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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. 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.))

  4. 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)

  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. 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.

  6. 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.

  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. 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)

  9. 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)

  10. 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.

  11. 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.

  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. 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)

  7. 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)

  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. 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

  18. 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.

  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. 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.

  3. 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...

  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. 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

  8. 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

  9. 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)

  10. 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)

  11. 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.

  12. 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.

  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

    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

  16. 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

  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. 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).

  6. 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.

  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. 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.

  10. 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

  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. 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.

  15. 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

  16. 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.

  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. 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.)

  6. 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.)

  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

    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.

  19. 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.

  20. 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)

  1. 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.)

  2. 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

  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. 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.

  13. 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

  14. 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.)

  15. 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

  16. 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.

  17. 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.)

  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. 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.)

  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. 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

  14. 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.)

  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. 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

  4. 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)

  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. 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)

  8. 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.

  9. 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...

  10. 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.