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Sample records for 57fe moessbauer spectroscopy

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

    International Nuclear Information System (INIS)

    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)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    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.)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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

  7. Low temperature 57Fe Moessbauer study of cucumber root

    International Nuclear Information System (INIS)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  9. Characterization of clays found in soils of the indian territories in Rio Grande do Sul State by using the {sup 57} Fe Moessbauer spectroscopy; Caracterizacao de argilas encontradas em solos de terras indigenas do RS com o auxilio da espectroscopia Moessbauer de {sup 57} Fe

    Energy Technology Data Exchange (ETDEWEB)

    Perez, C.A.S.; Gobbi, D.; Marcos, J.L.N. [Universidade de Passo Fundo, RS (Brazil), Inst. de Ciencias Exatas e Geociencias; Paduani, C. [Santa Catarina Univ., Florianopolis, SC (Brazil). Dept. de Fisica; Ardisson, J.D. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil)

    2004-06-01

    Clay samples collected from soils of indian territories of the middle plateau in Rio Grande do Sul were analyzed with the aim to obtain characterization data and technical parameters for their potential use as raw material for ceramic products. The mineralogical study in samples by using the X-ray diffraction technique demonstrated that the predominant clay mineral is kaolinite. Others minerals as quartz and rutile also are present in small amounts. Chemical analysis shows low percentages for oxides of Mg, Mn, K, Na, Ca, Cu and Zn (overall percentages smaller than 0.97%). The samples also were analyzed with the {sup 57} Fe Moessbauer spectroscopy. The Moessbauer spectra at room temperature confirm the presence of the mineral kaolinite. At 77 K they reveal the existence of the minerals goethite and hematite as ultrafine magnetic particles in a superparamagnetic state. The physical tests performed in the samples show that these soils are very fine material and present appropriate granulometric characteristics and plasticity, which can be taken in advantage for the production of materials for construction or production of ornamental artifacts. (author)

  10. Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    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.)

  11. Characterization of Ag-Ge-Se bulk glasses by means of Moessbauer effect on {sup 57}Fe and {sup 119}Sn atomic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Arcondo, B; Urena, M A; Garrido, J M Conde; Rocca, J A; Fontana, M, E-mail: barcond@fi.uba.a [Laboratorio de Solidos Amorfos, INTECIN, Facultad de IngenierIa, Universidad de Buenos Aires-CONICET (Argentina)

    2010-03-01

    In this work, the structure of Fe and Sn doped Ag{sub x}(Ge{sub 0.25}Se{sub 0.75}){sub 100-x} (x=0 to 25 at.%) intrinsically inhomogeneous glasses is analyzed employing {sup 119m}Sn and {sup 57}Fe Moessbauer spectroscopy, X-ray diffractometry and scanning electron microscopy. {sup 119m}Sn enters in the glass as a substitutional impurity for Ge whereas {sup 57}Fe enters as an interstitial impurity. Moessbauer spectra obtained with {sup 119m}SnO{sub 3}Ca source, from samples containing about 1% {sup 119}Sn for Ge, reveal that the local order of Ge in both amorphous phases is basically the same whereas Moessbauer spectra obtained with {sup 57}Fe(Rh) source, from samples containing about 0.5% {sup 57}Fe, evidence the differences between both phases.

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

    International Nuclear Information System (INIS)

    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.)

  13. 57Fe Moessbauer study of a deposit in an industrial cooling circuit supplied with raw river water

    International Nuclear Information System (INIS)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  16. 57Fe Moessbauer studies of Fe-Si based amorphous ferromagnetic ribbons and thin films

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    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.

  20. Instrumentation for Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. 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

    International Nuclear Information System (INIS)

    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)

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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.)

  5. {sup 151}Eu and {sup 57}Fe Moessbauer study of mechanically alloyed EuFeO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Seifu, Dereje [Department of Physics, Morgan State University, Baltimore, MD 21251 (United States)]. E-mail: dseifu@jewel.morgan.edu; Takacs, Lazlo [Department of Physics, University of Maryland at Baltimore County, Baltimore, MD 21250 (United States); Kebede, Abebe [Department of Physics, North Carolina A and T University, Greensboro, NC 27411 (United States)

    2006-07-15

    EuFeO{sub 3} was prepared by mechanical alloying starting from europium and iron oxides. After 20 h of milling the resulting compound is pure EuFeO{sub 3}. Samples were studied as a function of milling period using XRD, Moessbauer, SEM, and magnetic measurements. Moessbauer spectroscopy was used to probe both the transition metal and the rare-earth sites. Results are compared with previous works on EuFeO{sub 3} prepared by different methods.

  6. Moessbauer studies and magnetic properties of SnO{sub 2} doped with {sup 57}Fe

    Energy Technology Data Exchange (ETDEWEB)

    Sakuma, Junko [Faculty of Science, Toho University, 2-2-1, Miyama, Funabashi-city, Chiba, 274-8510 (Japan)], E-mail: 6105012s@nc.toho-u.ac.jp; Nomura, Kiyoshi [School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)], E-mail: k-nomura@t-adm.t.u-tokyo.ac.jp; Barrero, Cesar [School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Grupo de Estado Solido, Sede de Investigacion Universitaria, Universidad de Antioquia, A. A. 1226, Medellin (Colombia); Takeda, Masuo [Faculty of Science, Toho University, 2-2-1, Miyama, Funabashi-city, Chiba, 274-8510 (Japan)

    2007-10-15

    Transparent conducting SnO{sub 2} powders doped with 10% Fe content were prepared by a polymerized complex method under acidic solutions, and annealed finally at 550 deg. C, and at 600 deg. C. These samples were characterized by X-ray diffraction, magnetization, and Moessbauer spectrometry at room temperature. Rutile SnO{sub 2} phase was obtained for both samples, and the crystallite sizes were in the range of 13-14 nm. Both samples exhibit magnetization and the saturation magnetization was smaller for the sample annealed at 600 deg. C than for sample annealed at 550 deg. C. Room temperature Moessbauer spectra for both samples showed the presence of two different paramagnetic iron sites but no magnetic sextets. These results suggest that ferromagnetism originates from magnetic defects and not directly from iron ions.

  7. Moessbauer Spectroscopy in Materials Science

    International Nuclear Information System (INIS)

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

    International Nuclear Information System (INIS)

    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.)

  9. 57Fe Moessbauer investigation of oriented single-crystal and polycrystalline PbFe12O19

    International Nuclear Information System (INIS)

    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

  10. On the interpretation of {sup 57}Fe Moessbauer spectra from CdTe thin films with substitutions of Fe, In, and Sb

    Energy Technology Data Exchange (ETDEWEB)

    Yee-Madeira, H. [Centro de Investigacion y de Estudios Avanzados, IPN, Mexico City (Mexico). Dept. de Fisica]|[Depto. de Fisica, Esc. Sup. de Fisica y Matematicas (ESFM) del IPN, Edif. 9, U. P. ALM, 07738, Mexico D.F. (Mexico); Reguera, E.; Zelaya-Angel, O.; Sanchez-Sinencio, F. [Centro de Investigacion y de Estudios Avanzados, IPN, Mexico City (Mexico). Dept. de Fisica; Montiel-Sanchez, H. [Depto. de Fisica, Esc. Sup. de Fisica y Matematicas (ESFM) del IPN, Edif. 9, U. P. ALM, 07738, Mexico D.F. (Mexico); Scorzelli, R.B. [Centro Brasileiro de Pesquisas Fisicas, Rua Xavier Sigaud 150, CEP 22290, Urca, Rio de Janeiro (Brazil)

    1999-02-26

    {sup 57}Fe Moessbauer spectra of well characterized CdTe thin films with substitutions of Fe, In and Sb were recorded and interpreted according to the changes in the ionic radii and electronic properties of these substitutions relative to Cd in the CdTe framework. The literature reports of certain correlations among the iron valence, Fe{sup 2+} or Fe{sup 3+}, and the crystallinity of the films are critically discussed and an explanation of their origin is provided. The Moessbauer results also allow direct understanding of the effect of In and Sb substitutions on the properties of the films. (orig.) 22 refs.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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 + }.

  13. Moessbauer Spectroscopy of Locally Inhomogeneous Systems

    International Nuclear Information System (INIS)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.)

  15. Application of {sup 57}Co emission Moessbauer spectroscopy to studying biocomplexes in frozen solutions

    Energy Technology Data Exchange (ETDEWEB)

    Kamnev, A. A., E-mail: aakamnev@ibppm.sgu.ru [Laboratory of Biochemistry of Plant-Bacterial Symbioses, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences (Russian Federation); Kulikov, L. A.; Perfiliev, Yu. D. [M.V. Lomonosov Moscow State University, Laboratory of Nuclear Chemistry Techniques, Department of Radiochemistry, Faculty of Chemistry (Russian Federation); Antonyuk, L. P. [Laboratory of Biochemistry of Plant-Bacterial Symbioses, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences (Russian Federation); Kuzmann, E.; Vertes, A. [Eoetvoes Lorand University, Research Group for Nuclear Techniques in Structural Chemistry, Hungarian Academy of Sciences, Department of Nuclear Chemistry (Hungary)

    2005-09-15

    Emission Moessbauer spectroscopy with the {sup 57}Co isotope was used to study very dilute rapidly frozen aqueous solutions of cobalt(II) complexes with low-molecular-weight biomolecules (aromatic amino acids - anthranilic acid and L-tryptophan) and within a sophisticated biopolymer, bacterial glutamine synthetase, a key enzyme of nitrogen metabolism. The appearance of after-effects of the {sup 57}Co{sup {yields}57}Fe nuclear transformation as well as the coordination properties of the cation and the ligands in the complexes are discussed on the basis of their Moessbauer parameters.

  16. Processes in Geophysics Studied by Moessbauer Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. High-Pressure 57Fe Mössbauer Spectroscopy of LaFeAsO

    Science.gov (United States)

    Kawakami, Takateru; Kamatani, Takanori; Okada, Hironari; Takahashi, Hiroki; Nasu, Saburo; Kamihara, Yoichi; Hirano, Masahiro; Hosono, Hideo

    2009-12-01

    The electronic properties of an oxypnictide, LaFeAsO, pressurized in a diamond-anvil cell, were investigated by 57Fe Mössbauer spectroscopy and electrical resistance measurements at pressures up to 24 and 35 GPa, respectively. The Néel temperature gradually decreased from ˜140 K at 0.1 MPa to ˜50 K at 20 GPa, and fell below 8 K or disappeared at 24 GPa. The hyperfine field at 8 K decreased from 5.3 T at 0.1 MPa to 2.2 T at 20 GPa. On the other hand, the onset of superconductivity occurred at ˜9 K at 2 GPa. The superconductivity peaked at ˜21 K at 12 GPa, and then began a perceptible decline, disappearing at ˜35 GPa. This suggests that suppression of antiferromagnetic order plays an important role in the emergence of pressure-induced superconductivity.

  18. Applications of Moessbauer spectroscopy in cement studies

    International Nuclear Information System (INIS)

    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)

  19. Spherical electrostatic electron spectrometer for Moessbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. Moessbauer spectroscopy study of a natural zeolite

    International Nuclear Information System (INIS)

    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)

  1. Metallosupramolecular coordination polyelectrolytes investigated by Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    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.

  2. Moessbauer spectroscopy - applications of the Doppler principle

    International Nuclear Information System (INIS)

    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

  3. Moessbauer spectroscopy in neptunium compounds

    Energy Technology Data Exchange (ETDEWEB)

    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.)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. Moessbauer spectroscopy of laminar metallic systems

    International Nuclear Information System (INIS)

    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

  6. Moessbauer spectroscopy of Fe-based nanomaterials

    International Nuclear Information System (INIS)

    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.

  7. Magnetic anisotropy in FeSb studied by 57Fe Mössbauer spectroscopy

    Science.gov (United States)

    Komędera, K.; Jasek, A. K.; Błachowski, A.; Ruebenbauer, K.; Krztoń-Maziopa, A.

    2016-02-01

    The Fe1+xSb compound has been synthesized close to stoichiometry with x=0.023(8). The compound was investigated by 57Fe Mössbauer spectroscopy in the temperature range 4.2-300 K. The antiferromagnetic ordering temperature was found as 232 K i.e. much higher than for the less stoichiometric material. Regular iron was found to occupy two different positions in proportion 2:1. They differ by the electric quadrupole coupling constants and both of them exhibit extremely anisotropic electric field gradient tensor (EFG) with the asymmetry parameter η ≈ 1 . The negative component of both EFGs is aligned with the c-axis of the hexagonal unit cell, while the positive component is aligned with the direction. Hence, a model describing deviation from the NiAs P63/mmc symmetry group within Fe-planes has been proposed. Spectra in the magnetically ordered state could be explained by introduction of the incommensurate spin spirals propagating through the iron atoms in the direction of the c-axis with a complex pattern of the hyperfine magnetic fields distributed within a-b plane. Hyperfine magnetic field pattern of spirals due to major regular iron is smoothed by the spin polarized itinerant electrons, while the minor regular iron exhibits hyperfine field pattern characteristic of the highly covalent bonds to the adjacent antimony atoms. The excess interstitial iron orders magnetically at the same temperature as the regular iron, and magnetic moments of these atoms are likely to form two-dimensional spin glass with moments lying in the a-b plane. The upturn of the hyperfine field for minor regular iron and interstitial iron is observed below 80 K. Magneto-elastic effects are smaller than for FeAs, however the recoilless fraction increases significantly upon transition to the magnetically ordered state.

  8. Moessbauer spectroscopy of locally inhomogeneous systems

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    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.

  11. Moessbauer spectroscopy as a tool in astrobiology

    International Nuclear Information System (INIS)

    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.

  12. Moessbauer spectroscopy as a tool in astrobiology

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Christian, E-mail: schroedc@uni-mainz.de; Klingelhoefer, Goestar, E-mail: klingel@mail.uni-mainz.de [Johannes Gutenberg-Universitaet, Institut fuer Anorganische Chemie und Analytische Chemie (Germany); Bailey, Brad E., E-mail: bebailey@ucsd.edu; Staudigel, Hubert, E-mail: hstaudigel@ucsd.edu [University of California San Diego, Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography (United States)

    2005-11-15

    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.

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

    International Nuclear Information System (INIS)

    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.

  14. 57Fe Mössbauer spectroscopy and magnetic study of Al13Fe4

    International Nuclear Information System (INIS)

    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

  15. Indirect two-dimensional heteronuclear NMR spectroscopy. (/sup 31/P, /sup 57/Fe) spectra of organoiron complexes

    Energy Technology Data Exchange (ETDEWEB)

    Benn, R.; Brenneke, H.; Frings, A.; Lehmkuhl, H.; Mehler, G.; Rufinska, A.; Wildt, T.

    1988-08-17

    The indirect heteronuclear two-dimensional (2D) triple-resonance (S,I)-(/sup 1/H) NMR spectroscopy is introduced for measuring the chemical shift and scalar spin-spin coupling constants of an insensitive nucleus I via its scalar coupling J(S,I) by detection of the nucleus S of higher sensitivity. The versatility of this approach is demonstrated by extracting delta(/sup 57/Fe) and J(Fe,X) from (/sup 31/P,/sup 57/Fe)-(/sup 1/H) spectra of various dissolved ((/eta//sup 5/-Cp)(L/sub 2/(R)))Fe, ((/eta//sup 3/-allyl)(/eta//sup 5/-Cp)(L))Fe, and ((/eta//sup 1/,/eta//sup 2/-alkenyl)(/eta//sup 5/-Cp)(L))Fe complexes (R = alkyl, hydride; L = PR/sub 3/). In practice the sensitivity of 2D (/sup 31/P,/sup 57/Fe) spectra was found to be higher than that of the direct observation scheme by at least a factor (..gamma../sub P//..gamma../sub Fe/)/sup 5/2/. Due to the intrinsically higher resolving power of a two-dimensional experiment, small scalar couplings like /sup 2J/(Fe,F) and /sup 1/J(Fe,H) were readily obtained from indirect two-dimensional spectra. Combinations of (/sup 1/H,/sup 57/Fe) and (/sup 31/P,/sup 57/Fe) spectra yielded the relative signs of the J(Fe,X) couplings: /sup 1/J(Fe,P) is positive and increases with increasing ..pi..-acceptor power of the phosphorus ligand L from 55 (L = PMe/sub 3/, R = H) to 149 Hz (L = PF/sub 3/). /sup 1/J(Fe,H) is around +9 Hz (R = H), whereas /sup 2/J(P,H) in these complexes was found to be negative. In all of the allyl complexes investigated, /sup 2J/(Fe,F) (L = PF/sub 3/) is positive and around 3 Hz. In the quasi-tetragonal and -trigonal iron complexes, delta(/sup 57/Fe) varies by about 4000 ppM. This can be rationalized qualitatively by the electronegativity of the atoms directly bonded to iron and the higher oxidation potential in the presence of more basic ligands L via the paramagnetic shielding term. 52 references, 5 figures, 5 tables.

  16. Implementation of the Electron conversion Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    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

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.)

  19. 197Au Moessbauer study of gold ores, mattes, roaster products, and gold minerals

    International Nuclear Information System (INIS)

    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.)

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

    International Nuclear Information System (INIS)

    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)

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

    International Nuclear Information System (INIS)

    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)

  2. Thermal History of São João Nepomuceno (IVA) Iron Meteorite Inferred from Ganguly's Cooling Rate Model and 57Fe Mössbauer Spectroscopy Data

    Science.gov (United States)

    dos Santos, E.; Scorzelli, R. B.; Varela, M. E.

    2016-08-01

    The intracrystalline Fe-Mg distribution in orthopyroxenes, as measured by means of 57Fe Mössbauer spectroscopy and associated to Ganguly’s cooling rate numerical method, are used to infer the thermal history of São João Nepomuceno (IVA) meteorite.

  3. Chemical aspects of 237 Np Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    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. 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}

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. Characterization of magnetic nano-fluids via Moessbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Filoti, G., E-mail: filoti@infim.ro; Kuncser, V.; Schinteie, G.; Palade, P. [National Institute of Materials Physics (Romania); Morjan, I.; Alexandrescu, Rodica [National Institute for Lasers, Plasma and Radiation Physics (Romania); Bica, Doina; Vekas, L. [Romanian Academy-Timisoara Division, Centre of Fundamental and Advanced Technical Research (Romania)

    2009-06-15

    The laser pyrolysis became a useful tool, providing various ways, in production of nano materials. The iron Moessbauer spectroscopy is one very accurate method in evidencing the physical properties and related processes in the nano scale compounds. The effect of pressure, laser spot area and induced combustion, of gas mixture and laser power on the phase composition and inside particle distribution, grain size as well as the related phenomena were investigated by temperature dependent Moessbauer spectroscopy. A selection of most relevant properties is presented and discussed in details.

  6. Anelastic Relaxation Mechanisms Characterization by Moessbauer Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    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

  7. Emission Moessbauer spectroscopy of NiTi shape memory alloy

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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)

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  12. Application of Moessbauer spectroscopy in investigating Egyptian archaeology

    International Nuclear Information System (INIS)

    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.)

  13. Moessbauer Spectroscopy of Martian and Sverrefjell Carbonates

    Science.gov (United States)

    Agresti, David G.; Morris, Richard V.

    2011-01-01

    Mars, in its putative "warmer, wetter: early history, could have had a CO2 atmosphere much denser than its current value of CO2 has gone has long been debated. Now, several instruments on Mars Exploration Rover (MER) Spirit, including its Moessbauer spectrometer MIMOS II, have identified Mg-Fe carbonate in rock outcrops at Comanche Spur in the Columbia Hills of Gusev Crater. With this finding, carbonate cements in volcanic breccia collected on Sverrefjell Volcano on Spitzbergen Island in the Svalbard Archipelago (Norway) during the AMASE project are mineralogical and possible process analogues of the newly discovered martian carbonate. We report further analyses of Mossbauer spectra from Comanche Spur and discuss their relationship to Mossbauer data acquired on Sverrefjell carbonates. The spectra were velocity calibrated with MERView and fit using MERFit. Instead of the "average temperature" Comanche spectrum (data from all temperature windows summed), we refit the Comanche data for QS within each temperature window, modeling as doublets for Fe2+(carbonate), Fe2+(olivine), and Fe3+(npOx). The temperature dependences of QS for the Comanche carbonate and for a low-Ca carbonate from Chocolate Pots in Yellowstone National Park (YNP) are shown; they are the same within error. For Comanche carbonate summed over 210-270 K, (CS, QS) = (1.23, 1.95) mm/s. The value of QS for Sverrefjell carbonate at 295 K, (CS, QS) = (1.25, 1.87) mm/s, is also plotted, and the plot shows that the QS for the Sverrefjell carbonate agrees within error with the Comanche data extrapolated to 295 K. This agreement is additional evidence that the Sverrefjell carbonates are Mossbauer analogues for the Comanche carbonates, and that both carbonates might have precipitated from solutions that became carbonate rich by passing through buried carbonate deposits.

  14. Structural properties of sputter-deposited iron-garnets from Moessbauer-spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Schultes, N.; Schieder, H.; Litterst, F.J.; Kalvius, G.M. (Technische Univ. Muenchen, Garching (Germany, F.R.). Fakultaet Physik)

    1982-08-01

    Samples of non-crystalline iron garnets (RIG, R = Sm, Gd, Tm, Eu, Dy) and of stoichiometric mixtures of non-crystalline R/sub 2/O/sub 3/ and non-crystalline Fe/sub 2/O/sub 3/ have been prepared by dc-sputtering (Ar, 10 kV, 2 10/sup -4/ Torr Ar/sup +/), using polycrystalline material as targets and a mylar foil as substrate (77 K). The samples were studied by Moessbauer spectroscopy between 4.2 K and 300 K. In the paramagnetic state (above T approx. equal to 60 K) the /sup 57/Fe hyperfine (hf) spectra can be interpreted by a superposition of three quadrupole patterns, reflecting different iron sites. These are assigned to Fe/sup 2 +/ and tetrahedrally and octahedrally coordinated Fe/sup 3 +/. The quadrupole interactions reveal Gaussian distributions (sigma approx. equal to 0.2). The appearance of divalent iron is discussed in view of possible oxygen deficiency and the presence of tetravalent impurity cations.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    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)

  2. Characterization of Argentine Loess and Paleosols by Moessbauer Spectroscopy

    International Nuclear Information System (INIS)

    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

  3. Characterization of oxide catalysts by in situ Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    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)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    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)

  6. 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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  7. 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

    Energy Technology Data Exchange (ETDEWEB)

    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)

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

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    Institute of Scientific and Technical Information of China (English)

    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.

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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).

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

    International Nuclear Information System (INIS)

    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)

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

    International Nuclear Information System (INIS)

    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)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  15. Application of Moessbauer spectroscopy to study archaeological Egyptian pottery

    International Nuclear Information System (INIS)

    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

    International Nuclear Information System (INIS)

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

    Indian Academy of Sciences (India)

    U D Lanke; J Prabhjyot Pal

    2000-02-01

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

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

    International Nuclear Information System (INIS)

    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

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

    OpenAIRE

    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...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    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)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    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.

  5. Moessbauer study of C18N/Fe Langmuir-Blodgett layers

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmann, Erno [Institute of Chemistry, Eoetvoes Lorand University (Hungary); Telegdi, Judit [Institute of Nanochemistry and Catalysis, Chemical Research Center, HAS (Hungary); Nemeth, Zoltan, E-mail: hentes@chem.elte.hu; Vertes, Attila [Institute of Chemistry, Eoetvoes Lorand University (Hungary); Nyikos, Lajos [Institute of Nanochemistry and Catalysis, Chemical Research Center, HAS (Hungary)

    2012-03-15

    Langmuir-Blodgett (LB) films of octadecanoyl hydroxamic acid (C18N) complexed with Fe{sup 3 + } ions have been prepared at various subphase pH values. The LB films consisting of different number of layers were investigated by {sup 57}Fe conversion electron Moessbauer spectroscopy (CEM) at room temperature. The CEM detector contained a piece of {alpha}-iron, enriched with {sup 57}Fe, using as an internal standard. The Moessbauer pattern of the C18N/Fe LB films is a doublet with parameters {delta} = 0.35 mm/s and {Delta} = 0.74 mm/s. A gradual increase of the relative occurrence of the doublet compared to the sextet of the internal standard was observed with the increasing number of layers, indicating the nearly uniform distribution of Fe among the LB layers.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. 119Sn Moessbauer spectroscopy of tin containing float glass

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    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.

  13. 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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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.)

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

    International Nuclear Information System (INIS)

    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.

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

    International Nuclear Information System (INIS)

    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

  20. Fe-doped ZnO nanoparticles: the oxidation number and local charge on iron, studied by 57Fe Mößbauer spectroscopy and DFT calculations.

    Science.gov (United States)

    Xiao, Jianping; Kuc, Agnieszka; Pokhrel, Suman; Mädler, Lutz; Pöttgen, Rainer; Winter, Florian; Frauenheim, Thomas; Heine, Thomas

    2013-03-01

    Iron bru: Fe-doped ZnO may contain Fe(2+) and Fe(3+) species. Whilst Mößbauer spectroscopy can distinguish these sites in pure oxides FeO and Fe(2)O(3), it gives very similar shifts for Fe-doped phases. This result is rationalized by electron redistribution from the dopant site to the crystal matrix. Mößbauer shifts correlate with the local charge on the Fe sites and different dopant sites can be identified by the Mößbauer quadrupole splitting (see figure). PMID:23400908

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

    International Nuclear Information System (INIS)

    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.)

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

    International Nuclear Information System (INIS)

    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)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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

    International Nuclear Information System (INIS)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    International Nuclear Information System (INIS)

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

  10. 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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Moessbauer effect technique in mineral science

    International Nuclear Information System (INIS)

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

  12. Effect of titanium ion substitution in the barium hexaferrite studied by Moessbauer spectroscopy and X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Quiroz, Pamela, E-mail: pamela.quiroz-penaranda@tu-ilmenau.de; Halbedel, Bernd [Ilmenau University of Technology, Department of Inorganic-Nonmetallic Materials, Institute of Materials Engineering (Germany); Bustamante, Angel, E-mail: angelbd1@gmail.com [San Marcos National University, Laboratory of Ceramics and Nanomaterials, Faculty of Physical Sciences (Peru); Gonzalez, Juan C. [Materials Science Institute of Sevilla - CSIC, Surfaces Research Group-Interfaces and Thin Films (Spain)

    2011-11-15

    A series of M-type barium hexaferrite has been synthesized in a glass melt by partially substituting the Fe{sub 2}O{sub 3} with TiO{sub 2} for investigation of their structure. The glass melt has the basic composition (mol%): 40 BaO + 33 B{sub 2}O{sub 3} + (27-x) Fe{sub 2}O{sub 3} + x TiO{sub 2} with x = 0, 3.6, 5.4 and 7.2 mol% TiO{sub 2}. The substituted ferrites were studied by means of X-ray diffraction, Moessbauer spectroscopy and vibration sample magnetometer. X-ray diffraction studies revealed that not all samples have a single ferritic phase, a small second phase corresponding to BaTi{sub 6}O{sub 13} was also observed to form. The Moessbauer spectra changed from magnetically ordered (x = 0) to magnetically ordered with strong line broadening. Moreover, the broadening increases with TiO{sub 2} content. The Moessbauer parameters suggested that Ti{sup 4 + } occupies the 2a and 12k crystal sites, and the Ti{sup 4 + } substitution on the 2b and 4f{sub 2} site also occurs at high melt dopings. Therefore, coercivity and saturation magnetization decreased.

  13. Moessbauer Spectroscopy for Lunar Resource Assessment: Measurement of Mineralogy and Soil Maturity

    Science.gov (United States)

    Morris, R. V.; Agresti, D. G.; Shelfer, T. D.; Pimperl, M. M.; Shen, M.-H.; Gibson, M. A.; Wills, E. L.

    1992-01-01

    First-order assessment of lunar soil as a resource includes measurement of its mineralogy and maturity. Soils in which the mineral ilmenite is present in high concentrations are desirable feedstock for the production of oxygen at a lunar base. The maturity of lunar soils is a measure of their relative residence time in the upper 1 mm of the lunar surface. Increasing maturity implies increasing load of solar wind species (e.g., N, H, and He-3), decreasing mean grain size, and increasing glass content. All these physicochemical properties that vary in a regular way with maturity are important parameters for assessing lunar soil as a resource. For example, He-3 can be extracted and potentially used for nuclear fusion. A commonly used index for lunar soil maturity is I(sub s)/FeO, which is the concentration of fine-grained metal determined by ferromagnetic resonance (I(sub s)) normalized to the total iron content (as FeO). I(sub s)/FeO has been measured for virtually every soil returned by the Apollo and Luna missions to the Moon. Because the technique is sensitive to both oxidation state and mineralogy, iron Moessbauer spectroscopy (FeMS) is a viable technique for in situ lunar resource assessment. Its utility for mineralogy is apparent from examination of published FeMS data for lunar samples. From the data published, it can be inferred that FeMS data can also be used to determine soil maturity. The use of FeMS to determine mineralogy and maturity and progress on development of a FeMS instrument for lunar surface use are discussed.

  14. Thermodynamic behavior of 57Fe implanted into ZrO2(Y) by CEMS and slow positron beam

    Institute of Scientific and Technical Information of China (English)

    张桂林; WengHui-Min; 等

    1996-01-01

    Using conversion electron Moessbauer spectroscopy(CEMS) and slow positron beam,the chemical state of 57Fe(100keV,3×1016cm-2)implanted into ZrO2 containing 0.03 mole fraction Y2O3(ZY3)and its thermodynamic behavior during annealing process at 200-500℃ are studied.For as-implanted sampled,Fe chemical states of Fe0,Fe2+ and Fe3+ are observed,and assigned to the superparamagnetic metallic iron cluster,iron dimer(and trimer)and complex of the Fe3+ associated with cation vacancy(V) and oxygen,respectively.After annealing at 400℃ the complexes of Fe3+-V are mostly dissolved,and the prior phase to αFe and α-Fe nano-crystalline cluster are present in the sample .Meanwhile the mixed conducting of oxygen-ions and electrons in the ZY3 sample containing Fe appears,it maty correlate with the different iron charge states and their relative amounts,in particular with the α-Fe nano-granule.

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  17. 2D-correlation analysis applied to in situ and operando Moessbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-02-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-07-01

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

  2. Crystal structure, magnetic properties, and 57Fe Mössbauer spectroscopy of the two-dimensional coordination polymers [M(1,2-bis(1,2,4-triazol-4-yl)ethane)2(NCS)2] (MII = Fe, Co).

    Science.gov (United States)

    Garcia, Yann; Bravic, Georges; Gieck, Christine; Chasseau, Daniel; Tremel, Wolfgang; Gütlich, Philipp

    2005-12-26

    New coordination polymers of the formula [M(btre)(2)(NCS)(2)] (btre = 1,2-bis(1,2,4-triazol-4-yl)ethane; M(II) = Fe, Co) have been synthesized, and their crystal structures have been determined at 293 K by X-ray analysis. The Fe(II) compound (C(7)H(8)FeN(7)S(2)) crystallizes in the monoclinic space group P2(1)/n, a = 12.439(5) A, b = 8.941(2) A, c = 9.321(3) A, beta = 90.88(2) degrees , V = 1036.6(6) A(3), Z = 2, 3791 reflections [I > 3sigma(I)], R(F) = 0.036, wR2 = 0.123. The Co(II) compound is isostructural to the Fe(II) compound. The crystal structure consists of a 2D sheet in which the metal ions are linked by bis monodentate (N1, N1') 1,2,4-triazole ligands. The structure is stabilized by pi-bond interactions between two adjacent sheets and by S...S interactions. Temperature-dependent SQUID, (57)Fe Mössbauer, and X-ray diffraction measurements indicate that [Fe(btre)(2)(NCS)(2)] retains a HS ground state upon cooling from 293 K down to 8 K. The surprising absence of spin-crossover behavior for this Fe(II)-1,2,4-triazole polymeric coordination compound that has been confirmed by pressure experiments up to approximately 12 kbar and by light irradiation experiments at 10 K is discussed on the basis of its structural features. Insight into the origin of the cooperative effects of the spin transition in [Fe(btr)(2)(NCS)(2)].H(2)O (btr = 4,4'-bis-1,2,4-triazole) is also given thanks to a re-evaluation of its distortion parameters in the high- and low-spin states. PMID:16363841

  3. Iron implantation in gadolinium gallium garnet studied by conversion-electron Moessbauer spectroscopy

    CERN Document Server

    Szucs, I; Fetzer, C; Langouche, G

    1998-01-01

    Gadolinium gallium garnet single crystals were implanted with doses of sup 5 sup 7 Fe ions in the range 8x10 sup 1 sup 5 - 6x10 sup 1 sup 6 atoms cm sup - sup 2. Depending on the dose, iron with Fe sup 2 sup + or Fe sup 3 sup + charge states was found to have formed after the implantation. After a subsequent annealing in air, the iron oxidized to Fe sup 3 sup +. The Moessbauer and channelling measurements showed lattice recrystallization taking place at 600 deg. C. After recrystallization, the iron was found to have substituted for gallium ions both at the octahedral and at the tetrahedral positions. The relative concentration of the two types of iron at the two sites shifted towards the equilibrium distribution upon high-temperature annealing. (author)

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

    International Nuclear Information System (INIS)

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

  5. Spin dynamics in {sup 57}Fe-doped TiO{sub 2} anatase nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Grecu, Maria Nicoleta; Constantinescu, Serban; Tarabasanu-Mihaila, Doina; Ghica, Daniela; Bibicu, Ion [National Institute of Materials Physics Bucharest-Magurele, Atomistilor Str. 105 bis, 077125 Magurele-Ilfov (Romania)

    2011-12-15

    In this paper we present electron paramagnetic resonance (EPR) and Moessbauer (transmission method, TMS and measurements in the scattering method, CEMS) experiments on {sup 57}Fe (0.1-1 at.%) doped nanocrystalline anatase-type TiO{sub 2}, synthesized by a hydrothermal method. Different Fe{sup 3+} and Fe{sup 2+} ions positions, with various hyperfine interactions evidenced in Moessbauer spectra (MS), confirm a partial magnetic ordering at room temperature. The magnetic hyperfine fields in the TMS spectra, better resolved at lower temperatures, do not change essentially with temperature. The first CEMS measurements, carried out on iron-doped TiO{sub 2} nanoparticles, reveal a larger disorder in the surface particles layer. The temperature dependence of the double integral EPR spectral intensity, proportional with the sample susceptibility, shows an anomalous behaviour. It suggests the bound magnetic polaron (BMP) mechanism for the magnetic ordering. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-05-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-03-15

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

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

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

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

    2003-01-01

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

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

    International Nuclear Information System (INIS)

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

  12. Structural and Electronic Properties Study of Colombian Aurifer Soils by Moessbauer Spectroscopy and X-ray Diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Bustos Rodriguez, H., E-mail: hbustos@ut.edu.co; Rojas Martinez, Y.; Oyola Lozano, D. [Universidad del Tolima, Departamento de Fisica (Colombia); Perez Alcazar, G. A.; Fajardo, M. [Universidad del Valle, Departamento de Fisica (Colombia); Mojica, J. [Ingeominas Valle, Departamento de Geologia (Colombia); Molano, Y. J. C. [Universidad Nacional, Departamento de Geologia (Colombia)

    2005-02-15

    In this work a study on gold mineral samples is reported, using optical microscopy, X-ray diffraction (XRD) and Moessbauer spectroscopy (MS). The auriferous samples are from the El Diamante mine, located in Guachavez-Narino (Colombia) and were prepared by means of polished thin sections. The petrography analysis registered the presence, in different percentages that depend on the sample, of pyrite, quartz, arsenopyirite, sphalerite, chalcopyrite and galena. The XRD analysis confirmed these findings through the calculated cell parameters. One typical Rietveld analysis showed the following weight percent of phases: 85.0% quartz, 14.5% pyrite and 0.5% sphalerite. In this sample, MS demonstrated the presence of two types of pyrite whose hyperfine parameters are {delta}{sub 1} = 0.280 {+-} 0.002 mm/s and {Delta}{sub 1} = 0.642 {+-} 0.002 mm/s, {delta}{sub 2} = 0.379 {+-} 0.002 mm/s and {Delta}{sub 2} = 0.613 {+-} 0.002 mm/s.

  13. 121Sb Moessbauer spectroscopy of antimony (V) chloro fluorides SbClsub(5-x)Fsub(x)

    International Nuclear Information System (INIS)

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

  14. Fe^2^+-Mg Order-Disorder Processes in Orthopyroxenes from São João Nepomuceno (IVA) Iron Meteorite: ^57Fe Mössbauer Spectroscopy and Single-Crystal X-Ray Diffraction Studies

    Science.gov (United States)

    Dos Santos, E.; Scorzelli, R. B.; Abdu, Y. A.; Varela, M. E.; Munayco, P.

    2013-09-01

    Here we study cation distribution in orthopyroxenes from São João Nepomuceno meteorite by Mössbauer spectroscopy, electron microprobe and single-crystal X-ray diffraction, in order to get insights into the thermal history of this meteorite.

  15. Moessbauer effect study of ancient Egyptian pottery

    International Nuclear Information System (INIS)

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

  16. Moessbauer spectroscopic analysis of ancient Egyptian pottery

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2016-02-01

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

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

    Directory of Open Access Journals (Sweden)

    S. Manjura Hoque

    2016-02-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-03-01

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

  20. Syntheses, Structure, Magnetic Properties and 57Fe Mossbauer Spectroscopies of Two Iron(Ⅱ) Complexes: Room-temperature Spin Crossover Behavior Observed in [Fe(dpq)(MePy)2(NCS)2

    Institute of Scientific and Technical Information of China (English)

    TAO, Jianqing; GU, Yunlan; ZHOU, Xinhui; GU, Zhiguo; ZUO, Jinglin; YOU, Xiaozeng

    2009-01-01

    Two new complexes [Fe(dpq)(MePy)2(NCS)2] (1) and [Fe(Medpq)(MePy)2(NCS)2] (2) (dpq=2-dipyrido[3,2-f: 2',3'-h]quinoxaline, Medpq=2-methyidipyrido[3,2-f.2',3'-h]quinoxaline, MePy=4-methylpyridine) have been syn- thesized. The crystal structure of 2 was characterized by X-ray diffraction at room temperature. It crystallizes in or- thorhombic space group I212121, with a =15.057(3)A, b =14.569(3)A, c=13.180(3) A,α=90.00°,β= 90.00°,γ= 90.00°, and V=2891.2(11)A3. The distorted [FEN6] octahedron in 2 is formed by six nitrogen atoms from Medpq, two trans-MePy molecules and two cis-NCS- anions. Variable-temperature magnetic susceptibilities and Moss- bauer spectroscopies of 1 and 2 reveal the occurrence of a gradual spin transition. The transition for I spans the 200 -450 K temperature range with a T1/2 of 340 K, while for 2, the transition in low temperature is incomplete.

