moessbauer gamma optics. Essentially it is a gamma-ray (Moessbauer) susceptibility of the excited, non-equilibrium state of the nuclear spin system. We analyze the Moessbauer transitions in the strong coherent excitation of nuclear spins regime and the possibilities to deliberately vary the polarization, spectral and/or temporal properties of gamma-radiation propagating through a time-modulated medium.

  11. Moessbauer study of LaFeAsO and F-doped superconductors in external magnetic fields

    Kitao, S; Kobayashi, Y; Higashitaniguchi, S; Kurokuzu, M; Saito, M; Seto, M [Research Reactor Institute, Kyoto University, Kumatori, Osaka 590-0494 (Japan); Mitsui, T [CREST, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012 (Japan); Kamihara, Y [TRiP, JST, in Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama 226-8503 (Japan); Hirano, M; Hosono, H, E-mail: kitao@rri.kyoto-u.ac.j [ERATO SORST, JST, in Frontier Research Center, Tokyo Institute of Technology, Yokohama 226-8503 (Japan)

    2010-03-01

    The iron-based F-doped superconductors LaFeAsO{sub 1-x}F{sub x} with a transition temperature of 24 K (for x = 0.07) and 26 K (x = 0.11) and its parent material LaFeAsO were studied using {sup 57}Fe Moessbauer spectroscopy. Further investigation was carried out by applying external magnetic fields. F-doped superconductors showed a singlet pattern with no magnetic splitting throughout the temperature range from 4.2 to 298 K. On the other hand, magnetically-split spectra were observed in the parent LaFeAsO below the Neel temperature of about 140 K. The internal magnetic field reached 5.3 T at 4.2 K. The external magnetic fields up to 14 T were applied to the singlet phases, F-doped superconductors and the parent LaFeAsO above the Neel temperature. The induced magnetically-split spectra showed the internal magnetic fields with the comparable value to the applied fields. This fact confirmed that these singlet phases have the paramagnetic feature. The magnetic fields were also applied to the magnetically-ordered phase of LaFeAsO below the Neel temperature. The evolution of the spectra depending on the external magnetic fields was clearly explained by a model with two sublattice spins of the powdered antiferromagnet. This fact confirmed the magnetically-ordered phase is an antiferromagnet. The spin-flop field was also estimated by the model as about 26 T.

  12. Mössbauer spectroscopic study of 57Fe metabolic transformations in the rhizobacterium Azospirillum brasilense Sp245

    Kamnev, Alexander A.; Tugarova, Anna V.; Kovács, Krisztina; Biró, Borbála; Homonnay, Zoltán; Kuzmann, Ernő

    2014-04-01

    Preliminary 57Fe transmission Mössbauer spectroscopic data were obtained for the first time for live cells of the plant-growth-promoting rhizobacterium Azospirillum brasilense (wild-type strain Sp245) grown aerobically with 57FeIII-nitrilotriacetate (NTA) complex as a sole source of iron. The results obtained have shown that live cells actively reduce part of the assimilated iron(III) to iron(II), the latter amounting up to 33 % of total cellular iron after 18 h of growth, and 48 % after additional 3 days of storage of the dense wet cell suspension in nutrient-free saline solution in air at room temperature (measured at 80 K). The cellular iron(II) was found to be represented by two quadrupole doublets of different high-spin forms, while the parameters of the cellular iron(III) were close to those typical for bacterioferritins.

  13. The Miniaturized Moessbauer Spectrometer MIMOS II for the Asteroid Redirect Mission(ARM): Quantative Iron Mineralogy And Oxidation States

    Schroeder, C.; Klingelhoefer, G; Morris, R. V.; Yen, A. S.; Renz, F.; Graff, T. G.

    2016-01-01

    The miniaturized Moessbauer spectrometer MIMOS II is an off-the-shelf instrument with proven flight heritage. It has been successfully deployed during NASA’s Mars Exploration Rover (MER) mission and was on-board the UK-led Beagle 2 Mars lander and the Russian Phobos-Grunt sample return mission. A Moessbauer spectrometer has been suggested for ASTEX, a DLR Near-Earth Asteroid (NEA) mission study, and the potential payload to be hosted by the Asteroid Redirect Mission (ARM). Here we make the case for in situ asteroid characterization with Moessbauer spectroscopy on the ARM employing one of three available fully-qualified flight-spare Moessbauer instruments.

  14. Moessbauer-spectroscopic study of structure and magnetism of the exchange-coupled layer systems Fe/FeSn2, and Fe/FeSi/Si and the ion-implanted diluted magnetic semiconductor SiC(Fe)

    In line with this work the strucural and magnetic properties of the exchange coupled layered systems Fe/FeSn2 and Fe/FeSi/Si and of the Fe ion implanted diluted magnetic semiconductor (DMS) SiC(Fe) were investigated. The main measuring method was the isotope selective 57Fe conversion electron Moessbauer spectroscopy (CEMS), mostly in connection with the 57Fe tracer layer technique, in a temperature range from 4.2 K to 340 K. Further measurement techniques were X-ray diffraction (XRD), electron diffraction (LEED, RHEED), SQUID magnetometry and FMR (Ferromagnetic Resonance). In the first part of this work the properties of thin AF FeSn2(001) films and of the exchange-bias system Fe/FeSn2(001) on InSb(001) were investigated. With the application of 57Fe-tracer layers and CEMS both the Fe-spin structure and the temperature dependence of the magnetic hyperfine field (Bhf) of FeSn2 could be examined. The evaporation of Fe films on the FeSn2 films produced in the latter ones a high perpendicular spin component at the Fe/FeSn2 interface. In some distance from the interface the Fe spins rotate back into the sample plane. Furthermore 57Fe-CEMS provided a correlation between the absolute value of the exchange field vertical stroke He vertical stroke and the amount of magnetic defects within the FeSn2. Temperature dependent CEMS-measurements yielded informations about the spin dynamics within the AF. The transition temperatures TB*, which were interpreted as superparamagnetic blocking temperatures, obtain higher values compared to the temperatures TB of the exchange-bias effect, obtained with magnetometry measurements. The second part of this work deals with the indirect exchange coupling within Fe/FeSi/Si/FeSi/Fe multilayers and FeSi diffusion barriers. The goal was to achieve Fe free Si interlayers. The CEMS results show that starting from a thickness of tFeSi=10-12 A of the ''lower'' FeSi layers the interdiffusion of Fe is inhibited. For thicker FeSi layers (tFeSi ∼ 20 A

  15. Moessbauer spectroscopic determination of chemical state of iron in bauxite

    The chemical state of iron contained in several kinds of bauxite, which are utilized as a raw material in the aluminum industry in Japan, were investigated by Moessbauer spectroscopy. The main compounds of iron were identified from the results, which showed variations of the Moessbauer absorption spectra with calcination and measuring temperature. Although the absorption intensities of the spectra differed significantly, major species identified were paramagnetic or superparamagnetic α-Fe2O3 in all of these bauxite samples. The superparamagnetic α-Fe2O3 was found mainly in the gibbsite-type bauxite, but not in the boehmite/gibbsite-type or the boehmite-type bauxite. The Moessbauer absorption spectra of red mud and its calcined products were also given. (author)

  16. Further studies on electronic guest/host interactions of FeCl3-graphite from Moessbauer spectroscopy - a comparative investigation with FeOCl

    Moessbauer spectra of first stage FeCl3-graphite and of the inverse Fe(C5H5)2-iron oxide chloride intercalation compounds have been measured between room temperature and 4 K. The spectra at 295 K consist of resonance lines which are characteristic of ferric ions only. In addition the spectra showed high-spin Fe2+ sites at low temperatures. This result may be accounted for by an incomplete redox reaction caused by partial transfer of the π-electrons of the graphite (host layer), or of the ferricinium ions (guest layers), to the adjacent layers. Contrary to what is found in the literature, at low temperatures only these delocated electrons are fixed in the d-orbitals of some Fe3+ atoms resulting in Fe2+ sites. This result suggests that a shielding effect of the chlorine layers exists in these intercalation compounds which hinders a complete electron transfer to the Fe3+ centers at room temperature. (Auth.)

  17. Crystal structure and Moessbauer spectroscopy of Y2SrFeCuO6.5, a double layer perovskite intergrowth phase

    The crystal structure of Y2SrFeCuO6.5 was determined from single-crystal X-ray and neutron powder diffraction studies. Mr = 488.81, orthorhombic, Ibam, a = 5.4036(8)[5.4149(1)] angstrom, b = 10.702(1)[10.7244(1)] angstrom, c = 20.250(2)[20.2799(2)] angstrom; values in square brackets are neutron data. V = 1171.0(4), Z = 8, Dx = 5.544 g cm-3, λ = 0.71069 angstrom, μ = 345.1 cm-1, R = 0.048 for 567 observed reflections. The Fe/Cu atoms occupy randomly the approximate center of oxygen pyramids. The pyramids share the apical oxygen and articulate laterally by corner sharing of oxygen to form a double pyramidal layer perpendicular to c. The pyramidal slabs are separated by double layers of Y that are in 7-fold coordination to oxygen, forming a defect fluorite unit. Moessbauer spectra indicate a unique iron environment and magnetic ordering at about 265 K. The paramagnetic phase coexists with the magnetic phase over an approximate temperature range 300-263 K, characteristic of magnetic ordering in 2-D magnetic structures

  18. Moessbauer Study of Ferrite-garnets as Matrixes for Disposal of Highly Radioactive Waste Products

    Moessbauer study of synthesized ferrite-garnet samples containing Zr, Th, Ce and Gd of the following composition: 1C - Ca2,5 Ce0,5 Zr2 Fe3 O12, 2C - Ca1,5 GdCe0,5 ZrFeFe3 O12, 1T - Ca2,5 Th0,5Zr2 Fe3 O12 and 2T - Ca1,5 GdTh0,5 ZrFeFe3 O12 are carried out. As a result of 57Fe Moessbauer study it is found that iron atoms in all investigated samples of garnets are in a trivalent state. The analysis of experimental Moessbauer spectra definitely specifies a various structural state of iron atoms in two investigated groups of samples: 1T, 1C and 2T, 2C. X-ray study have shown that 1T and 1C garnet samples crystallize in tetragonal space group I41/acd, but 2T and 2C samples crystallize in cubic space group Ia3d.