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

    International Nuclear Information System (INIS)

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

  2. Hyperfine interactions by Moessbauer effect

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2012-12-01

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

  4. 57Fe hyperfine interaction parameters and selected magnetic properties of high purity MFe12O19 (M = Sr, Ba)

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Flores Ll, H.J

    1990-08-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Bustamante, A., E-mail: abustamanted@unmsm.edu.pe [Universidad Nacional Mayor de San Marcos, Laboratorio de Ceramicos y Nanomateriales, Facultad de Ciencias Fisicas (Peru); Lovera, D. [Universidad Nacional Mayor de San Marcos, Facultad de Ingenieria Geologica, Minera, Metalurgica y Geografica (Peru); Quille, R. [Universidad Nacional Mayor de San Marcos, Laboratorio de Ceramicos y Nanomateriales, Facultad de Ciencias Fisicas (Peru); Arias, A. V.; Quinones, J. [Universidad Nacional Mayor de San Marcos, Facultad de Ingenieria Geologica, Minera, Metalurgica y Geografica (Peru)

    2010-01-15

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

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

    Science.gov (United States)

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

    1972-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-06-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-11-15

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

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

    International Nuclear Information System (INIS)

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

  11. DFT study of the hyperfine parameters and magnetic properties of ZnO doped with 57Fe

    Science.gov (United States)

    Abreu, Y.; Cruz, C. M.; Piñera, I.; Leyva, A.; Cabal, A. E.; Van Espen, P.

    2014-05-01

    Magnetic state of 57Fe implanted and doped ZnO samples have been reported and studied by Mössbauer spectroscopy at different temperatures. The Mössbauer spectra mainly showed four doublets and three sextets, but some ambiguous identification remains regarding the probe site location and influence of defects in the hyperfine and magnetic parameters. In the present work some possible implantation configurations are suggested and evaluated using Monte Carlo simulation and electronic structure calculations within the density functional theory. Various implantation environments were proposed and studied considering the presence of defects. The obtained 57Fe hyperfine parameters show a good agreement with the reported experimental values for some of these configurations. The possibility of Fe pair formation, as well as a Zn site vacancy stabilization between the second and third neighborhood of the implantation site, is supported.

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

    International Nuclear Information System (INIS)

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

  13. Research by Moessbauer and infrared spectroscopy of films of polyacrylonitrile doped with FeCl{sub 2} and FeCl{sub 3};Estudo de filmes de poliacrilonitrila dopados com Fe(II) e Fe(III) por espectroscopia Moessbauer e infravermelho

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Vadilson M. dos; Silva Filho, Eloi A. da, E-mail: vadilson@click21.com.b [Universidade Federal do Espirito Santo (UFES), Vitoria, ES (Brazil). Programa de Pos-graduacao em Quimica; Nunes Filho, Evaristo [Universidade Federal do Espirito Santo (UFES), Vitoria, ES (Brazil). Dept. de Fisica

    2009-07-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Alenkina, I.V.; Semionkin, V.A. [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); Oshtrakh, M.I. [Faculty of Physical Techniques and Devices for Quality Control, Ural Federal University, Ekaterinburg (Russian Federation); Klepova, Yu.V.; Sadovnikov, N.V. [Faculty of Physiology and Biotechnology, Ural State Agricultural Academy, Ekaterinburg, (Russian Federation); Dubiel, S.M. [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Krakow (Poland)

    2011-07-01

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

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

    International Nuclear Information System (INIS)

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

  18. A complex fitting program of Moessbauer transmission spectra

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-11-15

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-11-15

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

  2. A Moessbauer study of a new intermetallic phase Nd[sub 2](Fe,Ti)[sub 19] and its nitride

    Energy Technology Data Exchange (ETDEWEB)

    Cadogan, J.M. (School of Physics, Univ. of New South Wales, Kensington, NSW (Australia)); Day, R.K. (CSIRO Div. of Applied Physics, Lindfield, NSW (Australia)); Dunlop, J.B. (CSIRO Div. of Applied Physics, Lindfield, NSW (Australia)); Margarian, A. (CSIRO Div. of Applied Physics, Lindfield, NSW (Australia))

    1993-11-12

    In this paper we present [sup 57]Fe Moessbauer spectra of a new ternary intermetallic phase Nd[sub 2](Fe, Ti)[sub 19] and its nitride. Our previous work suggests that the 2-19 phase is related to the hexagonal TbCu[sub 7] structure. The average [sup 57]Fe magnetic hyperfine field of Nd[sub 2](Fe, Ti)[sub 19] at 295 K is 20.8 T which corresponds to an average Fe atomic magnetic moment of 1.33[mu][sub B]. After nitrogenation, the average [sup 57]Fe hyperfine field at 295 K is 29.6 T, which corresponds to an average Fe atomic magnetic moment of 1.90[mu][sub B]. This enhancement in the Fe atomic magnetic moment (at 295 K) is attributed mainly to the N-induced increase in Curie temperature of about 200 K. (orig.)

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

    Institute of Scientific and Technical Information of China (English)

    高发明; 田永君; 谌岩; 李东春; 董海峰; 张思远

    2003-01-01

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

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

    International Nuclear Information System (INIS)

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

  5. A computer controlled Moessbauer spectrometer

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-15

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-12-15

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

  10. Moessbauer line-sharpening: application to magnetically-split spectra

    Energy Technology Data Exchange (ETDEWEB)

    Wulfhekel, W. [New South Wales Univ., Kensington (Australia). School of Physics; Cadogan, J.M. [New South Wales Univ., Kensington (Australia). School of Physics

    1994-11-01

    The contrast in a Moessbauer spectrum can be enhanced by a model-independent method of line sharpening, due to Afanas`ev and Tsymbal, which employs higher powers of Lorenztian lines. We have investigated the applicability of this process to the {sup 57}Fe spectrum of a new, ternary rare-earth intermetallic Nd{sub 2}(Fe, Ti){sub 19}. Fitting the processed spectrum gives a smaller {chi}{sup 2} value than a simple Lorentzian fit to the original data due to the deviation from the pure Lorentzian line shape in the spectrum caused by statistical fluctuations in the local chemical environment of the {sup 57}Fe nuclei. However, we find that the use of the Pearson VII line shape gives a better fit to the spectrum than either the standard Lorentzians or the sharpened, higher-power Lorentzians. The line-sharpening process based on higher-power Lorentzians appears to be of limited use in the study of complex, overlapping magnetic spectra. (orig.)

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-03-15

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

  13. Moessbauer firing study of Lishan clay

    International Nuclear Information System (INIS)

    Lishan clay has been characterized by Moessbauer spectroscopy, X-ray diffraction, X-ray fluorescence, neutron activation, thermal and chemical analysis. It is proved that Lishan clay is the material used for making the terra-cotta warriors and horses of Qin Dynasty. Firing testing of clay was carried out in various conditions. The transformations induced by firing of clay were characterized by Moessbauer spectra. The data on quadrupole splittings of Fe3+ or Fe2+ ions, and on nonmagnetic component distributions at different firing temperatures, may lead to valuable informations on the manufacture of ancient pottery. The sintering temperature for the treea-cotta warriors and horses of Qin Dynasty was thus evaluated to be 950-1030 deg C

  14. Moessbauer studies on Al-Co ferrites

    International Nuclear Information System (INIS)

    Moessbauer spectroscopy studies have been performed on the spinel CoAlxFe2-xO4 (.2≤x≤1.7) in the temperature range 77-750 K using either a liquid nitrogen bath cryostat or a furnace. The samples are magnetic at 77 K giving spectra that have magnetic sextets coexisting with a central line which increases in population with the Al-content indicating relaxation effects. The data shows that Al possesses no preference to either tetrahedral or octahedral sites of the ferrite over the whole range of concentration. The Moessbauer hyperfine interaction parameters and magnetic transition temperatures were determined. As expected the hyperfine field and Curie temperature decrease when the Al-content increases. (orig.)

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-04-15

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

  17. Microscopic 57 Fe electric-field-gradient and anisotropic mean-squared-displacement tensors: ferrous chloride tetrahydrate

    Science.gov (United States)

    Bull, James N.; Fitchett, Christopher M.; Tennant, W. Craighead

    2010-06-01

    This paper reports the determination of the electric-field-gradient and mean-squared-displacement tensors in 57Fe symmetry-related sites of bar {1} Laue class in monoclinic FeCl2.4H2O at room temperature by single-crystal Mössbauer spectroscopy. Contrary to all previous work, the mean-squared-displacement matrix (tensor), , is not constrained to be isotropic resulting in the determination of physically meaningful estimates of microscopic (local) electric-field gradient (efg) and tensors. As a consequence of anisotropy in the tensor the absorber recoilless fractions are also anisotropic. As expected of a low-symmetry site, Laue class bar{1} in this case, no two principal axes of the efg and tensors are coaxial, within the combined errors in the two. Further, no principal direction of the efg tensor seems related to bond directions in the unit cell. Within error, and in agreement with an earlier study of sodium nitroprusside, it appears that the tensor principal directions lie close to the crystallographic axes suggesting that they are determined by long wavelength (phonon) vibrations in the crystal rather than by approximate local symmetry about the 57Fe nucleus. Concurrent with the Mössbauer measurements, we determined as part of a new X-ray structural determination, precise atomic displacement parameters (ADPs) leading to an alternative determination of the matrix (tensor). The average of the eigenvalues of the Mössbauer-determined exceeds that of the average of the X-ray-determined eigenvalues by a factor of around 2.2. Assuming isotropic absorber recoilless fractions leads to substantially the same (macroscopic) efg tensor as had been determined in earlier work. Taking 1/3× the trace of the anisotropic absorber recoilless fractions leads to an isotropic value of 0.304 in good agreement with earlier single crystal studies where isotropy was assumed.

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

    DEFF Research Database (Denmark)

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

    1972-01-01

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

  19. Thermal treatment of the Fe{sub 78} Si{sub 9} B{sub 13} alloy and the analysis of it magnetic properties through Moessbauer spectroscopy and Positronium annihilation; Tratamiento termico de la aleacion Fe{sub 78} Si{sub 9} B{sub 13} y el analisis de sus propiedades magneticas mediante Espectroscopia de Moessbauer y Aniquilacion de positronio

    Energy Technology Data Exchange (ETDEWEB)

    Lopez M, A

    2005-07-01

    The present work is divided in five chapters. In the first one a general vision of the amorphous alloys is given from antecedents, structure, obtaining methods, properties and problems that at the moment, focusing us in a certain moment to the iron base alloys and the anomalous problem of hardness that it presents the alloy Fe{sub 78}Si{sub 9}B{sub 13} like previously mention us. The second chapter tries on the basic theory of the techniques of Moessbauer spectroscopy and Positron Annihilation spectroscopy, used for the characterization of our alloy as well as the complementary technique of X-ray diffraction (XRD) to observe that the amorphous phase was even studying. The third chapter describes the experimental conditions that were used to study the alloy Fe{sub 78}Si{sub 9}B{sub 13} in each one of their thermal treatments. In the fourth chapter the obtained results and their discussion are presented. In the fifth chapter the conclusions to which were arrived after analyzing the results are presented. (Author)

  20. Characterization of Zn-bearing chlorite by Moessbauer and infrared spectroscopy - occurrence associated to the Pb-Zn-Ag deposits of Canoas, PR, Brazil; Caracterizacao de clorita portadora de Zn por espectroscopia Moessbauer e espectroscopia infravermelho - uma ocorrencia associada ao deposito de Pb-Zn-Ag de Canoas, PR, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Imbernon, Rosely Aparecida Liguori [Universidade de Sao Paulo (EACH/USP), SP (Brazil). Escola de Artes, Ciencias e Humanidades; Blot, Alain [Institut de Recherche pour le Developpement (IRD), Paris (France); Pereira, Vitor Paulo [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Inst. de Geociencias; Franco, Daniel Ribeiro, E-mail: imbernon@usp.br, E-mail: brotalain@free.fr, E-mail: vitor.pereira@ufrgs.br, E-mail: drfranco@on.br [Observatorio Nacional do Brasil (COGE/ON), Rio de Janeiro, RJ (Brazil). Coordenacao de Geofisica

    2011-06-15

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

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

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-02-15

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

  3. A Moessbauer study of the thermal behaviour of iron(III) benzoate

    International Nuclear Information System (INIS)

    The thermal behaviour of three different iron(III) benzoate complexes was investigated by Moessbauer spectroscopy, conventional thermal analysis and infrared spectroscopy. Each of the complexes had six benzoate ligands within the first coordination sphere. Their Moessbauer spectra showed only quadrupole pattern, characteristic of high-spin iron(III). When the complexes were heated in air, two new iron(III) benzoate complexes were obtained, having five and four benzoate ligands within the first coordination sphere. The Moessbauer spectra of these new complexes showed two distinct quadrupole petterns with relative concentration close to 2:1, which could be related to the nonequivalence of the three iron ions in the molecule. (author)

  4. Moessbauer effect study of the diagenesis on the southern Brazilian Triassic paleoherpetofauna

    International Nuclear Information System (INIS)

    Moessbauer spectroscopy is applied to identify the iron contents of bony elements of southern Brazilian Triassic reptile remains, and the question of the paragenetic mineral assemblage is discussed. (orig.)

  5. Moessbauer study of function of magnesium in iron oxide catalysts

    Institute of Scientific and Technical Information of China (English)

    YangJie-Xin; MaoLian-Sheng; 等

    1997-01-01

    Moessbauer spectroscopy has been utilized for studying the action of Mg element in iron oxide catalysts used for the dehydrogenation of ethylbenzene to sytrene.The experimental results show that the presence of opportune amount of Mg can enhance the stability and dispersion of catalysts,i.e.Mg is an sueful structure promoter in this kind of catalysts.

  6. Moessbauer study of rock paintings from Minas Gerais (Brazil)

    International Nuclear Information System (INIS)

    Four samples of a wall containing rock paintings have been studied by Moessbauer spectroscopy in combination with optical microscopy analysis and X-ray diffraction. Hematite and goethite were identified as the pigments responsible for the colors and the mineral tinsleyite, as the principal component of a light pink layer that is present in some parts of the wall. (orig.)

  7. Moessbauer effect of the origin of the colour in the ancient Egyptian black ware

    International Nuclear Information System (INIS)

    Samples of ancient Egyptian pottery, Roman pottery and modern pottery were examined by Moessbauer spectroscopy, infrared spectroscopy and x-ray diffraction with the aim of establishing the origin of the black colour of the Egyptian pottery. The Moessbauer spectra and the values of isomer shift and quadrupole splitting were used to decide on the presence of magnetic or non-magnetic ferrous or ferricions. (A.K.)

  8. The Miniaturized Moessbauer Spectrometer MIMOS II for the Asteroid Redirect Mission(ARM): Quantative Iron Mineralogy And Oxidation States

    Science.gov (United States)

    Schroeder, C.; Klingelhoefer, G; Morris, R. V.; Yen, A. S.; Renz, F.; Graff, T. G.

    2016-01-01

    The miniaturized Moessbauer spectrometer MIMOS II is an off-the-shelf instrument with proven flight heritage. It has been successfully deployed during NASA’s Mars Exploration Rover (MER) mission and was on-board the UK-led Beagle 2 Mars lander and the Russian Phobos-Grunt sample return mission. A Moessbauer spectrometer has been suggested for ASTEX, a DLR Near-Earth Asteroid (NEA) mission study, and the potential payload to be hosted by the Asteroid Redirect Mission (ARM). Here we make the case for in situ asteroid characterization with Moessbauer spectroscopy on the ARM employing one of three available fully-qualified flight-spare Moessbauer instruments.

  9. A versatile Moessbauer analysis program

    International Nuclear Information System (INIS)

    MDA - Moessbauer Data Analysis, is a user oriented computer program, aiming to simulate a Moessbauer transmission spectrum, given by a set of parameters, and compare it with experimental data. The calculation considers a number of experimental situations and the comparisons can be made by least squares sums or by plotting the simulated and the measured spectrum. A fitting routine, minimizing the least squares sum, can be used to find the parameters characterizing the measured spectrum.(author)

  10. Further studies on electronic guest/host interactions of FeCl3-graphite from Moessbauer spectroscopy - a comparative investigation with FeOCl

    International Nuclear Information System (INIS)

    Moessbauer spectra of first stage FeCl3-graphite and of the inverse Fe(C5H5)2-iron oxide chloride intercalation compounds have been measured between room temperature and 4 K. The spectra at 295 K consist of resonance lines which are characteristic of ferric ions only. In addition the spectra showed high-spin Fe2+ sites at low temperatures. This result may be accounted for by an incomplete redox reaction caused by partial transfer of the π-electrons of the graphite (host layer), or of the ferricinium ions (guest layers), to the adjacent layers. Contrary to what is found in the literature, at low temperatures only these delocated electrons are fixed in the d-orbitals of some Fe3+ atoms resulting in Fe2+ sites. This result suggests that a shielding effect of the chlorine layers exists in these intercalation compounds which hinders a complete electron transfer to the Fe3+ centers at room temperature. (Auth.)

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

    Science.gov (United States)

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

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

  12. The history of the Moessbauer effect

    CERN Document Server

    Miglierini, M

    2003-01-01

    The background of the discovery of the Moessbauer effect and the development of Moessbauer spectrometry as an analytical technique are highlighted. The basic principles and instrumentation, application fields, and trends of future progress and outlined and discussed

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

    CERN Document Server

    Yap, Ian

    2016-01-01

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

  14. Aging effect in CaLaBa{l_brace}Cu{sub 1 - x}Fe{sub x}{r_brace}{sub 3}O{sub 7 - {delta}} with 0 {<=} x {<=} 0.07 studied by Moessbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bustamante, Angel, E-mail: angelbd1@gmail.com [Universidad Nacional Mayor de San Marcos, Laboratorio de Ceramicos y Nanomateriales, Facultad de Ciencias Fisicas (Peru); Santos Valladares, Luis De Los, E-mail: ld301@cam.ac.uk [University of Cambridge, Cavendish Laboratory (United Kingdom); Flores, Jesus [Universidad Nacional Mayor de San Marcos, Laboratorio de Ceramicos y Nanomateriales, Facultad de Ciencias Fisicas (Peru); Barnes, Crispin H. W. [University of Cambridge, Cavendish Laboratory (United Kingdom); Majima, Yutaka [Tokyo Institute of Technology, Materials and Structures Laboratory (Japan)

    2011-11-15

    In this work, we study the long-term aging effect caused by Fe atoms in the superconductor CaLaBa{l_brace}Cu{sub 1 - x}Fe{sub x}{r_brace}{sub 3}O{sub 7 - {delta}} with 0 {<=} x {<=} 0.07. XRD confirms that this system has a YBCO-like structure. The critical temperature (T{sub c}) is strongly affected by aging and depends on the amount of Fe in the structure. Room temperature Moessbauer spectroscopy reveals the presence of the typical species A, B-B Prime , C and new species E Prime and F. Interestingly; A, which corresponds to the Fe{sup 3 + } atom located in the Cu(1) of the chains with spin S{sub z} = 3/2, shows a drastic reduction which means migration to the species B, B Prime and C. Species B and B Prime correspond to the Fe{sup 3 + } in the Cu(2) site forming planar quasi-octahedral and planar square pyramidal, while the C specie is a square pyramidal with O(5) respectively (spin S{sub z} = 3/2 in all these cases). Aging causes loss of superconductivity in the samples with 5 and 7% of iron content.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-01-15

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

  16. The Moessbauer community in the USA

    International Nuclear Information System (INIS)

    Scientists in the United States assumed major roles in developing the Moessbauer community during its early years. However, since the termination of the Moessbauer Effect Methodology meetings in 1976, there has been little in the way of regular Moessbauer meetings in the United States. Nevertheless, there is an active United States Moessbauer community, as noted by the number of annual publications - 156 in 2004. In recent decades, attendance of Moessbauer researchers from the United States at the International Conferences on the Applications of the Moessbauer Effect (ICAME) has been far below what would be expected from the number of contributions in the Moessbauer literature. Attempts have been made, unsuccessfully, to arrange for regular Moessbauer meetings. Models for possible future Moessbauer meetings of US scientists are discussed, including a regular biannual meeting, and another being a virtual Moessbauer conference. Also discussed are other models to maintaining an active Moessbauer community in the United States, making use of information technologies that are available to us along with other resources we can use.

  17. The Contribution of 57Fe Mössbauer Spectrometry to Investigate Magnetic Nanomaterials

    Science.gov (United States)

    Greneche, Jean-Marc

    Fe containing nanomaterials and nanoparticles are quite important because their unusual physical properties make them excellent candidates for different applications. 57Fe Mössbauer spectrometry appears as an excellent tool to provide structural and magnetic data through the hyperfine parameters. After a short definition of nanostructures and their main characteristics originated from confinement effects, we established the relevant features to understand nanoscale magnetism. Some examples have been thus selected to illustrate first how Mössbauer spectrometry contributes to understand the chemical, structural and magnetic nature of nanostructures and the role of surface and grain boundaries. Then, they also demonstrate also how the fitting procedure remains a delicate task to model the hyperfine structure and does require on the one hand large experimental data basis obtained from different techniques including structural, morphological and magnetic parameters and on the other hand materials with high knowledge and control of synthesis conditions.

  18. Moessbauer-spectroscopic study of structure and magnetism of the exchange-coupled layer systems Fe/FeSn2, and Fe/FeSi/Si and the ion-implanted diluted magnetic semiconductor SiC(Fe)

    International Nuclear Information System (INIS)

    In line with this work the strucural and magnetic properties of the exchange coupled layered systems Fe/FeSn2 and Fe/FeSi/Si and of the Fe ion implanted diluted magnetic semiconductor (DMS) SiC(Fe) were investigated. The main measuring method was the isotope selective 57Fe conversion electron Moessbauer spectroscopy (CEMS), mostly in connection with the 57Fe tracer layer technique, in a temperature range from 4.2 K to 340 K. Further measurement techniques were X-ray diffraction (XRD), electron diffraction (LEED, RHEED), SQUID magnetometry and FMR (Ferromagnetic Resonance). In the first part of this work the properties of thin AF FeSn2(001) films and of the exchange-bias system Fe/FeSn2(001) on InSb(001) were investigated. With the application of 57Fe-tracer layers and CEMS both the Fe-spin structure and the temperature dependence of the magnetic hyperfine field (Bhf) of FeSn2 could be examined. The evaporation of Fe films on the FeSn2 films produced in the latter ones a high perpendicular spin component at the Fe/FeSn2 interface. In some distance from the interface the Fe spins rotate back into the sample plane. Furthermore 57Fe-CEMS provided a correlation between the absolute value of the exchange field vertical stroke He vertical stroke and the amount of magnetic defects within the FeSn2. Temperature dependent CEMS-measurements yielded informations about the spin dynamics within the AF. The transition temperatures TB*, which were interpreted as superparamagnetic blocking temperatures, obtain higher values compared to the temperatures TB of the exchange-bias effect, obtained with magnetometry measurements. The second part of this work deals with the indirect exchange coupling within Fe/FeSi/Si/FeSi/Fe multilayers and FeSi diffusion barriers. The goal was to achieve Fe free Si interlayers. The CEMS results show that starting from a thickness of tFeSi=10-12 A of the ''lower'' FeSi layers the interdiffusion of Fe is inhibited. For thicker FeSi layers (tFeSi ∼ 20 A

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

    OpenAIRE

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

    2014-01-01

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

  20. Moessbauer studies of bridged ferrocenophane derivative's polyiodides

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Masanobu; Sato, Kumiko; Motoyama, Izumi; Sano, Hirotoshi (Tokyo Metropolitan Univ. (Japan). Faculty of Science)

    1983-11-01

    (2)Ferrocenophanes, the ring tilted ferrocene derivatives, were oxidized with iodine in benzene and studied by means of Moessbauer spectroscopy. The quadrupole splitting value of the compounds is found to be 3.70 mms/sup -1/ at 78K, which is one of the largest found in ferrocene derivatives, suggesting the presence of a strong direct interaction between iron atoms and iodine atoms. The results were compared with (3) and (4)ferrocenophane's polyiodides.

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

    Science.gov (United States)

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

    2016-08-01

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

  2. Moessbauer Investigations of MDAS Diamond Powder

    International Nuclear Information System (INIS)

    Metal inclusions in synthetic MDAS diamond grits were investigated by Moessbauer spectroscopy as a function of the grit size. The larger grit sizes show a nicely developed sextet, which collapses to a paramagnetic singlet with decreasing grit size. This superparamagnetic behavior shows that the metal inclusions are of the order of 10 nm in size, and become larger with the grit size. One grit which was showing the collapse was further investigated from 300 K down to 4 K. Part of the paramagnetic singlet unfolds to a sextet with Bhf ∼33T, while another part unfolds with a narrower hyperfine magnetic field of ∼4T and is associated with the paramagnetic phase that coexists with a ferromagnetic phase in Invar at higher temperatures. A singlet with an isomer shift of about 1.1 mm/s is associated with similar findings in catalysts with iron particles supported on carbonaceous materials

  3. LACAME 2006: Latin American conference on the applications of the Moessbauer effects. Program and Abstract Book

    International Nuclear Information System (INIS)

    Theoretical and experimental papers are present in these proceedings on the following subjects: Moessbauer effects and spectroscopy, minerals, structural chemical analysis, crustal structure, ion oxides, hyperfine structure, geology, catalysts, transmission and absorption spectroscopies, materials, crystal and hyperfine structures, stereochemistry and geological materials

  4. LACAME 2006: Latin American conference on the applications of the Moessbauer effects. Program and Abstract Book

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    Theoretical and experimental papers are present in these proceedings on the following subjects: Moessbauer effects and spectroscopy, minerals, structural chemical analysis, crustal structure, ion oxides, hyperfine structure, geology, catalysts, transmission and absorption spectroscopies, materials, crystal and hyperfine structures, stereochemistry and geological materials.

  5. Moessbauer study of the chemical state of gold in gold ores

    International Nuclear Information System (INIS)

    Information on the chemical state of gold in gold ores has been obtained by 197Au Moessbauer spectroscopy in cases where the state of this element cannot be determined by such standard methods as optical or electron microscopy. Ore concentrates consisting mainly of pyrite or arsenopyrite and roasted ore and matte samples were studied. The results yielded directly the respective amounts of metallic and chemically bound gold. Unless the gold is metallic, its chemical state in the ores turns out to be different from that in the minerals studied so far as reference materials. The chemical processes taking place during various treatments of the ores, such as roasting or leaching, can also be followed by Moessbauer spectroscopy. It is hoped that Moessbauer spectroscopy will eventually facilitate the development of more efficient methods of gold extraction

  6. Dynamical Properties of 57Fe Dissolved in Al Observed by Mössbauer Effect

    DEFF Research Database (Denmark)

    Sørensen, K.; Trumpy, Georg

    1973-01-01

    broadening might be more accurate than the one used heretofore. Earlier determinations of the second-order Doppler shift were extended almost to the melting point of aluminum. The shift depends almost linearly on temperature, with the slope given by the Dulong—Petit rule for the heat capacity. From......The Mössbauer effect of 57Fe in aluminum was measured over the temperature range 20-642°C, using a source specimen of aluminum with 57Co in solid solution. The line-broadening values were converted to diffusion constants, which can be expressed by the temperature dependence D=0.12e-(1.4 eV) / kT cm......2/sec. This result differs from recent diffusion-constant determinations obtained by the tracer-sectioning method, which we feel might be in error because of solution trapping. From theoretical considerations we suggest that a new expression for the correlation factor for the diffusional line...

  7. Moessbauer study of a Western-Han dynasty pottery figure

    International Nuclear Information System (INIS)

    A grey pottery figure manufactured in the Western-Han Dynasty and the clay gathered from the same site of Beidongshan near Suzhou, China, have been studied by X-ray diffraction, X-ray fluorescence and Moessbauer spectroscopy. They were simultaneously fired under the same conditions in different atmospheres at various temperatures. The information on original firing atmosphere and temperature as well as its provenance can be inferred from the method of pottery re-firing and clay firing. The original firing temperatures deduced from both of them are in good self-agreement. It is found that the values of Moessbauer parameters for the un-re-fired pottery figure are approximately the same as those for the clay fired at 950 deg C for five hours in a reduced atmosphere. The XRF analysis confirmed that the locality of this pottery figure was somewhere near Beidongshan

  8. Moessbauer studies on ancient Chinese pottery of Yangshao Culture Period

    International Nuclear Information System (INIS)

    Eleven pieces of ancient Chinese pottery (4770 B.C. - 2960 B.C.) of Yangshao Culture Period collected from the Xi'an area have been studied by means of Moessbauer spectroscopy. The samples were refired up to 11000C in steps of 1000C for 2 h in air. The highest temperature up to which the Moessbauer pattern remains basically unchanged can be identified with the original firing temperature. The result indicates that the firing temperatures for most of the sherds were between 900-10000C. The function of the grit contained in the pottery has been discussed. The crimson and reddish painted materials on the surface of sherds have been studied, respectively. The first appearance of pottery can probably be traced back to an even earlier period. (orig.)

  9. Moessbauer study of the cubic Laves phase intermetallic compound TmFe/sub 2/

    Energy Technology Data Exchange (ETDEWEB)

    Bleaney, B.; Bowden, G.J.; Cadogan, J.M. (New South Wales Univ., Kensington (Australia). School of Physics); Day, R.K.; Dunlop, J.B. (Commonwealth Scientific and Industrial Research Organization, Lindfield (Australia). Div. of Applied Physics)

    1982-04-01

    The results of a /sup 169/Tm and /sup 57/Fe Moessbauer study of the cubic Laves compound TmFe/sub 2/ over the temperature range 1.3-550 K are presented and discussed. The new results are used, in conjunction with existing NMR, Moessbauer and magnetic anisotropy data for TmFe/sub 2/ and Tm metal, to deduce a value of Psub(4f) 536 +- 14 MHz for the saturation value of the first excited state of the /sup 169/Tm nucleus. Estimates are also given for the exchange field ..mu..sub(B)Bsub(ex)(T = O K)/ksub(B) = 153 +- 3 K acting on the Tm/sup 3 +/ ion in TmFe/sub 2/, the quadrupole moment of the I = 3/2 state of the /sup 169/Tm nucleus. Q = -1.36 +- 0.11 b, and the lattice contribution to the nuclear quadrupole interaction in Tm metal, Psub(c) = -54.8 +- 5 MHz (for Q = -1.20 +- 0.07 b) and Psub(c) = -61 +- 8 MHz (for Q = -1.36 +- 0.11 b). In addition estimates are given for the various transferred and parent hyperfine fields in TmFe.

  10. Magnetic and Moessbauer spectroscopic studies of NiZn ferrite nanoparticles synthesized by a combustion method

    Energy Technology Data Exchange (ETDEWEB)

    Sreeja, V.; Vijayanand, S.; Deka, S.; Joy, P. A., E-mail: pa.joy@ncl.res.in [National Chemical Laboratory, Physical and Materials Chemistry Division (India)

    2008-04-15

    The properties of nanocrystalline Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} synthesized by an auto-combustion method have been investigated by magnetic measurements and Moessbauer spectroscopy. The as-synthesized single phase nanosized ferrite powder is annealed at different temperatures in the range 673-1,273 K to obtain nanoparticles of different sizes. The powders are characterized by powder X-ray diffraction, vibrating sample magnetometer, transmission electron microscopy and Moessbauer spectroscopy. The as-synthesized powder with average particle size of {approx}9 nm is superparamagnetic. Magnetic transition temperature increases up to 665 K for the nanosized powder as compared to the transition temperature of 548 K for the bulk ferrite. This has been confirmed as due to the abnormal cation distribution, as evidenced from room temperature Moessbauer spectroscopic studies.

  11. Moessbauer and VNIR study of dust generated from olivine basalt: application to Mars

    International Nuclear Information System (INIS)

    Moessbauer spectroscopy of surface rocks, soil, and dust on Mars from the Mars Exploration Rovers (MER) suggests that the mineral olivine is widespread on the surface. Detection of the mineral by near-IR optical spectroscopy from Martian orbit indicates that it is found in relatively small isolated outcrops concentrated in the floors and rims of craters distributed around the ancient cratered highlands of Mars. To shed light on this apparent paradox, we have performed a detailed Moessbauer and visible-near-IR (VNIR) investigation of dust generated from Icelandic olivine basalt, which is a good Moessbauer analogue to the igneous rocks at Gusev crater on Mars. The results show that the amount of olivine relative to pyroxene can be underestimated by almost an order of a magnitude in VNIR reflectance spectra, most probably because of the longer effective optical path length in pyroxene compared to olivine.

  12. In Situ Resource Utilization (ISRU) on the Moon: Moessbauer Spectroscopy as a Process Monitor for Oxygen Production. Results from a Field Test on Mauna Kea Volcano, Hawaii

    Science.gov (United States)

    Morris, R.V.; Schroder, C.; Graff, T.G.; Sanders, G.B.; Lee, K.A.; Simon, T.M.; Larson, W.E.; Quinn, J.W.; Clark, L.D.; Caruso, J.J.

    2009-01-01

    Essential consumables like oxygen must to be produced from materials on the lunar surface to enable a sustained, long-term presence of humans on the Moon. The Outpost Precursor for ISRU and Modular Architecture (OPTIMA) field test on Mauna Kea, Hawaii, facilitated by the Pacific International Space Center for Exploration Systems (PISCES) of the University of Hawaii at Hilo, was designed to test the implementation of three hardware concepts to extract oxygen from the lunar regolith: Precursor ISRU Lunar Oxygen Testbed (PILOT) developed by Lockheed Martin in Littleton, CO; Regolith & Environmental Science and Oxygen & Lunar Volatiles Extraction (RESOLVE) developed at the NASA Kennedy Space Center in Cape Canaveral, FL; and ROxygen developed at the NASA Johnson Space Center in Houston, TX. The three concepts differ in design, but all rely on the same general principle: hydrogen reduction of metal cations (primarily Fe2+) bonded to oxygen to metal (e.g., Fe0) with the production of water. The hydrogen source is residual hydrogen in the fuel tanks of lunar landers. Electrolysis of the water produces oxygen and hydrogen (which is recycled). We used the miniaturized M ssbauer spectrometer MIMOS II to quantify the yield of this process on the basis of the quantity of Fe0 produced. Iron M ssbauer spectroscopy identifies iron-bearing phases, determines iron oxidation states, and quantifies the distribution of iron between mineral phases and oxidation states. The oxygen yield can be calculated by quantitative measurements of the distribution of Fe among oxidation states in the regolith before and after hydrogen reduction. A M ssbauer spectrometer can also be used as a prospecting tool to select the optimum feedstock for the oxygen production plants (e.g., high total Fe content and easily reduced phases). As a demonstration, a MIMOS II backscatter spectrometer (SPESI, Germany) was mounted on the Cratos rover (NASA Glenn Research Center in Cleveland, OH), which is one of

  13. Mössbauer spectroscopic study of 57Fe metabolic transformations in the rhizobacterium Azospirillum brasilense Sp245

    Science.gov (United States)

    Kamnev, Alexander A.; Tugarova, Anna V.; Kovács, Krisztina; Biró, Borbála; Homonnay, Zoltán; Kuzmann, Ernő

    2014-04-01

    Preliminary 57Fe transmission Mössbauer spectroscopic data were obtained for the first time for live cells of the plant-growth-promoting rhizobacterium Azospirillum brasilense (wild-type strain Sp245) grown aerobically with 57FeIII-nitrilotriacetate (NTA) complex as a sole source of iron. The results obtained have shown that live cells actively reduce part of the assimilated iron(III) to iron(II), the latter amounting up to 33 % of total cellular iron after 18 h of growth, and 48 % after additional 3 days of storage of the dense wet cell suspension in nutrient-free saline solution in air at room temperature (measured at 80 K). The cellular iron(II) was found to be represented by two quadrupole doublets of different high-spin forms, while the parameters of the cellular iron(III) were close to those typical for bacterioferritins.

  14. Moessbauer spectroscopic studies of the coordination polymers [A(Me3Sn)3Fe(CN)6]x (A=Me3Sn+, Et4N+, Cp2Fe+, etc.)

    International Nuclear Information System (INIS)

    The structural diagnosis and lattice dynamics of the coordination polymers [(Me3Sn)3Fe(CN)6]x and [A(Me3Sn)3Fe(CN)6]x (A=Me3Sn+, Et4N+, Cp2Fe+, etc.) have been carried out by means of 57Fe- and 119Sn-Moessbauer spectroscopic techniques. The 119Sn-Moessbauer parameters for the polymers indicate that all the tin atoms are coordinated to three methyl groups and two cyano groups, having a trigonal-bipyramidal structure. The temperature dependences of the area under the 119Sn-resonance line for [A(Me3Sn)3Fe(CN)6]x were smaller than that for the host polymer [(Me3Sn)3Fe(CN)6]x. The 57Fe-Moessbauer spectra of [A(Me3Sn)3Fe(CN)6]x show that the iron atoms are Fe(II) in a low-spin state. This suggests that the guest ions are intercalated into the host lattice after reduction of its Fe(III) ions. (orig.)

  15. Two-electronic Moessbauer the centers with negative correlation energy as the tool of research of Bose-condensation in superconductors

    International Nuclear Information System (INIS)

    Two-electronic centers with negative correlation energy; crystal probe; Bose condensation of Cooper pairs; changes of electronic density in the lattice sites; isomer shift; gravity center of a spectrum; superconducting phase transition; temperature of transition; minimal size of a Cooper pair. Objects of research: solid solutions of lead chalcogenides Pb1-x-ySnxNayS, Pb1-x-ySnxNaySe, Pb1-x-yGexNayS, Pb1-x-yGexNaySe, (Pb1-xSnx)1-zInzTe; classical super-conductor Nb3Al; high-temperature superconductors La2-x(Sr,Ba)xCuO4, YBa2Cu3O7-x, YBa2Cu4O8, Tl2Ba2Can-1CunO2n+4, Bi2Sr2Can-1CunO2n+4, HgBa2Can-1CunO2n+2, where n=1,2,3; Objective of study: development and application of methodology of the Moessbauer spectroscopy of systems with negative correlation energy in order to identify the impurity U- centers in semiconductors and Bose condensation of Cooper pairs in classical and high-temperature superconductors. Method of research: emission Moessbauer spectroscopy on 119mmSn (119mSn), 73As(73Ge), 67Cu(67Zn), 67Ga(67Zn), 57Co(57mFe), 119mTe(119mSn) isotopes; absorption Moessbauer spectroscopy on 119Sn, 151Eu, 57Fe isotopes; temperature dependence of the conductivity; Hall effect. Obtained results and their novelty. The research of the crystal lead chalcogenides has shown that tin and germanium impurity atoms are U- centers of a donor type, neutral and twice ionized states of the U- centers are in cation sites of a lattice. Temperature dependence of the chemical potential, the first and the second ionization energy of U- centers, correlation energy and energy of activation of own conductivity as well as their dependence on concentration of acceptors and tin atoms have been determined for tin impurity atoms. Impurity tin and germanium atoms specially entered into antistructural positions of lead chalcogenides lattices (a method of radiation doping) are electrically inactive. The two-electronic exchange between neutral and ionized impurity U- tin (and germanium) centers in Pb

  16. Moessbauer studies of non-linear excitations and gold cluster compounds

    International Nuclear Information System (INIS)

    Moessbauer effect spectroscopy has been applied to the study of three polynuclear gold cluster compounds. The resulting information on the local vibrational density of states has been compared to several models which take the finite size of the particles into consideration. 188 refs.; 34 figs.; 103 schemes; 8 tabs

  17. Moessbauer study of Sn(Fe)O2 prepared by mechanosynthesis

    International Nuclear Information System (INIS)

    Samples of Sn0.90Fe0.10O2 were prepared by mechanosynthesis method. The structure and magnetic behavior of the samples have been investigated by X-ray diffraction (XRD) and Moessbauer spectroscopy. It has been found that for short milling times a small percentage of the initial hematite remains simultaneously with the formation of metallic Fe. Additionally a paramagnetic contribution appears in the Moessbauer spectra. For milling times, over 2 h, the iron ions are in paramagnetic states having +3 and +2 oxidation states while by XRD only the rutile structure diffraction lines were observed.

  18. Moessbauer effect study f environmental iron pollution of air and water at regions near Cairo

    International Nuclear Information System (INIS)

    Moessbauer spectroscopy has been applied for identification of the different phases of iron (with their relative abundance) containing particles in atmosphere aerosol and water pollution from Helwan, Turrah, and Shoubra Elkheima regions. Measurements were performed at room and liquid nitrogen temperatures. It was possible to identify the different iron forms in each case and to estimate the particle size of the superparamagnetic iron containing aerosol particles. The Moessbauer technique allowed to suggest the possible source of iron pollutant in each region. 2 figs, 2 tabs

  19. A review of Moessbauer spectroscopic studies of ancient pottery

    International Nuclear Information System (INIS)

    Moessbauer spectroscopy has proven itself to be invaluable to archaeologists by providing a means to classify pottery and to provide information on particular providences for various ancient pottery finds. The original firing atmospheres can often by deduced from the ratio of Fe2+ to Fe3+. The change in the quadrupole splitting and the magnetic hyperfine splittings allow for the determination of the original firing temperatures. Ancient pottery samples from many cultures have been studied and a number of general conclusions are possible. (Auth.)

  20. Temperature and Field Dependent Moessbauer Studies of the Metallic Inclusions in Synthetic MDAS Diamond Grits

    International Nuclear Information System (INIS)

    Moessbauer spectroscopy of the metallic inclusions in diamond grits produced in high-temperature high-pressure synthesis have revealed varying but interesting results. The MDAS1 grits synthesized with Fe/Ni solvent-catalysts show Moessbauer spectra that vary with grit size, with the ferromagnetic order observed in the larger grits collapsing as one went to smaller grit sizes. Two sets of De Beers MDAS diamond grits of US mesh size 400-500 (d=30-38 μm) and 200-230 (d=63-75 μm) were selected for temperature- and field-dependent investigations. Transmission Moessbauer measurements were made at temperatures of 300 K and 80 K, in zero field and in an external field of 0.60 T, on the metallic inclusions in these grits. The Moessbauer spectra of the inclusions are rather complex, reflecting the contributions of several different magnetic phases. Our results show that the temperature variation of the Moessbauer spectra is not due to superparamagnetic relaxation of ferromagnetic inclusions but rather to magnetic ordering temperatures of the order of room temperature. Based on the spectral lineshapes and elemental analyses, we suggest the inclusions in the 63-75 μm grits contain iron mainly in Fe-Ni alloys with composition in the vicinity of 70 at.% Fe, and those in the 30-38 μm grits contain, in addition to Fe-Ni alloys, a phase with hyperfine parameters close to those of a Fe-Co alloy

  1. Mineralogical and Moessbauer studies on the paramagnetic separate of Al-Kidirate meteorite

    Energy Technology Data Exchange (ETDEWEB)

    Gismelseed, A.M.; Worthing, M.A.; Yousif, A.A.; Elzain, M.E.; Al-Rawas, A.D. [College of Science, Sultan Qaboos University, Box 36 Alkhoud, 123 Sultanate of Oman (Oman); Kamal, H.M. [Faculty of Education, University of Khartoum, Khartoum (Sudan)

    2004-02-01

    The paramagnetic fraction of the chondritic meteorite (Al Kidirate) has been studied by scanning electron microscopy (SEM) and Moessbauer spectroscopy at different temperatures. The mineralogical analysis indicates that the fraction consists mostly of olivine and pyroxene. The pyroxene is present in two restricted compositions; bronzitic orthopyroxene and clinopyroxene in the diopside-endiopside range. The Moessbauer measurements confirm the above characterization showing two paramagnetic doublets for olivine and pyroxene. The Moessbauer relative area under the resonance curve together with the atomic concentration derived from the microprobe data are used to derive the chemical formulae for orthopyroxene and clinopyroxene. The formulae derived using the two methods show good agreement. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Moessbauer Studies of Nanosize CuFe2O4 Particles

    International Nuclear Information System (INIS)

    Nanocrystalline CuFe2O4 particles are prepared by wet chemical method. The particles of various sizes are obtained by heat treatment in the temperature range 773-1073 K. The room temperature Moessbauer spectrum for all samples shows the presence of both sextet and doublet indicating the presence of superparamagnetic fractions. The isomer shift, quadrupole splitting and hyperfine field values are found to change with particle size. However, these changes in Moessbauer parameters may also be due to the Jahn-Teller effect that essentially arises due to the migration of Cu2+ from tetrahedral sites to octahedral sites resulting in crystal structure change from cubic to tetragonal system. These aspects are studied by using Moessbauer spectroscopy and are correlated to the X-ray diffraction data.

  3. The stannides RE{sub 3}Au{sub 6}Sn{sub 5} (RE = La, Ce, Pr, Nd, Sm). Synthesis, structure, magnetic properties and {sup 119}Sn Moessbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fickenscher, Thomas; Rodewald, Ute C.; Niehaus, Oliver; Gerke, Birgit; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Haverkamp, Sandra; Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie

    2015-07-01

    The Ce{sub 3}Pd{sub 6}Sb{sub 5}-type rare earth stannides RE{sub 3}Au{sub 6}Sn{sub 5} (RE = La, Ce, Pr, Nd, Sm) were synthesized by arc-melting of the elements and subsequent annealing in open tantalum crucibles within sealed evacuated silica ampoules. The polycrystalline samples were studied by powder X-ray diffraction. The structures of three crystals were refined from single crystal X-ray diffractometer data: Pmmn, a = 1360.3(9), b = 455.9(2), c = 1023.6(4) pm, wR2 = 0.0275, 1069 F{sup 2} values, 48 variables for Ce{sub 3}Au{sub 6}Sn{sub 5}, a = 1352.4(4), b = 455.1(1), c = 1023.7(3) pm, wR2 = 0.0367, 1160 F{sup 2} values, 48 variables for Nd{sub 3}Au{sub 6}Sn{sub 5}, and a = 1339.8(2), b = 452.80(7), c = 1012.4(2) pm, wR2 = 0.1204, 1040 F{sup 2} values, 49 variables for Sm{sub 3}Au{sub 5.59(2)}Sn{sub 5.41(2)}. One of the gold sites of the samarium compound shows a significant degree of Au/Sn mixing. The RE{sub 3}Au{sub 6}Sn{sub 5} structures are composed of three-dimensional [Au{sub 6}Sn{sub 5}] polyanionic networks with the two crystallographically independent rare earth atoms in larger cages, i.e., RE1 rate at Au{sub 10}Sn{sub 6} and RE2 rate at Au{sub 8}Sn{sub 8}. The [Au{sub 6}Sn{sub 5}] network is stabilized by Au-Sn (266-320 pm), Au-Au (284-301 pm) as well as Sn-Sn (320 pm; distances given for the cerium compound) interactions. Temperature-dependent magnetic susceptibility measurements reveal an antiferromagnetic ordering only for Sm{sub 3}Au{sub 6}Sn{sub 5}, while the other compounds exhibit Curie-Weiss paramagnetism. {sup 119}Sn Moessbauer spectroscopy shows resonances in the typical range for intermetallic tin compounds where tin takes part in the polyanionic network [isomer shifts between 1.73(1) and 2.28(1) mm . s{sup -1}]. With the help of theoretical electric field gradient calculations using the WIEN2k code it was possible to resolve the spectroscopic contributions of all three crystallographically independent atomic tin sites in the {sup 119}Sn

  4. Neutron Cross section Covariances in the Resonance region: 50,53Cr, 54,57Fe and 60Ni

    Energy Technology Data Exchange (ETDEWEB)

    Oblozinsky, P.; Cho,Y.-S.; Mattoon,C.M.; Mughabghab,S.F.

    2010-11-23

    We evaluated covariances in the neutron resonance region for capture and elastic scattering cross sections on minor structural materials, {sup 50,53}Cr, {sup 54,57}Fe and {sup 60}Ni. Use was made of the recently developed covariance formalism based on kernel approximation along with data in the Atlas of Neutron Resonances. Our results of most interest for advanced fuel cycle applications, elastic scattering cross section uncertainties at energies around 100 keV, are on the level of about 7-10%.

  5. Time differential 57Fe Mössbauer spectrometer with unique 4π YAP:Ce 122.06 keV gamma-photon detector

    Science.gov (United States)

    Novak, Petr; Pechousek, Jiri; Prochazka, Vit; Navarik, Jakub; Kouril, Lukas; Kohout, Pavel; Vrba, Vlastimil; Machala, Libor

    2016-10-01

    This paper presents a conceptually new design of the 57Fe Time Differential Mössbauer Spectrometer (TDMS) with the gamma-photon detector optimized for registration of a radiation emitted in a maximum solid angle. A high detection efficiency of 80% in 4π region was achieved for 122.06 keV photons emitted from 57Co source. Detector parameters have been optimized for the use in the Time Differential Mössbauer Spectroscopy where the high time resolution in range of 176-200 ns is highly required. Technical concept of the TDMS is based on the virtual instrumentation technique and uses fast digital oscilloscope. Performance and detector utilization have been clarified by decreasing the Mössbauer spectral line-width of K2MgFe(CN)6 reference sample from 0.33 mm/s (integral mode) to 0.23 mm/s (time differential mode). This report also describes characterization and utilization of the detector together with additional electronic blocks and two-channel fast data-acquisition system construction.

  6. Local structure and magnetism of L10-type FeNi alloy films with perpendicular magnetic anisotropy studied through 57Fe nuclear probes

    International Nuclear Information System (INIS)

    The local structure and magnetism of FeNi alloy films prepared by alternate deposition of Fe and Ni monatomic layers, where perpendicular magnetic anisotropy has been observed, were investigated through 57Fe nuclear probes using Mössbauer spectroscopy. It was confirmed that the films are composed of L10-type ordered FeNi phase and A1-type disordered FeNi phase. For the films grown at 40–70 °C, which have no perpendicular anisotropy, the A1-disordered phase is dominant, whereas for the films grown at 100–190 °C, which have a stronger perpendicular anisotropy, the relative amount of the L10-ordered phase reaches 40% or more. It was clearly shown that the magnetic anisotropy of these films is strongly correlated with the local environments of Fe in the films. The results imply that if a further increase in the ratio of the L10-ordered phase is successfully achieved, one would obtain films with a stronger magnetic anisotropy applicable to perpendicular magnetic recording. (paper)

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

    Science.gov (United States)

    Brown, B Alex; Larsen, A C

    2014-12-19

    A strong enhancement at low γ-ray energies has recently been discovered in the γ-ray strength function of ^{56,57}Fe. In this work, we have for the first time obtained theoretical γ decay spectra for states up to ≈8  MeV in excitation for ^{56,57}Fe. We find large B(M1) values for low γ-ray energies that provide an explanation for the experimental observations. The role of mixed E2 transitions for the low-energy enhancement is addressed theoretically for the first time, and it is found that they contribute a rather small fraction. Our calculations clearly show that the high-ℓ(=f) diagonal terms are most important for the strong low-energy M1 transitions. As such types of 0ℏω transitions are expected for all nuclei, our results indicate that a low-energy M1 enhancement should be present throughout the nuclear chart. This could have far-reaching consequences for our understanding of the M1 strength function at high excitation energies, with profound implications for astrophysical reaction rates.

  8. Moessbauer-spectroscopic study of structure and magnetism of the exchange-coupled layer systems Fe/FeSn{sub 2}, and Fe/FeSi/Si and the ion-implanted diluted magnetic semiconductor SiC(Fe); Moessbauerspektroskopische Untersuchung von Struktur und Magnetismus der austauschgekoppelten Schichtsysteme Fe/FeSn{sub 2} und Fe/FeSi/Si und des ionenimplantierten verduennten magnetischen Halbleiters SiC(Fe)

    Energy Technology Data Exchange (ETDEWEB)

    Stromberg, Frank

    2009-07-07

    In line with this work the structural and magnetic properties of the exchange coupled layered systems Fe/FeSn{sub 2} and Fe/FeSi/Si and of the Fe ion implanted diluted magnetic semiconductor (DMS) SiC(Fe) were investigated. The main measuring method was the isotope selective {sup 57}Fe conversion electron Moessbauer spectroscopy (CEMS), mostly in connection with the {sup 57}Fe tracer layer technique, in a temperature range from 4.2 K to 340 K. Further measurement techniques were X-ray diffraction (XRD), electron diffraction (LEED, RHEED), SQUID magnetometry and FMR (Ferromagnetic Resonance). In the first part of this work the properties of thin AF FeSn{sub 2}(001) films and of the exchange-bias system Fe/FeSn{sub 2}(001) on InSb(001) were investigated. With the application of {sup 57}Fe-tracer layers and CEMS both the Fe-spin structure and the temperature dependence of the magnetic hyperfine field (B{sub hf}) of FeSn{sub 2} could be examined. The evaporation of Fe films on the FeSn{sub 2} films produced in the latter ones a high perpendicular spin component at the Fe/FeSn{sub 2} interface. In some distance from the interface the Fe spins rotate back into the sample plane. Furthermore {sup 57}Fe-CEMS provided a correlation between the absolute value of the exchange field vertical stroke He vertical stroke and the amount of magnetic defects within the FeSn{sub 2}. Temperature dependent CEMS-measurements yielded informations about the spin dynamics within the AF. The transition temperatures T{sub B}{sup *}, which were interpreted as superparamagnetic blocking temperatures, obtain higher values compared to the temperatures T{sub B} of the exchange-bias effect, obtained with magnetometry measurements. The second part of this work deals with the indirect exchange coupling within Fe/FeSi/Si/FeSi/Fe multilayers and FeSi diffusion barriers. The goal was to achieve Fe free Si interlayers. The CEMS results show that starting from a thickness of t{sub FeSi}=10-12 A of the

  9. Design of the MsAa-4 Moessbauer Spectrometer

    International Nuclear Information System (INIS)

    An entirely new Moessbauer spectrometer MsAa-4 is currently being under design and construction. New features as compared to the basic features of the previous generation MsAa-3 spectrometer could be summarized as follows. Completely digital processing of the γ-ray detector signal beyond the Gaussian shape filter/amplifier is to be implemented. The spectrometer is going to be able to accommodate external multiple detector heads. Up to 128 γ-ray spectra in 16384 channels of 32-bit each and up to 512 Moessbauer spectra in 4096 channels of 32-bit each could be collected simultaneously, provided the proper external multiple detector head is used. The count-rate per single detector is limited to about 105 counts per second in total. Improved precision of the reference function from 12-bit to 16-bit is to be provided. The reference function is stored in 8192 channels per a complete cycle. Addition of the random noise to the reference corner prism of the Michelson-Morley calibration interferometer is to be introduced to avoid spurious fringes due to the phase lock-up. An integrated universal temperature controller being able to use a variety of the temperature sensors is to be interconnected properly with the spectrometer. The spectrometer is now a stand-alone network device as it is equipped with the Ethernet connection to the outside world. Fast and high precision digital oscilloscope is to be incorporated to the spectrometer as the intrinsic unit. This oscilloscope could monitor signals at various crucial points of the internal spectrometer electronics. Modular design and use of the strict standards allows easy reconfiguration for other applications than Moessbauer spectroscopy.

  10. Inelastic scattering in condensed matter with high intensity Moessbauer radiation

    Energy Technology Data Exchange (ETDEWEB)

    Yelon, W.B.; Schupp, G.

    1990-10-01

    We give a progress report for the work which has been carried out in the last three years with DOE support. A facility for high-intensity Moessbauer scattering is now fully operational at the University of Missouri Research Reactor (MURR) as well as facility at Purdue, using special isotopes produced at MURR. High precision, fundamental Moessbauer effect studies have been carried out using scattering to filter the unwanted radiation. These have led to a new Fourier transform method for describing Moessbauer effect (ME) lineshape and a direct method of fitting ME data to the convolution integral. These methods allow complete correction for source resonance self absorption (SRSA) and the accurate representation of interference effects that add an asymmetric component to the ME lines. We have begun applying these techniques to attenuated ME sources whose central peak has been attenuated by stationary resonant absorbers, to more precisely determine interference parameters and line-shape behavior in the resonance asymptotic region. This analysis is important to both the fundamental ME studies and to scattering studies for which a deconvolution is essential for extracting the correct recoilless fractions and interference parameters. A number of scattering studies have been successfully carried out including a study of the thermal diffuse scattering in Si, which led to an analysis of the resolution function for gamma-ray scattering. Also studied was the anharmonic motion in Na and the satellite reflection Debye-Waller factor in TaS{sub 2}, which indicate phason rather than phonon behavior. We have begun quasielastic diffusion studies in viscous liquids and current results are summarized. These advances, coupled to our improvements in MIcrofoil Conversion Electron spectroscopy lay the foundation for the proposed research outlined in this request for a three-year renewal of DOE support.

  11. Gamma scattering in condensed matter with high intensity Moessbauer radiation

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    We give a progress report for the work which has been carried out in the last three years with DOE support. A facility for high-intensity Moessbauer scattering is now fully operational at the University of Missouri Research Reactor (MURR) as well as a facility at Purdue, using special isotopes produced at MURR. High precision, fundamental Moessbauer effect studies have been carried out using scattering to filter the unwanted radiation. These have led to a new Fourier transform method for describing Moessbauer effect (ME) lineshape and a direct method of fitting ME data to the convolution integral. These methods allow complete correction for source resonance self absorption (SRSA) and the accurate representation of interference effects that add an asymmetric component to the ME lines. We have begun applying these techniques to attenuated ME sources whose central peak has been attenuated by stationary resonant absorbers, to more precisely determine interference parameters and line-shape behavior in the resonance asymptotic region. This analysis is important to both the fundamental ME studies and to scattering studies for which a deconvolution is essential for extracting the correct recoilless fractions and interference parameters. A number of scattering studies have been successfully carried out including a study of the thermal diffuse scattering in Si, which led to an analysis of the resolution function for gamma-ray scattering. Also studied was the anharmonic motion in Na and the satellite reflection Debye-Waller factor in TaS{sub 2}, which indicate phason rather than phonon behavior. We have begun quasielastic diffusion studies in viscous liquids and current results are summarized. These advances, coupled to our improvements in MIcrofoil Conversion Electron spectroscopy lay the foundation for the proposed research outlined in this request for a three-year renewal of DOE support.

  12. Moessbauer studies on impactites from Lonar impact crater

    Energy Technology Data Exchange (ETDEWEB)

    Verma, H. C., E-mail: hcverma@iitk.ac.in [I I T Kanpur, Department of Physics (India); Misra, S., E-mail: misrasaumitra@gmail.com [Indian Institute of Geomagnetism (India); Shyam Prasad, M., E-mail: shyam@nio.org [National Institute of Oceanography, Geological Oceanography Division (India); Bijlani, N.; Tripathi, A., E-mail: rpt2002@sify.com [J.N.V. University, Department of Physics (India); Newsom, Horton, E-mail: newsom@unm.edu [University of New Mexico, Institute of Meteoritics and Department of Earth and Planetary Sciences (United States)

    2008-09-15

    Iron mineralogy has been studied using Moessbauer spectroscopy on eight glassy impactite samples from different parts of the Lonar Crater Rim Region. Distinct changes are observed when compared to the host basaltic samples. Significant amount of Fe{sup 3+} phase is observed in the impactite samples whereas this phase is known to be almost absent in the basalt. Besides this we have a strong Fe{sup 2+} doublet showing up corresponding to the main iron-containing mineral. The Moessbauer results are very similar to those with glasses from Ries crater which is also believed to have formed by meteoritic impact but on nonbasaltic rock bed. Besides the glassy samples, we also study some spherules found in the crater region and some fine glassy particles on the surfaces of melt impact bombs. These contain a good amount of magnetically ordered phase, most likely nanosize hematite. Interestingly, part of it is strongly attracted by a magnet and part of it is not. But both parts show a significantly strong six-line component corresponding to hematite.

  13. Magnetic and Moessbauer Studies of Quaternary Argentine Loessic Soils and Paleosols

    Energy Technology Data Exchange (ETDEWEB)

    Mercader, R. C., E-mail: mercader@fisica.unlp.edu.ar; Sives, F. R. [Universidad Nacional de La Plata, Departamento de Fisica, IFLP, Facultad de Ciencias Exactas (Argentina); Imbellone, P. A. [Universidad Nacional de La Plata, Instituto de Geomorfologia y Suelos (Argentina); Vandenberghe, R. E. [Ghent University, NUMAT, Department of Subatomic and Radiation Physics (Belgium)

    2005-02-15

    This paper is a review of the current status about the remaining problems that are found in the investigation of the Quaternary Argentine soils and loessic sediments, and the way that Moessbauer studies can assist in solving them. There are two main types of investigations that make use of the magnetic response of the samples to correlate them with information gathered by other methods. On the one hand, there is the stratigraphic and chronological research, which is of importance from the geological and paleontological points of view. On the other hand, the paleoclimatic records, of significance toward a possible model of the past climate, are also studied because of their close relation to the sediments history. However, there is not yet a model that can tell the difference between the modifications due to the climatic conditions at the time when the soils were buried from processes that occurred after burial. Some examples are given that show that Moessbauer studies can be applied with a certain degree of success when cross-checked with magnetic measurements toward understanding the processes that occurred in alluvial B (paleosols) and C horizons (loess) from the eastern part of Buenos Aires Province. Although the application of Moessbauer studies to hydromorphic processes in soils is not straightforward, there are cases in which Moessbauer spectroscopy, if applied properly and correlated with other techniques, is able to characterize the type of iron oxides existing in the materials and thus assist theories about its origin and history.

  14. Mössbauer study of exogenous iron redistribution between the brain and the liver after administration of {sup 57}Fe{sub 3}O{sub 4} ferrofluid in the ventricle of the rat brain

    Energy Technology Data Exchange (ETDEWEB)

    Polikarpov, Dmitry, E-mail: polikarpov.imp@gmail.com [National Research Center “Kurchatov Institute”, Moscow (Russian Federation); Russian National Research Medical University named after N.I.Pirogov, Moscow (Russian Federation); Gabbasov, Raul; Cherepanov, Valery [National Research Center “Kurchatov Institute”, Moscow (Russian Federation); Loginova, Natalia; Loseva, Elena [Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow (Russian Federation); Nikitin, Maxim [Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow (Russian Federation); Yurenia, Anton; Panchenko, Vladislav [National Research Center “Kurchatov Institute”, Moscow (Russian Federation); Lomonosov Moscow State University, Moscow (Russian Federation)

    2015-04-15

    Iron clearance pathways after the injection of {sup 57}Fe{sub 3}O{sub 4}-based ferrofluid into the brain ventricles were studied histologically and by Mössbauer spectroscopy. It was found that the dextran coated initial nanobeads of the ferrofluid disintegrated in the brain into separate superparamagnetic nanoparticles within a week after the injection. The exogenous iron completely exited all ventricular cavities of the brain within a week after the injection but remained in the white matter for months. Kupffer cells with the exogenous iron appeared in the rat liver 2 hours after the injection. Their concentration reached its maximum on the third day and dropped to zero within a week. The exogenous iron appeared in the spleen a week after the injection and remained in the spleen for months.

  15. Mössbauer study of exogenous iron redistribution between the brain and the liver after administration of 57Fe3O4 ferrofluid in the ventricle of the rat brain

    International Nuclear Information System (INIS)

    Iron clearance pathways after the injection of 57Fe3O4-based ferrofluid into the brain ventricles were studied histologically and by Mössbauer spectroscopy. It was found that the dextran coated initial nanobeads of the ferrofluid disintegrated in the brain into separate superparamagnetic nanoparticles within a week after the injection. The exogenous iron completely exited all ventricular cavities of the brain within a week after the injection but remained in the white matter for months. Kupffer cells with the exogenous iron appeared in the rat liver 2 hours after the injection. Their concentration reached its maximum on the third day and dropped to zero within a week. The exogenous iron appeared in the spleen a week after the injection and remained in the spleen for months

  16. Moessbauer Studies in Chinese Archaeology: A Review

    Energy Technology Data Exchange (ETDEWEB)

    Hsia Yuanfu; Huang Hongbo [Nanjing University, Department of Physics (China)

    2003-09-15

    The Moessbauer effect has been applied to a wide variety of objects related to Chinese archaeology. Besides ceramic artifacts, materials like porcelain, glazes, bronzes, ancient coins, ancient mineral drugs, and even fossils were studied. This article reviews these applications with particular emphasis on the study of the famous terracotta warriors and horses of the Qin Dynasty.

  17. Moessbauer study of mixed crystalline (Eu sub 2 O sub 3) sub x (Fe sub 2 O sub 3) sub 1 sub - sub x (x=0.45)

    CERN Document Server

    Kim, J G; Kim, Y H; Kim, E C

    1998-01-01

    The crystallography and the temperature dependence of the Moessbauer parameters of mixed crystalline (Eu sub 2 O sub 3) sub x (Fe sub 2 O sub 3) sub 1 sub - sub x (x=0.45) were studied by the method of X-ray diffraction at room temperature and Moessbauer spectroscopy within the temperature range from liquid nitrogen temperature to 540 K. The X-ray diffraction pattern of the sample showed the coexistence of cubic and orthorhombic crystal phases. The Moessbauer spectrum of 540 K indicated a crystal phase which was in good agreement with the X-ray result and gave no indication, within the experimental error, of any other crystal phases. By analyzing the temperature dependence of the Moessbauer parameters by using the spin-wave theory and the Debye model, useful result were obtained for examining the changes in the physical properties in mixed crystalline system.

  18. Synthesis and infrared and moessbauer spectrometric study of europium(3) complexes with some derivatives of semi- and thiosemicarbazide

    International Nuclear Information System (INIS)

    Europium complexes with semi- and thiosemicarbazidediacetic acid, as well as thiosemicarbazones of glyoxylic, pyruvic and benzoyl formic acids have been investigated by the methods of infrared and the Moessbauer spectroscopy. It is established that the resonance absorption effect constitutes a value of one order and testifies to their polymeric structure

  19. Theoretical study of Moessbauer hyperfine parameters of Fe bound to ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Terra, J.; Guenzburger, D.

    1995-01-01

    The first-principles Discrete Variational method was employed to study the species formed by the interaction of an Fe atom and ammonia. Total energy calculations were performed for several configurations. The hyperfine parameters isomer shift, quadrupole splitting and magnetic hyperfine were calculated for the ground state found, and compared to reported experimental values obtained by Moessbauer spectroscopy in frozen ammonia. (author). 14 refs, 1 tab.

  20. Estimation of natural radiation dose and of the age of ancient pottery by Moessbauer effect

    International Nuclear Information System (INIS)

    The effect of natural radioactive radiation on the Moessbauer Effect (ME) spectra of ancient Egyptian pottery samples of known age has been studied. An empirical relation between the intensity ratio of the non-magnetic peaks and the dose has been established. It is suggested that this relation can be used for dating of ancient potteries as a new application of the ME spectroscopy in archaeology

  1. Electron magnetic resonance and Moessbauer studies on iron doped SnO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Grecu, Maria Nicoleta, E-mail: mgrecu@infim.ro; Constantinescu, Serban Gr.; Ghica, Daniela; Tarabasanu-Mihaila, Doina; Diamandescu, Lucian [National Institute of Materials Physics (Romania)

    2012-03-15

    Iron doped (0.25-7.5% molar) hydrothermal nano-SnO{sub 2} was characterized by electron magnetic resonance (EMR) and Moessbauer spectroscopies. Only a small fraction of transition metal ions are in magnetic ordered state, contrary to the similar crystallographic compound TiO{sub 2}. Temperature dependences of spectra suggest that by increasing iron concentration, or annealing temperature, iron ions migrate to nanoparticles surfaces forming disordered iron oxides.

  2. TEMPERATURE DEPENDENCE OF 57Fe-MÖSSBAUER SPECTRA FOR A 〖〖Fe〗_Fc^II-Fe〗_tpy^II-〖Fe〗_Fc^II TRINUCLEAR SYSTEM

    Directory of Open Access Journals (Sweden)

    Dumitru Sirbu

    2015-06-01

    Full Text Available 57Fe Mӧssbauer spectra were recorded for 1'-terpyridine ferrocenecarboxylic acid and [bis(1'-terpyridine ferrocenecarboxylic acid Fe(II]2+ in the temperature range 7 – 293 K. The temperature dependence of the Quadrupole Splitting, Isomer Shift and Debye-Waller factor are discussed. The Debye temperature for the iron nuclei in the investigated compounds was determined.

  3. Moessbauer analysis of Yuan dynasty Jun porcelain glaze

    International Nuclear Information System (INIS)

    The firing temperature dependence has been studied of the quadrupole splitting (QS) and isomeric shift (IS) for the structure iron in Yuan dynasty Jun porcelain glaze and simulated ancient blue Jun glaze by Moessbauer spectroscopy. The QS and IS for the two kinds of glaze were compared. Firing temperature for the former was determined to be above 1250 C deg, and coordination number for Fe2+ and Fe3+ was four. It has been found that the latter has a broad process of dehydroxylation and vitrification, which may be profitable to form the unique glaze colour of Jun porcelain. When firing temperature is above 1200 C deg, coordination number for the latter becomes 4 too

  4. Moessbauer studies of hemoglobin in erythrocytes exposed to neutron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Niemiec, Katarzyna; Kaczmarska, Magdalena; Buczkowski, Mateusz [AGH University, Faculty of Physics and Computer Science, Department of Medical Physics and Biophysics (Poland); Fornal, Maria [Collegium Medicum, Jagiellonian University, Department of Internal Medicine and Gerontology (Poland); Pohorecki, Wladyslaw [AGH University, Faculty of Energy and Fuels (Poland); Matlak, Krzysztof; Korecki, Jozef [AGH University, Faculty of Physics and Computer Science, Department of Solid State Physics (Poland); Grodzicki, Tomasz [Collegium Medicum, Jagiellonian University, Department of Internal Medicine and Gerontology (Poland); Burda, Kvetoslava, E-mail: kvetoslava.burda@fis.agh.edu.pl [AGH University, Faculty of Physics and Computer Science, Department of Medical Physics and Biophysics (Poland)

    2012-03-15

    We studied radiation effects on the stability of various states of hemoglobin (Hb) in red blood cells (RBC) irradiated with a very low dose of neutron rays, 50 {mu}Gy. We investigated RBCs isolated from blood of healthy donors. Moessbauer spectroscopy was applied to monitor different forms of Hb. Our results show, for the first time, that oxyhemoglobin (OxyHb) and deoxyhemoglobin (DeoxyHb) are two Hb forms sensitive to such a low neutron radiation. Both Hbs change into a new Hb form (Hb{sub irr}). Additionally, OxyHb transfers into HbOH/H{sub 2}O, which under our experimental conditions is resistant to the action of neutron rays.

  5. Electrical resistivity and Moessbauer effect investigations on Tb{sub 0.27}Dy{sub 0.73}(Mn{sub 1-x}Fe{sub x}){sub 2} intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Bodnar, W. [Faculty of Physics and Applied Computer Science, AGH, Al. Mickiewicza 30, 30-059 Krakow (Poland); Stoch, P. [Institute of Atomic Energy, 05-400 Swierk-Otwock (Poland); Faculty of Materials Science and Ceramics, AGH, Al. Mickiewicza 30, 30-059 Krakow (Poland); Chmist, J. [Faculty of Physics and Applied Computer Science, AGH, Al. Mickiewicza 30, 30-059 Krakow (Poland); Pszczola, J., E-mail: pszczola@agh.edu.p [Faculty of Physics and Applied Computer Science, AGH, Al. Mickiewicza 30, 30-059 Krakow (Poland); Zachariasz, P.; Suwalski, J. [Institute of Atomic Energy, 05-400 Swierk-Otwock (Poland)

    2010-09-03

    This paper concerns synthesis, X-ray analysis (300 K), electrical resistivity and {sup 57}Fe Moessbauer effect studies (4.2 K) of complete Tb{sub 0.27}Dy{sub 0.73}(Mn{sub 1-x}Fe{sub x}){sub 2} intermetallic series, with a borderline compound Tb{sub 0.27}Dy{sub 0.73}Fe{sub 2} known as Terfenol-D. A cubic Laves phase Fd3m of the MgCu{sub 2}-type is observed across the series. The lattice parameter decreases parabolically with x. Electrical resistivity was measured in a wide temperature region across the Tb{sub 0.27}Dy{sub 0.73}(Mn{sub 1-x}Fe{sub x}){sub 2} series and the parameters which characterize resistivity dependence on temperature, including Debye temperature, were determined. Residual, phonon and magnetic contributions were separated from electrical resistivity. The magnetic contribution to electrical resistivity was applied to estimate Curie temperatures. The Curie temperature increases significantly with x. {sup 57}Fe Moessbauer effect measurements for the Tb{sub 0.27}Dy{sub 0.73}(Mn{sub 1-x}Fe{sub x}){sub 2} intermetallic system evidence an [1 0 0] easy axis of magnetization. Mn/Fe substitution introduces a local area, at sub-nanoscale, with different Mn/Fe neighbourhoods of the tested {sup 57}Fe atoms. Hyperfine interaction parameters, an isomer shift, a magnetic hyperfine field and a quadrupole interaction parameter were determined from the spectra both for the local neighbourhood area and, as averaged values, for the sample as bulk. The average magnetic hyperfine field increases parabolically with x. The correlation between Curie temperatures and magnetic hyperfine fields is discussed.

  6. Magnetic transitions in La{sub 1x}Y{sub x}Mn{sub 2}Si{sub 2} - Moessbauer effect study

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, X.L.; Campbell, S.J. [Australian Defence Academy, Canberra, ACT (Australia). School of Physics, University College; Cadogan, J.M.; Li, H.S. [The University of New South Wales, Sydney, NSW (Australia). School of Physics

    1996-12-31

    Investigation of ternary rare-earth manganese silicides (RMn{sub 2S}i{sub 2}) with the tetragonal ThCr{sub 2}Si{sub 2} structure (space group I4/mmm) continues to attract a great deal of interest due to the large variety of magnetic behaviours which they exhibit. The set of La{sub 1{sub x}}Y{sub x}Mn{sub 2}Si{sub 2}({sup 57}Fe) samples (x = 0.00, 0.10, 0.15, 0.20, 0.25, 0.30, 0.50 and 1.00) was prepared using conventional argon-arc melting and examined by x-ray diffraction. One of the striking features of our results is that the ordering temperatures of the compounds with low Y concentration (x < 0.3) are significantly higher than previously reported values, while, also at low Y concentrations, a transferred magnetic hyperfine field associated with {sup 57}Fe atoms on the Si sites is found to persist well above Tc. These observations are in general agreement with the new findings of a high temperature antiferromagnetic phase in LaMn{sub 2}Si{sub 2}. Magnetic phase transitions (as indicated by distinct temperature- and concentration- dependent anomalies in the hyperfine magnetic field and quadrupole splitting ), have been determined for the La{sub 1-x}Y{sub x}Mn {sub 2}Si{sub 2}({sup 57}Fe) samples, leading to clarification of the magnetic phase diagram. Around the critical concentration (x{approx}0.2) which separates the predominant antiferromagnetic and ferromagnetic regions, the Moessbauer spectra exhibit broadened lines indicative of a spin glass-like or frustrated magnetic system Truncated abstract. 3 refs.

  7. Moessbauer Studies of Implanted Impurities in Solids

    CERN Multimedia

    2002-01-01

    Moessbauer studies were performed on implanted radioactive impurities in semiconductors and metals. Radioactive isotopes (from the ISOLDE facility) decaying to a Moessbauer isotope were utilized to investigate electronic and vibrational properties of impurities and impurity-defect structures. This information is inferred from the measured impurity hyperfine interactions and Debye-Waller factor. In semiconductors isoelectronic, shallow and deep level impurities have been implanted. Complex impurity defects have been produced by the implantation process (correlated damage) or by recoil effects from the nuclear decay in both semiconductors and metals. Annealing mechanisms of the defects have been studied. \\\\ \\\\ In silicon amorphised implanted layers have been recrystallized epitaxially by rapid-thermal-annealing techniques yielding highly supersaturated, electrically-active donor concentrations. Their dissolution and migration mechanisms have been investigated in detail. The electronic configuration of Sb donors...

  8. VSM and Moessbauer study of nanostructured hematite

    International Nuclear Information System (INIS)

    In the present work, we have synthesized nanostructured hematite samples using chemical precipitation method. The crystal structure and the grain size of the samples were studied using XRD. The zero field cooled and field cooled magnetization curves of the samples were recorded in the temperature range from 300 to 10 K. The variations of Morin transition temperature and blocking temperature with the grain size of the samples were investigated. The hysterics curves of the samples were recorded and the samples showed a superparamagnetic nature at room temperature whereas, at 10 K the samples showed open hysteresis curves. The sample with smaller grain size showed higher value of coercivity compared to samples with larger grain size. Moessbauer spectra of the samples were recorded and the grain size dependence on Moessbauer parameters was investigated.

  9. Moessbauer spectrometry applied to the study of laboratory samples made of iron gall ink

    Energy Technology Data Exchange (ETDEWEB)

    Burgaud, C. [Centre de Recherche pour la Conservation des Collections, MNHN, CNRS, MCC, 36 rue Geoffroy Saint Hilaire, CP 21, Paris (France); Universite de La Rochelle, LEMMA, Batiment Marie Curie, La Rochelle Cedex 01 (France); Rouchon, V. [Centre de Recherche pour la Conservation des Collections, MNHN, CNRS, MCC, 36 rue Geoffroy Saint Hilaire, CP 21, Paris (France); Refait, P. [Universite de La Rochelle, LEMMA, Batiment Marie Curie, La Rochelle Cedex 01 (France); Wattiaux, A. [Universite de Bordeaux 1, Institut de Chimie de la Matiere Condensee de Bordeaux, CNRS, Pessac Cedex (France)

    2008-07-15

    Iron gall inks consist of a mixture of vitriol, gall nut extracts and gum arabic. The association of the iron(II) sulphate present in vitriols, and the carboxyphenolic acids present in gall nut extracts leads to the formation of dark coloured iron-based precipitates. In order to evaluate the percentage of iron used in the formation of these precipitates, transmission Moessbauer spectroscopy (MS) measurements were performed on laboratory made inks at room temperature. These were completed by X-ray diffraction (XRD), and Raman spectroscopy measurements. The samples consisted of several solutions of iron(II) sulphate, gallic acid and gum arabic. After evaporation, the residues were analysed. Up to eight different Moessbauer signatures were detected, most of them correlated to iron sulphates. The Moessbauer signature of the iron gall precipitate was also isolated. It is not distinctly defined and may overlap with the signatures of iron(III) hydroxy-sulphates, such as jarosite or copiapite. Raman spectrometry then proved to be a useful complementary technique for the identification of the precipitate. (orig.)