  19. Moessbauer spectroscopic characterization of ferrite ceramics

    The principle of Moessbauer effect and the nature of hyperfine interactions were presented. The discovery of the Moessbauer effect was the basis of a new spectroscopic technique, called Moessbauer spectroscopy, which has already made important contribution to research in physics, chemistry, metallurgy, mineralogy and biochemistry. In the present work the selected ferrites such as spinel ferrite, NiFe2O4, and some rare earth orthoferrites and garnets were investigated using Moessbauer spectroscopy. X-ray powder diffraction and Fourier transform infrared spectroscopy were used as complementary techniques. The formation of NiFe2O4 was monitored during the thermal decomposition of mixed salt (Ni(NO3)2+2Fe(NO3)3)nH2O. The ferritization of Ni2+ ions was observed at 500 deg. C and after heating at 1300 deg. C the stoichiometric NiFe2O4 was produced. The Moessbauer parameters obtained for NiFe2O4, dFe = 0.36 mm s-1 and HMF = 528 kOe, can be ascribed to Fe3+ ions in the octahedral sublattice, while parameters dFe = 0.28 mm s-1 and HMF = 494 kOe can be ascribed to Fe3+ ions in the tetrahedral lattice. The effect of ball-milling of NiFe2O4 was monitored. The formation of oxide phases and their properties in the systems Nd2O3-Fe2O3, Sm2O3-Fe2O3, Gd2O3-Fe2O3, Eu2O3-Fe2O3 and Er2O3-Fe2O3 were also investigated. Quantitative distributions of oxide phases, a-Fe2O3, R2O3, R3Fe5O12 and RFeO3, R = Gd or Eu, were determined for the systems xGd2O3+(1-x)Fe2O3 and xEu2O3+(1-x)Fe2O3. The samples, prepared by chemical coprecipitation in the system xEu2O3+(1-x)Fe2O3, 0≤x≤1, were completely amorphous as observed by XRD, even at the relatively high temperature of the sample preparation (600 deg. C). Similar behavior was observed during the formation of Er3Fe5O12. Moessbauer spectroscopy indicated that this 'amorphous' phase is actually composed of very small and/or poor crystalline Fe-bearing oxide particles. The nature of these particles was discussed. These results can be of importance

  20. A versatile Moessbauer analysis program

    MDA - Moessbauer Data Analysis, is a user oriented computer program, aiming to simulate a Moessbauer transmission spectrum, given by a set of parameters, and compare it with experimental data. The calculation considers a number of experimental situations and the comparisons can be made by least squares sums or by plotting the simulated and the measured spectrum. A fitting routine, minimizing the least squares sum, can be used to find the parameters characterizing the measured spectrum.(author)

  1. Moessbauer study of the effect of oxygen stoichiometry on the high T/sub c/ superconductor Y/sub 1/Ba/sub 2/(Cu/sub 0. 97/Fe/sub 0. 03/)/sub 3/O/sub 7-x/

    Swartzendruber, L.J.; Bennett, L.H.; Harford, M.Z.; Rubinstein, M.

    1988-06-01

    The Moessbauer effect of oxygen-depleted YBa/sub 2/Cu/sub 3/O/sub 7-x/ and PrBa/sub 2/Cu/sub 3/O/sub 7-x/ doped with 3% /sup 57/Fe has been investigated at room temperature. A manifold of quadrupole-split spectra has been found, whose parameters are in general agreement with those found by other workers. In addition, the Moessbauer spectra show that a fraction of the Fe sites develop magnetic order at room temperature when the oxygen content is reduced. It is demonstrated that the observed asymmetries in the Moessbauer spectra can be the result of a preferential alignment of the platelike crystallites that arises during the normal sample preparation process. The tendency to bond with the oxygen atoms is presumed to be responsible for the discreteness of the Moessbauer spectra as a function of oxygen depletion.

  2. The history of the Moessbauer effect

    Miglierini, M

    2003-01-01

    The background of the discovery of the Moessbauer effect and the development of Moessbauer spectrometry as an analytical technique are highlighted. The basic principles and instrumentation, application fields, and trends of future progress and outlined and discussed

  3. The history of the Moessbauer effect

    The background of the discovery of the Moessbauer effect and the development of Moessbauer spectrometry as an analytical technique are highlighted. The basic principles and instrumentation, application fields, and trends of future progress and outlined and discussed

  4. 197Au Moessbauer studies of gold components and γ-ray irradiation effect

    The 197Au Moessbauer spectra of Au(I) (tmH2) and [Au(III)(tpp)][Au(III)Cl4] were measured. The isomer shifts and quadrupole splittings indicate that the gold compounds are in typical aurous and auric state, respectively. While no γ-ray irradiation effect was found in Au(tmH2), a novel Au(I) species was observed in γ-irradiated [Au(tpp)][AuCl4] by means of Moessbauer spectroscopy. (author)

  5. Static disorder in Ca-Ga-Ge-trigonal and tetragonal structures investigated by Moessbauer technique

    Full text: The tetragonal and trigonal Ca-gallo-germanate (Tt- and respectively Tr- CGGO) structures are an important family of the so called 'static disordered crystalline media'. The interest for such structures derives from their lack of inversion centre combined with relatively large oxygen cages and crystal field disorder. Indeed, the large acentric oxygen polyhedra, which are suitable hosts for laser ions ( e.g. Cr3+ ,Nd3+), show a crystal field dispersion owing to the random occupation of the neighboring T1 tetrahedral sites by the Ga3+ or Ge4+ ions. It was found that systems having such activator centers occupying sites with slightly different crystal field (described by the 'quasi-centre' concept) have specific spectroscopic and laser properties ( e.g. the broad band tunable stimulated emission of Cr3+ ions in crystals with Ca-gallo-germanate structure reported in literature. The Tt and Tr-CGGO structures, with extremely high Fe3+ content, have been investigated by Moessbauer spectroscopy. The refined analyze of RT and LHeT spectra of 2[Fex,Z1-x]T1[Fey,Z1-y]2T2O7 and 1-z,Lnz>3{FeyGe1-y}Oh [Fex,Ge1-x]3T1[Ge]2T2O14 ( A= Ba, Sr; Ln= La, Nd; Z=Ge, Si ) samples revealed well-known hyperfine fields' dispersions (HFD), due to the random substitution Fe3+/Ge4+ and Ln3+/A2+ on T1, T2, Oh and A crystallographic sites. The non-equivalent surroundings characterizing by different weights and hyperfine splitting values (ΔQ, ΔH) of observed sublattices generated by the different filling of cationic sites, around 57Fe, arises. The HFD parameters (mean value Δ bar, variance DΔ and asymmetry γΔ) have been obtained by a rigorous statistical analyze. A detailed discussion of the observed dispersion of hyperfine parameters is given taking into account a theoretical model and the resulting numerical calculation obtained by a specialized software. (author)

  6. Moessbauer Study of Electrodeposited Fe/Fe-Oxide Multilayers

    Iron has been deposited electrochemically by short current pulses in Na-saccharin containing FeII-chloride and sulphate solution electrolytes. Combined electrochemical techniques with initial pulse plating of iron nanolayer and its subsequent anodic oxidation under potential control have been used for production of Fe/Fe-oxide multilayers. 57Fe CEM spectra of pulse plated iron revealed the presence of a minor doublet attributed mainly to γ-FeOOH in addition to the dominant sextet of α-iron. In the case of anodically oxidized pulse plated iron and of samples after repeated deposition of anodically oxidized pulse plated iron an additional minor doublet, assigned to ferrous chloride, also appears in the Moessbauer spectra. A significant change in the magnetic anisotropy of α-iron was observed with the anodic oxidation. The thickness of the layers were estimated from the CEM spectrum data by a modified computer program of the Liljequist method. The coercive field and the power loss versus frequency data showed that the pulse plated iron cores are good inductive elements up to several kHz frequencies

  7. Local structure and magnetism of L10-type FeNi alloy films with perpendicular magnetic anisotropy studied through 57Fe nuclear probes

    The local structure and magnetism of FeNi alloy films prepared by alternate deposition of Fe and Ni monatomic layers, where perpendicular magnetic anisotropy has been observed, were investigated through 57Fe nuclear probes using Mössbauer spectroscopy. It was confirmed that the films are composed of L10-type ordered FeNi phase and A1-type disordered FeNi phase. For the films grown at 40–70 °C, which have no perpendicular anisotropy, the A1-disordered phase is dominant, whereas for the films grown at 100–190 °C, which have a stronger perpendicular anisotropy, the relative amount of the L10-ordered phase reaches 40% or more. It was clearly shown that the magnetic anisotropy of these films is strongly correlated with the local environments of Fe in the films. The results imply that if a further increase in the ratio of the L10-ordered phase is successfully achieved, one would obtain films with a stronger magnetic anisotropy applicable to perpendicular magnetic recording. (paper)

  8. The Moessbauer community in the USA

    Scientists in the United States assumed major roles in developing the Moessbauer community during its early years. However, since the termination of the Moessbauer Effect Methodology meetings in 1976, there has been little in the way of regular Moessbauer meetings in the United States. Nevertheless, there is an active United States Moessbauer community, as noted by the number of annual publications - 156 in 2004. In recent decades, attendance of Moessbauer researchers from the United States at the International Conferences on the Applications of the Moessbauer Effect (ICAME) has been far below what would be expected from the number of contributions in the Moessbauer literature. Attempts have been made, unsuccessfully, to arrange for regular Moessbauer meetings. Models for possible future Moessbauer meetings of US scientists are discussed, including a regular biannual meeting, and another being a virtual Moessbauer conference. Also discussed are other models to maintaining an active Moessbauer community in the United States, making use of information technologies that are available to us along with other resources we can use.

  9. Multi-level relaxation model for describing the Moessbauer spectra of single-domain particles in the presence of quadrupolar hyperfine interaction

    A multi-level stochastic model taking into account the magnetic anisotropy, precession and diffusion of the uniform magnetization of single-domain particles is developed in order to describe the Moessbauer absorption spectra of an ensemble of magnetic nanoparticles in the presence of quadrupolar hyperfine interaction with an arbitrary orientation of its principal axes. This model allows one to take into account physical mechanisms for forming the hyperfine structure in a real situation and can be easily realized even on a personal computer. In particular, now one can numerically describe qualitative features of temperature evolution of the Moessbauer spectral shape from a 'symmetric' magnetic sextet to a quadrupolar doublet of lines, which has been observed in a large number of experimental spectra of 57Fe nuclei in magnetic nanoparticles for almost half a century. (paper)

  10. Moessbauer effect of 197Au, 99Ru, 193Ir, 195Pt, and 151Eu diluted in hydrogenated palladium

    The study of hidrogenation in transition metals by Moessbauer spectroscopy of 197Au, 99Ru, 195Pt, 193Ir and 151Eu diluted in palladium is presented. The measured parameters in the Moessbauer effect are sensitive to hydrogenation and allow to obtain information about phases of hydrogened systems, modifications of electronic structure and effects related to hydrogen mobility. The (Pd1-x Agx)0.99 Au0.01 was also investigated by 197Au Moessbauer effect. The relantioship between α and β phase Debye - Waller factors by Moessbauer effect was estimated. Source and absorber Moessbauer experiments to verifying isomer shift variation in function of hydrogen concentration were done. A proposal for description of the isomer shift of transition (or rare) impurities in transition matrices from state density of each system is presented. The contribution of H+ ions bound to IS is discussed qualitatively. (M.C.K.)

  11. Moessbauer studies of bridged ferrocenophane derivative's polyiodides

    Watanabe, Masanobu; Sato, Kumiko; Motoyama, Izumi; Sano, Hirotoshi (Tokyo Metropolitan Univ. (Japan). Faculty of Science)

    1983-11-01

    (2)Ferrocenophanes, the ring tilted ferrocene derivatives, were oxidized with iodine in benzene and studied by means of Moessbauer spectroscopy. The quadrupole splitting value of the compounds is found to be 3.70 mms/sup -1/ at 78K, which is one of the largest found in ferrocene derivatives, suggesting the presence of a strong direct interaction between iron atoms and iodine atoms. The results were compared with (3) and (4)ferrocenophane's polyiodides.