  10. Iron in Alzheimer's and Control Hippocampi - Moessbauer, Atomic Absorption and ELISA Studies

    International Nuclear Information System (INIS)

    Alzheimer disease is a neurodegenerative process of unknown mechanism taking place in a part of the brain - hippocampus. Oxidative stress and the role of iron in it is one of the suggested mechanisms of cells death. In this study several methods were used to assess iron and iron binding compounds in human hippocampus tissues. Moessbauer spectroscopy was used for identification of the iron binding compound and determination of total iron concentration in 12 control and one Alzheimer disease sample of hippocampus. Moessbauer parameters obtained for all samples suggest that most of the iron is ferritin-like iron. The average concentration of iron determined by Moessbauer spectroscopy in control hippocampus was 45 ± 10 ng/mg wet tissue. The average concentration of iron in 10 Alzheimer disease samples determined by atomic absorption was 66 ± 13 ng/mg wet tissue. The concentration of H and L chains of ferritin in 20 control and 10 AD hippocampi was assessed with enzyme-linked immuno-absorbent assay. The concentration of H and L ferritin was higher in Alzheimer disease compared to control (19.36 ± 1.51 vs. 5.84 ± 0.55 ng/μg protein for H, and 1.39 ± 0.25 vs. 0.55 ± 0.10 for L). This 3-fold increase of the concentration of ferritin is accompanied by a small increase of the total iron concentration. (authors)

  11. Fourier evaluation of broad Moessbauer spectra

    International Nuclear Information System (INIS)

    It is shown by the Fourier analysis of broad Moessbauer spectra that the even part of the distribution of the dominant hyperfine interaction (hyperfine field or quadrupole splitting) can be obtained directly without using least-square fitting procedures. Also the odd part of this distribution correlated with other hyperfine parameters (e.g. isomer shift) can be directly determined. Examples for amorphous magnetic and paramagnetic iron-based alloys are presented. (author)

  12. A Moessbauer study of an ancient pottery figure (Western-Han Dynasty)

    International Nuclear Information System (INIS)

    The grey pottery figure manufactured in the Western-Han Dynasty (175-118 B.C.) and the clay gathered from the same site of Beidongshan in Xuzhou have been studied by X-ray Diffration (XRD), X-ray Fluorescence (XRF), and Moessbauer spectroscopy. They were simultaneously fired under the same conditions in different atmospheres at various temperature up to 1100degC. This study deals with the original firing atmosphere, original firing temperature and its provenance. The information mentioned above can be inferred from the method of the refiring pottery and the firing clay. The results of the original firing temperature deduced from both of them are in goodself agreement. It is found that the values of the Moessbauer parameters for the unrefired pottery figure are approximately the same as those for the clay fired at 950degC for five hours in a reduced atmosphere. The XRF analysis confirmed the locality of this pottery figure. (orig.)

  13. Moessbauer Study of Ceramic Finds from the Galeria de las Ofrendas, Chavin de Huantar

    Energy Technology Data Exchange (ETDEWEB)

    Lumbreras, L. G. [Museo Nacional de Antropologia (Peru); Gebhard, R. [Archaeologische Staatssammlung Muenchen (Germany); Haeusler, W. [Technische Universitaet Muenchen, Physik-Department E15 (Germany); Kauffmann-Doig, F. [Universidad Peruana de Ciencias Aplicadas (UPC) (Peru); Riederer, J. [Rathgen-Forschungslabor (Germany); Sieben, G.; Wagner, U. [Technische Universitaet Muenchen, Physik-Department E15 (Germany)

    2003-09-15

    Ceramic finds from the Galeria de las Ofrendas at Chavin de Huantar and surface finds from the settlement of Chavin were characterised by combining the results of archaeological typology with archaeometric studies using neutron activation analysis, Moessbauer spectroscopy, X-ray diffraction and thin-section microscopy. Sherds from the pyramid Tello are included in the study as representative of local material. The analyses show that the vessels were made from different raw materials and that different firing procedures were used in their production. Sherds of certain styles largely exhibit similar types of Moessbauer patterns and in many instances also have similar element compositions. This supports the archaeological notion that the vessels were brought to Chavin from the provinces, perhaps on the occasion of a festivity.

  14. Effect of nanocrystallization on the electrical conductivity enhancement and Moessbauer hyperfine parameters of iron based glasses

    Energy Technology Data Exchange (ETDEWEB)

    El-Desoky, M.M., E-mail: mmdesoky@gmail.com [Department of Physics, Faculty of Education, Suez Canal University, Al-Arish 45511, North Sinaa (Egypt); Ibrahim, F.A. [Department of Physics, Faculty of Education, Suez Canal University, Al-Arish 45511, North Sinaa (Egypt); Mostafa, A.G.; Hassaan, M.Y. [Department of Physics, Faculty of Science, Al-Azhar University, Nasr City 11884, Cairo (Egypt)

    2010-09-15

    Selected glasses of Fe{sub 2}O{sub 3}-PbO{sub 2}-Bi{sub 2}O{sub 3} system have been transformed into nanomaterials by annealing at temperature close to crystallization temperature (T{sub c}) for 1 h. The effects of the annealing of the present samples on its structural and electrical properties were studied by Moessbauer spectroscopy, transmission electron micrograph (TEM), differential scanning calorimeter (DSC) and dc conductivity ({sigma}). Moessbauer spectroscopy was used in order to determine the states of iron and its hyperfine structure. The effect of nanocrystalization on the Moessbauer hyperfine parameters did not exhibit significant modifications in present glasses. However, in case of glass ceramic nanocrystals show a distinct decrease in the quadrupole splitting ({Delta}) is observed, reflecting an evident decrease in the distortion of structural units like FeO{sub 4} units. In general, the Moessbauer parameters of the nano-crystalline phase exhibit tendency to increase with PbO{sub 2} content. TEM of as-quenched glasses confirm the homogeneous and essentially featureless morphology. TEM of the corresponding glass ceramic nanocrystals indicates nanocrystals embedded in the glassy matrix with average particle size of about 32 nm. The crystallization temperature (T{sub c}) was observed to decrease with PbO{sub 2} content. The glass ceramic nanocrystals obtained by annealing at T{sub c} exhibit improvement of electrical conductivity up to four orders of magnitude than the starting glasses. This considerable improvement of electrical conductivity after nanocrystallization is attributed to formation of defective, well-conducting phases 'easy conduction paths' along the glass-crystallites interfaces.

  15. Moessbauer studies of superparamagnetic ferrite nanoparticles for functional application

    Energy Technology Data Exchange (ETDEWEB)

    Mazeika, K., E-mail: kestas@ar.fi.lt; Jagminas, A.; Kurtinaitiene, M. [SSRI Center for Physical Sciences and Technology (Lithuania)

    2013-04-15

    Nanoparticles of CoFe{sub 2}O{sub 4} and MnFe{sub 2}O{sub 4} prepared for functional applications in nanomedicine were studied using Moessbauer spectrometry. Superparamagnetic properties of nanoparticles of different size and composition were compared applying collective excitations and multilevel models for the description of the Moessbauer spectra.

  16. Moessbauer Effect applications using intense radioactive ion beams

    International Nuclear Information System (INIS)

    The Moessbauer Effect is reviewed as a promising tool for a number of new solid state studies when used in combination with radioactive beam/implantation facilities. The usual Moessbauer Effect involves long-lived radioactive parents (days to years) that populate low-lying nuclear excited states that subsequently decay to the ground state. Resonant emission/absorption of recoil-free gamma rays from these states provide information on a number of properties of the host materials. Radioactive ion beams (RIB) produced on-line allow new Moessbauer nuclei to be studied where there is no suitable parent. The technique allows useful sources to be made having extremely low local concentrations. The ability to separate the beams in both Z and A should provide high specific activity ''conventional'' sources, a feature important in some applications such as Moessbauer studies in diamond anvil high pressure cells. Exotic chemistry is proposed using RIB and certain Krypton and Xenon Moessbauer isotopes

  17. Moessbauer study of reordering of cold-worked iron-aluminum alloys

    International Nuclear Information System (INIS)

    The process of atomic reordering of cold-worked Fe-Al alloys containing about 25 to 35at%Al during isothermal annealing has been investigated using Moessbauer spectroscopy. Moessbauer spectra from the specimens filed and annealed were observed at each stage of annealing and analyzed to obtain the distribution function of the internal magnetic field in the alloys. Furthermore, for the alloy with 24.9at%Al the information on the nearest neighbor configurations of constituent atoms could also be obtained directly from the Moessbauer spectra by assuming the Gaussian distribution function of hyperfine field acting on iron atoms with various number of iron neighbors, and the detailed process of reordering was clarified. The alloy with the DO3 type of order, which is either weakly magnetic or nonmagnetic depending on the composition, became strongly magnetic by filing. The alloy as-filed was much complicated in structure and the atomic configuration seemed to be distinctly different from that of the thermally disordered state. The alloy reordered very slowly in the course of annealing by way of perfect disorder and B2 type of order. The ordered alloy with B2 symmetry, which is nonmagnetic, was partially disordered by filing and changed into a weakly magnetic state. The alloy recovered promptly to its initial state by low temperature annealing. (author)

  18. Moessbauer study on atomic reordering of cold-worked iron-aluminum alloys

    International Nuclear Information System (INIS)

    The process of atomic reordering of cold-worked Fe-Al alloys in the composition range from about 25 to 35 at% Al has been investigated by means of Moessbauer spectroscopy. Moessbauer spectra for the specimens field and subsequently annealed were taken at each stage of annealing and analyzed to obtain the distribution of internal magnetic field in the alloys. Furthermore, for the alloy with 24.9 at% Al information on the neighbor configurations of constituent atoms was successfully able to be obtained directly from the Moessbauer spectra by assuming the Gaussian distribution function of internal magnetic field acting on iron atoms with various numbers of iron neighbors, and a detailed process of reordering during annealing was clarified. The ordered alloy with the DO3 type, which is either weakly magnetic or nonmagnetic depending on the composition, became strongly magnetic by cold working. The alloy as-filed was much complicated in structure, and the atomic configuration seemed to be distinctly different from that of the thermally disordered state. The alloy reordered very slowly in the course of annealing by way of the perfect disorder and the B2 type of order. The ordered alloy with the B2 symmetry, which is nonmagnetic, was partially disordered by cold working and changed into a weakly magnetic state. The alloy reordered promptly to its initial state by a relatively low temperature annealing. (author)

  19. Moessbauer study of nanocrystalline PrFeB and PrFeCrB alloys

    Energy Technology Data Exchange (ETDEWEB)

    Barra-Barrera, A.D.; Murakami, R.K.; Partiti, C.S.M.; Villas-Boas, V. E-mail: val@macbeth.if.usp.br

    2001-05-01

    Ribbons of Pr{sub 4.5}Fe{sub 77}B{sub 18.5} and Pr{sub 5}Fe{sub 74}Cr{sub 3}B{sub 18} alloys were produced by melt spinning and then annealed by flash or conventional annealing to develop enhanced-remanence nanocrystalline magnetic material. These materials were studied by magnetic measurements, X-ray diffraction and Moessbauer spectroscopy in order to understand the relationship between structural and magnetic properties. These analyses showed that the phases present in these materials are Pr{sub 2}Fe{sub 14}B, Fe{sub 3}B and {alpha}-Fe. The samples with Cr present a coercive field 50% higher than the Cr-free samples. The Moessbauer spectra were analyzed as a superposition of the well-known spectra of Pr{sub 2}Fe{sub 14}B, Fe{sub 3}B and {alpha}-Fe. The mean hyperfine magnetic field of each phase was obtained from the spectral analysis, as well as, the relative amount of each phase present. From Moessbauer results it seems that Cr atoms preferentially dissolves in the Fe{sub 3}B phase.

  20. A {sup 119}Sn Moessbauer study of heptacoordinated tin complexes with multidentate ligands

    Energy Technology Data Exchange (ETDEWEB)

    Abras, A. [Minas Gerais Univ., Belo Horizonte (Brazil). Dept. de Fisica; Sousa, G.F. de [Dept. de Quimica, Univ. Federal de Minas Gerais, Belo Horizonte (Brazil); Filgueiras, C.A.L. [Dept. de Quimica, Univ. Federal de Minas Gerais, Belo Horizonte (Brazil)

    1994-11-01

    Three novel heptacoordinated tin complexes with multidentate ligands were prepared and studied by Moessbauer spectroscopy. The complexes were identified as [MeSnCl(Hdaptsc)]Cl . MeOH, [MeSnCl(H{sub 2}dapsc)]Cl{sub 2} . 2H{sub 2}O and [ClSnCl(Hdaptsc)]Cl, where H{sub 2}daptsc = 2,6-diacetylpyridinebis (thiosemicarbazone) and H{sub 2}dapsc = 2,6-diacetylpyridinebis (semicarbazone). The structures of the first two complexes were determined by X-ray crystallography. The ligand H{sub 2}dapsc originated a fourth complex, which was characterised as [(Me{sub 2}SnCl{sub 2}){sub 2}(H{sub 2}dapsc)] in which the two Sn atoms are probably hexacoordinated, as suggested by Moessbauer data. The isomer shifts and the quadrupole splittings of the complexes are consistent with the structural interpretation, and correlate well with other literature examples and with X-ray data whenever available. The correlation between Moessbauer results and structural information is important considering the paucity of published data for heptacoordinated species. (orig.)

  1. Moessbauer studies of superexchange interactions in NiFe sub 2 O sub 4

    CERN Document Server

    Kim, S J; Kim, C S; Lee, S W

    2000-01-01

    NiFe sub 2 O sub 4 has been studied using Moessbauer spectroscopy and X-ray diffraction. The crystal was found to have a inverse cubic spinel structure with the lattice constant a sub 0 =8.326+-0.003 A. Moessbauer spectra of NiFe sub 2 O sub 4 was obtained at various absorber temperatures from 13 K to the Neel temperature. The Moessbauer spectra consisted of two sets of six lines corresponding to Fe sup + sup 3 at the tetrahedral (A) and the octahedral (B) sites. The temperature dependence of the magnetic hyperfine fields at sup 5 sup 7 Fe nuclei at the tetrahedral (A) and the octahedral (B) sites was analyzed by the Neel theory of ferrimagnetism. The intersublattice A-O-B and intrasublattice A-O-A superexchange interactions were found to be antiferromagnetic with strengths of J sub A sub - sub B =-25.0 k sub B and J sub A sub - sub A =-4.0 K sub B , respectively, while the intrasublattice B-O-B superexchange interaction is ferromagnetic with a strength J sub B sub - sub B =4.2 k sub B.

  2. Hydride bridge in [NiFe]-hydrogenase observed by nuclear resonance vibrational spectroscopy

    OpenAIRE

    Ogata, Hideaki; Krämer, Tobias; Wang, Hongxin; Schilter, David; Pelmenschikov, Vladimir; van Gastel, Maurice; Neese, Frank; Rauchfuss, Thomas B.; Gee, Leland B.; Scott, Aubrey D.; Yoda, Yoshitaka; Tanaka, Yoshihito; Lubitz, Wolfgang; Cramer, Stephen P.

    2015-01-01

    The metabolism of many anaerobes relies on [NiFe]-hydrogenases, whose characterization when bound to substrates has proven non-trivial. Presented here is direct evidence for a hydride bridge in the active site of the 57Fe-labeled fully reduced Ni-R form of Desulfovibrio vulgaris Miyazaki F (DvMF) [NiFe]-hydrogenase. A unique ‘wagging’ mode involving H− motion perpendicular to the Ni(μ-H)57Fe plane was studied using 57Fe-specific nuclear resonance vibrational spectroscopy (NRVS) and density fu...

  3. SURFACE ELECTRICAL PROPERTIES AND STRUCTURE OF YTTRIA-PARTIALLY-STABILIZED ZIRCONIA IMPLANTED WITH 57Fe IONS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Sintered plates of 5mol% yttria-partially-stabilized zirconia have been implanted at room temperature with 5×1015to 2×1017 Fe+ ions/cm2 at 140 KeV.Electrical measurement,Rutherford backscattering spectroscopy(RBS),Raman spectroscopy and X-ray photoelectron spectroscopy(XPS) have been used to study the surface electrical properties and the structure of the implanted layer before and after thermal annealing treatment in N2.

  4. Preparation, characterization, magnetic property, and Moessbauer spectra of the {beta}-FeOOH nanoparticles modified by nonionic surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y.X. [Department of Chemistry, Chemistry and Molecule Engineering College, East China University of Science and Technology, Meilong Road 130, Xuhui District, Shanghai 200237 (China); State Key Laboratory of Coordination Chemistry, Nanjing University 210093 (China)], E-mail: yuxyang@online.sh.cn; Liu, M.L. [Analysis Test Center, Jilin University, Changchun 130023 (China); Zhu, H.; Chen, Y.R.; Mu, G.J. [Department of Chemistry, Chemistry and Molecule Engineering College, East China University of Science and Technology, Meilong Road 130, Xuhui District, Shanghai 200237 (China); Liu, X.N. [Analysis Test Center, Yangzhou University, Yangzhou 225009 (China); Jia, Y.Q. [Department of Chemistry, Chemistry and Molecule Engineering College, East China University of Science and Technology, Meilong Road 130, Xuhui District, Shanghai 200237 (China)

    2008-11-15

    {beta}-FeOOH nanoparticles have been prepared in a microemulsion system with nonionic surfactant polyoxyethylene(4)nonylphenylether CH{sub 3}(CH{sub 2}){sub 8}C{sub 6}H{sub 4}O(CH{sub 2}OCH{sub 2}){sub 4}H. The powder X-ray diffraction, infrared spectra, and transmission electron microscopic images indicate that the products are 20-30 nm length nanorods with a crystal structure belonging to monoclinic {beta}-FeOOH and lattice parameters of a=0.9981, b=0.2948, c=1.0485 nm and {beta}=92.26 deg. The size and shapes of {beta}-FeOOH nanoparticles can be manipulated by the surfactant. The modified {beta}-FeOOH nanoparticles are paramagnetic at room temperature and may be antiferromagnetic or weakly ferrimagnetic at lower temperatures. The {sup 57}Fe Moessbauer spectra show that the magnetic structure transforms below 150 K and two kinds of Fe-O octahedra exist in the lattice of the modified {beta}-FeOOH nanoparticles. The numbers of each kind of Fe-O octahedra are not the same at room temperature or at low temperatures.

  5. A Moessbauer investigation of complexes of tin tetrahalides with ambidentate Lewis bases containing nitrogen, sulphur and oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Teles, W.M. (Dept. de Quimica, ICEx, Univ. Federal de Minas Gerais, Belo Horizonte (Brazil)); Allain, L.R. (Dept. de Quimica, ICEx, Univ. Federal de Minas Gerais, Belo Horizonte (Brazil)); Filgueiras, C.A.L. (Dept. de Quimica, ICEx, Univ. Federal de Minas Gerais, Belo Horizonte (Brazil)); Abras, A. (Dept. de Fisica, ICEx, Univ. Federal de Minas Gerais, Belo Horizonte (Brazil))

    1994-02-01

    A series of 1 : 1 complexes was prepared with SnX[sub 4] (X = Cl, Br, I) and the Lewis bases 2-mercaptobenzothiazole, 2-mercapto-1-methylimidazole, 2-aminothiazole, 2-acetylpyridine, and 2,2'-bis(pyridyl)ketone. The latter two ligands yielded bidentate, N, O-bonded hexacoordinate complexes, whereas the other ligands produced monodentate, N-bonded pentacoordinate species, as suggested by Moessbauer parameters, which correlate quite well with the IR spectroscopy data. (orig.)

  6. Moessbauer and magnetic characterisation of carbon-coated small iron particles

    Energy Technology Data Exchange (ETDEWEB)

    Rechenberg, H.R. E-mail: hercilio@macbeth.if.usp.br; Coaquira, J.A.H.; Marquina, C.; Garcia-Landa, B.; Ibarra, M.R.; Benito, A.M.; Maser, W.; Munoz, E.; Martinez, M.T

    2001-05-01

    Carbon-coated Fe particles have been produced by the Kraetschmer-Huffmann carbon-arc discharge method. Soot, collarette and cathode samples have been separately characterised by Moessbauer spectroscopy and magnetisation measurements in the temperature range 4.2-300 K. From the analysis of the results the content of the different Fe phases and Fe-carbon solid solutions in our samples has been determined, as well as an estimation of particle sizes, which were found to be approximately 9 and 13 nm for the soot and collarette samples, respectively.

  7. Moessbauer studies of mercury(II) salt adducts of (2)ferrocenophane derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Masanobu; Ichikawa, Hajime; Motoyama, Izumi; Sano, Hirotoshi (Tokyo Metropolitan Univ. (Japan). Faculty of Science)

    1983-11-01

    Various adducts of mercuric salts with (2)ferrocenophane and 1,1,2,2-tetramethyl(2)ferrocenophane, were prepared by treating HgX/sub 2/ (X=Cl/sup -/, I/sup -/, CN/sup -/) with the (2)ferrocenophane derivatives in ether. The adducts were studied by Moessbauer spectroscopy and other physicochemical measurements. Anomalously large quadrupole splitting values of the adducts (about 3.10-3.30 mms/sup -1/ at 78 K) suggest the presence of a strong direct interaction between the Fe and Hg atoms.

  8. Moessbauer studies of frataxin role in iron-sulfur cluster assembly and dysfunction-related disease

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Serres, Ricardo [Universite Joseph Fourier (France); Clemancey, Martin [CNRS, UMR5249 (France); Oddou, Jean-Louis [Universite Joseph Fourier (France); Pastore, Annalisa [Medical Research Council National Institute for Medical Research (United Kingdom); Lesuisse, Emmanuel [Laboratoire Mitochondries, Metaux et Stress oxydant, Institut Jacques Monod, CNRS-Universite Paris (France); Latour, Jean-Marc, E-mail: jean-marc.latour@cea.fr [CEA, iRTSV, LCBM (France)

    2012-03-15

    Friedreich ataxia is a disease that is associated with defects in the gene coding for a small protein frataxin. Several different roles have been proposed for the protein, including iron chaperoning and iron storage. Moessbauer spectroscopy was used to probe these hypotheses. Iron accumulation in mutant mitochondria unable to assemble iron sulfur clusters proved to be insensitive to overexpression of frataxin, ruling out its potential involvement as an iron storage protein similar to ferritin. Rather, it was found that frataxin negatively regulates iron sulfur cluster assembly.

  9. Moessbauer characterization of joints of steel pieces in transient liquid phase bonding experiences

    Energy Technology Data Exchange (ETDEWEB)

    Di Luozzo, N.; Martinez Stenger, P. F.; Canal, J. P.; Fontana, M. R.; Arcondo, B., E-mail: barcond@fi.uba.ar [INTECIN (UBA-CONICET), Laboratorio de Solidos Amorfos, Facultad de Ingenieria (Argentina)

    2011-11-15

    Joining of seamless, low carbon, steel tubes were performed by means of Transient Liquid Phase Bonding process employing a foil of Fe-Si-B metallic glass as filler material. The influence of the main parameters of the process was evaluated: temperature, holding time, pressure and post weld heat treatment. Powder samples were obtained from the joint of tubes and characterized employing Moessbauer Spectroscopy in transmission geometry. The sampling was performed both in tubes successfully welded and in those which show joint defects. The results obtained are correlated with the obtained microstructure and the diffusion of Si and B during the process.

  10. Moessbauer meets Fano at X-ray energies: Controlled line shapes in cooperative emission from nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Heeg, Kilian P.; Ott, Christian; Pfeifer, Thomas; Evers, Joerg [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Schumacher, Daniel; Wille, Hans-Christian; Roehlsberger, Ralf [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany)

    2014-07-01

    Control of spectroscopic line shapes at hard X-ray energies is demonstrated in the reflectance of a thin film cavity with embedded Moessbauer nuclei. Tunable Fano interference between a spectrally broad cavity response and a narrow bound state nuclear contribution enables us to switch between Lorentz- and Fano-profiles. Spectroscopic signatures such as the cooperative Lamb shift and superradiant line broadening are extracted from the recorded asymmetric line shapes with high precision and agree excellently with our theoretical model. Our results advance spectroscopy and precision metrology in the hard X-ray domain, and provide access to a multitude of applications linked to Fano interference.

  11. Moessbauer meets Fano at X-ray energies: Controlled line shapes in cooperative emission from nuclei

    International Nuclear Information System (INIS)

    Control of spectroscopic line shapes at hard X-ray energies is demonstrated in the reflectance of a thin film cavity with embedded Moessbauer nuclei. Tunable Fano interference between a spectrally broad cavity response and a narrow bound state nuclear contribution enables us to switch between Lorentz- and Fano-profiles. Spectroscopic signatures such as the cooperative Lamb shift and superradiant line broadening are extracted from the recorded asymmetric line shapes with high precision and agree excellently with our theoretical model. Our results advance spectroscopy and precision metrology in the hard X-ray domain, and provide access to a multitude of applications linked to Fano interference.

  12. Early Pottery Making in Northern Coastal Peru. Part III: Moessbauer Study of Sican Pottery

    International Nuclear Information System (INIS)

    Sican blackware from a 1000-year old elite tomb at Huaca Loro was characterised by neutron activation analysis, optical thin-section microscopy, X-ray diffraction and Moessbauer spectroscopy. A number of blackware fragments from the later site of Puerto Pobre (ca. AD 1460-1550) were included in the analysis for comparison and found to be of different origin. The black surface of the specimens from Huaca Loro is mostly due to carbon deposition during firing in a reducing environment. Part of the pottery was merely dried at temperatures below 400 deg. C, perhaps because it was made in haste for funeral use.

  13. Mössbauer emission measurements on highly dilute ^{57}Fe impurities in the high T_C superconductors La{2 -x}SrxCuO4

    Science.gov (United States)

    Garcin, C.; Imbert, P.; Bonville, P.; Hodges, J. A.

    1994-12-01

    Mössbauer emission measurements on quasi-isolated ^{57}Fe impurities substituted for Cu in La{2-x}SrxCuO4 show a rapid change in the local magnetic behaviour when the Sr content x exceeds an effective value x_t, which is roughly at the centre of the superconducting x range in the phase diagram For x x_t, the probe no longer detects local antiferromagnetic ordering, but it reveals the presence of an induced locahzed magnetization in the Cu sublattice, which is preferentially oriented near the {bar c} axis for the largest x values. The results are discussed and compared with other available measurements, including our previous ^{57}Fe Mössbauer absorption study in the saine sertes. Des expériences d'émission Mössbauer effectuées sur des impuretés quasi-isolées de ^{57}Fe substituées à Cu dans La{2-x}Sr{x}CuO4 montrent un changement rapide du comportement magnétique local quand la teneur x en Sr excède une valeur effective x_t, située approximativement au centre du domaine en x associé à la supraconductivité dans le diagramme de phase. Pour x cuivre s'orientent au voisinage du plan de base, avec une température de gel de 8 ± 1 K vis-à-vis du temps de réponse caractéristique de la sonde Mössbauer. Pour x > x_t, la sonde ne détecte plus d'ordre antiferromagnétique local, mais elle révèle l'existence d'une aimantation locale induite dans le sous-réseau du cuivre, qui présente une orientation préférentielle suivant l'axe {bar c} pour les valeurs de x les plus grandes. Les résultats sont discutés et comparés aux autres mesures disponibles, y compris celles de notre étude précédente par absorption Mössbauer sur ^{57}Fe dans la même série.

  14. Latin American conference on the applications of the Moessbauer effect

    International Nuclear Information System (INIS)

    This work includes all the papers presented at the LACAME'92 Latin American conference on the applications of the Moessbauer effect, held in Buenos Aires (Argentine Republic), from 5th. through 9th., 1992

  15. The moessbauer study on ancient pottery with known age

    International Nuclear Information System (INIS)

    It is of important scientific value in archaeology to study the age effect with Moessbauer effect. 13 samples of ancient pottery from different excavated places and with different technology of production have been measured by transmission Moessbauer technique at room temperature. The experimental results show that the paramagnetic Fe2+ Q.S. values for 11 samples linearly increase with the age of pottery and that the mangnetic component of pottery with very old age almost disappears

  16. Moessbauer-Spectrometer MIMOS II: Future applications

    Energy Technology Data Exchange (ETDEWEB)

    Klingelhoefer, Goestar; Blumers, Mathias; Schroeder, Christian; Fleischer, Iris; Lopez, Jordi G.; Sanchez, Jose F.; Hahn, Michaela; Upadhyay, Chandan [Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg Universitaet, Staudinger Weg 9, 55128 Mainz (Germany); Rodionov, Daniel [Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg Universitaet, Staudinger Weg 9, 55128 Mainz (Germany); Space Research Institute IKI, 117997 Moskau (Russian Federation)

    2007-07-01

    The Miniaturized Moessbauer Spectrometer MIMOS II operates on the surface of Mars for the last three years (part of NASA Mars Exploration Rovers scientific payload). Successful application of MIMOS II as a tool for detection/analysis of Fe-bearing minerals on the extraterrestrial surfaces has proven its use for other missions. Currently MIMOS II is a part of ExoMars and Phobos-Grunt missions. ExoMars is managed by the European Space Agency and planned to be launched in 2013. It involves the development of a sophisticated Mars rover with set of instruments to further characterize the biological environment on Mars in preparation for robotic missions and human exploration. Data from the mission should provide an input for broader studies of exobiology. Phobos-Grunt is developed by Russian Space Agency. Currently, launch is planned in 2009. The main goals of the mission are Phobos regolith sample return, Phobos in situ study and Mars/Phobos remote sensing.

  17. Velocity scales for Mars Moessbauer data

    International Nuclear Information System (INIS)

    Raw Moessbauer data acquired from surface rocks and soils by two Mars Exploration Rovers (MERs) are being made available on-line to the general science community for independent analysis and interpretation. The data are released as counts per channel, so a velocity scale must be defined. The Windows-based computer program MERView does this in two steps. In the first, a scale proportional to the true velocity is derived by adjusting the magnitudes of the drive error signal and a phase shift. This report focuses on the second step, in which mm/s units are assigned to the proportional scale by comparing laboratory-measured α-iron peak positions with those of spectra of the internal MER calibration targets. We contrast MERView-derived velocity scales for different MER measurement conditions with the velocity scales provided on-line by the MER team, and conclude that independent velocity calibration is generally desirable.

  18. Mössbauer spectroscopy of Basal Ganglia

    Energy Technology Data Exchange (ETDEWEB)

    Miglierini, Marcel, E-mail: marcel.miglierini@stuba.sk [Institute of Nuclear and Physical Engineering, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovičova 3, 812 19 Bratislava, Slovakia and Regional Centre of Advanced Technologies and Materials (Czech Republic); Lančok, Adriana [Institute of Inorganic Chemistry AS CR, v. v. i., 250 68 Husinec-Řež 1001 (Czech Republic); Kopáni, Martin [Institute of Medical Physics, Biophysics, Informatics and Telemedicine, Faculty of Medicine, Comenius University, Sasinkova 2, 811 08 Bratislava (Slovakia); Boča, Roman [Department of Chemistry, Faculty of Natural Sciences, University of SS. Cyril and Methodius, 917 01 Trnava (Slovakia)

    2014-10-27

    Chemical states, structural arrangement, and magnetic features of iron deposits in biological tissue of Basal Ganglia are characterized. The methods of SQUID magnetometry and electron microscopy are employed. {sup 57}Fe Mössbauer spectroscopy is used as a principal method of investigation. Though electron microscopy has unveiled robust crystals (1-3 μm in size) of iron oxides, they are not manifested in the corresponding {sup 57}Fe Mössbauer spectra. The latter were acquired at 300 K and 4.2 K and resemble ferritin-like behavior.

  19. Moessbauer and XRD Comparative Study of Host Rock and Iron Rich Mineral Samples from Paz del Rio Iron Ore Mineral Mine in Colombia

    Energy Technology Data Exchange (ETDEWEB)

    Fajardo, M.; Perez Alcazar, G. A. [Universidad del Valle, Departamento de Fisica (Colombia); Moreira, A. M.; Speziali, N. L. [Universidade Federal de Minas Gerais, Departamento de Fisica (Brazil)

    2004-12-15

    A comparative study between the host rock and the iron rich mineral samples from the Paz del Rio iron ore mineral mine in Colombia was performed using X-ray diffraction and Moessbauer spectroscopy. Diffraction results of the iron rich mineral sample show that goethite, hematite, quartz, kaolinite and siderite are the main phases, and that a small amount of illite is also present. By Moessbauer spectroscopy at room temperature (RT) the presence of all the above mentioned phases was detected except quartz as well as an additional presence of small amount of biotite. The goethite, which appears as four sextets with hyperfine fields of 33.5, 30.5, 27.5 and 18.5 T, respectively, is the majority phase. This result shows the different grades of formation of this oxyhydroxide. The Moessbauer spectrum of this sample at 80 K presents the same phases obtained at RT without any superparamagnetic effect. In this case the goethite appears as two sextets. Diffraction results of the host rock sample show a large amount of quartz and kaolinite and small amounts of illite and biotite, whereas by Moessbauer spectroscopy illite, kaolinite and biotite were detected.

  20. Moessbauer study of fired Lishan clay and terra-cotta warriors and horses of Qin Dynasty (221 B.C.)

    International Nuclear Information System (INIS)

    The sherds of terracotta warriors and horses and Lishan clay were characterized by Moessbauer spectroscopy, XRD, XRF, NAA, thermal and chemical analyses. Lishan clay was testified as the original material of terracotta warriors and horses, the kilning of these warriors and horses was first carried out in an oxidizing atmosphere, and then changed to a predominantly reducing atmosphere. With refiring experiments, the temperatures of Q3 and Q4 samples were determined to be 830 ± 50 and 980 ± 50degC respectively. Transformations of Lishan clay were determined by firing in oxidizing and reducing atmospheres. The Moessbauer parameters of Lishan clay, which was taken after 2-24h firing, were changing up to 12h. (orig.)

  1. I-129 Moessbauer effect of polyacetylene with iodine addition

    International Nuclear Information System (INIS)

    The I-129 Moessbauer effect of polyacetylene with iodine addition was measured. The gamma-ray used was emitted from the first excited state of I-129, which is a decay product of Te-129. The Te-129 was produced by neutron irradiation of ZnTe128. The state of iodine in the #betta#-carotene-iodine complex was studied by the Moessbauer method. An obtained Moessbauer spectrum showed the presence of two kinds of iodine. As a result, it can be said that the #betta#-carrotene iodine complex is present in an ionic state of (C40H56)+ I3-. The states of iodine doped into cis- and trans-polyacetylene were also measured by the Moessbauer method. The test samples were made by dipping the polyacetylene into carbon tetrachloride solution of iodine. The obtained Moessbauer spectra were more complex than that of the #betta#-carotene iodine complex. Eight components of iodine were assumed for the analysis of spectra. It is suggested that the iodine states in polyacetylene are I3- and I5-. The I5- ions are linear. The number of I5- increases with increase of the iodine concentration in cis and trans polyacetylene. (Kato, T.)

  2. Study of the iron-nickel alloys of the Santa Catharina meteorite by Moessbauer spectrometry and X-ray diffraction

    International Nuclear Information System (INIS)

    The composition and structure of the iron-nickel alloys in the iron meteorite Santa Catharina were studied by metallographic technics, electron microprobe analysis and by detailed Moessbauer spectroscopy and X-ray diffraction. The natural occurence of the ordered Fe-Ni alloy with L10 superstructure, was demonstrated. This phase which is present in large proportions in the Santa Catharina meteorite, had been previously discovered in Grenoble (1962) by irradiation of disordered Fe-Ni alloys with neutrons or electrons. The ordered phase in Santa Catharina was identified by its Moessbauer spectra, which is unique among the Fe-Ni alloys since it exhibits an asymetric pattern due to the presence of quadrupolar splitting arising from the non cubic symmetry of its lattice. A detailed study of the Moessbauer spectra down to the temperature of liquid helium and under different conditions such as the presence of magnetic fields allowed to show that the metallic phases of Santa Catharina do behave as the Invar alloys measured in Grenoble with similar techniques. A comparative study by X-ray diffraction of Santa Catharina Fe-Ni and arradiated alloys confirmed the L10 superstructure to be present in this meteorite. Lattice parameter variations with temperature were found to be identical for the meteorite and irradiated artificial alloys. Finally the instability of the superstruture in the Santa Catharina meteorite was investigated as a function of temperature (up to 1073K) and under the effect of shock waves by flying plates methods. (Author)

  3. Hydride bridge in [NiFe]-hydrogenase observed by nuclear resonance vibrational spectroscopy

    Science.gov (United States)

    Ogata, Hideaki; Krämer, Tobias; Wang, Hongxin; Schilter, David; Pelmenschikov, Vladimir; van Gastel, Maurice; Neese, Frank; Rauchfuss, Thomas B.; Gee, Leland B.; Scott, Aubrey D.; Yoda, Yoshitaka; Tanaka, Yoshihito; Lubitz, Wolfgang; Cramer, Stephen P.

    2015-08-01

    The metabolism of many anaerobes relies on [NiFe]-hydrogenases, whose characterization when bound to substrates has proven non-trivial. Presented here is direct evidence for a hydride bridge in the active site of the 57Fe-labelled fully reduced Ni-R form of Desulfovibrio vulgaris Miyazaki F [NiFe]-hydrogenase. A unique `wagging' mode involving H- motion perpendicular to the Ni(μ-H)57Fe plane was studied using 57Fe-specific nuclear resonance vibrational spectroscopy and density functional theory (DFT) calculations. On Ni(μ-D)57Fe deuteride substitution, this wagging causes a characteristic perturbation of Fe-CO/CN bands. Spectra have been interpreted by comparison with Ni(μ-H/D)57Fe enzyme mimics [(dppe)Ni(μ-pdt)(μ-H/D)57Fe(CO)3]+ and DFT calculations, which collectively indicate a low-spin Ni(II)(μ-H)Fe(II) core for Ni-R, with H- binding Ni more tightly than Fe. The present methodology is also relevant to characterizing Fe-H moieties in other important natural and synthetic catalysts.

  4. Moessbauer studies of GdFe{sub 2-x}Hf{sub x} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Al-Omari, I. A., E-mail: ialomari@yahoo.com; Gismelseed, A.; Widatallah, H.; Elzain, M.; Al-Rawas, A.; Yousif, A. [Sultan Qaboos University, Department of Physics (Oman)

    2008-11-15

    GdFe{sub 2-x}Hf{sub x} alloys, where x = 0, 0.10, 0.15, 0.20, and 0.30, are produced by arc-melting of pure elements. The samples are investigated by x-ray diffraction and Fe{sup 57} Moessbauer spectroscopy at 78 K and 300 K. We find that the alloy system GdFe{sub 2-x}Hf{sub x} have the single phase cubic Cu{sub 2}Mg type structure in the whole concentration range. Moessbauer spectroscopic results show that all the samples studied are magnetically ordered at 78 K, and at room temperature. The room temperature spectra are fitted with two magnetic components where the direction of magnetization is along the [111] while the spectra at 78 K are fitted with four magnetic subspectra indicating a complex direction of magnetization for all samples under investigation. The average magnetic hyperfine field and the average isomer shift are found to decrease almost linearly with increasing the Hf concentration at 78 K and 300 K due to the replacement of Fe by nonmagnetic Hf.

  5. Cation distribution in Ni–Cu–Zn nanoferrites from {sup 57}Fe in-field Mössbauer spectra

    Energy Technology Data Exchange (ETDEWEB)

    Prameela, P. [Department of Physics, GITAM University, Visakhapatnam 530045 (India); Kumar, A. Mahesh, E-mail: drmaheshnano@gmail.com [Department of Physics, RGUKT, IIIT, Nuzvid 521201 (India); Choudary, G.S.V.R.K. [Department of Physics, BVB Vivekanada College, Sainikpuri, Secunderabad 500094 (India); Rao, K.H. [Department of Physics, RGUKT, IIIT, Nuzvid 521201 (India); Reddy, V.R. [UGC-DAE-CSR, Indore 452001 (India)

    2014-11-15

    Highlights: • Occupancy of copper ions at about 20% towards tetrahedral sites. • Distribution is proposed on the basis of % of Fe ions at both A and B sites. • Distribution is checked by estimating the theoretical lattice constant values. - Abstract: The nanoparticles of Ni{sub 1−x}Cu{sub x}Zn{sub 0.35}Fe{sub 2}O{sub 4} were synthesized by sol–gel method using polyvinyl alcohol as a chelating agent. X-ray diffraction patterns of all the samples confirmed the single phase spinel structure. The site occupancy of copper in the nanosized nickel–zinc ferrite spinels was investigated with the help of in-field Mössbauer spectroscopy. Cation distribution for the whole series of compositions was proposed by considering the amounts of iron ions present at both tetrahedral and octahedral interstitial sites in the spinel lattice. Confirmation of the proposed distributions was done by estimating quantitatively the lattice parameters for these compositions and comparing their values with those of the experimentally observed ones.