  12. Moessbauer Investigations of MDAS Diamond Powder

    Metal inclusions in synthetic MDAS diamond grits were investigated by Moessbauer spectroscopy as a function of the grit size. The larger grit sizes show a nicely developed sextet, which collapses to a paramagnetic singlet with decreasing grit size. This superparamagnetic behavior shows that the metal inclusions are of the order of 10 nm in size, and become larger with the grit size. One grit which was showing the collapse was further investigated from 300 K down to 4 K. Part of the paramagnetic singlet unfolds to a sextet with Bhf ∼33T, while another part unfolds with a narrower hyperfine magnetic field of ∼4T and is associated with the paramagnetic phase that coexists with a ferromagnetic phase in Invar at higher temperatures. A singlet with an isomer shift of about 1.1 mm/s is associated with similar findings in catalysts with iron particles supported on carbonaceous materials

  13. LACAME 2006: Latin American conference on the applications of the Moessbauer effects. Program and Abstract Book

    Theoretical and experimental papers are present in these proceedings on the following subjects: Moessbauer effects and spectroscopy, minerals, structural chemical analysis, crustal structure, ion oxides, hyperfine structure, geology, catalysts, transmission and absorption spectroscopies, materials, crystal and hyperfine structures, stereochemistry and geological materials

  14. LACAME 2006: Latin American conference on the applications of the Moessbauer effects. Program and Abstract Book

    NONE

    2006-07-01

    Theoretical and experimental papers are present in these proceedings on the following subjects: Moessbauer effects and spectroscopy, minerals, structural chemical analysis, crustal structure, ion oxides, hyperfine structure, geology, catalysts, transmission and absorption spectroscopies, materials, crystal and hyperfine structures, stereochemistry and geological materials.

  15. Moessbauer study of the chemical state of gold in gold ores

    Information on the chemical state of gold in gold ores has been obtained by 197Au Moessbauer spectroscopy in cases where the state of this element cannot be determined by such standard methods as optical or electron microscopy. Ore concentrates consisting mainly of pyrite or arsenopyrite and roasted ore and matte samples were studied. The results yielded directly the respective amounts of metallic and chemically bound gold. Unless the gold is metallic, its chemical state in the ores turns out to be different from that in the minerals studied so far as reference materials. The chemical processes taking place during various treatments of the ores, such as roasting or leaching, can also be followed by Moessbauer spectroscopy. It is hoped that Moessbauer spectroscopy will eventually facilitate the development of more efficient methods of gold extraction

  16. 57Fe Mössbauer spectroscopic phase analysis of nonstoichiometric Nd-Fe-B alloys

    Ćosović, V.; Talijan, N.; Žák, Tomáš; Živkovič, D.; Stajić-Trošić, J.; Grujić, A.

    Beograd : University of Belgrade - Technical Faculty in Bor, 2010 - (Ivanov, S.; Živković, D.), s. 21-24 ISBN 978-86-80987-79-8. [International October Conference on Mining and Metallurgy. Kladovo (SR), 10.10.2010-13.10.2010] R&D Projects: GA MŠk 1M0512 Institutional research plan: CEZ:AV0Z20410507 Keywords : Nd-Fe-B alloys * Mössbauer spectroscopy * thermomagnetic measurements * phase composition * magnetic properties Subject RIV: BM - Solid Matter Physics ; Magnetism

  17. On the Moessbauer site assignment in YBa2(Cu1-xFex)3Oy

    The assignment of the four 57Fe Moessbauer sites which are observed in Fe-substituted YBa2Cu3Oy is presented. We present a systematic study of highly-controlled samples with low Fe-concentration over the whole oxygen concentration range. Two sites are found to dominate in the limit of high oxidation (y→7), indentified as Fe4+ on the two crystallographic Cu sites: Cu(1) and Cu(2). These are replaced at lower oxidation (y→6) by two others, which we identify with Fe3+ on these same two sites. Consistency is found with the sign of the electric field gradient (EFG), the asymmetry parameter η and the isomer shift IS for this model. The magnetic structure in the limit y→6 shows changes in the antiferromagnetic (AF) structure dependent on iron concentration. Moessbauer and spin-echo NMR results show a change in the Cu(2) AF layer sequence at low temperatures, without any magnetic moments on the Cu(1) chain sites. (orig.)

  18. Moessbauer spectroscopic studies of the coordination polymers [A(Me3Sn)3Fe(CN)6]x (A=Me3Sn+, Et4N+, Cp2Fe+, etc.)

    The structural diagnosis and lattice dynamics of the coordination polymers [(Me3Sn)3Fe(CN)6]x and [A(Me3Sn)3Fe(CN)6]x (A=Me3Sn+, Et4N+, Cp2Fe+, etc.) have been carried out by means of 57Fe- and 119Sn-Moessbauer spectroscopic techniques. The 119Sn-Moessbauer parameters for the polymers indicate that all the tin atoms are coordinated to three methyl groups and two cyano groups, having a trigonal-bipyramidal structure. The temperature dependences of the area under the 119Sn-resonance line for [A(Me3Sn)3Fe(CN)6]x were smaller than that for the host polymer [(Me3Sn)3Fe(CN)6]x. The 57Fe-Moessbauer spectra of [A(Me3Sn)3Fe(CN)6]x show that the iron atoms are Fe(II) in a low-spin state. This suggests that the guest ions are intercalated into the host lattice after reduction of its Fe(III) ions. (orig.)

  19. Redox condition of the late Neoproterozoic pelagic deep ocean: 57Fe Mössbauer analyses of pelagic mudstones in the Ediacaran accretionary complex, Wales, UK

    Sato, Tomohiko; Sawaki, Yusuke; Asanuma, Hisashi; Fujisaki, Wataru; Okada, Yoshihiro; Maruyama, Shigenori; Isozaki, Yukio; Shozugawa, Katsumi; Matsuo, Motoyuki; Windley, Brian F.

    2015-11-01

    We report geological and geochemical analysis of Neoproterozoic pelagic deep-sea mudstones in an accretionary complex in Lleyn, Wales, UK. Ocean plate stratigraphy at Porth Felen, NW Lleyn, consists of mid-ocean ridge basalt (> 4 m), bedded dolostone (2 m), black mudstone (5 m), hemipelagic siliceous mudstone (1 m,) and turbiditic sandstone (15 m), in ascending order. The absence of terrigenous clastics confirms that the black and siliceous mudstone was deposited in a pelagic deep-sea. Based on the youngest U-Pb age (564 Ma) of detrital zircons separated from overlying sandstone, the deep-sea black mudstone was deposited in the late Ediacaran. The 5 m-thick black mudstone contains the following distinctive lithologies: (i) black mudstone with thin pyritic layers (0.8 m), (ii) alternation of black mudstone and gray/dark gray siliceous mudstone (2.4 m), (iii) thinly-laminated dark gray shale (1 m), and (iv) black mudstone with thin pyritic layers (1 m). 57Fe Mössbauer spectroscopy confirms that these black mudstones contain pyrite without hematite. In contrast, red bedded claystones (no younger than 542 Ma) in the neighboring Braich section contain hematite as their main iron mineral. These deep-sea mudstones in the Lleyn Peninsula record a change of redox condition on the pelagic deep-sea floor during the Ediacaran. The black mudstone at Porth Felen shows that deep-sea anoxia existed in the late Ediacaran. The eventual change from a reducing to an oxidizing deep-sea environment likely occurred in the late Ediacaran (ca. 564-542 Ma).

  20. Mineralogical and Geochemical Analyses of Antarctic Lake Sediments: A Reflectance and Moessbauer Spectroscopy Study with Applications for Remote Sensing on Mars

    Froeschl, Heinz; Lougear, Andre; Trautwein, Alfred X.; Newton, Jason; Doran, Peter T.; Koerner, Wilfried; Koeberl, Christian; Bishop, Janice (Technical Monitor); DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Lakebottom sediments from the Dry Valleys region of Antarctica have been analyzed here in order to study the influence of water chemistry on the mineralogy and geochemistry of these sediments, as well as to evaluate techniques for remote spectral identification of potential biomarker minerals on Mars. Lakes from the Dry Valleys region of Antarctica have been investigated as possible analogs for extinct lake environments on early Mars. Sediment cores were collected in the present study from perennially ice-covered Lake Hoare in the Taylor Valley. These sediments were taken from a core in an oxic region of the lake and another core in an anoxic zone. Differences between the two cores were observed in the sediment color, Fe(II)/Fe(III) ratio, the presence of pyrite, the abundance of Fe, S and some trace elements, and the C, N and S isotope fractionation patterns. The results of visible-infrared reflectance spectroscopy (0.3-25 microns) Mossbauer spectroscopy (77 and 4 K) and X-ray diffraction are combined to determine the mineralogy and composition of these samples. The sediments are dominated by plagioclase, K-feldspar, quartz and pyroxene. Algal mats grow on the bottom of the lake and organic material has been found throughout the cores. Calcite is abundant in some layers of the aerobic core (shallow region) and pyrite is abundant in some layers of the anaerobic core (deep region). Analysis of the spectroscopic features due to organics and carbonates with respect to the abundance of organic C and carbonate contents was performed in order to select optimal spectral bands for remote identification of these components in planetary regoliths. Carbonate bands near 4 and 6.8 microns (approx.2500 and 1500/cm) were detected for carbonate abundances as low as 0.1 wt.% CO2. Organic features at 3.38, 3.42 and 3.51 microns (2960, 2925 and 2850/cm) were detected for organic C abundances as low as 0.06 wt.% C. The d13C trends show a more complex organic history for the anaerobic

  1. Mössbauer study of exogenous iron redistribution between the brain and the liver after administration of 57Fe3O4 ferrofluid in the ventricle of the rat brain

    Iron clearance pathways after the injection of 57Fe3O4-based ferrofluid into the brain ventricles were studied histologically and by Mössbauer spectroscopy. It was found that the dextran coated initial nanobeads of the ferrofluid disintegrated in the brain into separate superparamagnetic nanoparticles within a week after the injection. The exogenous iron completely exited all ventricular cavities of the brain within a week after the injection but remained in the white matter for months. Kupffer cells with the exogenous iron appeared in the rat liver 2 hours after the injection. Their concentration reached its maximum on the third day and dropped to zero within a week. The exogenous iron appeared in the spleen a week after the injection and remained in the spleen for months

  2. Mössbauer study of exogenous iron redistribution between the brain and the liver after administration of 57Fe3O4 ferrofluid in the ventricle of the rat brain

    Polikarpov, Dmitry; Gabbasov, Raul; Cherepanov, Valery; Loginova, Natalia; Loseva, Elena; Nikitin, Maxim; Yurenia, Anton; Panchenko, Vladislav

    2015-04-01

    Iron clearance pathways after the injection of 57Fe3O4-based ferrofluid into the brain ventricles were studied histologically and by Mössbauer spectroscopy. It was found that the dextran coated initial nanobeads of the ferrofluid disintegrated in the brain into separate superparamagnetic nanoparticles within a week after the injection. The exogenous iron completely exited all ventricular cavities of the brain within a week after the injection but remained in the white matter for months. Kupffer cells with the exogenous iron appeared in the rat liver 2 hours after the injection. Their concentration reached its maximum on the third day and dropped to zero within a week. The exogenous iron appeared in the spleen a week after the injection and remained in the spleen for months.

  3. Mössbauer study of exogenous iron redistribution between the brain and the liver after administration of {sup 57}Fe{sub 3}O{sub 4} ferrofluid in the ventricle of the rat brain

    Polikarpov, Dmitry, E-mail: polikarpov.imp@gmail.com [National Research Center “Kurchatov Institute”, Moscow (Russian Federation); Russian National Research Medical University named after N.I.Pirogov, Moscow (Russian Federation); Gabbasov, Raul; Cherepanov, Valery [National Research Center “Kurchatov Institute”, Moscow (Russian Federation); Loginova, Natalia; Loseva, Elena [Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow (Russian Federation); Nikitin, Maxim [Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow (Russian Federation); Yurenia, Anton; Panchenko, Vladislav [National Research Center “Kurchatov Institute”, Moscow (Russian Federation); Lomonosov Moscow State University, Moscow (Russian Federation)

    2015-04-15

    Iron clearance pathways after the injection of {sup 57}Fe{sub 3}O{sub 4}-based ferrofluid into the brain ventricles were studied histologically and by Mössbauer spectroscopy. It was found that the dextran coated initial nanobeads of the ferrofluid disintegrated in the brain into separate superparamagnetic nanoparticles within a week after the injection. The exogenous iron completely exited all ventricular cavities of the brain within a week after the injection but remained in the white matter for months. Kupffer cells with the exogenous iron appeared in the rat liver 2 hours after the injection. Their concentration reached its maximum on the third day and dropped to zero within a week. The exogenous iron appeared in the spleen a week after the injection and remained in the spleen for months.

  4. Moessbauer study of a Western-Han dynasty pottery figure

    A grey pottery figure manufactured in the Western-Han Dynasty and the clay gathered from the same site of Beidongshan near Suzhou, China, have been studied by X-ray diffraction, X-ray fluorescence and Moessbauer spectroscopy. They were simultaneously fired under the same conditions in different atmospheres at various temperatures. The information on original firing atmosphere and temperature as well as its provenance can be inferred from the method of pottery re-firing and clay firing. The original firing temperatures deduced from both of them are in good self-agreement. It is found that the values of Moessbauer parameters for the un-re-fired pottery figure are approximately the same as those for the clay fired at 950 deg C for five hours in a reduced atmosphere. The XRF analysis confirmed that the locality of this pottery figure was somewhere near Beidongshan

  5. Moessbauer studies on ancient Chinese pottery of Yangshao Culture Period

    Eleven pieces of ancient Chinese pottery (4770 B.C. - 2960 B.C.) of Yangshao Culture Period collected from the Xi'an area have been studied by means of Moessbauer spectroscopy. The samples were refired up to 11000C in steps of 1000C for 2 h in air. The highest temperature up to which the Moessbauer pattern remains basically unchanged can be identified with the original firing temperature. The result indicates that the firing temperatures for most of the sherds were between 900-10000C. The function of the grit contained in the pottery has been discussed. The crimson and reddish painted materials on the surface of sherds have been studied, respectively. The first appearance of pottery can probably be traced back to an even earlier period. (orig.)

  6. Moessbauer studies of a martensitic transformation and of cryogenic treatments of a D2 tool steel

    Costa, B. F. O., E-mail: benilde@ci.uc.pt [University of Coimbra, CEMDRX, Department of Physics (Portugal); Blumers, M. [University Mainz, Institute of Inorganic Chemistry (Germany); Kortmann, A. [Ingpuls GmbH (Germany); Theisen, W. [Ruhr-Universitaet Bochum, Institute of Materials (Germany); Batista, A. C. [University of Coimbra, CEMDRX, Department of Physics (Portugal); Klingelhoefer, G. [University Mainz, Institute of Inorganic Chemistry (Germany)

    2013-04-15

    A D2 tool steel X153CrVMo12 with composition C1.53 Cr12 V0.95 Mo0.80 Mn0.40(wt% Fe balanced) was studied by use of Moessbauer spectroscopy and X-ray diffraction. It was observed that the study of carbides by X-ray diffraction was difficult while Moessbauer spectroscopy gives some light on the process occurring during cryogenic treatment. With the increase of the martensitic phase the carbides decrease and are dissolved in solid solution of martensite as well as the chromium element.

  7. Moessbauer investigations of iron containing catalysts used for hydrogenation of brown coal at high pressure

    The changes of the composition of added iron compounds are investigated in catalytic brown coal hydrogenation at high pressure by Moessbauer spectroscopy. The liquid yields are enhanced in dependence on both the vacancy content of the obtained pyrrhotite (FexS) and the dispersity of the active component. Iron compounds on carrier material are shown to be more efficient in the hydrogenation process than directly imposed iron sulfate due to pyrrhotite with lower iron content and the high dispersity of the active iron phase. Moessbauer spectroscopy is proved to represent a sensitive analytical method to characterize changes of iron containing phases in the course of hydrogenation process. (author)

  8. In Situ Resource Utilization (ISRU) on the Moon: Moessbauer Spectroscopy as a Process Monitor for Oxygen Production. Results from a Field Test on Mauna Kea Volcano, Hawaii

    Morris, R.V.; Schroder, C.; Graff, T.G.; Sanders, G.B.; Lee, K.A.; Simon, T.M.; Larson, W.E.; Quinn, J.W.; Clark, L.D.; Caruso, J.J.

    2009-01-01

    Essential consumables like oxygen must to be produced from materials on the lunar surface to enable a sustained, long-term presence of humans on the Moon. The Outpost Precursor for ISRU and Modular Architecture (OPTIMA) field test on Mauna Kea, Hawaii, facilitated by the Pacific International Space Center for Exploration Systems (PISCES) of the University of Hawaii at Hilo, was designed to test the implementation of three hardware concepts to extract oxygen from the lunar regolith: Precursor ISRU Lunar Oxygen Testbed (PILOT) developed by Lockheed Martin in Littleton, CO; Regolith & Environmental Science and Oxygen & Lunar Volatiles Extraction (RESOLVE) developed at the NASA Kennedy Space Center in Cape Canaveral, FL; and ROxygen developed at the NASA Johnson Space Center in Houston, TX. The three concepts differ in design, but all rely on the same general principle: hydrogen reduction of metal cations (primarily Fe2+) bonded to oxygen to metal (e.g., Fe0) with the production of water. The hydrogen source is residual hydrogen in the fuel tanks of lunar landers. Electrolysis of the water produces oxygen and hydrogen (which is recycled). We used the miniaturized M ssbauer spectrometer MIMOS II to quantify the yield of this process on the basis of the quantity of Fe0 produced. Iron M ssbauer spectroscopy identifies iron-bearing phases, determines iron oxidation states, and quantifies the distribution of iron between mineral phases and oxidation states. The oxygen yield can be calculated by quantitative measurements of the distribution of Fe among oxidation states in the regolith before and after hydrogen reduction. A M ssbauer spectrometer can also be used as a prospecting tool to select the optimum feedstock for the oxygen production plants (e.g., high total Fe content and easily reduced phases). As a demonstration, a MIMOS II backscatter spectrometer (SPESI, Germany) was mounted on the Cratos rover (NASA Glenn Research Center in Cleveland, OH), which is one of

  9. Characteristic properties of high- and low-spin-state five-coordinate σ-bonded aryl-, alkyl-, and perfluoroaryliron(III) porphyrins: 1H NMR, ESR, Moessbauer, and magnetic studies

    The magnetic behavior of σ-alkyliron(III) (or σ-aryliron(III)) porphyrins is studied in solution and in solution and in solid state by various spectroscopic methods: 1H NMR, ESR, and 57Fe Moessbauer spectroscopies. Variable-temperature magnetic susceptibility measurements were also performed on these complexes. The iron(III) atom of these compounds is present in different spin states. These are high (S = 5/2) or low spin (S = 1/2) at room temperature. Several factors can affect the spin state, the major parameter being the nature of the axial ligand. The perfluoroaryl axial groups (C6F4H, C6F5) lead to complexes in a pure high-spin state whatever the temperature. In contrast, the (P)Fe(R(Ar)) complexes where R = CH3, Ar = C6H5 and p-MeC6H4, and P = OEP, TPP, T(m-Me)PP, T(p-Me)PP, T(p-Et2N)PP, and (β-CN)4TPP behave differently and are in a low-spin state at room temperature. However, for the latter compounds in frozen solution or in the solid state, some high-spin sites are observed by ESR spectroscopy. The amount is critically dependent on the nature of the axial and porphyrin ligands. Moreover, the solvent matrix appears very important. In the solid state and on the basis of ESR data, the spin mixture could be slightly modified by grinding of the crystalline sample, leading to high-spin entity increase. The effect of these parameters is examined with respect to the nature of the metal-porphyrin and metal-ligand bond. Correlations between stereochemistry, spin state, and the nature of ligands are discussed. 64 refs., 9 figs., 8 tabs

  10. 57Fe Mössbauer and X-ray characterisation of sandstones

    Sandstones from the Free State province in South Africa have been mined and processed mainly by small scale and artisanal miners in the rural areas. In the present investigation basic fire proof and water absorption tests, X-ray and γ-ray based characterisation techniques were used to study the sandstones. The collected samples were grouped according to their apparent colour in day light conditions and the elemental analysis showed the presence of a high amount of oxygen (>52%) and silicon (>38%) with Mn, Al, Fe and Ca as major elements in proportions related to the colour distribution of the various sandstones. The uniaxial compressive stress was found to be the highest (56 MPa) for the greyish sandstone and the lowest (8 MPa) for the white sandstone sample, also associated with the lowest (Al+Fe)/Si value of 0.082. The humidity test showed that the 6 % water absorption was lower than the recommended ASTM value of 8 %. The sandstone samples were also subjected to various high temperatures to simulate possible fire conditions and it was found that the non alteration of the mineral species might be one of the reasons why the sandstones are regarded as the most refractory amongst the building materials typically used. Mössbauer spectroscopy revealed that iron is present in all the sandstones, mainly as Fe3 +  with the black sandstone showing an additional presence of 3 % Fe2 +  indicating that a higher iron content coupled to higher silicon content, contributes to an increase in the uniaxial compressive strength.

  11. Moessbauer-spectroscopic study of structure and magnetism of the exchange-coupled layer systems Fe/FeSn{sub 2}, and Fe/FeSi/Si and the ion-implanted diluted magnetic semiconductor SiC(Fe); Moessbauerspektroskopische Untersuchung von Struktur und Magnetismus der austauschgekoppelten Schichtsysteme Fe/FeSn{sub 2} und Fe/FeSi/Si und des ionenimplantierten verduennten magnetischen Halbleiters SiC(Fe)

    Stromberg, Frank

    2009-07-07

    In line with this work the structural and magnetic properties of the exchange coupled layered systems Fe/FeSn{sub 2} and Fe/FeSi/Si and of the Fe ion implanted diluted magnetic semiconductor (DMS) SiC(Fe) were investigated. The main measuring method was the isotope selective {sup 57}Fe conversion electron Moessbauer spectroscopy (CEMS), mostly in connection with the {sup 57}Fe tracer layer technique, in a temperature range from 4.2 K to 340 K. Further measurement techniques were X-ray diffraction (XRD), electron diffraction (LEED, RHEED), SQUID magnetometry and FMR (Ferromagnetic Resonance). In the first part of this work the properties of thin AF FeSn{sub 2}(001) films and of the exchange-bias system Fe/FeSn{sub 2}(001) on InSb(001) were investigated. With the application of {sup 57}Fe-tracer layers and CEMS both the Fe-spin structure and the temperature dependence of the magnetic hyperfine field (B{sub hf}) of FeSn{sub 2} could be examined. The evaporation of Fe films on the FeSn{sub 2} films produced in the latter ones a high perpendicular spin component at the Fe/FeSn{sub 2} interface. In some distance from the interface the Fe spins rotate back into the sample plane. Furthermore {sup 57}Fe-CEMS provided a correlation between the absolute value of the exchange field vertical stroke He vertical stroke and the amount of magnetic defects within the FeSn{sub 2}. Temperature dependent CEMS-measurements yielded informations about the spin dynamics within the AF. The transition temperatures T{sub B}{sup *}, which were interpreted as superparamagnetic blocking temperatures, obtain higher values compared to the temperatures T{sub B} of the exchange-bias effect, obtained with magnetometry measurements. The second part of this work deals with the indirect exchange coupling within Fe/FeSi/Si/FeSi/Fe multilayers and FeSi diffusion barriers. The goal was to achieve Fe free Si interlayers. The CEMS results show that starting from a thickness of t{sub FeSi}=10-12 A of the