  6. Direct Oxidation of Benzene to Phenol: investigation of the active iron species in [Fe,Al]MFI catalysts by 57Fe Mössbauer spectroscopy

    NARCIS (Netherlands)

    Taboada, J.B.

    2006-01-01

    Steam-treated isomorphously substituted [Fe,Al]MFI zeolite is known to exhibit superior catalytic performance in the direct oxidation of benzene to phenol, using N2O as oxidant (BTOP). However, despite extensive efforts, the nature of the active sites in the [Fe,Al]MFI catalyst for the BTOP reaction

  7. Moessbauer effect and full-potential linearized augmented plane wave band structure studies on Ho(Fe{sub 1-x}Co{sub x}){sub 2} intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Bednarski, M; Pszczola, J; Bodnar, W [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, A Mickiewicza Avenue 30, 30-059 Krakow (Poland); Stoch, P; Zachariasz, P; Suwalski, J, E-mail: pszczola@agh.edu.pl [Institute of Atomic Energy, 05-400 Swierk-Otwock (Poland)

    2011-05-01

    {sup 57}Fe Moessbauer effect spectra were collected at 4.2 K for the Ho(Fe{sub 1-x}Co{sub x}){sub 2} C15 Laves phases. The hyperfine interaction parameters, i.e. isomer shift, the magnetic hyperfine field and the quadrupole interaction parameter, were determined for the individual Fe/Co nearest neighbourhoods of iron atoms and also as average values for the sample as bulk. As a result of Fe/Co substitution, Slater-Pauling-type dependences for magnetic hyperfine fields corresponding to both the local area and the sample as bulk were observed, and a linear correlation between the local magnetic hyperfine field and the average magnetic hyperfine field was observed. Magnetic moments of atoms were obtained from band structure calculations using the full-potential linearized augmented plane wave method. The magnetic hyperfine field obtained from the experiment correlates linearly (but separately for weak and strong ferromagnetic areas) with the magnetic moment calculated per transition metal atom.

  8. [Gamma scattering in condensed matter with high intensity Moessbauer radiation

    International Nuclear Information System (INIS)

    This report discusses: quasielastic scattering studies on glycerol; gamma-ray scattering from alkali halides; lattice dynamics in metals; Moessbauer neutron scattering, x-ray diffraction, and macroscopic studies of high Tc superconductors containing tungsten; NiAl scattering studies; and atomic interference factors and nuclear Casimir effect

  9. SEM, optical, and Moessbauer studies of submicrometer chromite in Allende

    Science.gov (United States)

    Housley, R. M.

    1982-01-01

    New scanning electron and optical microscope results are presented showing that sub-micrometer chromite is abundant along healed cracks and grain boundaries in Allende chondrule olivine. Some wider healed cracks also contain pentlandite and euhedral Ni3Fe grains. Also reported are Moessbauer measurements on Allende HF-HCl residues confirming a high Fe(+++)/Fe(++) ratio.

  10. Rayleigh scattering of Moessbauer radiation in hyaluronate oriented fibres

    Energy Technology Data Exchange (ETDEWEB)

    Albanese, G.; Cavatorta, F.; Deriu, A. [Parma Univ. (Italy). Dip. di Fisica]|[Istituto Nazionale di Fisica della Materia, Parma (Italy); Rupprecht, A. [Stockholm Univ. (Sweden). Dep. of Physical Chemistry

    1996-02-01

    The Rayleigh scattering of Moessbauer radiation has been measured on highly oriented fibres of Na-hyaluronate at different hydration levels. The elastic- and-inelastic-scattering intensities, measured as a function of the scattering vector Q, have provided information on the dynamic structuring of the water molecules to the polysaccharidic chains.

  11. (Gamma scattering in condensed matter with high intensity Moessbauer radiation)

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    This report discusses: quasielastic scattering studies on glycerol; gamma-ray scattering from alkali halides; lattice dynamics in metals; Moessbauer neutron scattering, x-ray diffraction, and macroscopic studies of high {Tc} superconductors containing tungsten; NiAl scattering studies; and atomic interference factors and nuclear Casimir effect.

  12. Molecular dynamics in cytochrome c oxidase Moessbauer spectra deconvolution

    Energy Technology Data Exchange (ETDEWEB)

    Bossis, Fabrizio [Department of Medical Biochemistry, Medical Biology and Medical Physics (DIBIFIM), University of Bari ' Aldo Moro' , Bari (Italy); Palese, Luigi L., E-mail: palese@biochem.uniba.it [Department of Medical Biochemistry, Medical Biology and Medical Physics (DIBIFIM), University of Bari ' Aldo Moro' , Bari (Italy)

    2011-01-07

    Research highlights: {yields} Cytochrome c oxidase molecular dynamics serve to predict Moessbauer lineshape widths. {yields} Half height widths are used in modeling of Lorentzian doublets. {yields} Such spectral deconvolutions are useful in detecting the enzyme intermediates. -- Abstract: In this work low temperature molecular dynamics simulations of cytochrome c oxidase are used to predict an experimentally observable, namely Moessbauer spectra width. Predicted lineshapes are used to model Lorentzian doublets, with which published cytochrome c oxidase Moessbauer spectra were simulated. Molecular dynamics imposed constraints to spectral lineshapes permit to obtain useful information, like the presence of multiple chemical species in the binuclear center of cytochrome c oxidase. Moreover, a benchmark of quality for molecular dynamic simulations can be obtained. Despite the overwhelming importance of dynamics in electron-proton transfer systems, limited work has been devoted to unravel how much realistic are molecular dynamics simulations results. In this work, molecular dynamics based predictions are found to be in good agreement with published experimental spectra, showing that we can confidently rely on actual simulations. Molecular dynamics based deconvolution of Moessbauer spectra will lead to a renewed interest for application of this approach in bioenergetics.

  13. Moessbauer studies of one representative hydromorphic soil of the coastal area of the Rio de La Plata

    Energy Technology Data Exchange (ETDEWEB)

    Guichon, B. A. [Universidad Nacional de La Plata, Instituto de Geomorfologia y Suelos (Argentina); Desimoni, J.; Mercader, R. C., E-mail: mercader@fisica.unlp.edu.ar [Universidad Nacional de La Plata, Departamento de Fisica, IFLP-CONICET, Facultad de Ciencias Exactas (Argentina); Imbellone, P. A. [Universidad Nacional de La Plata, Instituto de Geomorfologia y Suelos (Argentina)

    2010-01-15

    In the present work, we have applied Moessbauer spectroscopy as well as the traditional chemical analyses to assess the contents of different states of Fe in oxides and hydroxides in an Entisol soil from the Argentine coastal plain of the Rio de La Plata. Tentative assignments for the different Fe ion sites are proposed. Our findings show that the isomer shift and quadrupole splitting are sensitive to the changes detected in the Fe{sup 2+} contents of the soluble phase while others remain constant within the experimental uncertainties.

  14. 197Au Moessbauer study of the deactivation and reactivation of a carbon-supported AuCl4- hydrochlorination catalyst

    International Nuclear Information System (INIS)

    Acetylene hydrochlorination catalysts consisting of activated carbon impregnated with a solution of HAuCl4.xH2O in aqua regia have been studied by 197Au Moessbauer spectroscopy. The relative amounts of AuCl4-, of Au(0), and of an Au(I) species formed under certain process conditions were determined quantitatively. Deactivation of the catalyst at low and high temperatures was shown to be due to different mechanisms, and the reactivation of the catalyst by Cl2 gas was studied. (orig.)

  15. The Binding of Iron to Perineuronal Nets: A Combined Nuclear Microscopy and Moessbauer Study

    Energy Technology Data Exchange (ETDEWEB)

    Morawski, M. [Universitaet Leipzig, Paul Flechsig Institute fuer Hirnforschung (Germany); Reinert, T. [Universitaet Leipzig, Fakultaet fuer Physik und Geowissenschaften (Germany); Brueckner, G. [Universitaet Leipzig, Paul Flechsig Institute fuer Hirnforschung (Germany); Wagner, F. E. [Technische Universitaet Muenchen, Physik-Department E15 (Germany); Arendt, T. H. [Universitaet Leipzig, Paul Flechsig Institute fuer Hirnforschung (Germany); Troeger, W., E-mail: troeger@physik.uni-leipzig.de [Universitaet Leipzig, Fakultaet fuer Physik und Geowissenschaften (Germany)

    2004-12-15

    A specialized form of extracellular matrix (ECM) surrounds subpopulations of neurons termed 'perineuronal nets' (PNs). These PNs form highly anionic charged structures in the direct microenvironment of neurons, assumed to be involved in local ion homeostasis since they are able to scavenge and bind redox-active iron ions. The quantity and distribution of iron-charged PNs of the extracellular matrix in the rat brain areas of the cortex and the red nucleus was investigated using the powerful combination of Particle-Induced X-ray Emission (PIXE) and Moessbauer spectroscopy. These studies reveal that the iron is bound to the PNs as Fe(III). PNs in both brain regions accumulate up to three to five times more Fe{sup 3+} than any other tissue structure in dependency on the applied Fe concentration with local amount maximums of 480 mmol/l Fe at PNs.

  16. The Binding of Iron to Perineuronal Nets: A Combined Nuclear Microscopy and Moessbauer Study

    International Nuclear Information System (INIS)

    A specialized form of extracellular matrix (ECM) surrounds subpopulations of neurons termed 'perineuronal nets' (PNs). These PNs form highly anionic charged structures in the direct microenvironment of neurons, assumed to be involved in local ion homeostasis since they are able to scavenge and bind redox-active iron ions. The quantity and distribution of iron-charged PNs of the extracellular matrix in the rat brain areas of the cortex and the red nucleus was investigated using the powerful combination of Particle-Induced X-ray Emission (PIXE) and Moessbauer spectroscopy. These studies reveal that the iron is bound to the PNs as Fe(III). PNs in both brain regions accumulate up to three to five times more Fe3+ than any other tissue structure in dependency on the applied Fe concentration with local amount maximums of 480 mmol/l Fe at PNs.

  17. Moessbauer studies on ancient pottery from a neolithic site in Tung Wan, Hong Kong

    International Nuclear Information System (INIS)

    Twelve ceramic sherds unearthed from different archaeological layers at a neolithic site in Tung Wan, Hong Kong, were studied by means of X-ray diffraction (XRD) and Moessbauer spectroscopy. The results show that the firing techniques used for ancient pottery wares at different layers were very different. For the oldest sherds (4000-3000 B.C.) from layer No. 4, the original firing temperature was low and craftmanship was inferior. For the sherds (1650-250 B.C.) from layer No. 2, the original firing temperature was above 1000 C. In addition, the results indicate that the ancient pottery wares from the ruins might not have been manufactured in the Tung Wan region. (orig.)

  18. Sensitivity of the CUORE detector to $14.4$ keV solar axions emitted by the M1 nuclear transition of$~^{57}$Fe

    CERN Document Server

    Li, Dawei; Avignone, Frank T; Wang, Yuanxu

    2015-01-01

    In this paper we present a calculation of the sensitivity of the CUORE detector to the monoenergetic $14.4$ keV solar axions emitted by the M1 nuclear transition of$~^{57}$Fe in the Sun and detected by inverse coherent Bragg-Primakoff conversion in single-crystal $TeO_2$ bolometers. The expected counting rate is calculated using density functional theory for the electron charge density of $TeO_2$ and realistic background and energy resolution of CUORE. Monte Carlo simulations for $5$ y $\\times$ $741$ kg=$3705-$kg$\\cdot$y of exposure are analyzed using time correlation of individual events with the theoretical time-dependent counting rate. We find an expected model-independent limit on the product of the axion-photon coupling and the axion-nucleon coupling $g_{a\\gamma\\gamma}\\{|-1.19g^0_{aN}+g^3_{aN}|\\}<1.105\\times 10^{-16}$ /GeV for axion masses less than 500 eV with $95\\%$ confidence level.

  19. The importance of a Ni correction with ion counter in the double spike analysis of Fe isotope compositions using a 57Fe/58Fe double spike

    Science.gov (United States)

    Finlayson, V. A.; Konter, J. G.; Ma, L.

    2015-12-01

    We present a new method capable of measuring iron isotope ratios of igneous materials to high precision by multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) using a 57Fe-58Fe double spike. After sample purification, near-baseline signal levels of nickel are still present in the sample solution, acting as an isobaric interference on 58 amu. To correct for the interference, the minor 60Ni isotope is monitored and used to subtract a proportional 58Ni signal from the total 58 amu beam. The 60Ni signal is difficult to precisely measure on the Faraday detector due to Johnson noise occurring at similar magnitude. This noise-dominated signal is subtracted from the total 58 amu beam, and its error amplified during the double spike correction. Placing the 60Ni beam on an ion counter produces a more precise measurement, resulting in a near-threefold improvement in δ56Fe reproducibility, from ±0.145‰ when measured on Faraday to 0.052‰. Faraday detectors quantify the 60Ni signal poorly, and fail to discern the transient 20Ne40Ar interference visible on the ion counter, which is likely responsible for poor reproducibility. Another consideration is instrumental stability (defined herein as drift in peak center mass), which affects high-resolution analyses. Analyses experiencing large drift relative to bracketing standards often yield nonreplicating data. Based on this, we present a quantitative outlier detection method capable of detecting drift-affected data. After outlier rejection, long-term precision on individual runs of our secondary standard improves to ±0.046‰. Averaging 3-4 analyses further improves precision to 0.019‰, allowing distinction between ultramafic minerals.

  20. Moessbauer conversion electron studies of tantalum metal surface layers

    International Nuclear Information System (INIS)

    Conversion electrons following the Moessbauer absorption of the 6.2 keV γ-rays of 181Ta were observed in backscattering geometry. Moessbauer spectra for tantalum single crystal and foil surfaces (mean-depth 330 A) are compared with normal transmission spectra for tantalum foils (bulk). While no broadening of lines is observed for carefully polished single crystal surfaces, foil surfaces show considerably broader lines than bulk spectra. The linewidth and isomer shift indicate an increase of the concentration of absorbed residual gases at the foil surfaces. The observed dispersion term arising from the interference between photo- and conversion electrons for this E1-transition, depends only on the absorber thickness. (Auth.)

  1. Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hellman, Hal

    1968-01-01

    This booklet discusses spectroscopy, the study of absorption of radiation by matter, including X-ray, gamma-ray, microwave, mass spectroscopy, as well as others. Spectroscopy has produced more fundamental information to the study of the detailed structure of matter than any other tools.

  2. Genesis of sandstone-type uranium deposits in the Sierra Pintada district, Mendoza, Argentina: a Moessbauer study

    International Nuclear Information System (INIS)

    The genesis of sandstone-type uranium deposits in the Cochico Group (Permo-Triassic) of the Sierra Pintada district, San Rafael, Mendoza, has been studied. This is the most important uranium district in Argentina. Uranium sources, uranium transport and precipitation are discussed. Uraninite and brannerite, the main uranium minerals, occur within the matrix of sandstone. Several phenomena can be deduced regarding the depositional environment. Where oxygen was available, precipitation of hydrated ferric oxides occurred; γFe2O3.nH2O varieties (identified by Moessbauer spectroscopy) precipitated in the upper levels of the aquifer, where CO2 partial pressure was lower, giving reddish or reddish-brown beds. The CO2 partial pressure also determines the distribution of biogenic agents such as bacteria. Bacteria thus find a more favourable environment for their development and action in upper levels of an aquifer. In the corresponding horizons local reduction occurred where UO2 precipitated; therefore the highest uranium concentrations correspond to sandstone levels with reddish or reddish-brown pigment. These pigments have been identified by Moessbauer spectroscopy. (Auth.)

  3. Spectroscopy

    CERN Document Server

    Walker, S

    1976-01-01

    The three volumes of Spectroscopy constitute the one comprehensive text available on the principles, practice and applications of spectroscopy. By giving full accounts of those spectroscopic techniques only recently introduced into student courses - such as Mössbauer spectroscopy and photoelectron spectroscopy - in addition to those techniques long recognised as being essential in chemistry teaching - sucha as e.s.r. and infrared spectroscopy - the book caters for the complete requirements of undergraduate students and at the same time provides a sound introduction to special topics for graduate students.

  4. Low temperature synthesis, magnetic and electrical properties of iron-magnesium superparamagnetic nanoalloy

    Energy Technology Data Exchange (ETDEWEB)

    Nazir, Rabia [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Mazhar, Muhammad [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan)], E-mail: mazhar42pk@yahoo.com; Akhtar, Muhammad Javed; Nadeem, Muhammad; Siddique, Muhammad [Physics Division, Pinstech, P.O. Nilore, Islamabad (Pakistan); Shah, Raza [HEJ Research Institute of Chemistry, University of Karachi, Karachi 75270 (Pakistan); Hasanain, S. Khurshid [Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    2009-06-24

    A low temperature chemical approach which beats the miscibility barrier of Fe and Mg has been designed to synthesize Fe-Mg{sub 2} nanoalloy and tested to result nanoparticles of average 30 nm size. The nanoalloy is amorphous in nature and characterized by XPRD, AFM, magnetometery, Moessbauer and impedance spectroscopies. The result of magnetic measurement suggests the sample to be superparamagnetic as evidenced by the {sup 57}Fe Moessbauer spectroscopy. The two Mg atoms occupy different positions around iron resulting in two phase system as shown by Moessbauer and impedance spectroscopies.

  5. Study of the local induction in the superconductor YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} by Moessbauer spectroscopy using the probe {sup 170}Yb{sup 3+}: methodology and results; Etude de l`induction locale dans le compose supraconducteur YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} par spectroscopie mossbauer sur la sonde {sup 170}Yb{sup 3+}: methodologie et resultats

    Energy Technology Data Exchange (ETDEWEB)

    Vaast-Paci, Ch

    1997-12-09

    This thesis is concerned with the measurement of the local induction in the anisotropic type II superconductor YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} in presence of an applied field. In this compound, the field penetrates in the form of vortices whose characteristics are governed by both intrinsic (critical fields, anisotropy, penetration lengths,...) and extrinsic parameters (such as pinning centers). We have developed a new microscopic technique to measure the local fields using Moessbauer probes {sup 170}Yb{sup 3+} dilutes for Y{sup 3+}. The measurements are based on the field dependence (size and direction) of the Moessbauer transitions between the electronuclear levels of the probe. These probes are distributed randomly over the sample so the measurements provide both the size and the direction of the internal field distribution over the whole sample. The possible measurement range extends from below 50 Oe to about 4000 Oe, for temperatures up to 60 deg.K. Measurements were made at T4.2 deg. K, for sintered pellets with different oxygen amount and for optimally doped ci-axis oriented single crystals. The penetration length measurements showed that the density of the superconducting condensate increases progressively with carrier doping. Field penetration measurements furnished the microscopic lower penetration field H{sub cl}, and enabled us to propose a model describing the profile of the flux distribution which is controlled by the pinning centers. The measurements also evidenced an anomalous penetration in small sized single crystals. In additions, we obtained the average direction of the vortices when the applied field is titled from the c axis and we showed that the vortex direction depends on the way the field is applied (ZFC or FC configuration) and that there exists a competition between the pinning forces and the intrinsic anisotropy. (author) 94 refs.

  6. Moessbauer and X-ray diffraction studies of nanostructured Fe{sub 70}Al{sub 30} powders elaborated by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Kezrane, M., E-mail: mohamedkezrane@yahoo.fr [LMP2M Laboratory, University of Medea, (26000) (Algeria); Guittoum, A. [Nuclear Research Centre of Algiers, 2 Bd Frantz Fanon, BP 399, Algiers (Algeria); Boukherroub, N.; Lamrani, S. [LMMC, M' hamed Bougara University, Boumerdes, 35000 (Algeria); Sahraoui, T. [Laboratory of Materials and Surface Treatments, LTSM, University of Saad Dahleb Blida, BP. 270 route de Soumaa, Blida (09000) (Algeria)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Nanocrystalline Fe{sub 70}Al{sub 30} powders were successfully elaborated by mechanical alloying. Black-Right-Pointing-Pointer The Moessbauer spectra show that from 4 h of milling, a disordered ferromagnetic. Black-Right-Pointing-Pointer Fe{sub 70}Al{sub 30} starts to form and dominates after 36 h. - Abstract: We have studied the effect of milling time on the structural and hyperfine properties of Fe{sub 70}Al{sub 30} compound elaborated by mechanical alloying. The elaboration was performed with a vario-planetary ball mill P4 at different milling times. The milled powders were characterized by X-ray diffraction (XRD) and Moessbauer spectroscopy. From XRD diffraction spectra, we show that the bcc Fe(Al) solid solution was completely formed after 27 h of milling time. When the milling time increases, the lattice parameter increases, whereas the grain size decreases and the mean level of microstrains increases. The analysis of Moessbauer spectra shows that from 4 h of milling, a disordered ferromagnetic Fe{sub 70}Al{sub 30} starts to form and dominates after 36 h.

  7. Moessbauer study of the relationship between magnetic properties and Jahn-Teller distortion in La1-xBax(Mn,Fe)O3 perovskites

    International Nuclear Information System (INIS)

    The local structural distortion and its effect on the magnetic and magnetotransport properties of the Fe-doped La1-xBaxMnO3 (0.00≤x≤0.35) compounds were investigated by means of X-ray diffraction, Moessbauer spectroscopy, and magnetization measurements. The Moessbauer spectra show clear evidence of the local structural distortion of the Mn(Fe)O6 octahedron on the basis of non-zero nuclear quadrupole interactions for high-spin Fe3+ ions. It was found that the local structural distortion decreases significantly with the introduction of a few per cent of Ba, reaches a minimum around x=0.13, and then increases slightly on further increasing the Ba concentration. The Ba-concentration dependence of the Jahn-Teller coupling strength estimated from the Moessbauer results was found to be consistent with the magnetic properties. Consequently, the connection between this local structural distortion and the colossal magnetoresistive behavior of this family of materials can be well explained. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Synthesis and Moessbauer-spectroscopic investigation of coordination compounds of tin(IV) with ligands based on thiosemicarbazide

    Energy Technology Data Exchange (ETDEWEB)

    Gerbeleu, N.V.; Rochev, V.Ya.; Turte, K.I.; Bologa, O.A.; Bobkova, S.A.; Lozan, V.I.; Lavrinyuk, I.P.

    1987-03-01

    Coordination compounds of Sn(IV) of the type SnX/sub 4/L/sub 2/, where X = Cl and Br, and L stands for pyruvic acid thiosemicarbazone (pyth), carboxybenzaldehyde thiosemicarbazone (beth), and thiosemicarbazidediacetic acid (thda), respectively, have been investigated by Moessbauer spectroscopy. The gamma-resonance spectra have the form of unbroadened singlet lines with values of the isomer shifts at 92/sup 0/K equal to 0.56 for SnCl/sub 4/ (pyth)/sub 2/, 0.52 for SnCl/sub 4/ (beth)/sub 2/, 0.65 for SnCl/sub 4/ (thda)/sub 2/, 0.78 for SnBr/sub 4/ (pyth)/sub 2/, and 0.91 mm/sec for SnBr/sub 4/ (thda)/sub 2/. An analysis of the IR spectra and Moessbauer spectra led to the conclusion that in all the compounds synthesized L acts as a neutral monodentate ligand, in which the sulfur atom is the donor site.

  9. Moessbauer studies of raw materials from Misti volcano of Arequipa (Peru) for its potential application in the ceramic field

    Energy Technology Data Exchange (ETDEWEB)

    Bustamante, Angel, E-mail: angelbd1@gmail.com [Universidad Nacional Mayor de San Marcos (Peru); Capel, Francisco; Barba, Flora, E-mail: flora@icv.csic.es; Callejas, Pio [Consejo Superior de investigaciones Cientificas (CSIC), Instituto de Ceramica y Vidrio (Spain); Guzman, Rivalino [Universidad Nacional de San Agustin de Arequipa (Peru); Trujillo, Alejandro [Universidad Nacional Mayor de San Marcos (Peru)

    2009-04-15

    We would like to introduce, the study of two different colour 'sillar' samples: white and pink, belonging to the Anashuayco quarry in the Arequipa Region (Peru). The X-ray diffraction (XRD) analysis indicates the presence of several mineralogical phases, such as feldpars and biotite for the both white and pink 'sillar' whereas cristobalite and quartz are detected only in the first sample and amorphous phase in the second one. In room temperature, Moessbauer spectroscopy, the presence of hematite ({alpha}-Fe{sub 2}O{sub 3}) was detected as the main phase for both samples, this was not detected in the XRD measurements. Moreover, corresponding doublets in the Moessbauer spectra indicate the presence of iron in the aluminium-silicate minerals. The rates Fe{sup 2+}/Fe{sup 3+} are 0.0752 and 0.0526 to the white and pink samples respectively. The minerals composing the white tuff form a heterogeneous aggregate of uniform aspect. Mining of these materials generates a great amount of waste in the form of lumps of varying size and which are raw materials studied in the present work for potential application in the ceramic field.

  10. Moessbauer spectroscopic study on inorganic compounds. Pt. 2

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Masashi; Kitazawa, Takafumi; Nanba, Hiroshi; Yoshinaga, Tomohiro; Nakajima, Norio; Sumisawa, Yasuhiro; Takeda, Masuo [Toho Univ., Funabashi, Chiba (Japan). Faculty of Science; Sawahata, Hiroyuki; Ito, Yasuo

    1998-01-01

    {sup 166}Er and {sup 127}I Moessbauer spectra were observed. {sup 166}Er Moessbauer spectrum of Er metal and 9 compounds were measured by {sup 166}Ho/Y{sub 0.6}Ho{sub 0.4}H{sub 2} source at 12K and the parameters such as e{sup 2}qQ(mm s{sup -1}), Heff(T) and {tau}(ns) were determined. The relaxation time of ErCl{sub 3}{center_dot}6H{sub 2}O was 0.7ns, long, but that of ErCl{sub 3} was 10 ps, short time. {sup 127}I Moessbauer spectrum of PhI(O{sub 2}CR){sub 2} (R=CH{sub 3}, CHF{sub 2}, CH{sub 2}Cl, CHCl{sub 2}, CCl{sub 3}, CH{sub 2}Br, CHBr{sub 2} and CBr{sub 3}) were observed and compared with that of R`{sub 3}Sb(O{sub 2}CR){sub 2} was similar to that of PhI(O{sub 2}CR){sub 2}. The correlation coefficient between e{sup 2}qQ({sup 127}I) and Mulliken population of carboxylic hydrogen atom of R{sub 2}CO{sub 2}H was -0.87. The relation between the hypervalent bond of O-I-O and that of O-Sb-0 was shown by the equation: e{sup 2}qQ({sup 121}Sb)/mm s{sup -1} = -47.2 + 1.32 e{sup 2}qQ({sup 127}I)/mm s{sup -1}. Hypervalent iodine complex such as (PhI(py){sub 2}){sup 2+} salt and E-Sb-I (E=O, I, N and C) were studied, too. (S.Y.)

  11. Moessbauer studies and magnetic properties of spinel lead ferrite

    International Nuclear Information System (INIS)

    In the present communication, we have reported the synthesis of nanocrystalline lead ferrite (PbFe2O4) by citrate mediated autocombustion method. X-ray diffraction pattern reveals the single phase formation in cubic (spinel) structure. The particle size and the surface morphology of the samples are characterized by TEM and SEM analysis. Magnetic studies are carried out using vibrating sample magnetometer (VSM) shows a very high coercive field for the material. Moessbauer studies were performed to investigate the local symmetry i.e. Fe is in octahedral/tetrahedral site and the charge states of Fe ions.

  12. Moessbauer and magnetic investigation of Fe-Mn alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yousif, A.A. [Sultan Qaboos Univ., Al Khoud (Oman). Dept. of Phys.; Elzain, M.E. [Sultan Qaboos Univ., Al Khoud (Oman). Dept. of Phys.; Rais, A. [Sultan Qaboos Univ., Al Khoud (Oman). Dept. of Phys.; Terzieff, P. [Inst. of Inorganic Chemistry, Univ. of Vienna (Austria)

    1994-11-01

    Moessbauer, X-ray, magnetization and susceptibility measurements were performed to study Fe{sub 100-x}Mn{sub x}, x = 5, 15, 39, 50. The different phases of Fe-Mn were identified, and hyperfine interaction parameters and average magnetic moments of some samples were determined. The average hyperfine field and average magnetic moment decrease as x increases. The influence of the Mn neighbourhood on the derived parameters is discussed in the light of calculations using the first principle discrete variational method in the local density approximation. (orig.)

  13. Relaxation studies using selective excitation double Moessbauer techniques

    International Nuclear Information System (INIS)

    Relaxation processes were studied in an iron powder scatterer at room temperature and in an α-Fe2O3 powder scatterer at liquid nitrogen temperature using the selective excitation double Moessbauer effect (SEDM) in the absence of time-dependent effects. The SEDM method was also used in studying the Morin transition (Tsub(N) = 263 K) in α-Fe2O3. The results are shown graphically. Very good agreement was found between the calculated and experimental spectra. (L.O.)

  14. Moessbauer studies of hemoglobin in high altitude polycythemia

    International Nuclear Information System (INIS)

    The Moessbauer spectra have been measured in erythrocytes from normal adults and the patients with high altitude polycythemia (HAPC). The results indicated that two subspectra ''a'' and ''b'', corresponding to oxy- and deoxyhemoglobin respectively, were present in all blood samples, and a third subspectrum ''c'' was found to exist in almost all samples from the patients. The parameters of the third subspectra ''c1'' in most samples from the patients were similar to those of carbon monoxyhemoglobin. The components were considered to be the denatured hemoglobin in RBCs (red blood cells). Together with clinical analysis, a possible mechanism of HAPC has been discussed. (orig.)

  15. Dimeric Fe (II, III) complex of quinoneoxime as functional model of PAP enzyme: Moessbauer, magneto-structural and DNA cleavage studies

    Energy Technology Data Exchange (ETDEWEB)

    Salunke-Gawali, Sunita; Ahmed, Khursheed [University of Pune, Department of Chemistry (India); Varret, Francois; Linares, Jorge [Universite de Versailles, Laboratoire de Magnetisme et d' Optique, CNRS, UMR 8634 (France); Zaware, Santosh [University of Pune, Department of Chemistry (India); Date, Sadgopal [University of Pune, Department of Physics (India); Rane, Sandhya, E-mail: syrane@chem.unipune.ernet.in [University of Pune, Department of Chemistry (India)

    2008-07-15

    Purple acid phosphatase, (PAP), is known to contain dinuclear Fe{sub 2}{sup +2,+3} site with characteristic Fe{sup +3} <- Tyr ligand to metal charge transfer in coordination. Phthiocoloxime (3-methyl-2-hydroxy-1,4-naphthoquinone-1-oxime) ligand L, mimics (His/Tyr) ligation with controlled and unique charge transfers resulting in valence tautomeric coordination with mixed valent diiron site in model compound Fe-1: [{mu}-OH-Fe{sub 2}{sup +2,+3} (o-NQ{sub CH3ox}) (o-NSQ{sub CH3ox}){sub 2} (CAT) H{sub 2}O]. Fe-2: [Fe{sup +3}(o-NQ{sub CH3ox}) (p-NQ{sub CH3ox}){sub 2}]{sub 2} a molecularly associated dimer of phthiocoloxime synthesized for comparison of charge transfer. {sup 57}Fe Moessbauer studies was used to quantitize unusual valences due to ligand in dimeric Fe-1 and Fe-2 complexes which are supported by EPR and SQUID studies. {sup 57}Fe Moessbauer spectra for Fe-1 at 300 K indicates the presence of two quadrupole split asymmetric doublets due to the differences in local coordination geometries of [Fe{sup +3}]{sub A} and [Fe{sup +2}]{sub B} sites. The hyperfine interaction parameters are {delta}{sub A} = 0.152, ({Delta}E{sub Q}){sub A} 0.598 mm/s with overlapping doublet at {delta}{sub B} = 0.410 and ({Delta}E{sub Q}){sub B} 0.468 mm/s. Due to molecular association tendency of ligand, dimer Fe-2 possesses 100% Fe{sup +3}(h.s.) hexacoordinated configuration with isomer shift {delta} = 0.408 mm/s. Slightly distorted octahedral symmetry created by NQ{sub CH3ox} ligand surrounding Fe{sup +3}(h.s.) state generates small field gradient indicated by quadrupole split {Delta}E{sub Q} = 0.213 mm/s. Decrease of isomer shifts together with variation of quadrupole splits with temperature in Fe-1 dimer compared to Fe-2 is result of charge transfers in [Fe{sub 2}{sup +2,+3} SQ] complexes. EPR spectrum of Fe-1 shows two strong signals at g{sub 1} = 4.17 and g{sub 2} = 2.01 indicative of S = 3/2 spin state with an intermediate spin of Fe{sup +3}(h.s.) configuration. SQUID data of

  16. Spectroscopy

    DEFF Research Database (Denmark)

    Berg, Rolf W.

    This introductory booklet covers the basics of molecular spectroscopy, infrared and Raman methods, instrumental considerations, symmetry analysis of molecules, group theory and selection rules, as well as assignments of fundamental vibrational modes in molecules.......This introductory booklet covers the basics of molecular spectroscopy, infrared and Raman methods, instrumental considerations, symmetry analysis of molecules, group theory and selection rules, as well as assignments of fundamental vibrational modes in molecules....

  17. Moessbauer In Situ Studies of the Surface of Mars

    Energy Technology Data Exchange (ETDEWEB)

    Klingelhoefer, G., E-mail: klingel@mail.uni-mainz.de [Johannes Gutenberg Universitaet, Inst. Anorganische and Analytische Chemie (Germany)

    2004-11-15

    For the first time in history, a Moessbauer spectrometer was placed on the surface of another planet. Our miniaturized Moessbauer spectrometer MIMOS II is part of the instrument payload of NASA's twin Mars Exploration Rovers (MER) 'Spirit' and 'Opportunity', which in January 2004 successfully landed at the Gusev crater and the Meridiani Planum landing sites, respectively. MIMOS II determines the Fe-bearing mineralogy of Martian soils and rocks at the Rovers' respective landing sites. The main goals of this planetary twin mission are to: (1) identify hydrologic, hydrothermal, and other processes that have operated and affected materials at the landing sites; (2) identify and investigate the rocks and soils at both landing sites, as there is a possible chance that they may preserve evidence of ancient environmental conditions and possible prebiotic or biotic activities. With MIMOS II, besides other minerals the Fe silicate olivine has been identified in both soil and rocks at both landing sites. At the Meridiani site the Fe sulfate jarosite has been identified by MIMOS II which is definitive mineralogical proof of the presence of water at this site in the past.

  18. Moessbauer In Situ Studies of the Surface of Mars

    International Nuclear Information System (INIS)

    For the first time in history, a Moessbauer spectrometer was placed on the surface of another planet. Our miniaturized Moessbauer spectrometer MIMOS II is part of the instrument payload of NASA's twin Mars Exploration Rovers (MER) 'Spirit' and 'Opportunity', which in January 2004 successfully landed at the Gusev crater and the Meridiani Planum landing sites, respectively. MIMOS II determines the Fe-bearing mineralogy of Martian soils and rocks at the Rovers' respective landing sites. The main goals of this planetary twin mission are to: (1) identify hydrologic, hydrothermal, and other processes that have operated and affected materials at the landing sites; (2) identify and investigate the rocks and soils at both landing sites, as there is a possible chance that they may preserve evidence of ancient environmental conditions and possible prebiotic or biotic activities. With MIMOS II, besides other minerals the Fe silicate olivine has been identified in both soil and rocks at both landing sites. At the Meridiani site the Fe sulfate jarosite has been identified by MIMOS II which is definitive mineralogical proof of the presence of water at this site in the past.

  19. Moessbauer spectroscopic study of potassium borosilicate glasses at low temperatures

    International Nuclear Information System (INIS)

    The Moessbauer technique at the liquid nitrogen temperature (78 K) was applied to the estimation of nonbridging oxygens in FeO4, BO4, and SiO4 units in potassium borosilicate glasses. Moessbauer spectra consist of a quadrupole doublet and a hyperfine structure due to Fe3+ ions with tetrahedral symmetry. The hyperfine structure is attributed to a relaxation effect because magnetic susceptibility measurements revealed the glasses to be paramagnetic in the temperature range 78 - 295 K. A linear decrease in the absorption area and a similar decrease in the internal magnetic field for the hyperfine structure were observed with an increase in the alkali content of glasses. The decrease is ascribed to a formation of non-bridging oxygen at the site adjacent to iron, because the mean life-time of the internal magnetic field produced by 3d-electrons of iron is considered to decrease with increasing thermal vibration of the iron and neighboring oxygens. Fractions of non-bridging oxygens obtained from the reduction rate of the absorption area of hyperfine structure are in good agreement with earlier results for borate glasses with the same K2O/B2O3 ratios, in the alkali region of 8 - 20 mol% where the borosilicate glasses are essentially considered to be borate glasses diluted with SiO2. (author)

  20. The Moessbauer effect and its application - Pt III : Magnetic hyperfine interaction

    International Nuclear Information System (INIS)

    The magnetic hyperfine interaction in a large number of nuclei such as Fe57, Sn119, Eu151 etc. have been studied using Moessbauer effect. A quantitative description of the basic principle underlying the nuclear magnetic interactions is given. Typical Moessbauer spectra of metallic iron, Fe2O3, FeB, are shown. The behavior of a diagmagnetic nucleus Sn119 embedded in a magnetically ordered lattice has also been studied by its Moessbauer spectrum. Magnetic hf interaction technique has been extended to investigate the composition of lunar materials and also to extract information on the provenance and thermal treatment of Greek and Roman earthenware. (A.K.)

  1. Moessbauer studies of YBa[sub 2](Cu[sub 1-x]Fe[sub x])[sub 3]O[sub 7-d] annealed in an inert atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Maknani, J. (Lab. de Magnetisme et Materiaux Magnetiques, CNRS, 92 Meudon (France)); Dormann, J.L. (Lab. de Magnetisme et Materiaux Magnetiques, CNRS, 92 Meudon (France)); Terziev, V.G. (Lab. de Magnetisme et Materiaux Magnetiques, CNRS, 92 Meudon (France)); Jove, J. (Inst. Curie, Paris (France)); Pankowska, H. (Lab. de Physique des Solides, CNRS, 92 Meudon (France)); Gorochov, O. (Lab. de Physique des Solides, CNRS, 92 Meudon (France)); Suryanarayanan, R. (Lab. de Physique des Solides, CNRS, 92 Meudon (France))

    1994-11-01

    YBa[sub 2](Cu[sub 1-x]Fe[sub x])[sub 3]O[sub 7-d] annealed in an Ar atmosphere, then reoxygenated at various temperatures, has been studied by Moessbauer spectroscopy at 300 K and low temperature with and without an applied field of 5.5 T. The results are interpreted as being due to Fe clustering remaining in the chains rather than a significant transfer to the planes. (orig.)