  12. Two-electronic Moessbauer the centers with negative correlation energy as the tool of research of Bose-condensation in superconductors

    Two-electronic centers with negative correlation energy; crystal probe; Bose condensation of Cooper pairs; changes of electronic density in the lattice sites; isomer shift; gravity center of a spectrum; superconducting phase transition; temperature of transition; minimal size of a Cooper pair. Objects of research: solid solutions of lead chalcogenides Pb1-x-ySnxNayS, Pb1-x-ySnxNaySe, Pb1-x-yGexNayS, Pb1-x-yGexNaySe, (Pb1-xSnx)1-zInzTe; classical super-conductor Nb3Al; high-temperature superconductors La2-x(Sr,Ba)xCuO4, YBa2Cu3O7-x, YBa2Cu4O8, Tl2Ba2Can-1CunO2n+4, Bi2Sr2Can-1CunO2n+4, HgBa2Can-1CunO2n+2, where n=1,2,3; Objective of study: development and application of methodology of the Moessbauer spectroscopy of systems with negative correlation energy in order to identify the impurity U- centers in semiconductors and Bose condensation of Cooper pairs in classical and high-temperature superconductors. Method of research: emission Moessbauer spectroscopy on 119mmSn (119mSn), 73As(73Ge), 67Cu(67Zn), 67Ga(67Zn), 57Co(57mFe), 119mTe(119mSn) isotopes; absorption Moessbauer spectroscopy on 119Sn, 151Eu, 57Fe isotopes; temperature dependence of the conductivity; Hall effect. Obtained results and their novelty. The research of the crystal lead chalcogenides has shown that tin and germanium impurity atoms are U- centers of a donor type, neutral and twice ionized states of the U- centers are in cation sites of a lattice. Temperature dependence of the chemical potential, the first and the second ionization energy of U- centers, correlation energy and energy of activation of own conductivity as well as their dependence on concentration of acceptors and tin atoms have been determined for tin impurity atoms. Impurity tin and germanium atoms specially entered into antistructural positions of lead chalcogenides lattices (a method of radiation doping) are electrically inactive. The two-electronic exchange between neutral and ionized impurity U- tin (and germanium) centers in Pb

  13. TEMPERATURE DEPENDENCE OF 57Fe-MÖSSBAUER SPECTRA FOR A 〖〖Fe〗_Fc^II-Fe〗_tpy^II-〖Fe〗_Fc^II TRINUCLEAR SYSTEM

    Dumitru Sirbu

    2015-06-01

    Full Text Available 57Fe Mӧssbauer spectra were recorded for 1'-terpyridine ferrocenecarboxylic acid and [bis(1'-terpyridine ferrocenecarboxylic acid Fe(II]2+ in the temperature range 7 – 293 K. The temperature dependence of the Quadrupole Splitting, Isomer Shift and Debye-Waller factor are discussed. The Debye temperature for the iron nuclei in the investigated compounds was determined.

  14. Moessbauer and VNIR study of dust generated from olivine basalt: application to Mars

    Moessbauer spectroscopy of surface rocks, soil, and dust on Mars from the Mars Exploration Rovers (MER) suggests that the mineral olivine is widespread on the surface. Detection of the mineral by near-IR optical spectroscopy from Martian orbit indicates that it is found in relatively small isolated outcrops concentrated in the floors and rims of craters distributed around the ancient cratered highlands of Mars. To shed light on this apparent paradox, we have performed a detailed Moessbauer and visible-near-IR (VNIR) investigation of dust generated from Icelandic olivine basalt, which is a good Moessbauer analogue to the igneous rocks at Gusev crater on Mars. The results show that the amount of olivine relative to pyroxene can be underestimated by almost an order of a magnitude in VNIR reflectance spectra, most probably because of the longer effective optical path length in pyroxene compared to olivine.

  15. A Moessbauer study on the deformed surface of high-manganese steels

    Conversion Electron Moessbauer Spectroscopy (CEMS) is a useful technique to study structures and properties near the surface of materials. In this study, CEMS was applied to investigate around the surface of a high-manganese steel, which is called Hadfield steel which is known for its remarkable work hardening. X-ray backscattering Moessbauer spectroscopy was also performed in order to compare the state of the Fe atom near surface to that of bulk and the cause of work hardening of Hadfield steel was discussed. Observed Moessbauer spectra were analyzed into two components, one was a singlet peak corresponding to Fe atoms without C atoms at the first or the second nearest neighboring interstitial site, the other a doublet peak corresponding to Fe atoms with C atoms at those sites. A widely split six line peak of α' martensites was not observed in any Moessbauer spectra so that α' martensites has no relation to work hardening of Hadfield steel. The comparison of CEMS spectra to X-ray backscattering Moessbauer spectra made it clear that the decarburization around the surface occurred even in the samples before working. The value of quadrupole splitting in CEMS spectra decreased by working and this could be explained by the introduction of stacking faults in samples. The decarburization around the surface and the decrease of quadrupole splitting by working lead to the conclusion that work hardening of Hadfield steel results from the introduction of stacking faults and the formation of thin ε martensites. (author)

  16. Moessbauer spectroscopic study on chemical changes of iron compounds with the aid of sulfate-reducing bacteria

    57Fe Moessbauer spectra were measured of reaction products formed during an incubation experiment with sulfate-reducing bacteria, which were isolated from estuarine sediments of the Tama River in Tokyo. The spectrum of the product incubated for several days showed some overlapping sextets. This product had a different chemical form from amorphous iron monosulfide produced by inorganic reaction between ferrous and sulfide ions. It was estimated that the structure of nearest neighbor of iron in this product was similar to that of pyrrhotite (Fe1-xS). After several months of incubation, other singlet and doublet appeared successively on the spectrum, corresponding to mackinawite (FeS1-x) and new sulfide, respectively. Both values of isomer shift and quadrupole splitting of new sulfide increased with increasing incubation time and approached those of pyrite (FeS2). Extended X-ray absorption fine structure (EXAFS) showed that iron atoms were coordinated by sulfur in the incubation product

  17. Moessbauer measurements of microstructural change in aged duplex stainless steel

    A duplex stainless steel (ASME SA351 CF8M) has usually been manufactured by a continuous casting technique. It consists of a paramagnetic austenite phase and a ferromagnetic ferrite phase. It has been known that the ferrite phase decomposition occurs in this steel after aging between 300 and 450 C. As a result of phase decomposition, a Fe-rich phase and a Cr-rich phase are produced in the ferrite phase. It is difficult to detect the phase decomposition even by not only optical microscopy but also transmission electron microscopy, since the decomposed structure is very fine. However, Moessbauer measurements that can detect the magnetic hyperfine field of magnetic substance may detect the microstructural change. An averaged magnetic hyperfine field increases in the ferrite phase, due to the production of the Fe-rich phase which has high magnetic hyperfine field. Therefore, the authors investigated the phase decomposition of the duplex stainless steel caused by aging, utilization Moessbauer spectroscopy which has capability of detecting this structural change in the atomic level quantitatively. The authors also investigated the potential of backscattering Moessbauer method for NDE technique

  18. Phenomenological simulation and density functional theory prediction of 57Fe Mössbauer parameters: application to magnetically coupled diiron proteins

    The use of phenomenological spin Hamiltonians and of spin density functional theory for the analysis and interpretation of Mössbauer spectra of antiferromagnetic or ferromagnetic diiron centers is briefly discussed. The spectroscopic parameters of the hydroxylase component of methane monooxygenase (MMOH), an enzyme that catalyzes the conversion of methane to methanol, have been studied. In its reduced diferrous state (MMOHRed) the enzyme displays 57Fe Mössbauer and EPR parameters characteristic of two ferromagnetically coupled high spin ferrous ions. However, Mössbauer spectra recorded for MMOHRed from two different bacteria, Methylococcus capsulatus (Bath) and Methylosinus trichosporium OB3b, display slightly different electric quadrupole splittings (ΔEQ) in apparent contradiction to their essentially identical active site crystallographic structures and biochemical functions. Herein, the Mössbauer spectral parameters of MMOHRed have been predicted and studied via spin density functional theory. The somewhat different ΔEQ recorded for the two bacteria have been traced to the relative position of an essentially unbound water molecule within their diiron active sites. It is shown that the presence or absence of the unbound water molecule mainly affects the electric field gradient at only one iron ion of the binuclear active sites.

  19. The stannides RE{sub 3}Au{sub 6}Sn{sub 5} (RE = La, Ce, Pr, Nd, Sm). Synthesis, structure, magnetic properties and {sup 119}Sn Moessbauer spectroscopy

    Fickenscher, Thomas; Rodewald, Ute C.; Niehaus, Oliver; Gerke, Birgit; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Haverkamp, Sandra; Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie

    2015-07-01

    The Ce{sub 3}Pd{sub 6}Sb{sub 5}-type rare earth stannides RE{sub 3}Au{sub 6}Sn{sub 5} (RE = La, Ce, Pr, Nd, Sm) were synthesized by arc-melting of the elements and subsequent annealing in open tantalum crucibles within sealed evacuated silica ampoules. The polycrystalline samples were studied by powder X-ray diffraction. The structures of three crystals were refined from single crystal X-ray diffractometer data: Pmmn, a = 1360.3(9), b = 455.9(2), c = 1023.6(4) pm, wR2 = 0.0275, 1069 F{sup 2} values, 48 variables for Ce{sub 3}Au{sub 6}Sn{sub 5}, a = 1352.4(4), b = 455.1(1), c = 1023.7(3) pm, wR2 = 0.0367, 1160 F{sup 2} values, 48 variables for Nd{sub 3}Au{sub 6}Sn{sub 5}, and a = 1339.8(2), b = 452.80(7), c = 1012.4(2) pm, wR2 = 0.1204, 1040 F{sup 2} values, 49 variables for Sm{sub 3}Au{sub 5.59(2)}Sn{sub 5.41(2)}. One of the gold sites of the samarium compound shows a significant degree of Au/Sn mixing. The RE{sub 3}Au{sub 6}Sn{sub 5} structures are composed of three-dimensional [Au{sub 6}Sn{sub 5}] polyanionic networks with the two crystallographically independent rare earth atoms in larger cages, i.e., RE1 rate at Au{sub 10}Sn{sub 6} and RE2 rate at Au{sub 8}Sn{sub 8}. The [Au{sub 6}Sn{sub 5}] network is stabilized by Au-Sn (266-320 pm), Au-Au (284-301 pm) as well as Sn-Sn (320 pm; distances given for the cerium compound) interactions. Temperature-dependent magnetic susceptibility measurements reveal an antiferromagnetic ordering only for Sm{sub 3}Au{sub 6}Sn{sub 5}, while the other compounds exhibit Curie-Weiss paramagnetism. {sup 119}Sn Moessbauer spectroscopy shows resonances in the typical range for intermetallic tin compounds where tin takes part in the polyanionic network [isomer shifts between 1.73(1) and 2.28(1) mm . s{sup -1}]. With the help of theoretical electric field gradient calculations using the WIEN2k code it was possible to resolve the spectroscopic contributions of all three crystallographically independent atomic tin sites in the {sup 119}Sn

  20. Moessbauer studies of non-linear excitations and gold cluster compounds

    Moessbauer effect spectroscopy has been applied to the study of three polynuclear gold cluster compounds. The resulting information on the local vibrational density of states has been compared to several models which take the finite size of the particles into consideration. 188 refs.; 34 figs.; 103 schemes; 8 tabs

  1. Moessbauer characterization of the corrosion products of steels in civil works: Suspension bridge and reinforced concrete

    The rusting condition of the cables of suspension bridges is usually evaluated by self-induction measurements. This method assumes that rusts of same chemical composition have always the same magnetic properties. Unfortunately in some cases, this assumption has shown to be questionable and this study has demonstrated that Moessbauer spectroscopy supplies additional information on the nature of some detected defects. In the case of reinforced concrete, it has been empirically pointed out that the content of agressive element, e.g. Cl- ions, should be under a trigger. Moessbauer studies have demonstrated the physical meaning of this practical rule. (orig.)

  2. Moessbauer study of the martensitic transformation in a Ni-Fe-Ga shape memory alloy

    We present the results of an extensive Moessbauer study of the magnetic and martensitic transformation at room temperature of a polycrystalline alloy with a Ni55Fe19Ga26 nominal composition. From calorimetric measurements, we have determined the martensitic transformation temperature of TM ∼ 240 K, in good agreement with the one obtained by magnetic characterization. This sample has a Curie temperature of TC ∼ 287 K. Additional Curie temperatures, belonging to a γ phase, have been also detected. Moessbauer spectroscopy performed at different temperatures monitored all these transformations and the fitting of the obtained spectrum at the highest temperature allow us to give percentages of the different phases in the sample.

  3. Moessbauer study of Sn(Fe)O2 prepared by mechanosynthesis

    Samples of Sn0.90Fe0.10O2 were prepared by mechanosynthesis method. The structure and magnetic behavior of the samples have been investigated by X-ray diffraction (XRD) and Moessbauer spectroscopy. It has been found that for short milling times a small percentage of the initial hematite remains simultaneously with the formation of metallic Fe. Additionally a paramagnetic contribution appears in the Moessbauer spectra. For milling times, over 2 h, the iron ions are in paramagnetic states having +3 and +2 oxidation states while by XRD only the rutile structure diffraction lines were observed.

  4. Moessbauer effect study f environmental iron pollution of air and water at regions near Cairo

    Moessbauer spectroscopy has been applied for identification of the different phases of iron (with their relative abundance) containing particles in atmosphere aerosol and water pollution from Helwan, Turrah, and Shoubra Elkheima regions. Measurements were performed at room and liquid nitrogen temperatures. It was possible to identify the different iron forms in each case and to estimate the particle size of the superparamagnetic iron containing aerosol particles. The Moessbauer technique allowed to suggest the possible source of iron pollutant in each region. 2 figs, 2 tabs

  5. Temperature and Field Dependent Moessbauer Studies of the Metallic Inclusions in Synthetic MDAS Diamond Grits

    Moessbauer spectroscopy of the metallic inclusions in diamond grits produced in high-temperature high-pressure synthesis have revealed varying but interesting results. The MDAS1 grits synthesized with Fe/Ni solvent-catalysts show Moessbauer spectra that vary with grit size, with the ferromagnetic order observed in the larger grits collapsing as one went to smaller grit sizes. Two sets of De Beers MDAS diamond grits of US mesh size 400-500 (d=30-38 μm) and 200-230 (d=63-75 μm) were selected for temperature- and field-dependent investigations. Transmission Moessbauer measurements were made at temperatures of 300 K and 80 K, in zero field and in an external field of 0.60 T, on the metallic inclusions in these grits. The Moessbauer spectra of the inclusions are rather complex, reflecting the contributions of several different magnetic phases. Our results show that the temperature variation of the Moessbauer spectra is not due to superparamagnetic relaxation of ferromagnetic inclusions but rather to magnetic ordering temperatures of the order of room temperature. Based on the spectral lineshapes and elemental analyses, we suggest the inclusions in the 63-75 μm grits contain iron mainly in Fe-Ni alloys with composition in the vicinity of 70 at.% Fe, and those in the 30-38 μm grits contain, in addition to Fe-Ni alloys, a phase with hyperfine parameters close to those of a Fe-Co alloy

  6. A review of Moessbauer spectroscopic studies of ancient pottery

    Moessbauer spectroscopy has proven itself to be invaluable to archaeologists by providing a means to classify pottery and to provide information on particular providences for various ancient pottery finds. The original firing atmospheres can often by deduced from the ratio of Fe2+ to Fe3+. The change in the quadrupole splitting and the magnetic hyperfine splittings allow for the determination of the original firing temperatures. Ancient pottery samples from many cultures have been studied and a number of general conclusions are possible. (Auth.)

  7. Moessbauer study of spin structure transformation from an incommensurate to a commensurate state

    We present crystallographic and magnetic properties of NiCr1.9857Fe0.02O4 by using X-ray diffractometry (XRD), vibrating sample magnetometry (VSM), and Moessbauer spectroscopy. The lattice constants a0 were determined to be 8.318 A. The ferrimagnetic Neel temperature (TN) for NiCr1.9857Fe0.02O4 is determined to be 90 K. The Moessbauer absorption spectra for all chromites at 4.2 K show two well developed sextets superposed with small difference of hyperfine fields (Hhf) caused by Cr3+ ions in two different magnetic sites. The values of the isomer shifts show that the charge states of Fe are Fe3+ for all temperature range. Ni-chromites Moessbauer spectra below TN present aline broadening due to a Jahn-Teller distortion and show that spin structure behavior of Cr ions change from an incommensurate to a commensurate state.

  8. Moessbauer Studies of Nanosize CuFe2O4 Particles

    Nanocrystalline CuFe2O4 particles are prepared by wet chemical method. The particles of various sizes are obtained by heat treatment in the temperature range 773-1073 K. The room temperature Moessbauer spectrum for all samples shows the presence of both sextet and doublet indicating the presence of superparamagnetic fractions. The isomer shift, quadrupole splitting and hyperfine field values are found to change with particle size. However, these changes in Moessbauer parameters may also be due to the Jahn-Teller effect that essentially arises due to the migration of Cu2+ from tetrahedral sites to octahedral sites resulting in crystal structure change from cubic to tetragonal system. These aspects are studied by using Moessbauer spectroscopy and are correlated to the X-ray diffraction data.

  9. Mineralogical and Moessbauer studies on the paramagnetic separate of Al-Kidirate meteorite

    Gismelseed, A.M.; Worthing, M.A.; Yousif, A.A.; Elzain, M.E.; Al-Rawas, A.D. [College of Science, Sultan Qaboos University, Box 36 Alkhoud, 123 Sultanate of Oman (Oman); Kamal, H.M. [Faculty of Education, University of Khartoum, Khartoum (Sudan)

    2004-02-01

    The paramagnetic fraction of the chondritic meteorite (Al Kidirate) has been studied by scanning electron microscopy (SEM) and Moessbauer spectroscopy at different temperatures. The mineralogical analysis indicates that the fraction consists mostly of olivine and pyroxene. The pyroxene is present in two restricted compositions; bronzitic orthopyroxene and clinopyroxene in the diopside-endiopside range. The Moessbauer measurements confirm the above characterization showing two paramagnetic doublets for olivine and pyroxene. The Moessbauer relative area under the resonance curve together with the atomic concentration derived from the microprobe data are used to derive the chemical formulae for orthopyroxene and clinopyroxene. The formulae derived using the two methods show good agreement. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Cross sections of the 57Fe(n,α)54Cr and 63Cu(n,α)60Co reactions in the MeV region

    Gledenov, Yu. M.; Sedysheva, M. V.; Stolupin, V. A.; Zhang, Guohui; Han, Jinhua; Wang, Zhimin; Fan, Xiao; Liu, Xiang; Chen, Jinxiang; Khuukhenkhuu, G.; Szalanski, P. J.

    2014-06-01

    Cross sections of the 57Fe(n,α)54Cr reaction are measured for the first time, and those of the 63Cu(n,α)60Co reaction are measured in the megaelectron volt region by the direct experimental method. Experiments were performed at the 4.5-MV Van de Graaff Accelerator of Peking University. Monoenergetic neutrons (5.0, 5.5, 6.0, and 6.5 MeV) were produced through the 2H(d,n)3He reaction with a deuterium gas target. Measurements were carried out using a double-section-gridded ionization chamber and back-to-back double 57Fe and 63Cu samples. Foreground and background were measured in separate runs. A 238U sample and a BF3 long counter were utilized for absolute neutron flux calibration and for neutron flux normalization, respectively. Present results are compared with talys-1.4 code predictions, existing measurements, and evaluations.

  11. Moessbauer and X-ray studies on the existence of a cubic stannite phase in natural ores

    In a study of natural stannite (GDR) samples (Cu2FeSnS4) of the Zinnwald deposit 57Fe Moessbauer patterns were found different from those measured by other authors for stannite samples. In addition to the usual doublet with a quadrupole splitting of 2.88 +- 0.02 mm/sec with respect to a 57Co-Pt source and a line width of 0.25 +- 0.04 mm/sec, a second doublet of lower intensity was found with a quadrupole splitting of 1.01 -+ 0.04 mm/sec, an isomer shift of -0.09 +-0.04 mm/sec and a line width of 0.46 +- 0.07 mm/sec. In the investigation a chemical analysis, Moessbauer spectrometry, X-ray diffraction and DTA were used. The measurement results indicate that the Zinnwald stannite contains a cubic modification in addition to the tetragonal phase. (Z.S.)

  12. Determination of Debye temperature from Moessbauer data

    The temperature dependence of Lamb-Moessbauer factor (W) from Moessbauer data has been fitted using numerical calculation in C-language. It is common ground, that the absorption are of the Moessbauer spectrum is proportional to recoilless fraction of Moessbauer atoms (f). In order to study the dynamical lattice properties of the solid is common to use the Debye model. This program allow us to estimate the Debye temperature (θD). In spite, the Debye model may be a poor description, particularly for complicated solids or systems with high impurity concentrations, we had perform it in some diluted sample. It is open the possibility to introduce the anharmonicity of the lattice vibrations in order to improve the model. (author). 3 refs, 4 figs

  13. Moessbauer isomer shift anomalies in a superconductor

    We have investigated the Moessbauer isomer shift in a superconductor within a simple model. Our results are in reasonable agreement with iron dopped superconductors data which has been reported in the literature. (author)

  14. Hydride bridge in [NiFe]-hydrogenase observed by nuclear resonance vibrational spectroscopy

    Ogata, Hideaki; Krämer, Tobias; Wang, Hongxin; Schilter, David; Pelmenschikov, Vladimir; van Gastel, Maurice; Neese, Frank; Rauchfuss, Thomas B.; Gee, Leland B.; Scott, Aubrey D.; Yoda, Yoshitaka; Tanaka, Yoshihito; Lubitz, Wolfgang; Cramer, Stephen P.

    2015-01-01

    The metabolism of many anaerobes relies on [NiFe]-hydrogenases, whose characterization when bound to substrates has proven non-trivial. Presented here is direct evidence for a hydride bridge in the active site of the 57Fe-labeled fully reduced Ni-R form of Desulfovibrio vulgaris Miyazaki F (DvMF) [NiFe]-hydrogenase. A unique ‘wagging’ mode involving H− motion perpendicular to the Ni(μ-H)57Fe plane was studied using 57Fe-specific nuclear resonance vibrational spectroscopy (NRVS) and density fu...