  2. Hyperfine interactions in soybean and lupin oxy-leghemoglobins studied using Mössbauer spectroscopy with a high velocity resolution

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, A. [University of Delhi South Campus, Department of Biochemistry (India); Alenkina, I. V. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation); Zakharova, A. P. [Ural Federal University, Department of Experimental Physics, Institute of Physics and Technology (Russian Federation); Oshtrakh, M. I., E-mail: oshtrakh@gmail.com; Semionkin, V. A. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation)

    2015-04-15

    A comparative study of monomeric soybean and lupin leghemoglobins in the oxy-form was carried out using Mössbauer spectroscopy with a high velocity resolution at 90 K. The {sup 57}Fe hyperfine parameters of measured spectra were evaluated and compared with possible structural differences in the heme Fe(II)–O {sub 2} bond.

  3. Moessbauer study of iron(II) and iron(III) complexes of some nitrogen-, oxygen- and sulphur donor ligands, reduction of iron(III) by the mercaptide group

    International Nuclear Information System (INIS)

    Complex formation reactions of iron(II) and iron(III) with semicarbazones and thiosemicarbazones of pyruvic acid and phenyl pyruvic acid have been studied by magnetic measurements and Moessbauer spectroscopy. With iron(II), all the ligands form hexa-coordinated octahedral complexes of the type Fe(ligand-H2). With iron(III) semicarbazones, complexes of the composition [Fe(ligand-H)2](OH) are formed. Thiosemicarbazones first reduce iron(III) to iron(II) and then form iron(II) complexes of the type Fe(ligand-H)2. (author)

  4. Moessbauer study of iron(II) and iron(III) complexes of some nitrogen-, oxygen- and sulphur donor ligands, reduction of iron(III) by the mercaptide group

    Energy Technology Data Exchange (ETDEWEB)

    Sawhney, G.L.; Baijal, J.S. (Delhi Univ. (India). Dept. of Physics and Astrophysics); Chandra, S. (Zakir Hussain College, Ajmeri Gate, Delhi (India). Dept. of Chemistry); Pandeya, K.B. (Delhi Univ. (India). Dept. of Chemistry)

    1981-01-01

    Complex formation reactions of iron(II) and iron(III) with semicarbazones and thiosemicarbazones of pyruvic acid and phenyl pyruvic acid have been studied by magnetic measurements and Moessbauer spectroscopy. With iron(II), all the ligands form hexa-coordinated octahedral complexes of the type Fe(ligand-H/sub 2/). With iron(III) semicarbazones, complexes of the composition (Fe(ligand-H)/sub 2/)(OH) are formed. Thiosemicarbazones first reduce iron(III) to iron(II) and then form iron(II) complexes of the type Fe(ligand-H)/sub 2/.

  5. Electronic and structural properties of Sb in stage 1 SbF5-graphite from 121Sb Moessbauer spectrometry

    International Nuclear Information System (INIS)

    The valence configuration of Sb in stage 1 SbF5-HOPG is essentially (>94%) Sb5+. Although not fully unambiguous owing to lack of resolution, the intercalated molecular state is assigned to SbF5 in a configuration similar to that of solid SbF5 (distorted octahedral coordination). These molecules are oriented with respect to the graphite host (T 5 into SbF3 and SbF6- within the solid is ruled out. It is rather suggested that the small (6%) Sb3+ component is actually not intercalated. 'Powder' samples present larger (20-30%) and non-reproducible Sb3+ proportions. It is argued that such samples are of intrinsic limited interest in Moessbauer spectroscopy (and other texture sensitive methods) because of unavoidable texture and chemical instability, which prevent precise and reliable data analyses. (Auth.)

  6. Moessbauer study of MgCr sub 0 sub . sub 1 Fe sub 1 sub . sub 9 O sub 4

    CERN Document Server

    Lee, S W; Kim, C S

    1999-01-01

    MgCr sub 0 sub . sub 1 Fe sub 1 sub . sub 9 O sub 4 has been studied with X-ray diffraction and Moessbauer spectroscopy. The crystal structure is found to have a cubic spinel structure with a lattice constant of a sub o =8.388+-0.005 A. The iron ions at both A (tetrahedral) and B (octahedral) sites are found to be in ferric high-spin stats. Its Neel temperature T sub N is found to be 687+-3K. The Debye temperatures for the A and the B sites are found 515+-5 K and 265+-5 K, respectively. Atomic migration from the A to the B sites start near 850 K and increase rapidly with increasing temperature to such a degree that 50% of the ferric ions at the A sites have moved over to the B sites by 600 K.

  7. Moessbauer study of Cu sub 0 sub . sub 8 Fe sub 2 sub . sub 2 O sub 4

    CERN Document Server

    Kim, S J; An, D H; Kang, K U; Baek, K S; Oak, H N

    2000-01-01

    Cu sub 0 sub . sub 8 Fe sub 2 sub . sub 2 O sub 4 has been studied by using Moessbauer spectroscopy and X-ray diffraction. The crystal is found to have a cubic spinel structure with the lattice constant a sub 0 =8.399 +- 0.005 A. It is noteworthy that a 20% replacement of Cu by Fe in the copper ferrite transforms the crystal structure from tetragonal to cubic and decreases the quadrupole shifts drastically. The iron ions at both A (tetrahedral) and B (octahedral) sites are found to be in ferric states. Atomic migration between A- and B-sites starts near 300 K and increases rapidly with increasing temperature to such a degree that 78% of the ferric ions at the A-sites move over to the B sites at 600 K.

  8. Fischer-Tropsch synthesis: Moessbauer studies of pretreated ultrafine iron oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Chenshi Huang; Davis, B.H. (Kentucky Univ., Lexington, KY (United States). Center for Applied Energy Research); Rao, K.R.P.M.; Huffman, G.P.; Huggins, F.E. (Kentucky Univ., Lexington, KY (United States). Inst. for Mining and Minerals Research)

    1992-01-01

    Moessbauer spectroscopy indicates that a 24 hour-pretreatment in CO at 260{degrees}C and 8 atm. in a tetralin solvent almost completely converts uftrafine iron oxide (about 3 nm) to iron carbide. However, pretreatment in hydrogen under the same conditions resulted in reduction of about 33% of the iron to metallic Fe; the remainder was Fe{sub 3}O{sub 4}. Exposure of the CO pretreated catalyst to a 1:1 HDCO synthesis gas resulted in the gradual reoxidation of the carbides to Fe{sub 3}O{sub 4}. During the first 2 hours of exposure of the H{sub 2} pretreated sample to synthesis gas,.the metallic Fe was converted to iron carbides. Further exposure of the H{sub 2} pretreatment sample to synthesis gas did not result in a composition change of the catalyst. Therefore, it is concluded that iron carbides with different oxidation characteristics were formed in these two cases.

  9. Applications of the Moessbauer effect in chemistry and solid-state physics

    International Nuclear Information System (INIS)

    Applications of the Moessbauer effect presented by the panel members include structural and kinetic investigations, recoil studies, magnetism, analytical measurements and standards. A description of apparatus and techniques is also included. Refs, figs and tabs

  10. Application of the Moessbauer effect in the investigation of mineral raw materials

    International Nuclear Information System (INIS)

    The application is described of a method for an improved resolution of complex experimental Moessbauer spectra. The method is based on the application of the speedy Fourier transformation. The efficiency is illustrated by the measured spectra and by the improved spectra obtained from them. The application of the Moessbauer effect is discussed in research on minerals of the isomorphous series enstatite-hypersthene and on amphiboles. (author)

  11. Moessbauer studies of nano phase Ce-Fe oxide composites

    International Nuclear Information System (INIS)

    Chemical co-precipitation method was used to synthesize nano-structured α-Fe2O3-CeO2 composite by calcination of the goethite-cerium hydroxide precursor. It was observed that the precursor contained goethite matrix doped with cerium. Calcination of the precursor at 400oC showed the formation of nanosize hematite. Moessbauer spectra show the presence of a paramagnetic component in the precursor but not in the samples calcined at 400oC to 800oC temperatures. Our study shows that Ce precipitated as CeO2 and stuck on the surface of hematite particles. The precipitation of Ce as CeO2 is independent of the concentration of Ce in the Ce-Fe-O composite.

  12. Modulation gamma resonance spectroscopy

    International Nuclear Information System (INIS)

    Possibility to control dynamic processes in a matter through gamma-resonance modulation by high-frequency external variable fields in excess of inverse lifetimes of the Moessbauer nuclei excited states, that is, within the megahertz frequency range lies in the heart of the modulation gamma-resonance spectroscopy. Through the use of the gamma-resonance process theoretical analysis methods and of the equation solution method for the density matrix with the secondary quantization of gamma-radiation field one attacks the problems dealing with the effect of both variable fields and relaxation on gamma-resonance. One has studied the gamma-radiation ultrasound modulation stages. One points out a peculiar role of the gamma-magnetic resonance effect in modulation gamma resonance spectroscopy formation. One forecasts development of the modulation gamma-resonance spectroscopy into the nonlinear gamma-resonance spectroscopy

  13. Role of Mo in the local configuration and structure stabilization of amorphous steels, a Synchrotron X-ray diffraction and Moessbauer study

    Energy Technology Data Exchange (ETDEWEB)

    Pineda, E., E-mail: eloi.pineda@upc.edu [Departament de Fisica i Enginyeria Nuclear, ESAB, Universitat Politecnica de Catalunya, Esteve Terradas 8, 08860 Castelldefels (Spain); Bruna, P. [Departament de Fisica Aplicada, EPSC, Universitat Politecnica de Catalunya, Avda. del Canal Olimpic s/n, 08860 Castelldefels (Spain); Serrano, J. [Departament de Fisica Aplicada, EPSC, Universitat Politecnica de Catalunya, Avda. del Canal Olimpic s/n, 08860 Castelldefels (Spain); Institucio Catalana de Recerca i Estudis Avancats, Catalonia (Spain); Torrens-Serra, J. [Grup de Nanomaterials i Microsistemes, Departament de Fisica, Universitat Autonoma de Barcelona. Edifici Cc, 08193 Bellaterra (Spain); Crespo, D. [Departament de Fisica Aplicada, EPSC, Universitat Politecnica de Catalunya, Avda. del Canal Olimpic s/n, 08860 Castelldefels (Spain)

    2011-06-15

    Highlights: > Mo substitution of Fe atoms stabilizes structure in amorphous steels. > Moessbauer spectroscopy evidences two distinct Fe atoms environments in the amorphous structure of the Mo containing glassy alloys. > Structural relaxation before crystallization produces homogenization of the Fe environments reducing population of sites with low hyperfine fields. - Abstract: Amorphous steels are promising materials with potential structural applications. The glass-forming ability (GFA) and mechanical properties of metallic glasses are intimately related to the local structure. In Fe-based alloys, Cr and Mo content seem to play a key role in stabilizing the amorphous atomic-level structure. Here we present a study on the effects of changing Mo content in Fe{sub 72-x}C{sub 7}Si{sub 3.3}B{sub 5.5}P{sub 8.7}Cr{sub 2.3}Al{sub 2}Mo{sub x} amorphous steels. We study the local structure of these alloys by Synchrotron X-ray diffraction and Moessbauer spectroscopy. The results show how the amorphous phase evolves from a ferromagnetic Fe-rich structure to a structure with predominance of paramagnetic environments with the increase of Mo content. The changes in the distribution of magnetic environments cannot be attributed only to the Fe-Mo substitution but to a change of local configuration in the amorphous phase.

  14. Effects of Al substitution and thermal annealing on magnetoelectric Ba0.5Sr1.5Zn2Fe12O22 investigated by the enhancement factor of 57Fe nuclear magnetic resonance.

    Science.gov (United States)

    Kwon, Sangil; Kang, Byeongki; Kim, Changsoo; Jo, Euna; Lee, Soonchil; Chai, Yi Sheng; Chun, Sae Hwan; Kim, Kee Hoon

    2014-04-01

    The magnetoelectric properties of hexaferrite Ba0.5Sr1.5Zn2Fe12O22 are significantly improved by Al substitution and thermal annealing. Measuring the enhancement factor of 57Fe NMR, we found direct microscopic evidence that the magnetic moments of the L and S blocks are rotated by a magnetic field in such a way as to increase the net magnetic moment of a magnetic unit, even after the field is removed. Al substitution makes magnetoelectric property arise easily by suppressing the easy-plane anisotropy. The effect of thermal annealing is to stabilize the multiferroic state by reducing the number of pinning sites and the electron spin fluctuation. The transverse conic structure gradually changes to the alternating longitudinal conic structure where spins fluctuate more severely.

  15. X-ray diffraction and Moessbauer studies on superparamagnetic nickel ferrite (NiFe{sub 2}O{sub 4}) obtained by the proteic sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, N.A.S. [Departamento de Engenharia Metalúrgica e de Materiais, Centro de Tecnologia, Campus do Pici, Universidade Federal do Ceará – UFC, 60455-760 Fortaleza, CE (Brazil); Utuni, V.H.S.; Silva, Y.C. [Departamento de Física, Universidade Federal do Ceará – UFC, Campus do Pici, 60440-970 Fortaleza, CE (Brazil); Kiyohara, P.K. [Instituto de Física, Universidade de São Paulo – USP, 05315-970 São Paulo, SP (Brazil); Vasconcelos, I.F. [Departamento de Engenharia Metalúrgica e de Materiais, Centro de Tecnologia, Campus do Pici, Universidade Federal do Ceará – UFC, 60455-760 Fortaleza, CE (Brazil); Miranda, M.A.R., E-mail: marcus.a.r.miranda@gmail.com [Departamento de Física, Universidade Federal do Ceará – UFC, Campus do Pici, 60440-970 Fortaleza, CE (Brazil); Sasaki, J.M. [Departamento de Física, Universidade Federal do Ceará – UFC, Campus do Pici, 60440-970 Fortaleza, CE (Brazil)

    2015-08-01

    Nickel ferrite (NiFe{sub 2}O{sub 4}) nanoparticles were synthesized by the proteic sol–gel method at synthesis temperature of 250 °C, 300 °C and 400 °C, with the objective of obtaining superparamagnetic nanoparticles. Thermogravimetric analysis (TGA) and temperature-programed oxidation (TPO) presented peaks around 290 °C indicating that nickel ferrite was forming at this temperature. X-ray powder diffraction (XRPD) confirmed that the polycrystalline sample was single phased NiFe{sub 2}O{sub 4} with space group Fd3m. Scherrer equation applied to the diffraction patterns and transmission electron microscopy (TEM) images showed that the size of the nanoparticles ranged from 9 nm to 13 nm. TEM images also revealed that the nanoparticles were agglomerated, which was supported by the low values of surface area provided by the Brunauer-Emmet-Teller (BET) method. Moessbauer spectroscopy presented spectra composed of a superposition of three components: a sextet, a doublet and a broad singlet pattern. The sample synthetized at 300 °C had the most pronounced doublet pattern characteristic of superparamagnetic nanoparticles. In conclusion, this method was partially successful in obtaining superparamagnetic nickel ferrite nanoparticles, in which the synthetized samples were a mixture of nanoparticles with blocking temperature above and below room temperature. Magnetization curves revealed a small hysteresis, supporting the Moessbauer results. The sample with the higher concentration of superparamagnetic nanoparticles being the one synthetized at 300 °C. - Highlights: • Superparamagnetic nickel ferrite nanoparticles were grown by the proteic sol–gel method. • The proteic sol–gel method provided superparamagnetic nickel ferrite nanoparticles with sizes in the range of 9–13 nm. • Nickel ferrite nanoparticles were prepared at temperatures as low as 250 °C. • The nickel ferrite nanoparticles were studied by x-ray diffraction and Moessbauer.

  16. Moessbauer, XRD, NAA and XRF study of archaeological slag

    International Nuclear Information System (INIS)

    In 1960, remains of four furnaces from Early Medieval Age were excavated in Nitra. Because a lot of glass-like findings were found on this site the function of furnaces was considered as being used for production of glass even though no analytical tests were performed. These dig-outs were divided into two groups: The first group contains dark glass-like archaeological fragments which were interpreted as a waste (slag) of a glass production. The second group consists of archaeological artefacts which were thought to be a slag from iron production. The main aim of this work is to investigate these two types of archaeological artefacts. Employing standard transmission geometry Moessbauer effect experiments, iron crystallographic sites are identified and compared. In all samples, Fe2+ and Fe3+ structural positions were revealed. In addition, some of the archaeological artefacts that are presumably coming from glass production show traces of metallic iron. On the other hand, slag from iron production exhibit minute contribution of iron oxides in several instances. Additional information about the composition of slag is obtained from X-ray diffraction (XRD), neutron activation analysis (NAA), and X-ray fluorescence (XRF) measurements. (authors)

  17. Velocity calibration for in-situ Moessbauer data from Mars

    International Nuclear Information System (INIS)

    Beginning in August 2004, raw data acquired by the Moessbauer spectrometers on the Mars Exploration Rovers (MERs) have been released to the science community as Experimental Data Records (EDRs) for each Martian day (sol) on which measurements were made. To provide convenient direct access to the EDR data, to enable independent assessment and analysis, and to allow confirmation of MER-team scientific conclusions, a new Windows-based computer program, MERView, has been developed. Direct inspection of the binary structure of an EDR file, conversion of the binary data to decimal column format for display or export, and full-screen graphical displays are included, allowing, in a highly transparent and user-friendly manner, immediate and thorough overview of the entire EDR data set. MERView also includes automated procedures for velocity calibration. Correction for non-linearity is done using the EDR-provided drive error signal, a phase shift, and the requirement that the two halves of a reference spectrum must overlap exactly when plotted on a correct velocity scale. Absolute velocity calibration (mm/s) is then accomplished by comparing each reference spectrum with known peak positions of standard reference materials.

  18. Instrumental analysis of bacterial cells using vibrational and emission Moessbauer spectroscopic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Kamnev, Alexander A. [Laboratory of Biochemistry of Plant-Bacterial Symbioses, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 410049 Saratov (Russian Federation)]. E-mail: aakamnev@ibppm.sgu.ru; Tugarova, Anna V. [Laboratory of Biochemistry of Plant-Bacterial Symbioses, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 410049 Saratov (Russian Federation); Antonyuk, Lyudmila P. [Laboratory of Biochemistry of Plant-Bacterial Symbioses, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 410049 Saratov (Russian Federation); Tarantilis, Petros A. [Laboratory of Chemistry, Department of Science, Agricultural University of Athens, 11855 Athens (Greece); Kulikov, Leonid A. [Laboratory of Nuclear Chemistry Techniques, Department of Radiochemistry, Faculty of Chemistry, M.V. Lomonosov Moscow State University, 119992 Moscow (Russian Federation); Perfiliev, Yurii D. [Laboratory of Nuclear Chemistry Techniques, Department of Radiochemistry, Faculty of Chemistry, M.V. Lomonosov Moscow State University, 119992 Moscow (Russian Federation); Polissiou, Moschos G. [Laboratory of Chemistry, Department of Science, Agricultural University of Athens, 11855 Athens (Greece); Gardiner, Philip H.E. [Division of Chemistry, School of Science and Mathematics, Sheffield Hallam University, Sheffield S1 1WB (United Kingdom)

    2006-07-28

    In biosciences and biotechnology, the expanding application of physicochemical approaches using modern instrumental techniques is an efficient strategy to obtain valuable and often unique information at the molecular level. In this work, we applied a combination of vibrational (Fourier transform infrared (FTIR), FT-Raman) spectroscopic techniques, useful in overall structural and compositional analysis of bacterial cells of the rhizobacterium Azospirillum brasilense, with {sup 57}Co emission Moessbauer spectroscopy (EMS) used for sensitive monitoring of metal binding and further transformations in live bacterial cells. The information obtained, together with ICP-MS analyses for metals taken up by the bacteria, is useful in analysing the impact of the environmental conditions (heavy metal stress) on the bacterial metabolism and some differences in the heavy metal stress-induced behaviour of non-endophytic (Sp7) and facultatively endophytic (Sp245) strains. The results show that, while both strains Sp7 and Sp245 take up noticeable and comparable amounts of heavy metals from the medium (0.12 and 0.13 mg Co, 0.48 and 0.44 mg Cu or 4.2 and 2.1 mg Zn per gram of dry biomass, respectively, at a metal concentration of 0.2 mM in the medium), their metabolic responses differ essentially. Whereas for strain Sp7 the FTIR measurements showed significant accumulation of polyhydroxyalkanoates as storage materials involved in stress endurance, strain Sp245 did not show any major changes in cellular composition. Nevertheless, EMS measurements showed rapid binding of cobalt(II) by live bacterial cells (chemically similar to metal binding by dead bacteria) and its further transformation in the live cells within an hour.

  19. Magnetism and Moessbauer spectral study of the FeAlO3 ferro electromagnetic phase obtained by high-energy ball-milling

    International Nuclear Information System (INIS)

    Full text: Ferro electromagnetic materials have attracted much academic and technological attention in the last years. This is because they present potential applications in those areas where (anti)ferromagnetic and (anti)ferroelectric materials are extensively employed. In this way, the electric and magnetic order parameter coupling opens the possibility of the integration between the ferro electromagnetic physical properties through the magnetoelectric effects, and can promote interesting technological advances in many electro-electronic technologies, in spite of the open issues concerning to the origin of the ferro electromagnetism. The FeAlO3 phase is an extremely attractive ferro electromagnetic material, which presents ferrimagnetic, magnetoelectric and piezoelectric effects at low temperatures. The (Fe2O3)0.50(Al2O3).0.50 composite was prepared in a Fritsch Pulverisette 6 planetary ball-mill and a home-made high hard and abrasive ceramic medium (composed of an alumina vial charged with stabilized zirconia rods) - high-energy ball-milling was employed for the first time to produce the FeAlO3 ferro electromagnetic phase. The FeAlO3 structural and magnetic properties were studied through X-ray diffraction (XRD), Moessbauer spectroscopy (Ms) and magnetization measurements. The crystallographic parameters were refined using the Rietveld analysis. The XRD diffraction peaks were assigned as being for Fe AlO3 phase, plus a residual aluminum substituted hematite (Fe1xAlx)2O3 and iron substituted alumina (FeyAl1-y)2O3 solid solutions, besides a pattern of a very disordered phase. Magnetic and Moessbauer studies revealed a classical Neel ferrimagnetic ordering at low temperatures. Due to the high surface area, high defect density, and small particle size distribution, the superposition of the Moessbauer signals and the apparent existence of only two Moessbauer spectra, in spite of those four dissimilar irons sites in the FeAlO3 structure, were detected at room

  20. Moessbauer spectroscopic study of the formation of non-bridging oxygen in the potassium borate glasses

    International Nuclear Information System (INIS)

    Moessbauer spectroscopic study was performed to investigate the formation of non-bridging oxygen in the potassium borate glasses denoted by the formula of x K2O(100 - x) B2O3 x 7 Fe2O3 (0 3+ decreased continuously with the concentration of the alkali oxide in the glass, showing the increase of the symmetry around the Fe3+ ions. The isomer shift value also decreased in almost the same x region. The drastic decrease of Moessbauer parameters was attributed to the formation of non-bridging oxygen at the adjacent site of the Fe3+ ions. In the region of lower alkali content (less than 10 mol%), Moessbauer spectra only showed the absorption due to α-Fe2O3. X-ray powder diffraction patterns also displayed the existence of α-Fe2O3, together with the microcrystal of potassium borate. (orig.)

  1. A Synthetic Single-Site Fe Nitrogenase: High Turnover, Freeze-Quench (57)Fe Mössbauer Data, and a Hydride Resting State.

    Science.gov (United States)

    Del Castillo, Trevor J; Thompson, Niklas B; Peters, Jonas C

    2016-04-27

    The mechanisms of the few known molecular nitrogen-fixing systems, including nitrogenase enzymes, are of much interest but are not fully understood. We recently reported that Fe-N2 complexes of tetradentate P3(E) ligands (E = B, C) generate catalytic yields of NH3 under an atmosphere of N2 with acid and reductant at low temperatures. Here we show that these Fe catalysts are unexpectedly robust and retain activity after multiple reloadings. Nearly an order of magnitude improvement in yield of NH3 for each Fe catalyst has been realized (up to 64 equiv of NH3 produced per Fe for P3(B) and up to 47 equiv for P3(C)) by increasing acid/reductant loading with highly purified acid. Cyclic voltammetry shows the apparent onset of catalysis at the P3(B)Fe-N2/P3(B)Fe-N2(-) couple and controlled-potential electrolysis of P3(B)Fe(+) at -45 °C demonstrates that electrolytic N2 reduction to NH3 is feasible. Kinetic studies reveal first-order rate dependence on Fe catalyst concentration (P3(B)), consistent with a single-site catalyst model. An isostructural system (P3(Si)) is shown to be appreciably more selective for hydrogen evolution. In situ freeze-quench Mössbauer spectroscopy during turnover reveals an iron-borohydrido-hydride complex as a likely resting state of the P3(B)Fe catalyst system. We postulate that hydrogen-evolving reaction activity may prevent iron hydride formation from poisoning the P3(B)Fe system. This idea may be important to consider in the design of synthetic nitrogenases and may also have broader significance given that intermediate metal hydrides and hydrogen evolution may play a key role in biological nitrogen fixation. PMID:27026402

  2. Moessbauer studies of perovskite Gd sub 0 sub . sub 5 Sr sub 0 sub . sub 5 FeO sub 3 sub - sub y

    CERN Document Server

    Kim, C S; Sur, J C

    2000-01-01

    Perovskite powder Gd sub 0 sub . sub 5 Sr sub 0 sub . sub 5 FeO sub 3 sub - sub y was studied by X-ray diffraction, Moessbauer spectroscopy, vibrating samples magnetometry, and Mohr's salt analysis. Gd sub 0 sub . sub 5 Sr sub 0 sub . sub 5 FeO sub 3 sub - sub y was synthesized by using the solid-solid reaction method. The crystal structure was found to be orthorhombic with lattice parameters, a sub 0 =5.531 A, b sub 0 =5.608 A and c sub 0 =7.724 A. Moessbauer spectra of Gd sub 0 sub . sub 5 Sr sub 0 sub . sub 5 FeO sub 3 sub - sub y have been taken at various temperatures ranging from 4.2 to 600 K. The spectrum pattern at 4.2 K consisted of four sets of six Lorentzians, and the magnetic hyperfine fields are found to be 275, 486, 514 and 540 kOe. The Neel temperature, T sub N , was found to be 478 K. Mohr's salt analysis for Gd sub 0 sub . sub 5 Sr sub 0 sub . sub 5 FeO sub 3 sub - sub y demonstrated the existence of the mixed valence states, Fe sup 3 sup + (73%) and Fe sup 4 sup + (27%), and y=0.11 at room t...

  3. Moessbauer and X-ray Study of Fe{sub 1-x}Al{sub x}, 0.2{<=}x{<=}0.5, Samples Produced by Mechanical Alloying

    Energy Technology Data Exchange (ETDEWEB)

    Oyola Lozano, D., E-mail: doyola@ut.edu.co; MartInez, Y. Rojas; Bustos, H.; Perez Alcazar, G. A. [Universidad del Tolima, Departamento de Fisica (Colombia)

    2004-12-15

    In this work we report the magnetic and structural properties obtained by Moessbauer spectroscopy and X-ray diffraction, of the Fe{sub 1-x}Al{sub x}, 0.2{<=}x{<=}0.5, alloys produced by mechanical alloying. Alloys with x=0.2, 0.3, 0.4 and 0.5, were for milled 12, 24, 36, and 48 hours. All the obtained alloys are in the bcc phase. The obtained Moessbauer spectra are characteristic of disordered ferromagnetic system. The lattice parameter remains nearly constant ({approx}2.91 A) for all the milling times and compositions. The mean grain sizes in the (110) and (211) direction are nearly constants with the milling time but vary from 15.5 to 11 nm and from 10.5 to 8.5 nm when Al content grow between x=0.2 to x=0.4, respectively. The difference between the mean grain sizes in these two directions shows that the grains are of prolate spheroid form.

  4. NMR and Moessbauer Study of Al{sub 2}O{sub 3}-Eu{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Nava, N., E-mail: tnava@imp.mx; Salas, P.; Llanos, M. E. [Programa de Ingenieria Molecular, Instituto Mexicano del Petroleo (Mexico); Perez-Pastenes, H.; Viveros, T. [Universidad Autonoma Metropolitana-Iztapalapa, Departamento de IPH (Mexico)

    2005-02-15

    Alumina-europia mixed oxides with 5 and 10 wt.% Eu{sub 2}O{sub 3} were studied by Moessbauer spectroscopy, {sup 27}Al MAS-NMR and X-ray diffraction (XRD). The samples were prepared by the sol-gel technique. The XRD patterns for the calcined samples show a broad peak around 2{theta} = 30{sup o} which is assigned to the Eu{sub 2}O{sub 3}; after treatment with hydrogen at 1073 K no reduction to Eu{sup +2} or Eu{sup 0} was observed. The NMR spectra show three peaks, which are assigned to the octahedral, pentahedral and tetrahedral aluminum sites; the intensity of each peak depends on the concentration of europium ions. The Moessbauer spectra of the calcined samples show a single peak near zero velocity which is attributed to the Eu{sup +3}; after H{sub 2} treatment at 1073 K similar spectra were obtained, suggesting Eu{sup +3} is not reducibly at this temperature.

  5. Moessbauer Studies of Stannous Fluoride Reactivity with Synthetic Tooth Enamel - A Model for the Tooth Cavity Protection Actions of Novel Dentifrices

    Energy Technology Data Exchange (ETDEWEB)

    Denes, Georges, E-mail: gdenes@vax2.concordia.ca; Muntasar, Abdualhafeed [Concordia University, Laboratory of Moessbauer Spectroscopy and Solid State Chemistry, Laboratories for Inorganic Materials, Department of Chemistry and Biochemistry (Canada); Kozak, Kathy M.; Baig, Arif A.; White, Donald J. [Procter and Gamble Company (United States)

    2002-06-15

    SnF{sub 2} is an important toothpaste ingredient, added for the provision of clinical efficacy for hard and soft tissue diseases and in breath protection. Synthetic calcium hydroxyapatite powders were exposed to liquid supernates (25 w/w% toothpaste water slurries, centrifuged) of Crest Gum Care (registered) (SnF{sub 2}) dentifrice. One-minute treatments were followed by 3x water washing, centrifugation and lyophilization. Post treatment, powders were analyzed by Moessbauer spectroscopy with 0.5-1 gram of treated apatite powder. Results show that tooth mineral stannous fluoride interactions include: (1) formation of surface reaction products with both Sn(II) and Sn(IV) oxidation states; (2) Sn-F binding on mineral surfaces with no evidence of SnO. The surface binding is, however, not pure Sn-F but contains contributions of other ligands, probably oxygens from surface phosphates or hydroxyl groups. Results also suggest that surface reacted stannous tin is oxidized with time, even when bound as a layer on the tooth surface. This study demonstrates for the first time the presence of Sn-F on tooth enamel post treatment and the contribution of passivation to long term stannous chemistry on tooth surfaces. The study also illustrates the practical applications of the Moessbauer technique.

  6. Moessbauer studies of magnetic and crystal field properties in Fe(III) mixed chelates

    International Nuclear Information System (INIS)

    Moessbauer studies were performed on mixed Fe(III) complexes with two ligands, one of the ligands being N,N-ethylene bis(salicyladimine) and the other N,N-dialkyldithiocarbamate. Moessbauer spectra were measured of four complexes with the dialkyl end group being N-ethyl2, N-butyl2, pyrrolidyl and piperidyl, respectively. Evaluation and comparison of the spectra and the relaxation patterns indicate that the size of the axial zero field splitting constant and consequently the spin of the ground state Kramer's doublet depends on the type of the alkyl group in the N,N-dialkyldithiocarbamate ligand. (A.K.)

  7. Moessbauer study of Celtic pottery from Bopfingen, Baden-Wuerttemberg, Germany

    International Nuclear Information System (INIS)

    In the course of a study of pottery from Celtic Central Europe, we report on an investigation of pottery found in the context of a Celtic ditched square enclosure near the modern town of Bopfingen in Baden-Wurttemberg, Germany. The studied pottery may be visually subdivided into wheel-turned ware, graphite ware, and coarse ware. The Moessbauer spectra are surprisingly uniform, indicating that all types of pottery were fired in a similar manner. Firing in a reducing environment at 800 0C was usually followed by re-oxidation during cooling, which leads to unique features in the low temperature Moessbauer patterns.

  8. Moessbauer study of epitaxial Co2Cr0.6Fe0.4Al thin films

    International Nuclear Information System (INIS)

    Epitaxial thin films of the promising for spintronic applications Heusler half-metallic compound Co2Cr0.6Fe0.4Al (CCFA) were investigated using conversion electron Moessssbauer spectroscopy (CEMS) in order to get insight into the structural and magnetic properties. Thin films of 100 nm thickness were deposited by rf magnetron sputtering on MgO substrates without and with 10 nm Fe buffer layer. We discuss a correlation between the annealing temperature and the structural disorder and hyperfine fields on Fe atoms measured by Moessbauer spectroscopy. Samples prepared at the optimum annealing temperature as determined by tunneling magnetoresistance measurements show the optimum degree of order on the Fe sites as determined by CEMS. Additionally, we observed evidence for a diffusion of Cr atoms from the CCFA thin film into the Fe buffer layer and the related diffusion of Fe atoms from the buffer into the CCFA film. Thus the thermal treatment changes the Fe to Cr ratio of the Heusler compound additional to influencing the degree of disorder on the Fe/Cr sites

  9. Precise determination of Moessbauer lineshape parameters including interference

    Energy Technology Data Exchange (ETDEWEB)

    Mullen, J.G.; Djedid, A.; Bullard, B.; Schupp, G.; Cowan, D.; Cao, Y.; Crow, M.L.; Yelon, W.

    1987-01-01

    Using 100 Ci /sup 183/Ta and 5 Ci /sup 182/Ta sources, with LiF and NaCl crystal monochromating filters, we have measured the lineshape parameters for the 46.5 keV and 99.1 keV Moessbauer effect (ME) transitions of /sup 183/W and the 100.1 keV transition of /sup 182/W. Using an analytic representation of the convolution integral and utilizing asymptotic analyses of the lineshape, we find, for both transmission and microfoil internal conversion (MICE) experiments, accurate values of all ME parameters including width, position, cross section, and interference. This new approach allows deconvolution of source and absorber spectra and gives a simple analytic expression for both as well as their Fourier transforms. The line widths for the 46.5, 99.1, and 100.1 keV transitions are 3.10(10), 0.369(18), and 0.195(12) cm/s, respectively. The interference parameters are -0.00257(9), -0.0093(12), and -0.0107(12) in the same respective order. The agreement between transmission and MICE measurements for the above lineshape parameters is within the experimental errors. We believe these measurements are the first having sufficient precision to allow a quantitative comparison with dispersion theory and they indicate interference parameters 10 to 20% smaller than predicted. Our measured line widths are less than earlier reported values. This is because our analysis of the true lineshape and the study of line asymptotics permits a quantitative determination of the isomer lifetimes rather than the usual lower bound found in earlier ME experiments. 37 refs., 4 figs., 2 tabs.

  10. Iron Mineralogy and Aqueous Alteration on Mars from the MER Moessbauer Spectrometers. Chapter 15

    Science.gov (United States)

    Morris, Richard V.; Klingelhoefer, Goestar

    2007-01-01

    The twin Mars Exploration Rovers Spirit (Gusev crater) and Opportunity (Meridiani Planum) used MIMOS II Moessbauer spectrometers to analyze martian surface materials in the first application of extraterrestrial Moessbauer spectroscopy. The instruments acquired spectra that identified the speciation of Fe according to oxidation state, coordination state, and mineralogical composition and provided quantitative information about the distribution of Fe among oxidation states, coordination states, and Fe-bearing phases. A total of 12 unique Fe-bearing phases were identified: Fe(2+) in olivine, pyroxene, and ilmenite; Fe(2+) and Fe(3+) in magnetite and chromite; Fe(3+) in nanophase ferric oxide (npOx), hematite, goethite, jarosite, an unassigned Fe3+ sulfate, and an unassigned Fe(3+) phase associated with jarosite; and Fe(0) in kamacite. Weakly altered basalts at Gusev crater (SO3 = 2.5 +/- 1.4 wt.% and Fe(3+)/Fe(sub T) = 0.24 +/- 0.11) are widespread on the Gusev plains and occur in less abundance on West Spur and Husband Hill in the Columbia Hills. Altered low-S rocks (SO3 = 5.2 +/- 2.0 wt.% and Fe(3+)/Fe(sub T) = 0.63 +/- 0.18) are the most common type of rock in the Columbia Hills. Ilm-bearing, weakly altered basalts were detected only in the Columbia Hills, as was the only occurrence of chromite in an altered low-S rock named Assemblee. Altered high-S rocks (SO3 > 14.2 wt.% and Fe(3+)/Fe(sub T) = 0.83 +/- 0.05) are the outcrop rocks of the ubiquitous Burns formation at Meridiani Planum. Two Fe(0)-bearing rocks at Meridiani Planum (Barberton and Heat Shield Rock) are meteorites. Laguna Class soil is weakly altered (SO3 = 6 +/- 2 wt.% and Fe(3+)/Fe(sub T) = 0.29 +/- 0.08) and widely distributed at both Gusev crater and Meridiani Planum, implying efficient global mixing processes or a global distribution of precursor rocks with comparable Fe mineralogical compositions. Paso Robles Class soil is heavily altered (SO3 approx. 31 wt.% and Fe(3+)/Fe(sub T) = 0.83 +/- 0

  11. Mössbauer study of ^{57}Fe-doped La{2-x}SrxCuO4 : local magnetic properties in the semiconducting, superconducting and normal metallic regions of the phase diagram

    Science.gov (United States)

    Imbert, P.; Jéhanno, G.; Debray, P.; Garcin, C.; Hodges, J. A.

    1992-07-01

    From Mössbauer and resistivity measurements on ^57Fe-doped La{2-x}SrxCuO4, we have explored the phase diagram of the series for 0leq x leq 0.30 and 1.5 K leq T leq 295 K and we have studied the local magnetic properties in the semiconducting, superconducting, and normal metallic phases. The most outstanding result concerns the coexistence over part (0.06 lesssim x lesssim 0.16) of the total (0.06 lesssim x lesssim 0.25) superconducting range of two different fractions showing different local behaviours. The first fraction corresponds to intrinsic spin-freezing, below sim 8 K, in the Cu sublattice. The relative sample volume of this fraction which is attributed to semiconducting domains decreases as x increases. In the second fraction which is presumably superconducting, there is no evidence of intrinsic Cu moments, however iron induced local magnetic order is present. In the semiconducting fraction the Cu magnetic moments remain essentially parallel to the basal plane, while in the superconducting fraction the iron-induced local magnetization moves towards the c axis as x increases. We have performed accurate ^{57}Fe hyperfine measurements in an argon annealed quasi-stoichiometric La2CuO4 sample and we have observed an abrupt variation of the magnetization near the Néel temperature. In an air annealed La2CuO{4+y} sample, we have evidenced the presence of oxygen interstitials and we have shown that the effective interlayer magnetic coupling is strongly reduced with respect to the y=0 sample. A partir de mesures de spectrométrie Mössbauer et de résistivité, nous avons exploré le diagramme de phase de la série de composés La{2-x}SrxCuO4 dopés en ^{57}Fe et nous avons étudié les propriétés magnétiques locales dans les phases semiconductice, supraconductrice et métallique normale. Nous avons notamment observé la coexistence de deux fractions présentant un comportement local différent, dans une partie importante (0,06lesssim x lesssim 0,16) de la zone

  12. Applied investigation of Moessbauer effect for the famous ancient chinese porcelains

    International Nuclear Information System (INIS)

    The famous Ru porcelain, Jun porcelain and Guan porcelain of Song Dynasty and Yuan Dynasty are analyzed. The Moessbauer parameters of the ancient porcelains and the imitative ancient porcelains are compared. The firing techniques, coloring mechanism and microstructures of the ancient Chinese porcelains have been discussed. (7 figs., 4 tabs.)