  15. Automation of the Analysis of Moessbauer Spectra

    In the present report we propose the automation of least square fitting of Moessbauer spectra, the identification of the substance, its crystal structure and the access to the references with the help of a genetic algorith, Fuzzy logic, and the artificial neural network associated with a databank of Moessbauer parameters and references. This system could be useful for specialists and non-specialists, in industry as well as in research laboratories

  16. Electrical resistivity and Moessbauer effect investigations on Tb{sub 0.27}Dy{sub 0.73}(Mn{sub 1-x}Fe{sub x}){sub 2} intermetallics

    Bodnar, W. [Faculty of Physics and Applied Computer Science, AGH, Al. Mickiewicza 30, 30-059 Krakow (Poland); Stoch, P. [Institute of Atomic Energy, 05-400 Swierk-Otwock (Poland); Faculty of Materials Science and Ceramics, AGH, Al. Mickiewicza 30, 30-059 Krakow (Poland); Chmist, J. [Faculty of Physics and Applied Computer Science, AGH, Al. Mickiewicza 30, 30-059 Krakow (Poland); Pszczola, J., E-mail: pszczola@agh.edu.p [Faculty of Physics and Applied Computer Science, AGH, Al. Mickiewicza 30, 30-059 Krakow (Poland); Zachariasz, P.; Suwalski, J. [Institute of Atomic Energy, 05-400 Swierk-Otwock (Poland)

    2010-09-03

    This paper concerns synthesis, X-ray analysis (300 K), electrical resistivity and {sup 57}Fe Moessbauer effect studies (4.2 K) of complete Tb{sub 0.27}Dy{sub 0.73}(Mn{sub 1-x}Fe{sub x}){sub 2} intermetallic series, with a borderline compound Tb{sub 0.27}Dy{sub 0.73}Fe{sub 2} known as Terfenol-D. A cubic Laves phase Fd3m of the MgCu{sub 2}-type is observed across the series. The lattice parameter decreases parabolically with x. Electrical resistivity was measured in a wide temperature region across the Tb{sub 0.27}Dy{sub 0.73}(Mn{sub 1-x}Fe{sub x}){sub 2} series and the parameters which characterize resistivity dependence on temperature, including Debye temperature, were determined. Residual, phonon and magnetic contributions were separated from electrical resistivity. The magnetic contribution to electrical resistivity was applied to estimate Curie temperatures. The Curie temperature increases significantly with x. {sup 57}Fe Moessbauer effect measurements for the Tb{sub 0.27}Dy{sub 0.73}(Mn{sub 1-x}Fe{sub x}){sub 2} intermetallic system evidence an [1 0 0] easy axis of magnetization. Mn/Fe substitution introduces a local area, at sub-nanoscale, with different Mn/Fe neighbourhoods of the tested {sup 57}Fe atoms. Hyperfine interaction parameters, an isomer shift, a magnetic hyperfine field and a quadrupole interaction parameter were determined from the spectra both for the local neighbourhood area and, as averaged values, for the sample as bulk. The average magnetic hyperfine field increases parabolically with x. The correlation between Curie temperatures and magnetic hyperfine fields is discussed.

  17. Analysis of Moessbauer Data from Mars: A Database and Artificial Neural Network for Identification of Iron-bearing Phases

    Morris, R. V.; deSouza, P. A.; Morris, R. V.; Klingelhoefer, G.

    2003-01-01

    The exploration of the planet Mars is one of the major goals within the Solar system exploration programs of the US-American space agency NASA and the European Space Agency ESA. In particular the search for water and life and understanding of the history of the surface and atmosphere will be the major tasks of the upcoming space missions to Mars. The miniaturized Moessbauer spectrometer MIMOS II has been selected for the NASA Mars-Exploration-Rover twin-mission to Mars in 2003 and the ESA 2003 Mars-Express Beagle 2 mission. Reduced in size and weight, in comparison to ordinary laboratory setup, the sensor head just weights approximately 400 g, with a volume of (50x50x90) cu mm, and holds two gamma-ray sources: the stronger for experiments and the weaker for calibrations. The collimator (in sample direction) also shields the primary radiation off the detectors. Around the drive four detectors are mounted. The detectors are made of Si-PIN-photodiodes in chip form (100 sq mm, thickness of 0.5 mm). The control unit is located in a separate electronics board. This board is responsible for the power supply, generation of the drive's velocity reference signal, read of the detector pulses to record the spectrum, data storage and communication with the host computer. After more than four decades from the discovery of the Moessbauer effect, more than 400 minerals were studied at different temperatures. Their Moessbauer parameters were reported in the literature, and have been recently collected in a data bank. Previous Mars-missions, namely Viking and Mars Pathfinder, revealed Si, Al, Fe, Mg, Ca, K, Ti, S and Cl to be the major constituents in soil and rock elemental composition of the red planet. More than 200 minerals already studied by Moessbauer spectroscopy contain significant amounts of these elements. A considerable number of Moessbauer studies were also carried out on meteorites and on Moon samples. Looking backward in the studies of the whole Moessbauer community

  18. Design of the MsAa-4 Moessbauer Spectrometer

    An entirely new Moessbauer spectrometer MsAa-4 is currently being under design and construction. New features as compared to the basic features of the previous generation MsAa-3 spectrometer could be summarized as follows. Completely digital processing of the γ-ray detector signal beyond the Gaussian shape filter/amplifier is to be implemented. The spectrometer is going to be able to accommodate external multiple detector heads. Up to 128 γ-ray spectra in 16384 channels of 32-bit each and up to 512 Moessbauer spectra in 4096 channels of 32-bit each could be collected simultaneously, provided the proper external multiple detector head is used. The count-rate per single detector is limited to about 105 counts per second in total. Improved precision of the reference function from 12-bit to 16-bit is to be provided. The reference function is stored in 8192 channels per a complete cycle. Addition of the random noise to the reference corner prism of the Michelson-Morley calibration interferometer is to be introduced to avoid spurious fringes due to the phase lock-up. An integrated universal temperature controller being able to use a variety of the temperature sensors is to be interconnected properly with the spectrometer. The spectrometer is now a stand-alone network device as it is equipped with the Ethernet connection to the outside world. Fast and high precision digital oscilloscope is to be incorporated to the spectrometer as the intrinsic unit. This oscilloscope could monitor signals at various crucial points of the internal spectrometer electronics. Modular design and use of the strict standards allows easy reconfiguration for other applications than Moessbauer spectroscopy.

  19. Gamma scattering in condensed matter with high intensity Moessbauer radiation

    We give a progress report for the work which has been carried out in the last three years with DOE support. A facility for high-intensity Moessbauer scattering is now fully operational at the University of Missouri Research Reactor (MURR) as well as a facility at Purdue, using special isotopes produced at MURR. High precision, fundamental Moessbauer effect studies have been carried out using scattering to filter the unwanted radiation. These have led to a new Fourier transform method for describing Moessbauer effect (ME) lineshape and a direct method of fitting ME data to the convolution integral. These methods allow complete correction for source resonance self absorption (SRSA) and the accurate representation of interference effects that add an asymmetric component to the ME lines. We have begun applying these techniques to attenuated ME sources whose central peak has been attenuated by stationary resonant absorbers, to more precisely determine interference parameters and line-shape behavior in the resonance asymptotic region. This analysis is important to both the fundamental ME studies and to scattering studies for which a deconvolution is essential for extracting the correct recoilless fractions and interference parameters. A number of scattering studies have been successfully carried out including a study of the thermal diffuse scattering in Si, which led to an analysis of the resolution function for gamma-ray scattering. Also studied was the anharmonic motion in Na and the satellite reflection Debye-Waller factor in TaS2, which indicate phason rather than phonon behavior. We have begun quasielastic diffusion studies in viscous liquids and current results are summarized. These advances, coupled to our improvements in MIcrofoil Conversion Electron spectroscopy lay the foundation for the proposed research outlined in this request for a three-year renewal of DOE support

  20. SURFACE ELECTRICAL PROPERTIES AND STRUCTURE OF YTTRIA-PARTIALLY-STABILIZED ZIRCONIA IMPLANTED WITH 57Fe IONS

    2000-01-01

    Sintered plates of 5mol% yttria-partially-stabilized zirconia have been implanted at room temperature with 5×1015to 2×1017 Fe+ ions/cm2 at 140 KeV.Electrical measurement,Rutherford backscattering spectroscopy(RBS),Raman spectroscopy and X-ray photoelectron spectroscopy(XPS) have been used to study the surface electrical properties and the structure of the implanted layer before and after thermal annealing treatment in N2.

  1. Moessbauer filtration of synchrotron radiation: advances and perspectives

    A short review of the conventional ways of Moessbauer filtration (obtaining highly monochromatized radiation limited only by the energy width of the Moessbauer line) is presented and some new proposals related to the Moessbauer filtration of synchrotron radiation (SR) are discussed

  2. A setup combining magneto-optical Kerr effect and conversion electron Moessbauer spectrometry for analysis of the near-surface magnetic properties of thin films

    We propose a system allowing the characterization of thin magnetic multilayer structures that combine conversion electron Moessbauer spectrometry (CEMS) under applied magnetic field with the magneto-optical Kerr effect (MOKE) technique. Measured hysteresis loops obtained from the MOKE part are used for investigation of sample surface magnetic properties. The CEMS part of such a system is suitable for studying the spatial spin distribution during magnetization reversal under applied magnetic field, whose values are established from the measured MOKE loop. The combined technique is demonstrated on the results obtained at 300 K on an exchange-coupled ferrimagnetic amorphous GdFe/TbFe bilayer, where the center of the GdFe layer is enriched in 57Fe. Both techniques confirm in-plane uniaxial anisotropy. The spin structure at the position of the probe layer is analyzed for several values of the external magnetic field applied in the hard magnetization axis direction.

  3. Fe Moessbauer effect in YxPr1-xBa2(Cu0.98Fe0.02)3O7

    57Fe Moessbauer effect and magnetic-susceptibility measurements were performed on Y0.2Pr0.8Ba2(Cu0.98Fe0.02)3O7-δ and Y0.8Pr0.2Ba2(Cu0.98Fe0.02)3O7-δ, where δ∼0. The insulating 80% Pr compound showed susceptibility anomalies and a large hyperfine field distribution at low temperatures in addition to a hyperfine field spectrum for Fe on the Cu(2) sites. The superconducting 20% Pr compound displayed none of these effects at any temperature. After examining the alternatives, it is postulated that magnetic ordering of the Pr ions and an enhanced rare-earth transition-metal interaction due to f-electron admixture is responsible for these observations

  4. Moessbauer studies on impactites from Lonar impact crater

    Verma, H. C., E-mail: hcverma@iitk.ac.in [I I T Kanpur, Department of Physics (India); Misra, S., E-mail: misrasaumitra@gmail.com [Indian Institute of Geomagnetism (India); Shyam Prasad, M., E-mail: shyam@nio.org [National Institute of Oceanography, Geological Oceanography Division (India); Bijlani, N.; Tripathi, A., E-mail: rpt2002@sify.com [J.N.V. University, Department of Physics (India); Newsom, Horton, E-mail: newsom@unm.edu [University of New Mexico, Institute of Meteoritics and Department of Earth and Planetary Sciences (United States)

    2008-09-15

    Iron mineralogy has been studied using Moessbauer spectroscopy on eight glassy impactite samples from different parts of the Lonar Crater Rim Region. Distinct changes are observed when compared to the host basaltic samples. Significant amount of Fe{sup 3+} phase is observed in the impactite samples whereas this phase is known to be almost absent in the basalt. Besides this we have a strong Fe{sup 2+} doublet showing up corresponding to the main iron-containing mineral. The Moessbauer results are very similar to those with glasses from Ries crater which is also believed to have formed by meteoritic impact but on nonbasaltic rock bed. Besides the glassy samples, we also study some spherules found in the crater region and some fine glassy particles on the surfaces of melt impact bombs. These contain a good amount of magnetically ordered phase, most likely nanosize hematite. Interestingly, part of it is strongly attracted by a magnet and part of it is not. But both parts show a significantly strong six-line component corresponding to hematite.