  13. Experimental design and methodology for a new Moessbauer scan experiment: absorption line tracking

    International Nuclear Information System (INIS)

    A new experimental setup and methodology that allows the automatic tracking of a Moessbauer absorption line as its energy position varies during the experiment is introduced. As a test the sixth spectral line of FeSn2 was tracked while temperature was varied between room temperature and a value slightly above its Neel temperature.

  14. Proceedings of the Polish Moessbauer Community meeting, 8-10 October 1986, Cracow

    International Nuclear Information System (INIS)

    Separate abstracts were prepared for 2 of the papers in this report. The remaining 26 papers, dealing with the use but not with advances in the use of Moessbauer effect in studies of solid state physics, were considered outside the subject scope of INIS. (M.F.W.)

  15. Moessbauer and EXAFS investigation of spin-equilibrium in a model-compound for heme proteins

    International Nuclear Information System (INIS)

    We have used temperature dependent magnetic susceptibility, Moessbauer and EXAFS measurements to study the high spin (HS) - low spin (LS) conversion in Fe(II) (bptn) (NCS)2, and we have combined consistently the information obtained from the different methods. (orig.)

  16. Moessbauer studies of magnetic Fe2O3/SiO2 nanocomposite

    International Nuclear Information System (INIS)

    Fe2O3/SiO2 magnetic nanocomposites rich in Fe2O3 have been obtained by annealing at 1000 grad C the xerogel samples, prepared under various conditions. The target concentrations of iron oxide in inert matrix were 20% and 30%. As mesoporous matrices both silica and polyvinyl alcohol - silica hybrid ones were used. The xerogel nanocomposite samples were obtained in situ and by impregnation under ultrasonic activation. All obtained samples were annealed under moderate oxidation conditions (air) and inert atmosphere such as vacuum or nitrogen. Moessbauer spectra were obtained using a conventional Moessbauer spectrometer with a 57Co/Rh source and constant acceleration. Velocity calibration was done using α-iron, and the Moessbauer parameters are given relative to this standard at room temperature. The Moessbauer spectra contained the sextets of ε-Fe2O3, hematite, and superparamagnetic component. The content of various phases in the samples depends on the conditions of preparation. In one of the samples also magnetite was present. The ranges of the ε-Fe2O3 area of the samples are 39-76%. The hematite phase is only residual, after transformation due to heat treatment. (authors)

  17. [sup 129]I Moessbauer spectroscopic study of metallocene-iodine adducts

    Energy Technology Data Exchange (ETDEWEB)

    Nakashima, Satoru (Dept. of Chemistry, Faculty of Science, Hiroshima Univ. (Japan)); Sakai, Hiroshi (Dept. of Chemistry, Faculty of Science, Hiroshima Univ. (Japan)); Watanabe, Masanobu (Dept. of Chemistry, Coll. of Arts and Sciences, Univ. of Tokyo (Japan)); Maeda, Yutaka (Research Reactor Inst., Kyoto Univ., Osaka (Japan))

    1994-05-01

    A [sup 129]I Moessbauer spectroscopic study of iodine adducts of ferrocenophane, biruthenocene, and osmocene is reported. The spectra show the existence of iodine bonded to the central metals of metallocenes in addition to triiodide anions. The valence state of iron in the ferrocenophane-iodine adduct is the same as those of ruthenium and osmium in their adducts. (orig.)

  18. First-principles calculations of Moessbauer hyperfine parameters for solids and large molecules

    Energy Technology Data Exchange (ETDEWEB)

    Guenzburger, Diana [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Ellis, D.E. [Northwestern Univ., Evanston, IL (United States). Dept. of Physics; Zeng, Z. [Academia Sinica, Hefei, AH (China). Inst. of Solid-State Physics

    1997-10-01

    Electronic structure calculations based on Density Functional theory were performed for solids and large molecules. The solids were represented by clusters of 60-100 atoms embedded in the potential of the external crystal. Magnetic moments and Moessbauer hyperfine parameters were derived. (author) 22 refs., 8 figs., 1 tab.

  19. Moessbauer analysis of BIOX treatment of ores at Wiluna gold mine, Western Australia

    Energy Technology Data Exchange (ETDEWEB)

    Gagliardi, F. M. [The Alfred, William Buckland Radiotherapy Centre (Australia); Cashion, J. D., E-mail: john.cashion@monash.edu [Monash University, School of Physics (Australia)

    2013-04-15

    Moessbauer phase analysis of samples taken from nine stages of the bacterial oxidation processing of gold ore at the Wiluna Gold Mine followed the transformation of the arsenopyrite/pyrite minerals. The principal end-stage phases were szomolnokite, ferric oxyhydroxides, ferric arsenates, jarosite and incompletely transformed pyrite, with higher hydrates of ferrous sulphate being created and then dehydrating to szomolnokite during the processing.

  20. Heterogeneous mixed valence in YbPd sub 3 S sub 4 : evidence from sup 1 sup 7 sup 0 Yb Moessbauer and x-ray L sub I sub I sub I -edge absorption measurements

    CERN Document Server

    Bonville, P; Alleno, E; Takahashi, F; Matsuoka, E; Ishikawa, M

    2003-01-01

    The intermetallic bronze YbPd sub 3 S sub 4 is shown to be a heterogeneous mixed-valence system, by means of sup 1 sup 7 sup 0 Yb Moessbauer spectroscopy and x-ray L sub I sub I sub I -edge absorption and magnetic measurements. Two valence states coexist in this compound: Yb sup 3 sup + and close-to-divalent Yb. The trivalent fraction (about 50%) undergoes a transition to magnetic ordering at about 2 K, with the GAMMA sub 7 doublet as the ground crystal field state. The possibility of charge (or valence) ordering is discussed. (letter to the editor)

  1. Fischer-Tropsch synthesis: Moessbauer studies of pretreated ultrafine iron oxide catalysts. Partial quarterly progress report, April--June 1992

    Energy Technology Data Exchange (ETDEWEB)

    Chenshi Huang; Davis, B.H. [Kentucky Univ., Lexington, KY (United States). Center for Applied Energy Research; Rao, K.R.P.M.; Huffman, G.P.; Huggins, F.E. [Kentucky Univ., Lexington, KY (United States). Inst. for Mining and Minerals Research

    1992-09-01

    Moessbauer spectroscopy indicates that a 24 hour-pretreatment in CO at 260{degrees}C and 8 atm. in a tetralin solvent almost completely converts uftrafine iron oxide (about 3 nm) to iron carbide. However, pretreatment in hydrogen under the same conditions resulted in reduction of about 33% of the iron to metallic Fe; the remainder was Fe{sub 3}O{sub 4}. Exposure of the CO pretreated catalyst to a 1:1 HDCO synthesis gas resulted in the gradual reoxidation of the carbides to Fe{sub 3}O{sub 4}. During the first 2 hours of exposure of the H{sub 2} pretreated sample to synthesis gas,.the metallic Fe was converted to iron carbides. Further exposure of the H{sub 2} pretreatment sample to synthesis gas did not result in a composition change of the catalyst. Therefore, it is concluded that iron carbides with different oxidation characteristics were formed in these two cases.

  2. Quadrupole coupling constants and isomeric Moessbauer shifts for halogen-containing gold, platinum, niobium, tantalum and antimony compounds

    International Nuclear Information System (INIS)

    We have analyzed by means of Density functional theory calculations the nuclear quadrupole coupling constants of a range of gold, antimony, platinum, niobium and tantalum compounds. The geometrical parameters and halogen nuclear quadrupole coupling constants obtained by these calculations substantially corresponded to the data of microwave and nuclear quadrupole resonance spectroscopy. An analysis of the quality of the calculations that employ pseudo-potentials and all-electron basis sets for the halogen compounds was carried out. The zero order regular approximation (ZORA) method is shown to be a viable alternative for the calculation of halogen coupling constants in molecules. In addition, the ZORA model, in contrast to the pseudo-potential model, leads to realistic values of all metal nuclear quadrupole coupling constants. From Klopman's approach, it follows that the relationship between the electrostatic bonding and covalent depends on the nature of the central atom. The results on Moessbauer chemical shifts are also in a good agreement with the coordination number of the central atom.

  3. Magnetic Behaviour of Iron Oxychloride and Its Organometallic Intercalation Compounds Studied by M(o)ssbauer Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    DAI Yao-Dong; HAN Wei; ZHENG Likun; XIA Yuan-Fu

    2005-01-01

    @@ Metallocene intercalate compounds with iron oxychloride, FeOCl(FeCp2)0.16 and FeOCl(CoCp2)0.36 with Cp being cyclopentadienyl group, are synthesized and characterized. Magnetism and the structure-property relations are investigated by magnetic measurement and 57Fe Mossbauer spectroscopy. The results show that the throughspace dipolar interactions play a critical role in three-dimensional magnetic ordering of such layered compounds.

  4. Spectrum processing and fitting on IBM PC: Moessbauer spectrum [Paper No.:D8

    International Nuclear Information System (INIS)

    Processing spectrum data on PC (compatibles) using data files in commonly used HEX-ASCII format is described, which can be used on PC, XT, or AT. On AT-386/387 this gives the fitting time per iteration - 4 sec., employing Newton-Raphson method for 256 channel six line spectrum. The on-line interaction in case of Moessbauer spectrum fitting being minimal use of additional hardware and special software for fitting is avoided. Reasonable iteration times using this method on PC with numerical coprocessors were obtained. The principles of analysis for Moessbauer data processing, which are used in various utilities of this software, are described. The performance index and results are then outlined. (author). 8 refs., 5 figs

  5. Moessbauer study of Martensitic transformation and collective magnetic excitations in Fe9Ni1 fine particles

    Institute of Scientific and Technical Information of China (English)

    H.M.Widatallah; 黄润生; 等

    1996-01-01

    The austenite to martensity ransformation in fine Fe90Ni.10 particles prepared by evaporation is studied by Moessbauer technique.Unlike bulk Fe.9Ni.1 which is entirely transformed to martensite.these particles show a remarkable austenite stability upon cooling upto liquid nitrogen temperature.This stability is associated with the oxide surface layer formed on the particles and also with their small size.A hyperfine field approach is employed to analyze the martensitic transformation in the particles.It is also shown that,in contrast with large particles ,the temperature variation of the Moessbauer average hyperfine field of the fine particles can be satisfactorily explained in terms of the collective magnetic excitations model.

  6. Moessbauer and magnetic studies of MFe2O4(M = Co, Ni) nanoparticles

    International Nuclear Information System (INIS)

    Nanocrystalline MFe2O4 (M = Co, Ni) particles are synthesized by citrate precursor technique. Moessbauer and magnetic studies are carried out with the CoFe2O4 samples having particle sizes of 9, 14 and 30 nm and the NiFe2O4 samples having particle sizes of 9, 21 and 30 nm. The intrinsic magnetic parameters are found to vary with the particle size. The magnetic interactions and cation distribution present in these systems influence the room temperature Moessbauer parameters. Ferrimagnetic sextets are observed for all the different particle sizes. The observed reduction of the magnetic hyperfine field values with the decrease in the size of MFe2O4 particles are attributed to the intrinsic size effect and the canted spin structure at the surface of the nanoparticles.

  7. Moessbauer study of the annealing effect on low-alloyed steels

    International Nuclear Information System (INIS)

    Structural analyses of Fe-Cr and Fe-Cr-Ni low-alloyed steels before and after annealing at 600 deg. C using Moessbauer spectrometry, X-ray diffraction and scanning electron microscopy are reported. At the received state, the two steels present a fine bainitic microstructure with equal hardness. From Moessbauer analysis, two iron sites are identified as substitutional by Cr, Mo, Ni atoms and as insertional by carbon in bainitic ferrite. Both sites are locally deformed by residual stresses. The presence of small quantities of retained austenite and ε carbide has been observed. Annealing for one hour at 600 deg. C causes a decrease in hardness for both steels with a decrease of retained austenite. After longer time of annealing, precipitation of (Fe,Ni)23C6 occurs in the Fe-Cr-Ni steel and increases hardness

  8. Moessbauer study of Al and Cr co-substituted Yttrium iron garnets

    International Nuclear Information System (INIS)

    The Moessbauer spectra of Y3AlxCrXFe5-2xO12 (x = 0.0 to 0.6) measured at 300 K have been fitted with two sextets in the ferrimagnetic state corresponding to Fe3+ at the octahedral (a) and the tetrahedral (d) sites for x ≤ 0.6. The isomer shifts (δ) and quadrupole splitting (ΔEQ) indicate the presence of high spin Fe3+ ions in the tetrahedral (d) and octahedral (a) sites, typical of yttrium of yttrium iron garnet structure. Moessbauer results have shown that Al3+, enters a-sites only but Cr3+ enters both a-and d-sites.

  9. Epitaxial gamma-iron silicide grown on single-crystal Si. A summary of Moessbauer results

    Energy Technology Data Exchange (ETDEWEB)

    Desimoni, J.; Sanchez, F.H

    1998-08-15

    Metastable {gamma}-FeSi{sub 2} grown on or into single-crystals of silicon can be produced by different techniques as molecular beam epitaxy, and ion implantation followed by ion beam induced epitaxial crystallisation. In these investigations, Moessbauer effect has been used to provide short range order information about the system. We present here a summary of these results, which will be compared and discussed.

  10. Moessbauer study of the Ru porcelain of Chinese Song Dynasty and Yuan Dynasty

    International Nuclear Information System (INIS)

    The Moessbauer spectra from the glazes of the Song Dynasty and the Yuan Dynasty Ru porcelains and the imitative ancient Ru porcelain are compared and analyzed. It is determined that the original firing atmosphere of the Yuan Dynasty Ru porcelain was reductive. The firing temperature was 1250 ± 20 C. The original firing atmosphere of the Song Dynasty Ru porcelain was also reductive; the firing temperature was above 1200 C. The coloring mechanism of these glazes is discussed. (orig.)

  11. Moessbauer study of the Ru porcelain of Chinese Song Dynasty and Yuan Dynasty

    Energy Technology Data Exchange (ETDEWEB)

    Gao Zhengyao [Zhengzhou Univ., HEN (China). Dept. of Physics; Chen Songhua [Dept. of Electronic Engineering, Zhengzhou Univ., HEN (China); Chen Xiande [Dept. of Metals and Materials Engineering, Univ. of British Columbia, Vancouver (Canada)

    1994-11-01

    The Moessbauer spectra from the glazes of the Song Dynasty and the Yuan Dynasty Ru porcelains and the imitative ancient Ru porcelain are compared and analyzed. It is determined that the original firing atmosphere of the Yuan Dynasty Ru porcelain was reductive. The firing temperature was 1250 {+-} 20 C. The original firing atmosphere of the Song Dynasty Ru porcelain was also reductive; the firing temperature was above 1200 C. The coloring mechanism of these glazes is discussed. (orig.)

  12. Moessbauer experiment to observe significance of vector potentials in quantum theory

    International Nuclear Information System (INIS)

    As a powerful method to confirm the Aharonov-Bohm effect in bound states, we propose the Moessbauer experiment with 53I129 nucleus fixed at the center of toroidal magnet. With a toroid of major radius 10 cm, minor radius 1.5 cm and 6000 turns of coil, we estimate the energy shift -1.1x10-8eV for the electric current of 1 mA. (author)

  13. Moessbauer and magnetic study of Mn{sup 2+}- and Cr{sup 3+}-substituted spinel magnesioferrites of the composition Mg{sub 1-x}Mn{sub x}Fe{sub 2-2x}Cr{sub 2x}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Widatallah, H. M., E-mail: hishammw@squ.edu.om; Al-Omari, I. A.; Gismelseed, A. M. [Sultan Qaboos University, Depertment of Physics (Oman); Yassin, O. A. [Al-Neelain University, School of Physics (Sudan); Al-Rawas, A. D.; Elzain, M. E.; Yousif, A. A. [Sultan Qaboos University, Depertment of Physics (Oman); Osman, O. A. [University of Khartoum, Physics Department (Fac. of Ed.) (Sudan)

    2006-04-15

    Chromium and manganese co-substituted spinel magnesioferrites of the composition Mg{sub 1-x}Mn{sub x}Fe{sub 2-2x}Cr{sub 2x}O{sub 4} (x = 0.0, 0.1, 0.2, 0.3, and 0.5) were investigated with X-ray diffraction (XRD), Moessbauer spectroscopy and magnetic measurements. The cation distribution inferred suggests that Mn{sup 2+} and Cr{sup 3+} ions dominantly occupy the A- and B-sites respectively. The gradual decrease of the hyperfine fields and Curie temperatures with increasing x reflects a gradual weakening in the AB exchange interaction. Moessbauer data of the sample with x = 0.5 is suggestive of cation clustering and/or superparamagnetism. The magnetization data is suggestive of Yafet-Kittel-type canted magnetism.

  14. Mineral Moessbauer spectroscopy: correlations between chemical shift and quadrupole splitting parameters

    International Nuclear Information System (INIS)

    The variety of coordination numbers, symmetries, distortions and ligand environments in thermally-stable iron-bearing minerals provide wide ranges of chemical shift (δ) and quadrupole splitting (Δ) parameters, which serve to characterize the crystal chemistries and site occupancies of Fe2+ and Fe3+ ions in minerals of terrestrial and extraterrestrial origins. Correlations between ferrous and ferric chemical shifts enable thermally-induced electron delocalization behavior in mixed-valence Fe2+-Fe3+ minerals to be identified, while chemical shift versus quadrupole splitting correlations serve to identify nanophase ferric oxides and oxyhydroxides in oxidized minerals and in meteorites subjected to aqueous oxidation before and after they arrived on Earth. (orig.)

  15. Characterization of airborne particulate matter in the metropolitan region of Belo Horizonte

    Energy Technology Data Exchange (ETDEWEB)

    Tavares, Fernanda V.F.; Ardisson, Jose Domingos; Rodrigues, Paulo Cesar H.; Brito, Walter de; Macedo, Waldemar Augusto A.; Jacomino, Vanusa Maria F., E-mail: ferufv@yahoo.com.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2013-07-01

    In this work soil samples, iron ore and airborne atmospheric particulate matter (PM) in the Metropolitan Region of Belo Horizonte (MRBH), State of Minas Gerais, Brazil, are investigated with the aim of identifying if the sources of the particulate matter are of natural origin, such as, resuspension of particles from soil, or due to anthropogenic origins from mining and processing of iron ore. Samples were characterized by powder X-ray diffraction, X-ray fluorescence and {sup 57}Fe-Moessbauer spectroscopy. The results showed that soil samples studied are rich in quartz and have low contents of iron mainly iron oxide with low crystallinity. The samples of iron ore and PM have high concentration of iron, predominantly well crystallized hematite. {sup 57}Fe-Moessbauer spectroscopy confirmed the presence of similar iron oxides in samples of PM and in the samples of iron ore, indicating the anthropogenic origin in the material present in atmosphere of the study area. (author)

  16. Triangular Zn{sub 3} and Ga{sub 3} units in Sr{sub 2}Au{sub 6}Zn{sub 3}, Eu{sub 2}Au{sub 6}Zn{sub 3}, Sr{sub 2}Au{sub 6}Ga{sub 3}, and Eu{sub 2}Au{sub 6}Ga{sub 3}. Structure, magnetism, {sup 151}Eu Moessbauer and {sup 69;71}Ga solid state NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gerke, Birgit; Niehaus, Oliver; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Korthaus, Alexander; Haarmann, Frank [RWTH Aachen Univ. (Germany). Inst. fuer Anorganische Chemie

    2016-08-01

    The gold-rich intermetallic compounds Sr{sub 2}Au{sub 6}Zn{sub 3}, Eu{sub 2}Au{sub 6}Zn{sub 3}, Sr{sub 2}Au{sub 6}Ga{sub 3}, and Eu{sub 2}Au{sub 6}Ga{sub 3} were synthesized from the elements in sealed tantalum ampoules in induction or muffle furnaces. The europium compounds are reported for the first time and their structures were refined from single crystal X-ray diffractometer data: Sr{sub 2}Au{sub 6}Zn{sub 3} type, R anti 3c, a = 837.7(1), c = 2184.5(4) pm, wR2 = 0.0293, 572 F{sup 2} values for Eu{sub 2}Au{sub 6.04}Zn{sub 2.96} and a = 838.1(2), c = 2191.7(5) pm, wR2 = 0.0443, 513 F{sup 2} values for Eu{sub 2}Au{sub 6.07}Ga{sub 2.93} with 20 variables per refinement. The structures consist of a three-dimensional gold network with a 6R stacking sequence, similar to the respective diamond polytype. The cavities of the network are filled in a ratio of 2:1 by strontium (europium) atoms and Ga{sub 3} (Zn{sub 3}) triangles in an ordered manner. Sr{sub 2}Au{sub 6}Zn{sub 3} and Sr{sub 2}Au{sub 6}Ga{sub 3} are diamagnetic with room temperature susceptibilities of -3.5 x 10{sup -4} emu mol{sup -1}. Temperature dependent susceptibility and {sup 151}Eu Moessbauer spectroscopic measurements show a stable divalent ground state for both europium compounds. Eu{sub 2}Au{sub 6}Zn{sub 3} and Eu{sub 2}Au{sub 6}Ga{sub 3} order antiferromagnetically below Neel temperatures of 16.3 and 12.1 K, respectively. Anisotropic electrical conductivity of Sr{sub 2}Au{sub 6}Ga{sub 3} is proven by an alignment of the crystallites in the magnetic field. Orientation-dependent {sup 69;71}Ga NMR experiments combined with quantum mechanical calculations (QM) give evidence for a highly anisotropic charge distribution of the Ga atoms.

  17. Mössbauer spectroscopy of Fe/S proteins.

    Science.gov (United States)

    Pandelia, Maria-Eirini; Lanz, Nicholas D; Booker, Squire J; Krebs, Carsten

    2015-06-01

    Iron-sulfur (Fe/S) clusters are structurally and functionally diverse cofactors that are found in all domains of life. (57)Fe Mössbauer spectroscopy is a technique that provides information about the chemical nature of all chemically distinct Fe species contained in a sample, such as Fe oxidation and spin state, nuclearity of a cluster with more than one metal ion, electron spin ground state of the cluster, and delocalization properties in mixed-valent clusters. Moreover, the technique allows for quantitation of all Fe species, when it is used in conjunction with electron paramagnetic resonance (EPR) spectroscopy and analytical methods. (57)Fe-Mössbauer spectroscopy played a pivotal role in unraveling the electronic structures of the "well-established" [2Fe-2S](2+/+), [3Fe-4S](1+/0), and [4Fe-4S](3+/2+/1+/0) clusters and -more-recently- was used to characterize novel Fe/S clustsers, including the [4Fe-3S] cluster of the O2-tolerant hydrogenase from Aquifex aeolicus and the 3Fe-cluster intermediate observed during the reaction of lipoyl synthase, a member of the radical SAM enzyme superfamily. PMID:25498248

  18. Structural properties and hyperfine characterization of Sn-substituted goethites

    Energy Technology Data Exchange (ETDEWEB)

    Larralde, A.L. [INQUIMAE, Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina); Ramos, C.P. [Departamento de Fisica de la Materia Condensada, GIyA - CAC - CNEA, Av. Gral. Paz 1499 (1650), San Martin, Bs. As. (Argentina); Arcondo, B. [Departamento de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires, Av. Paseo Colon 850 (C1063ACV), Bs. As. (Argentina); Tufo, A.E. [INQUIMAE, Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina); Saragovi, C. [Departamento de Fisica de la Materia Condensada, GIyA - CAC - CNEA, Av. Gral. Paz 1499 (1650), San Martin, Bs. As. (Argentina); Sileo, E.E., E-mail: sileo@qi.fcen.uba.ar [INQUIMAE, Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina)

    2012-04-16

    Highlights: Black-Right-Pointing-Pointer Pure and tin-doped goethites were synthesized from Sn(II) solutions at ambient pressure and 70 Degree-Sign C. Black-Right-Pointing-Pointer The Rietveld refinement of PXRD data indicated that Sn partially substituted the Fe(III) ions. Black-Right-Pointing-Pointer The substitution provoked unit cell expansion, and a distortion of the coordination polyhedron. Black-Right-Pointing-Pointer {sup 119}Sn Moessbauer spectroscopy revealed that Sn(II) is incorporated as Sn(IV). Black-Right-Pointing-Pointer {sup 57}Fe Moessbauer spectroscopy showed a lower magnetic coupling as tin concentration increased. - Abstract: Tin-doped goethites obtained by a simple method at ambient pressure and 70 Degree-Sign C were characterized by inductively coupled plasma atomic emission spectrometry, scanning electron microscopy, Rietveld refinement of powder X-ray diffraction data, and {sup 57}Fe and {sup 119}Sn Moessbauer spectroscopy. The particles size and the length to width ratios decreased with tin-doping. Sn partially substituted the Fe(III) ions provoking unit cell expansion and increasing the crystallinity of the particles with enlarged domains that grow in the perpendicular and parallel directions to the anisotropic broadening (1 1 1) axis. Intermetallic E, E Prime and DC distances also change although the variations are not monotonous, indicating different variations in the coordination polyhedron. In general, the Sn-substituted samples present larger intermetallic distances than pure goethite, and the greatest change is shown in the E Prime distance which coincides with the c-parameter. {sup 119}Sn Moessbauer spectroscopy revealed that Sn(II) is incorporated as Sn(IV) in the samples. On the other hand, Fe(II) presence was not detected by {sup 57}Fe Moessbauer spectroscopy, suggesting the existence of vacancies in the Sn-doped samples. A lower magnetic coupling is also evidenced from the average magnetic hyperfine field values obtained as tin

  19. Moessbauer and mineral magnetic studies on archaeological potteries from Adhichanallur, Tamilnadu, India

    Energy Technology Data Exchange (ETDEWEB)

    Venkatachalapathy, R., E-mail: venkatr5@rediffmail.com [Annamalai University, C.A.S in Marine Biology (India); Bakas, T. [University of Ioannina, Department of Physics (Greece); Basavaiah, N.; Deenadayalan, K. [New Panvel, Indian Institute of Geomagnetism (India)

    2008-09-15

    Megalithic potteries collected from Adhichanallur, Tamilnadu, India (Lat. 8{sup o}44' N; Long. 77{sup o}42' E) have been subjected to various spectroscopic and rock magnetic studies. The type of clay, their origin, level of structural deformation due to firing, firing temperature and atmospheric condition followed during making the potteries are analyzed. The potteries were subjected to Moessbauer and X-ray diffraction studies to analyze the iron phases in them. It is found that the samples were made of local clay (red clay), fired above 600{sup o}C under open atmospheric and/or reduced atmospheric conditions and air has been allowed during cooling. The Moessbauer spectra reveal the presence of Fe{sup 3+}, Fe{sup 2+} and iron oxides of hematite and magnetite. The firing temperature and firing conditions established from Moessbauer studies are similar to the observation made from FT-IR studies. The magnetic mineral types, the mass fractions and the domain states of the constituent magnetic grains were elucidated from a range of rock magnetic measurements including variation of susceptibility with low field, frequency and temperature, hysteresis parameters and isothermal remanence acquisition data. The magnetic mineralogy of most pottery samples was dominated by magnetite/(titano) magnetite, while magnetic grain size spectrum varies from very fine (super paramagnetic) to fine (stable single domain, pseudo single domain). The reversible thermo magnetic behavior reflects no mineralogical transformations during reheating and all the samples show same Curie temperature 580{sup o}C due to magnetite. From the above information it is demonstrated that these samples are suitable for determining the reliable ancient geomagnetic field intensity values existed during that period.

  20. Moessbauer and mineral magnetic studies on archaeological potteries from Adhichanallur, Tamilnadu, India

    International Nuclear Information System (INIS)

    Megalithic potteries collected from Adhichanallur, Tamilnadu, India (Lat. 8o44' N; Long. 77o42' E) have been subjected to various spectroscopic and rock magnetic studies. The type of clay, their origin, level of structural deformation due to firing, firing temperature and atmospheric condition followed during making the potteries are analyzed. The potteries were subjected to Moessbauer and X-ray diffraction studies to analyze the iron phases in them. It is found that the samples were made of local clay (red clay), fired above 600oC under open atmospheric and/or reduced atmospheric conditions and air has been allowed during cooling. The Moessbauer spectra reveal the presence of Fe3+, Fe2+ and iron oxides of hematite and magnetite. The firing temperature and firing conditions established from Moessbauer studies are similar to the observation made from FT-IR studies. The magnetic mineral types, the mass fractions and the domain states of the constituent magnetic grains were elucidated from a range of rock magnetic measurements including variation of susceptibility with low field, frequency and temperature, hysteresis parameters and isothermal remanence acquisition data. The magnetic mineralogy of most pottery samples was dominated by magnetite/(titano) magnetite, while magnetic grain size spectrum varies from very fine (super paramagnetic) to fine (stable single domain, pseudo single domain). The reversible thermo magnetic behavior reflects no mineralogical transformations during reheating and all the samples show same Curie temperature 580oC due to magnetite. From the above information it is demonstrated that these samples are suitable for determining the reliable ancient geomagnetic field intensity values existed during that period.

  1. Co{sup 2 + } interaction with Azospirillum brasilense Sp7 cells: a {sup 57}Co emission Moessbauer spectroscopic study

    Energy Technology Data Exchange (ETDEWEB)

    Kamnev, Alexander A.; Tugarova, Anna V. [Russian Academy of Sciences, Institute of Biochemistry and Physiology of Plants and Microorganisms (Russian Federation); Biro, Borbala [Hungarian Academy of Sciences, Research Institute for Soil Science and Agricultural Chemistry (Hungary); Kovacs, Krisztina, E-mail: kkriszti@chem.elte.hu; Homonnay, Zoltan; Kuzmann, Erno; Vertes, Attila [Eoetvoes Lorand University, Institute of Chemistry (Hungary)

    2012-03-15

    Preliminary {sup 57}Co emission Moessbauer spectroscopic data were obtained for the soil bacterium Azospirillum brasilense Sp7 (T = 80 K) in frozen {sup 57}Co{sup 2 + }-containing suspensions and in their dried residues. The Moessbauer parameters were compared with those for A. brasilense strain Sp245 differing from strain Sp7 by ecological behaviour. Live cells of both strains showed metabolic transformations of {sup 57}Co{sup 2 + } within an hour. Differences in the parameters observed for the two strains under similar conditions suggest dissimilarities in their metabolic response to Co{sup 2 + }.

  2. A structural and Moessbauer study of Y{sub 3}Fe{sub 5}O{sub 12} nanoparticles prepared with high energy ball milling and subsequent sintering

    Energy Technology Data Exchange (ETDEWEB)

    Widatallah, H. M., E-mail: hishammw@squ.edu.om [Sultan Qaboos University, Department of Physics (Oman); Johnson, C. [Open University, Chemistry Department (United Kingdom); Al-Harthi, S. H.; Gismelseed, A. M.; Al-Rawas, A. D.; Stewart, S. J.; Elzain, M. E.; Al-Omari, I. A.; Yousif, A. A. [Sultan Qaboos University, Department of Physics (Oman)

    2008-04-15

    The influence of ball milling and subsequent sintering of a 3:5 molar mixture of Y{sub 2}O{sub 3} and {alpha}-Fe{sub 2}O{sub 3} on the formation of nanocrystalline Y{sub 3}Fe{sub 5}O{sub 12} (YIG) particles is studied. Pre-milling the mixture for 100 h lowers the onset temperature at which the material forms to 900 deg. C which is 200 deg. C lower than that reported when a similar mixture of reactants was premilled for shorter times. A single-phased nanocrystalline Y{sub 3}Fe{sub 5}O{sub 12} phase develops as a sole product when the pre-milled mixture is heated at 1,000 deg. C (12 h). This temperature is {approx}300-400 deg. C lower than those used to prepare the material conventionally. The bulk and surface crystal structure of the nanoparticles is studied with X-ray diffraction, Moessbauer spectroscopy, Atomic Force Microscope (AFM) and X-ray photoelectron spectroscopy.

  3. Moessbauer study of epitaxial Co{sub 2}Cr{sub 0.6}Fe{sub 0.4}Al thin films.

    Energy Technology Data Exchange (ETDEWEB)

    Ksenofontov, Vadim; Felser, Claudia [Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg - University, 55099 Mainz (Germany); Herbort, Christian; Jourdan, Martin [Institute of Physics, Johannes Gutenberg - University, 55099 Mainz (Germany)

    2008-07-01

    Epitaxial thin films of the promising for spintronic applications Heusler half-metallic compound Co{sub 2}Cr{sub 0.6}Fe{sub 0.4}Al (CCFA) were investigated using conversion electron Moessssbauer spectroscopy (CEMS) in order to get insight into the structural and magnetic properties. Thin films of 100 nm thickness were deposited by rf magnetron sputtering on MgO substrates without and with 10 nm Fe buffer layer. We discuss a correlation between the annealing temperature and the structural disorder and hyperfine fields on Fe atoms measured by Moessbauer spectroscopy. Samples prepared at the optimum annealing temperature as determined by tunneling magnetoresistance measurements show the optimum degree of order on the Fe sites as determined by CEMS. Additionally, we observed evidence for a diffusion of Cr atoms from the CCFA thin film into the Fe buffer layer and the related diffusion of Fe atoms from the buffer into the CCFA film. Thus the thermal treatment changes the Fe to Cr ratio of the Heusler compound additional to influencing the degree of disorder on the Fe/Cr sites.

  4. Moessbauer spectroscopic study of the thermal neutron irradiated potassium borate glasses

    International Nuclear Information System (INIS)

    Moessbauer study was performed for thermal neutron irradiated potassium borate glasses containing 7 mol % of ferric oxide. The alkali contents of the glasses were changed from 10 to 40 mol %. The decrease of isomer shift was observed by the irradiation of the glasses when the alkali content was higher than 20 mol %. The increase of the quadrupole splitting was also observed in the low alkali content region. These results were discussed in connection with the nuclear reaction of 10B(n,α)7Li and the network structure of the borate glasses. (author)

  5. Moessbauer Study of the Thermal Behaviour of Garnets Used in High-Energy Water Jet Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Barcova, K.; Mashlan, M. [Palacky University, Department of Experimental Physics (Czech Republic); Martinec, P. [Academy of Sciences of the Czech Republic, Institute of Geonics (Czech Republic)

    2002-03-15

    A high-energy water jet combined with silicate garnets as abrasives has been proven to be a powerful tool for disintegration of hard materials. Thermal heating of the garnets is one way for structure improvement of the abrasive material. Room-temperature Moessbauer spectra of initial powdered almandine samples are characterised by one doublet corresponding to Fe{sup 2+} in dodecahedral position 24c. Almandine garnet, industrial product Barton HP 80 as reference material in all experiments, has a second doublet corresponding to Fe{sup 3+} in octahedral position 16a. In room-temperature spectra of heated almandine garnet samples from locality Ktis and Medenec (heated under temperatures 200-1000 deg. C by 100 degrees for 1 hour in air) a new doublet originating from {gamma}-Fe{sub 2}O{sub 3} nanoparticles appeared. Under a heating temperature of higher than 800 deg. C, the broad sextets of {alpha}-Fe{sub 2}O{sub 3} and {epsilon}-Fe{sub 2}O{sub 3} in spectra were discovered. No additional doublets or sextets appeared in room-temperature Moessbauer spectra of reference material of almandine garnet Barton HP 80 heated under each temperature.

  6. Moessbauer study of the fraction of non-bridging oxygens in potassium borate glasses

    International Nuclear Information System (INIS)

    A Moessbauer study was performed to find the fraction of non-bridging oxygens in potassium borate glasses containing a small amount of iron. The borate glasses with alkali contents of 15, 20, 25, 30 and 40 mol% were irradiated with 60Co-γ rays at room temperature in a nitrogen atmosphere. The Moessbauer absorption area for the irradiation-induced Fe2+ increased with the total γ-ray dose in the range of 1 x 106 - 2 x 108 R, and became constant after irradiation ranging from 2 x 108 R - 1 x 109 R. The absorption area for the Fe2+ at the saturated region was correlated with the difference in the glass structure, i.e., the fraction of the non-bridging oxygens was estimated from the increased absorption area for the Fe2+ as a function of the alkali content of the glasses. The fraction of the non-bridging oxygen increased with the alkali content of the glasses in the alkali region above 20 mol%, and about 14% of the fraction was obtained for an alkali content of 40 mol%. (orig.)

  7. Application of 57Co emission Mössbauer spectroscopy to studying biocomplexes in frozen solutions

    Science.gov (United States)

    Kamnev, A. A.; Kulikov, L. A.; Perfiliev, Yu. D.; Antonyuk, L. P.; Kuzmann, E.; Vértes, A.

    2005-09-01

    Emission Mössbauer spectroscopy with the 57Co isotope was used to study very dilute rapidly frozen aqueous solutions of cobalt(II) complexes with low-molecular-weight biomolecules (aromatic amino acids anthranilic acid and L-tryptophan) and within a sophisticated biopolymer, bacterial glutamine synthetase, a key enzyme of nitrogen metabolism. The appearance of after-effects of the 57Co→57Fe nuclear transformation as well as the coordination properties of the cation and the ligands in the complexes are discussed on the basis of their Mössbauer parameters.

  8. Crystallization and Moessbauer studies of the Fe sub 7 sub 8 Al sub 4 Nb sub 5 B sub 1 sub 2 Cu sub 1 alloy

    CERN Document Server

    Kim, C S; Kim, S B; Park, J Y; Kim, K Y; Noh, T H; Oak, H N

    1998-01-01

    A melt-spun Fe sub 7 sub 8 Al sub 4 Nb sub 5 B sub 1 sub 2 Cu sub 1 alloy with an ultra-thin ribbon has been studied by x-ray diffraction, Moessbauer spectroscopy, and vibrating sample magnetometry. The average hyperfine field H sub h sub f (T) of the amorphous state shows temperature dependence of [H sub h sub f (T) - H sub h sub f (0)]/H sub h sub f (0) -0.53(T/T sub c) sup 3 sup / sup 2 - 0.21(T/T sub c < 0.7, indicative of spin-wave excitation. The quadrupole splitting just above the Curie temperature Tc is 0.42 mm/s, whereas the quadrupole shift below T sub c is zero. The Curie and the crystallization temperature are T sub c = 450 K and T sub x = 703 K, respectively, for a heating rate of 5 K/min. The occupied area ratio of the alpha-Fe phase flash-annealed at 723 K is 59% and remains unchanged. The crystallization temperature of the flash-annealed alloy becomes lower, and the formation of an alpha-Fe is easier than that of the conventional alloy. The flash-annealing technique is effective in improvin...