  5. Magnetic and Moessbauer Studies of Quaternary Argentine Loessic Soils and Paleosols

    This paper is a review of the current status about the remaining problems that are found in the investigation of the Quaternary Argentine soils and loessic sediments, and the way that Moessbauer studies can assist in solving them. There are two main types of investigations that make use of the magnetic response of the samples to correlate them with information gathered by other methods. On the one hand, there is the stratigraphic and chronological research, which is of importance from the geological and paleontological points of view. On the other hand, the paleoclimatic records, of significance toward a possible model of the past climate, are also studied because of their close relation to the sediments history. However, there is not yet a model that can tell the difference between the modifications due to the climatic conditions at the time when the soils were buried from processes that occurred after burial. Some examples are given that show that Moessbauer studies can be applied with a certain degree of success when cross-checked with magnetic measurements toward understanding the processes that occurred in alluvial B (paleosols) and C horizons (loess) from the eastern part of Buenos Aires Province. Although the application of Moessbauer studies to hydromorphic processes in soils is not straightforward, there are cases in which Moessbauer spectroscopy, if applied properly and correlated with other techniques, is able to characterize the type of iron oxides existing in the materials and thus assist theories about its origin and history.

  6. Mössbauer spectroscopy of Basal Ganglia

    Miglierini, Marcel, E-mail: marcel.miglierini@stuba.sk [Institute of Nuclear and Physical Engineering, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovičova 3, 812 19 Bratislava, Slovakia and Regional Centre of Advanced Technologies and Materials (Czech Republic); Lančok, Adriana [Institute of Inorganic Chemistry AS CR, v. v. i., 250 68 Husinec-Řež 1001 (Czech Republic); Kopáni, Martin [Institute of Medical Physics, Biophysics, Informatics and Telemedicine, Faculty of Medicine, Comenius University, Sasinkova 2, 811 08 Bratislava (Slovakia); Boča, Roman [Department of Chemistry, Faculty of Natural Sciences, University of SS. Cyril and Methodius, 917 01 Trnava (Slovakia)

    2014-10-27

    Chemical states, structural arrangement, and magnetic features of iron deposits in biological tissue of Basal Ganglia are characterized. The methods of SQUID magnetometry and electron microscopy are employed. {sup 57}Fe Mössbauer spectroscopy is used as a principal method of investigation. Though electron microscopy has unveiled robust crystals (1-3 μm in size) of iron oxides, they are not manifested in the corresponding {sup 57}Fe Mössbauer spectra. The latter were acquired at 300 K and 4.2 K and resemble ferritin-like behavior.

  7. Mössbauer spectroscopy of Basal Ganglia

    Chemical states, structural arrangement, and magnetic features of iron deposits in biological tissue of Basal Ganglia are characterized. The methods of SQUID magnetometry and electron microscopy are employed. 57Fe Mössbauer spectroscopy is used as a principal method of investigation. Though electron microscopy has unveiled robust crystals (1-3 μm in size) of iron oxides, they are not manifested in the corresponding 57Fe Mössbauer spectra. The latter were acquired at 300 K and 4.2 K and resemble ferritin-like behavior

  8. Oxidation study by Moessbauer and optic microscopy of steels from boiler tubes used in sugar industry

    Optic microscopy and Moessbauer spectroscopy were used to study the fail and the inner rusted surface of two boiler tubes used in the sugar industry, respectively. The studied tubes, of the type ASTM A 192, were found to have cracks. By optic microscopy it was observed that the failure begins in the inner surface with circumferential cracking. Also, inside and around the surface close to the cracks a rusted layer was detected. Powder from these layers was collected for Moessbauer spectroscopy analysis. By this method the presence of two or three types of Fe oxides such as wuestite, magnetite and hematite, was proved. These results permit to conclude that the failure mechanism was the thermal fatigue due to a hot work in an O2 -rich vapor atmosphere. The rusted products are stable at high temperatures

  9. Synthesis and infrared and moessbauer spectrometric study of europium(3) complexes with some derivatives of semi- and thiosemicarbazide

    Europium complexes with semi- and thiosemicarbazidediacetic acid, as well as thiosemicarbazones of glyoxylic, pyruvic and benzoyl formic acids have been investigated by the methods of infrared and the Moessbauer spectroscopy. It is established that the resonance absorption effect constitutes a value of one order and testifies to their polymeric structure

  10. Moessbauer study of mixed crystalline (Eu sub 2 O sub 3) sub x (Fe sub 2 O sub 3) sub 1 sub - sub x (x=0.45)

    Kim, J G; Kim, Y H; Kim, E C

    1998-01-01

    The crystallography and the temperature dependence of the Moessbauer parameters of mixed crystalline (Eu sub 2 O sub 3) sub x (Fe sub 2 O sub 3) sub 1 sub - sub x (x=0.45) were studied by the method of X-ray diffraction at room temperature and Moessbauer spectroscopy within the temperature range from liquid nitrogen temperature to 540 K. The X-ray diffraction pattern of the sample showed the coexistence of cubic and orthorhombic crystal phases. The Moessbauer spectrum of 540 K indicated a crystal phase which was in good agreement with the X-ray result and gave no indication, within the experimental error, of any other crystal phases. By analyzing the temperature dependence of the Moessbauer parameters by using the spin-wave theory and the Debye model, useful result were obtained for examining the changes in the physical properties in mixed crystalline system.

  11. A New Method of Moessbauer Spectra Treatment Based on the Method of Self-Organisation of Mathematical Models

    A new technique for the treatment of high noisy measurement data is proposed based on the methods of self-organisation. This technique has been used to develop two methods for data treatment: the extraction of deterministic component from high noisy data with a controlled accuracy, and the Moessbauer spectra component expansion (Lorentz functions). These two methods were applied correspondingly to the treatment of X-ray Photoelectron Spectroscopy (XPS) measurements and to the model Moessbauer spectra with a different noise level. It is shown that these methods are highly effective.

  12. Moessbauer and positron annihilation studies of structural modifications of hemoglobin in solution

    Structural modifications of human adult oxyhemoglobin in concentrated solution were studied by Moessbauer and positron life-time spectroscopies. The effects of non-sterile degradation and irradiation by γ-rays were compared by both techniques. It was found that positron annihilation parameters were sensitive to the structural modifications of hemoglobin molecules in solution and could be related with the conformational states of hemoglobin. (author)15 refs.; 3 tabs

  13. Estimation of natural radiation dose and of the age of ancient pottery by Moessbauer effect

    The effect of natural radioactive radiation on the Moessbauer Effect (ME) spectra of ancient Egyptian pottery samples of known age has been studied. An empirical relation between the intensity ratio of the non-magnetic peaks and the dose has been established. It is suggested that this relation can be used for dating of ancient potteries as a new application of the ME spectroscopy in archaeology

  14. Moessbauer study of archaeological ceramics from Valle del Alto Sinu (Colombia)

    A physico-chemical characterization of ceramic samples from the arachaeological sites of El Cabrero, El Gallo, and El Frasquillo (Valle del Alto Sinu) is presented. Extensive use of Moessbauer spectroscopy data reveals that the currently used typological classification scheme of Dolmatoff is related to the production technology of the different artifacts. In addition, a model for firing conditions for ''Rojo Sencillo'', ''Tierra Impresa'', ''Tierra Incisa'', and ''Blanco'' types of ceramics is proposed. (orig.)

  15. Theoretical study of Moessbauer hyperfine parameters of Fe bound to ammonia

    Terra, J.; Guenzburger, D.

    1995-01-01

    The first-principles Discrete Variational method was employed to study the species formed by the interaction of an Fe atom and ammonia. Total energy calculations were performed for several configurations. The hyperfine parameters isomer shift, quadrupole splitting and magnetic hyperfine were calculated for the ground state found, and compared to reported experimental values obtained by Moessbauer spectroscopy in frozen ammonia. (author). 14 refs, 1 tab.

  16. Moessbauer Studies in Chinese Archaeology: A Review

    Hsia Yuanfu; Huang Hongbo [Nanjing University, Department of Physics (China)

    2003-09-15

    The Moessbauer effect has been applied to a wide variety of objects related to Chinese archaeology. Besides ceramic artifacts, materials like porcelain, glazes, bronzes, ancient coins, ancient mineral drugs, and even fossils were studied. This article reviews these applications with particular emphasis on the study of the famous terracotta warriors and horses of the Qin Dynasty.

  17. Moessbauer analysis of Yuan dynasty Jun porcelain glaze

    The firing temperature dependence has been studied of the quadrupole splitting (QS) and isomeric shift (IS) for the structure iron in Yuan dynasty Jun porcelain glaze and simulated ancient blue Jun glaze by Moessbauer spectroscopy. The QS and IS for the two kinds of glaze were compared. Firing temperature for the former was determined to be above 1250 C deg, and coordination number for Fe2+ and Fe3+ was four. It has been found that the latter has a broad process of dehydroxylation and vitrification, which may be profitable to form the unique glaze colour of Jun porcelain. When firing temperature is above 1200 C deg, coordination number for the latter becomes 4 too

  18. Conversion electron Moessbauer study of vacuum and thermally treated vivianite

    Natural vivianite samples were studied by Moessbauer transmission and conversion electron spectroscopy. The intensities of ferrous doublets in vivianite and the widths of the resonance lines depend strongly on the origin of the samples, on their preparation history, and on exposures in vacuo as well as on thermal treatments. An additional ferrous doublet appearing in samples after vacuum treatment can be ascribed to a tetrahydrate phosphate phase appearing at the surface due to dehydration. Heating at 413 K in dry air for periods of 15-240 min causes a higher oxidation and decomposition rate at the surface region than in the bulk of vivianite. All results do not confirm the assumption published elsewhere that there is an inertness of the surface region against oxidation due to a preferential dehydration. (orig.)

  19. Moessbauer study of corrosion induced by acid rain

    Strictly speaking acid rain refers to wet precipitation of pollutants S0/sub 2/SO/sub 3/ and NO/sub x/HNO/sub 3/ which have dissolved in cloud and rain droplets to from sulphuric and nitric acids. Acid rain has seriously damaged pine and spruce forests in Canada, USA and Europe. In these areas it has caused damage to buildings, reduced fish population due to acidification of lakes and rivers, and affected health of human beings as a result of poor water quality. The corrosion products formed in a simulated acid rain environment have been identified with transmission Moessbauer spectroscopy using a /sup 57/Co source. They were found to be gamma-FeOOH, alpha-FeOOH, gamma-Fe/sub 2/O/sub 3/ and a phase with unfamiliar parameters which seems to be amorphous in nature and can be considered as an intermediate phase. (author)

  20. Moessbauer study of iron redox in West Valley glass

    High-level nuclear wastes at West Valley are high in iron which results in a target glass composition for the vitrification process that contains about 12 wt% Fe2O3. We have developed a series of high-iron glass formulations (up to 21 wt% Fe2O3) in order to accommodate all reasonable waste stream variability. An additional process control variable is the glass redox ratio, Fe2+/(Fe2++Fe3+), since this affects the resultant glass properties including durability, crystallization, glass transition temperature, and melt viscosity. In this study, a range of redox states was obtained by bubbling CO/CO2 mixtures through the melts. The redox state was determined by Moessbauer spectroscopy and correlations between redox state and CO/CO2 ratio, flow rate, and time were obtained. Analysis of the spectroscopic data provides additional information on changes in the occupation of tetrahedral and octahedral sites with redox state