  9. Characterisation of Kaolinitic Clays from the Ivory Coast: Identification of Structural Fe

    Energy Technology Data Exchange (ETDEWEB)

    Sei, J.; Abba Toure, A. [Universite de Cocody-Abidjan, Laboratoire de Chimie Minerale, UFR SSMT (Cote d' Ivoire); Olivier-Fourcade, J. [Universite Montpellier II, Laboratoire des Agregats Moleculaires et Materiaux Inorganiques, UMR 5072 CNRS (France); Quiquampoix, H.; Staunton, S. [INRA, Unite Rhizosphere et Symbiose (France); Jumas, J. C., E-mail: jumas@univ-montp2.fr; Womes, M. [Universite Montpellier II, Laboratoire des Agregats Moleculaires et Materiaux Inorganiques, UMR 5072 CNRS (France)

    2004-09-15

    Five clays from four different deposits in the Ivory Coast (Adattie, Nieki, Grand-Bassam, Nigui-Saff) were studied by {sup 57}Fe Moessbauer spectroscopy and electron paramagnetic resonance (EPR) at room temperature. Their chemical compositions were determined by X-ray fluorescence and the most important crystalline phases were identified by X-ray diffraction. In these natural clays, kaolinite is the dominant mineral phase with minor amounts of other minerals including quartz, haematite, goethite, lepidocrocite and illite. Room-temperature {sup 57}Fe Moessbauer spectra of the samples from Nieki, Adattie and Nigui-Saff show mainly a broad quadrupole-split doublet which indicates that iron is essentially present as Fe(III). Samples from Grand-Bassam contain important amounts of goethite ({alpha}-FeOOH) and lepidocrocite ({gamma}-FeOOH). Some samples from Nigui-Saff contain large amounts of haematite. Clays from Nieki and Adattieare characterised by very low concentrations of iron oxides or hydroxides, and by small amounts of structural Fe(II) in the kaolinite lattice. Oxidation states and lattice sites of structural iron in the kaolinites were determined by {sup 57}Fe Moessbauer spectra recorded after iron extraction with dithionite-citrate-bicarbonate (DCB). The results were confirmed by electron paramagnetic resonance (EPR) measurements.

  10. Application of Mössbauer Spectroscopy in Earth Sciences

    Science.gov (United States)

    Vandenberghe, Robert E.; De Grave, Eddy

    Iron being the fourth most abundant element in the earth crust, 57Fe Mössbauer spectroscopy has become a suitable additional technique for the characterization of all kind of soil materials and minerals. However, for that purpose a good knowledge of the spectral behavior of the various minerals is indispensable. In this chapter a review of the most important soil materials and rock-forming minerals is presented. It starts with a description of the Mössbauer spectroscopic features of the iron oxides and hydroxides, which are essentially present in soils and sediments. Further, the Mössbauer spectra from sulfides, sulfates and carbonates are briefly considered. Finally, the Mössbauer features of the typical and most common silicate and phosphate minerals are reported. The chapter ends with some typical examples, illustrating the use and power of Mössbauer spectroscopy in the characterization of minerals.

  11. Effects of trapped electrons on the line shape in emission Moessbauer spectra

    International Nuclear Information System (INIS)

    To explain line broadening in emission Moessbauer spectra as compared to the corresponding absorber measurements, the model of trapped electrons has been proposed. Auger electrons (emitted, e.g. after electron capture by 57Co or after the converted isomeric transition of 119mSn), as well as secondary electrons, may be trapped in the proximity to the nucleogenic ion. Electrons captured by lattice traps at different distances from the daughter ion induce an asymmetric distribution of quadrupole splitting in the resulting emission spectra, as shown in a few examples. This model is supported by estimates of quadrupole splitting values which may be caused by such trapped electrons located at specified distances from the nucleogenic atom.

  12. Thermal decomposition and Moessbauer analysis of two iron hydroxy-carbonate complexes

    International Nuclear Information System (INIS)

    Full text:The two iron hydroxy carbonate complexes (NH4)2Fe2(OH)4(CO3)2.H2O and (NH4)4Fe2(OH)4(CO3)3.3H2O were prepared by the method of Dvoak and Feitknecht. Moessbauer spectra of the first sample at room temperature and 81K showed principally a ferric doublet with a small quadrupole splitting while spectra of the second sample showed a broad ferric doublet with a large mean quadrupole splitting of 1mm/s. Parameters for both spectra were characteristic of distorted octahedral coordination to oxygens. Thermal gravimetric analysis of both samples up to 750 K showed several fractions corresponding to the loss of the more volatile components

  13. Moessbauer and magnetic studies of PbFe12-xCrxO19 hexagonal ferrites

    International Nuclear Information System (INIS)

    Moessbauer and magnetic measurements have been performed on Cr substituted Pb-hexaferrite of composition PbFe12-xCrxO19 (0≤x≤6). The main hyperfine parameters for the Fe3+ nuclei of the various sublattices have been determined in the temperature range of 78-800 K. The data obtained give no evidence of deviation of the Fe3+ magnetic moments from the axial magnetic order. In addition, the Cr3+ ions do not occupy the hexahedral lattice sites. The rapid fall of the saturation magnetisation with increasing x cannot be simply explained with the replacement of the magnetic moment of the Fe3+ with that of Cr3+. The onset of a complex magnetic order induced by the presence of Cr3+ ions is involved. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  14. Magnetic and Moessbauer spectroscopic characterization of EuNi{sub 2}Sb{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Schellenberg, Inga; Eul, Matthias; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2011-11-15

    ThCr{sub 2}Si{sub 2}-type EuNi{sub 2}Sb{sub 2} (I4/mmm, a = 438.1(1), c = 1068.1(4) pm) was synthesized by arc-melting of the elements. Magnetic susceptibility measurements show Curie- Weiss behavior with an experimental magnetic moment of 8.03(1) {mu}{sub B}/Eu atom, indicating stable divalent europium. EuNi{sub 2}Sb{sub 2} orders antiferromagnetically at T{sub N} = 5.8(1) K. A {sup 151}Eu Moessbauer spectrum at 4.2 K shows two spectral components with hyperfine fields of 19.1 and 12.9 T, indicative of different magnetically ordered domains. (orig.)

  15. Moessbauer Investigation of Electrodeposited Sn-Zn, Sn-Cr, Sn-Cr-Zn and Fe-Ni-Cr Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmann, E.; Stichleutner, S. [Eoetvoes University, Department of Nuclear Chemistry and Research Group of Nuclear Methods in Structural Chemistry HAS (Hungary); El-Sharif, M.; Chisholm, C. U. [Glasgow Caledonian University (United Kingdom); Sziraki, L.; Homonnay, Z.; Vertes, A. [Eoetvoes University, Department of Nuclear Chemistry and Research Group of Nuclear Methods in Structural Chemistry HAS (Hungary)

    2002-06-15

    {sup 57}Fe and {sup 119}Sn CEMS, XRD and electrochemical measurements were used to investigate the effect of the preparation parameters and the components on the structure and phase composition of electrodeposited Fe-Ni-Cr alloys in connection with their corrosion behavior. XRD of the electrodeposits reflect an amorphous-like character. {sup 57}Fe CEM spectra of Fe-Ni-Cr electrodeposited samples, prepared in a continuous flow plating plastic circulation cell with variation of current density, electrolyte velocity and temperature, can be evaluated as a doublet associated with a highly disordered paramagnetic solid solution phase. This phase was identified earlier in Fe-Ni-Cr electrodeposits that were prepared by another plating method and contained both ferromagnetic and paramagnetic metastable phases. This is the first time that we have succeeded to prepare Fe-Ni-Cr alloys containing only the metastable paramagnetic phase. The effect of the plating parameters on the structure is also analysed by the quadrupole splitting distribution method. {sup 119}Sn CEM spectra of all Sn-containing plated alloys show a broad line envelop which can be decomposed at least into two components. One can be associated with {beta}-tin. The other one can be assigned to an alloy phase. The structure and distribution of microenvironments of these phases depends on the plating parameters especially on the parameters of the reverse pulse applied.

  16. Experimental investigation of some coordination complexes using the sup(151)Eu Moessbauer resonance

    International Nuclear Information System (INIS)

    Several Schiff base complexes containing Eu151 metal ions have been synthesized and their Moessbauer spectra are recorded using the constant acceleration velocity spectrometer. The least-square analysis method for the evaluation of the hyperfine field coupling constants is adopted using the computer dec system-10. From the systematic analysis of the quadrupole coupling constants (q.c.c.) and isomer shifts it has been established that the coordination number of the metal ion of Bis(acetylacetone) benzidine and thiourea complexes is five, that of bis-vanillin benzidine and bis-salicylaldehyde-o-dianisidine is six, and that of bis-vanillin-o-phenylene diamine is seven. It is also found that the q.c.c. being negative in all these complexes decreases monotonically as the coordination number increases. One unusual aspect of this experimental data is that most of the coordination complexes have very low f-factors whereas the Schiff base complexes studied here have a fairly high recoilless fractions. Attempts are in progress to synthesize and study the Fe Schiff base complexes in place of Eu. (auth.)

  17. Enhanced 119Sn Moessbauer quadrupole interactions below the magnetic phase transition of UPt2Sn

    International Nuclear Information System (INIS)

    119Sn Moessbauer effect measurements (4.2 K 2Sn and UCu2Sn. For temperatures above TN we find that the quadrupole splitting (ΔEQ) in UPt2Sn is about 3 times larger than in UCu2Sn. This difference in ΔEQ is suggested to be due to a large electronic contribution from the Pt-ligands in UPt2Sn. Upon decreasing temperature below TN, we find only in UPt2Sn an anomalous increase of ΔEQ relative to the extrapolated ΔEQ values in the paramagnetic phase (4% increase at 4.2 K). In addition, we have measured the thermal expansion coefficient (α) of a polycrystalline UPt2Snsample (4.2 K N of Δα ∼ 1.1 x 10-6 K-1. It is shown that the enhancement of ΔEQ is of electronic origin and related to the onset of AF order in UPt2Sn. (orig.)

  18. characterization of alumino and ferosilicate high siliceous zeolites by thermo analytical and Moessbauer spectroscopic techniques

    International Nuclear Information System (INIS)

    Simultaneous thermogravimetric/differential thermal analysis (TG/DTA) and differential scanning calorimetric (DSC) techniques were used to measure quantitatively the degree of crystallization and confirmation of tetrapropylammonium (TPA /sup +/) and tetraethylammonium (TEA /sup +/) species incorporated in ZSM5 and BETA-zeolite structure framework respectively. It is observed from thermal analysis that 3.3 to 3.8 TPA entities are normally present per unit cell of the ZSM-5 structure while for BETA the corresponding values are 6.2 to 6.7 for TEA. The propyl organic molecule was found to be located preferentially in the zigzag channel of ZSM5-AL and ZSM5-Fe in agreement with the results of the other techniques. 67Fe Moessbauer spectroscopic studies on as-synthesized and calcined samples have confirmed the uniform dispersion of Fe/sup 3+/ in the tetrahedral framework of ZSM5-Fe zeotype. Crystallinity and unit cell parameters of the materials were determined by powder x-ray diffraction, which are the function of Al and Fe content of the zeolites. A good correlation was obtained between the degree of crystallinity as established by TG/DSC techniques and x-ray diffraction crystallinity. (author)

  19. Rayleigh scattering of Moessbauer radiation in oriented fibres of hydrated biopolymers

    Energy Technology Data Exchange (ETDEWEB)

    Albanese, G. [Parma Univ. (Italy). Ist. di Fisica; Deriu, A. [Parma Univ. (Italy). Ist. di Fisica; Cavatorta, F. [Parma Univ. (Italy). Ist. di Fisica; Rupprecht, A. [Stockholm Univ. (Sweden). Dept. of Physical, Inorganic and Structural Chemistry

    1995-03-01

    The Rayleigh scattering of Moessbauer radiation (RSMR) has been measured on films of highly oriented hydrated polynucleotides (A-NaDNA) and polysaccharides (Na-hyaluronate). Both DNA and hyaluronate (HA) have helical secondary structures with a similar pitch (28.2 A for A-DNA, and 32.8 A for Na-HA), but they differ in the basic elements which make up the helices and in the extent of water-biopolymer interactions. These differences are responsible for the diverse stiffness of the polymer backbone, and also affect the dynamics of the first hydration layers. For both samples the elastic scattering intensity shows a sharp peak at about 2 A{sup -1} only for samples oriented with Q parallel to the fibre direction. Its position is close to that of the first maximum in the structure factor of bulk water; it is, however, much narrower than in pure H{sub 2}O and it is similar to a crystalline Bragg peak. It can be attributed to an ordered structure of water along the double helices. From the temperature dependence of the elastic intensity under the peak maximum, the mean square displacement of water oxygens in the direction parallel to the helices has been deduced. The thermal diffuse scattering intensity is also peaked at the same Q values of the elastic intensity, indicating the presence of coherent vibrational excitations propagating along the ordered water filaments. (orig.)

  20. Use of a ring detector in the technique of Rayleigh scattering of Moessbauer radiaiton

    International Nuclear Information System (INIS)

    An installation for measuring Rayleigh scattering of Moessbauer radiation is described. The detector of the ring configuration collects radiation scattered at average angle relatively to the symmetry axis that gives 20 time advantage in counting rate as compared with usual geometry. Laminated collimator made in the form of lead cylinder with cone hole is chosen for decrease of undesirable background radiation from secondary X-rays within 14.4 keV range. Inner working channels are made of copper and intermediate layer- of cadmium. Scintillation counter located behind the collimator comprises NaI(Tl) crystal made in the form of a ring with outside 62 and 28 mm internal diameters, 0.1 mm thickness and photomultiplier PEI-82. Application of the crystal in the form of a ring instead of disk permits to increase 1.5 times signal/bakground ratio. The average scattering angle is =12 deg, reception angle approximately 5 deg. A conclusion is made on good coincidence of measurement results exercised by means of the described installation with the data obtained in installation of general geometry

  1. Use of a ring detector in the technique of Rayleigh scattering of Moessbauer radiaiton

    Energy Technology Data Exchange (ETDEWEB)

    Gaubman, E.E.; Krupyanskii, Yu.F.; Suzdalev, I.P. (AN SSSR, Moscow. Inst. Khimicheskoj Fiziki)

    An installation for measuring Rayleigh scattering of Moessbauer radiation is described. The detector of the ring configuration collects radiation scattered at average <2 THETA > angle relatively to the symmetry axis that gives 20 time advantage in counting rate as compared with usual geometry. Laminated collimator made in the form of lead cylinder with cone hole is chosen for decrease of undesirable background radiation from secondary X-rays within 14.4 keV range. Inner working channels are made of copper and intermediate layer- of cadmium. Scintillation counter located behind the collimator comprises NaI(Tl) crystal made in the form of a ring with outside 62 and 28 mm internal diameters, 0.1 mm thickness and photomultiplier PEI-82. Application of the crystal in the form of a ring instead of disk permits to increase 1.5 times signal/bakground ratio. The average scattering angle is <2THETA>=12 deg, reception angle approximately 5 deg. A conclusion is made on good coincidence of measurement results exercised by means of the described installation with the data obtained in installation of general geometry.

  2. X-ray quantum optics with Moessbauer nuclei in thin-film cavities

    Energy Technology Data Exchange (ETDEWEB)

    Heeg, Kilian Peter

    2014-12-09

    In this thesis thin-film cavities with embedded Moessbauer nuclei probed by near-resonant X-ray light are studied from a quantum optical perspective. A theoretical framework is developed and compact expressions for the observables are derived for the linear excitation regime, which is encountered in current experiments. Even advanced cavity layouts can be modeled in excellent agreement with the results of previous experiments and semi-classical approaches. In the absence of magnetic hyperfine splitting, the spectral response of the system is found to be formed by tunable Fano profiles. An experimental implementation of this line shape control allows to extract spectroscopic signatures with high precision and to reconstruct the phase of the nuclear transition in good agreement with the theoretical predictions. The alignment of medium magnetization and polarization control of the X-rays enable to engineer advanced quantum optical level schemes, in which vacuum induced coherence effects are predicted and successfully demonstrated in an experiment. Furthermore, it is shown that group velocity control for x-ray pulses can be achieved in the cavity. A scheme for its observation is proposed and then employed to experimentally confirm sub-luminal X-ray propagation. Finally, non-linear effects, which could become accessible with future light sources, are explored and a non-linear line shape control mechanism is discussed.

  3. Reaction Kinetics and Oxidation Mechanisms of the Conversion of Pyrite to Ferrous Sulphate: A Moessbauer Spectroscopy Study

    International Nuclear Information System (INIS)

    Pyrite undergoes a series of exothermic reactions during mine roasting to porous hematite. At low temperatures, the first non-refractive phase to form is ferrous sulphate and could be a cheaper alternative to hematite roasting for the mining industry. In this study, pyrite powder is heated in air at temperatures between 200 and 370 deg. C for 1 to 256 h in a temperature and time series. The rate of oxidation of pyrite to ferrous sulphate is modelled by combining the Arrhenius equation with the Weibull function to extract reliable thermodynamic data, including the energy of activation, the frequency factor and the overall order of reaction. From the thermodynamic data obtained, two possible oxidation mechanisms are recognized, depending on the bond dissociation energies of the S-S and Fe-S bonds in pyrite.

  4. Reaction Kinetics and Oxidation Mechanisms of the Conversion of Pyrite to Ferrous Sulphate: A Moessbauer Spectroscopy Study

    Energy Technology Data Exchange (ETDEWEB)

    Ferrow, Embaie A., E-mail: embaie.ferrow@geol.lu.se; Mannerstrand, Maria [Lund University, GeoBiosphere Science Centre, Department of Geology, Lithosphere Biosphere Science (Sweden); Sjoeberg, Bosse [Swedish Museum of Natural History (Sweden)

    2005-06-15

    Pyrite undergoes a series of exothermic reactions during mine roasting to porous hematite. At low temperatures, the first non-refractive phase to form is ferrous sulphate and could be a cheaper alternative to hematite roasting for the mining industry. In this study, pyrite powder is heated in air at temperatures between 200 and 370 deg. C for 1 to 256 h in a temperature and time series. The rate of oxidation of pyrite to ferrous sulphate is modelled by combining the Arrhenius equation with the Weibull function to extract reliable thermodynamic data, including the energy of activation, the frequency factor and the overall order of reaction. From the thermodynamic data obtained, two possible oxidation mechanisms are recognized, depending on the bond dissociation energies of the S-S and Fe-S bonds in pyrite.

  5. A 119Sn Moessbauer Study of Tin(IV) Complexes of 2- and 4-Benzoylpyridine Thiosemicarbazone and 4-Benzoylpyridine Semicarbazone

    International Nuclear Information System (INIS)

    A 119Sn Moessbauer study was carried out of tin(IV) complexes with 2-benzoylpyridine thiosemicarbazone (H2Bz4DH) and its N(4)-methyl (H2Bz4M) and N(4)-phenyl (H2Bz4Ph) derivatives: [Sn(2Bz4DH)Cl3] (1), [Sn(2Bz4DH)PhCl2] (2), [Sn(2Bz4M)Cl3] (3), [H22Bz4M]2[Ph2SnCl4] (4), [Sn(2Bz4Ph)PhCl2] (5), [Sn(2Bz4Ph)Ph2Cl] (6), in which H2Bz4R stands for the neutral ligand and 2Bz4R stands for the anionic thiosemicarbazone. In addition, 119Sn Moessbauer studies of the tin(IV) complexes [Sn(H4Bz4DH)2Cl4H2O] (7), [Sn(H4BzPS)2Cl4H2O] (8) with 4-benzoylpyridine thiosemicarbazone (H4Bz4DH) and the correspondent semicarbazone (H4BzPS) were performed. The isomer shifts decrease upon coordination due to the variation in the percentage of s character as tin changes from approximately sp3 hybridization in the tin salts to sp3d2 in the octahedral or sp3d3 in the heptahedral complexes. The Moessbauer parameters of compound (4) showed the existence of two tin(IV) sites, which have been attributed to the presence of the cis and trans isomers.

  6. Moessbauer studies of the H2 reduction effects on magnetic properties of Ba-Sr hexagonal ferrite

    International Nuclear Information System (INIS)

    The concept of composite magnets with hard materials and soft materials have been applied for increasing specific saturation magnetization (σs) of M-type hexagonal ferrites. We have synthesized Ba0.5Sr0.5Fe10O19 and Ba0.3Sr0.7Fe10CoTiO19 by the sol-gel method. These Ba-Sr ferrite particles were reduced in H2 gas with varying temperature from 250 deg. C to 500 deg. C. As the reduction temperature increases, the patterns of X-ray diffraction show that the peaks of α-Fe appear above 250 deg. C and the pattern corresponding to M-type hexagonal ferrite of Ba0.5Sr0.5Fe10O19 disappears above 450 deg. C. However, that for M-type hexagonal ferrite can be found at 450 deg. C in Ba0.3Sr0.7Fe10CoTiO19. Moessbauer spectra have been analysed with 7 sub-patterns which correspond to the 4fVI, 2b, 12k, 4fIV, 2a, α-Fe and paramagnetic Fe. The Moessbauer results show that Co and Ti substitutions suppress the reduction process. This behavior between Ba0.5Sr0.5Fe10O19 and Ba0.3Sr0.7Fe10CoTiO19 is explicable with the site preference of Co2+ ions and Ti4+ ions. Moessbauer analysis revealed that α-Fe, which influences coercivity and specific saturation magnetization of particles, is introduced from the 12k site mainly, and from 4fVI

  7. Moessbauer Mineralogical Evidence for Aqueous Processes at Gusev Crater and Meridiani Planum

    Science.gov (United States)

    Morris, R. V.; Klingelhoefer, G.

    2004-12-01

    The Moessbauer spectrometers on the MER rovers have measured the relative abundances of iron with respect to both oxidation state and iron-bearing phase at Gusev Crater (Spirit rover) and Meridiani Planum (Opportunity rover). The assemblage of phases indicates aqueous alteration processes at both landing sites. Although the rock and soil of the Gusev Crater plains are dominated by Fe(2+) in olivine-bearing basalt (~Fo60), a Fe(3+)-rich component (nanophase ferric oxide, np-Ox) has significant abundance in surface soils (13-28% of total Fe) and in the surface coatings (rinds) of certain rocks (39%) but not in rock interiors exposed by grinding (5-6%). The mode of occurrence of np-Ox implies that it is the product of oxidative alteration of Fe(2+) silicate and oxide phases in the presence of H2O. The ubiquitous presence of sulfur in soil and in rock coatings, as determined by the MER-A APXS instrument, suggests that the alteration occurred under acid-sulfate conditions, so that both hydrolytic and sulfatic reactions are viable. A possible source for the weathering agents is volcanic emanations rich in H2O and SO2. Generally, rocks in the Columbia Hills are significantly more altered than those in the Gusev plains, with a higher proportion of Fe(3+) oxide phases compared to Fe(2+) silicate phases. This mineralogical dichotomy implies a difference in the timing, rate, duration, and/or mechanism of alteration for basaltic material in the Gusev plains compared to basaltic material in the Columbia Hills. It is possible, for example, that the basaltic material in the Columbia Hills underwent aqueous alteration in a paleoclimate that favored nearly complete alteration and that the basaltic material of the Gusev plains will not achieve the degree of alteration exhibited by the Columbia Hills under current martian surface conditions. Because its structure contains the hydroxide anion, the Moessbauer detection of the hydroxide sulfate jarosite (K,Na)Fe3(SO4)2(OH)6 in outcrops

  8. Evaluation of the Debye temperature for iron cores in human liver ferritin and its pharmaceutical analogue Ferrum Lek using Mossbauer spectroscopy

    CERN Document Server

    Dubiel, S M; Alenkina, I V; Oshtrakh, M I; Semionkin, V A

    2014-01-01

    An iron polymaltose complex Ferrum Lek used as antianemic drug and considered as a ferritin analogue and human liver ferritin were investigated in the temperature range from 295K to 90K by means of 57Fe Mossbauer spectroscopy with a high velocity resolution i.e. in 4096 channels. The Debye temperatures equal to 502K for Ferrum Lek and to 461K for human liver ferritin were determined from the temperature dependence of the center shift obtained using two different fitting procedures.

  9. Mössbauer spectroscopy monitoring the spin transition of a FeII 1D chain with a fluorinated 4-R-1,2,4-triazole

    Science.gov (United States)

    Railliet, Antoine P.; Naik, Anil D.; Rotaru, Aurelian; Garcia, Yann

    2014-04-01

    The spin transition properties of [Fe(fletrz)3](BF4)2•2H2O are described. Fletrz (4-(2'-fluoroethyl)-4H-1,2,4-triazole) is a novel fluorine substituted 1,2,4-triazole ligand which forms 1D chain upon self-assembly with FeII ions. This coordination polymer exhibits reversible abrupt thermochromic spin transition that has been probed by SQUID magnetometry, variable temperature 57Fe Mossbauer spectroscopy (77-300 K) and differential scanning calorimetry (100-300 K).

  10. Energy calibration issues in nuclear resonant vibrational spectroscopy: observing small spectral shifts and making fast calibrations.

    Science.gov (United States)

    Wang, Hongxin; Yoda, Yoshitaka; Dong, Weibing; Huang, Songping D

    2013-09-01

    The conventional energy calibration for nuclear resonant vibrational spectroscopy (NRVS) is usually long. Meanwhile, taking NRVS samples out of the cryostat increases the chance of sample damage, which makes it impossible to carry out an energy calibration during one NRVS measurement. In this study, by manipulating the 14.4 keV beam through the main measurement chamber without moving out the NRVS sample, two alternative calibration procedures have been proposed and established: (i) an in situ calibration procedure, which measures the main NRVS sample at stage A and the calibration sample at stage B simultaneously, and calibrates the energies for observing extremely small spectral shifts; for example, the 0.3 meV energy shift between the 100%-(57)Fe-enriched [Fe4S4Cl4](=) and 10%-(57)Fe and 90%-(54)Fe labeled [Fe4S4Cl4](=) has been well resolved; (ii) a quick-switching energy calibration procedure, which reduces each calibration time from 3-4 h to about 30 min. Although the quick-switching calibration is not in situ, it is suitable for normal NRVS measurements.

  11. Nuclear resonance vibrational spectroscopy (NRVS) of rubredoxin and MoFe protein crystals

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yisong [University of California, Department of Applied Science (United States); Brecht, Eric [Montana State University, Department of Chemistry and Biochemistry (United States); Aznavour, Kristen [University of Southern California, Department of Chemistry (United States); Nix, Jay C. [Lawrence Berkeley National Laboratory, Physical Biosciences Division (United States); Xiao, Yuming; Wang, Hongxin [University of California, Department of Applied Science (United States); George, Simon J. [Lawrence Berkeley National Laboratory, Physical Biosciences Division (United States); Bau, Robert [University of Southern California, Department of Chemistry (United States); Keable, Stephen; Peters, John W. [Montana State University, Department of Chemistry and Biochemistry (United States); Adams, Michael W. W. [University of Georgia, Department of Biochemistry and Molecular Biology (United States); Jenney, Francis E. Jr. [Georgia Campus, Philadelphia College of Osteopathic Medicine (United States); Sturhahn, Wolfgang; Alp, Ercan E.; Zhao, Jiyong [Argonne National Laboratory, Advanced Photon Source (United States); Yoda, Yoshitaka [JASRI (Japan); Cramer, Stephen P., E-mail: spcramer@lbl.gov [University of California, Department of Applied Science (United States)

    2013-12-15

    We have applied {sup 57}Fe nuclear resonance vibrational spectroscopy (NRVS) for the first time to study the dynamics of Fe centers in Iron-sulfur protein crystals, including oxidized wild type rubredoxin crystals from Pyrococcus furiosus, and the MoFe protein of nitrogenase from Azotobacter vinelandii. Thanks to the NRVS selection rule, selectively probed vibrational modes have been observed in both oriented rubredoxin and MoFe protein crystals. The NRVS work was complemented by extended X-ray absorption fine structure spectroscopy (EXAFS) measurements on oxidized wild type rubredoxin crystals from Pyrococcus furiosus. The EXAFS spectra revealed the Fe-S bond length difference in oxidized Pf Rd protein, which is qualitatively consistent with the crystal structure.

  12. Phonon density of states in nanocrystalline 57Fe

    Indian Academy of Sciences (India)

    Ranber Singh; S Prakash; R Meyer; P Entel

    2003-03-01

    The Born–von Karman model is used to calculate phonon density of states (DOS) of nanocrystalline bcc Fe. It is found that there is an anisotropic stiffening in the interatomic force constants and hence there is shrinking in the nearest-neighbour distances in the nanophase. This leads to additional vibrational modes above the bulk phonons near the bottom of the phonon band. It is found that the high energy phonon modes of nanophase Fe are the surface modes. The calculated phonon DOS closely agree with the experimental data except a peak at 37 meV. The calculated phonon dispersion relations are also compared with those of the bulk phonons and anomalous behaviour is discussed in detail. The specific heat in nanophase enhances as compared to bulk phase at low temperatures and the calculated Debye temperature agrees with the experimental results. It is predicted that the nanocrystalline Fe may consist of about 14 GPa pressure.

  13. Moessbauer study of iron-carbide growth and Fischer-Tropsch activity

    Energy Technology Data Exchange (ETDEWEB)

    Rao, K.R.P.M.; Huggins, F.E.; Huffman, G.P. [Univ. of Kentucky, Lexington, (United States)] [and others

    1995-12-31

    There is a need to establish a correlation between the Fischer-Tropsch (FT) activity of an iron-based catalyst and the catalyst phase during FT synthesis. The nature of iron phases formed during activation and FT synthesis is influenced by the nature of the gas and pressure apart from other parameters like temperature, flow rate etc., used for activation. Moessbauer investigations of iron-based catalysts subjected to pretreatment at two different pressures in gas atmospheres containing mixtures of CO, H{sub 2}, and He have been carried out. Studies on UCI 1185-57 (64%Fe{sub 2}O{sub 3}/5%CuO/1%K{sub 2}O/30% Kaolin) catalyst indicate that activation of the catalyst in CO at 12 atms. leads to the formation of 100% magnetite and the magnetite formed gets rapidly converted to at least 90% of {chi}-Fe{sub 5}C{sub 2} during activation. The FT activity was found to be good at 70-80% of (H{sub 2}+CO) conversion. On the other hand, activation. The FT activity was found to be good at 70-80% of (H{sub 2}+CO) conversion. On the other hand, activation of the catalyst in synthesis gas at 12 atms. leads to formation of Fe{sub 3}O{sub 4} and it gets sluggishly converted to {chi}-Fe{sub 5}C{sub 2} and {epsilon}-Fe{sub 2.2}C during activation and both continue to grow slowly during FT synthesis. FT activity is found to be poor. Pretreatment of the catalyst, 100fe/3.6Si/0.71K at a low pressure of 1 atms. in syngas gave rise to the formation of {chi}-Fe{sub 5}C{sub 2} and good FT activity. On the other hand, pretreatment of the catalyst, 100Fe/3.6Si/0.71K at a relatively high pressure of 12 atms. in syngas did not give rise to the formation any carbide and FT activity was poor.

  14. Influence of hydrogenation and mechanical grinding on the structural and ferromagnetic properties of GdFeSi

    Energy Technology Data Exchange (ETDEWEB)

    Chevalier, Bernard; Duttine, Mathieu; Wattiaux, Alain [Universite de Bordeaux, CNRS ICMCB, Pessac (France)

    2016-08-01

    Hydrogen insertion into GdFeSi induces (i) a structural transition from a tetragonal CeFeSi-type to a tetragonal ZrCuSiAs-type, (ii) an anisotropic expansion of the unit cell parameters because the a parameter decreases, whereas the c parameter increases, and (iii) a decrease in Curie temperature from 121 to 20 K. On the contrary, an amorphous ferromagnet (T{sub C} = 65 K) is obtained by mechanical grinding of GdFeSi. The three compounds (GdFeSi, GdFeSiH, and amorphous GdFeSi) were investigated by {sup 57}Fe Moessbauer spectroscopy. At 4.2 K, this study has revealed that the magnetically ordered Gd substructure produces a small transferred hyperfine magnetic field at the {sup 57}Fe nucleus.

  15. Characterization of the corrosion products formed on mild steel in acidic medium with N-octadecylpyridinium bromide as corrosion inhibitor

    Energy Technology Data Exchange (ETDEWEB)

    Nava, N., E-mail: tnava@imp.mx; Likhanova, N. V. [Direccion de Investigacion y Posgrado, Instituto Mexicano del Petroleo (Mexico); Olivares-Xometl, O. [Benemerita Universidad Autonoma de Puebla, Facultad de Ingenieria Quimica (Mexico); Flores, E. A. [Direccion de Investigacion y Posgrado, Instituto Mexicano del Petroleo (Mexico); Lijanova, I. V. [CIITEC, Instituto Politecnico Nacional (Mexico)

    2011-11-15

    The characterization of the corrosion products formed on mild steel SAE 1018 after 2 months exposure in aqueous sulfuric acid with and without corrosion inhibitor N-octadecylpyridinium bromide has been carried out by means of transmission {sup 57}Fe Moessbauer spectroscopy and X-ray powder diffraction (XRD). The major constituent of the rust formed in this environment without corrosion inhibitor is goethite ({alpha}-FeOOH). The samples with N-octadecylpyridinium bromide contain rozenite and large amounts of melanterite in the corrosion layers.

  16. Morin transition suppression in Polycrystalline 57Hematite (α-Fe2O3) exposed to 56Fe(II)

    International Nuclear Information System (INIS)

    We used the isotope selectivity of 57Fe Moessbauer spectroscopy to investigate changes in the magnetic properties of polycrystalline hematite exposed to ferrous iron (Fe(II)). We found that sorption of 56Fe(II), followed by interfacial electron exchange, alters the bulk magnetic properties of 57hematite. After reaction with 56Fe(II), we observed partial suppression of the Morin transition of 57hematite to below 13 K. This is significantly lower than the Morin temperature (TM) of ∼230 K measured for isotopically enriched polycrystalline 57hematite, as well as the TM of 264 ± 2 K reported for normal polycrystalline hematite.

  17. CEMS interface study of Fe(100)/Pd film structures

    Energy Technology Data Exchange (ETDEWEB)

    Kisters, G. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Festkoerperforschung; Sauer, C. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Festkoerperforschung; Tsymbal, E. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Festkoerperforschung; Zinn, W. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Festkoerperforschung

    1994-11-01

    The magnetic hyperfine fields B{sub hf} near the interface in epitaxial Fe(100)/Pd thin film structures were analyzed using in-situ {sup 57}Fe conversion electron Moessbauer spectroscopy. B{sub hf} is enhanced by about 12% in the 2nd Fe monolayer and approaches the Fe bulk value after a few oscillations within 8-10 Fe monolayers. This oscillating behavior can be described by a superposition of an exponential short-range and an RKKY-like long-range exchange interaction. (orig.)

  18. Magnetic and microstructural properties of (Nd,Pr)-(Tb,Dy,Gd)-(Fe,Co,Al,Cu)-B type magnets

    Energy Technology Data Exchange (ETDEWEB)

    Arinicheva, O. A.; Lileev, A. S. [National University of Science and Technology ' MISIS' (Russian Federation); Reissner, M., E-mail: reissner@ifp.tuwien.ac.at [Vienna University of Technology (Austria); Lukin, A. A. [Ltd. Research and Production Complex ' Magnets and Magnetic Systems' (Russian Federation); Starikova, A. S. [National University of Science and Technology ' MISIS' (Russian Federation)

    2013-04-15

    (Nd,Pr)-(Tb,Dy,Gd)-(Fe,Co,Al,Cu)-B magnets were heat treated in two different ways and investigated in the temperature range 4.2 to 400 K. After optimal heat treatment intrinsic coercive field {sub i}H{sub c} = 1640 and 5040 kA/m for room temperature and 10 K was obtained and the temperature coefficient of remanence {alpha} = -0.01 for temperature range 80 to 375 K was found. On basis of magnetic measurements and {sup 57}Fe Moessbauer spectroscopy, the possible reasons for the increase of {sub i}H{sub c} during multi-step heat treatment are discussed.

  19. Effect of substitutions on 3d magnetism in Gd2Fe14-xMxC compounds, with M=Ni, Si, Cu or V

    International Nuclear Information System (INIS)

    Results of magnetic measurements and 57Fe Moessbauer spectroscopy performed on Gd2Fe14-xMxC compounds, with M=Ni, Si, Cu or V are presented. As M is substituted for Fe, the six crystallographically inequivalent iron sites split into seven inequivalent sites for M=Si, Cu, V, or eight for M=Ni. The analysis of the hyperfine fields and relative intensities supports a preferential distribution of the substitutional elements on the Fe lattice sites. The effects of the substitutional elements on Curie temperatures and anisotropy fields as well as on Fe hyperfine parameters are discussed on the grounds of the preferential Fe site occupancy. (orig.)

  20. Application gives the spectrometria Moessbauer to the study chemical structural he/she gives the iron sulphate used monohidratado as payment in parcel he/she gives peaches (Prunus Persica) in Cartaya (Huelva) it leaves

    International Nuclear Information System (INIS)

    In the present work, a study of chemical-structural properties of the mono hydrous iron sulphate (FeSO4.1H2O) with a 15% approximately of free sulphuric acid, used like improvement of soil is carried out. This work is the first of a series, where the experiences of the use of this product in parcels (where peaches (Prunus persica) are cultivated) in the zone of Cartaya (Huelva, Spain) are undertaken. The characterisation of soil from the parcel before application of this product is carried out in order to analyse and compare with the final results by using the methods of the Moessbauer spectroscopy. High contents of Fe, S, and Zn at the studied product are observed . This elements are very important for plants. The knowledge of the main chemical-structural properties of this product, used like improvement of soil, will permit the study of their influence to) on the soil properly, b) on the foliate levels of the peach leaves and c) on the foodstuff fruit

  1. A quasi-continuous observation of the α-transition of Fe1+xS by Moessbauer line tracking

    International Nuclear Information System (INIS)

    Moessbauer absorption line tracking methodology, under a constant velocity strategy, is used for a quasi-continuous observation of the α-transition on slightly non stoichiometric Fe1+xS alloy. To this end, two strategies were applied: an intelligent absorption line tracking with a control algorithm that uses the data measured in the previous region to establish the position of the next partial spectral range; and a predetermined line tracking in which temperature evolution of a partial spectral region of interest (ROI) is programmed. The latter uses results from the former, in order to achieve a quasi-continuous partial spectral observation. These experiments clearly demonstrate that line tracking allows a more efficient use of the radioactive source, as the effort is concentrated in a partial region of the spectra from which the desired information can be obtained.

  2. Moessbauer and molecular orbital (MO) study of localized and delocalized mixed-valence organo-Fesup(II)Fesup(I)bisandwiches

    International Nuclear Information System (INIS)

    A Moessbauer study of two mixed-valence Fesup(II)Fesup(I) compounds was carried out from 4.2K to room temperature. Zero-field spectra show two types of iron atoms for the first and one type for the second. Hence the first compound is a localized mixed-valence complex and the second a delocalized mixed-valence complex. High magnetic field spectra for the second compound give a negative sign for the EFG and show the valence electron is delocalized on the two centers. IEHT-MO calculations confirm the results and allow to explain the temperature independence of the quadrupole splitting (QS) of the second compound. (Auth.)

  3. Ag-Sn alloys and dental amalgams: A 119Sn Moessbauer, X-ray diffraction and scanning electron microscopy study

    International Nuclear Information System (INIS)

    Examination has been made on aged and fresh Ag-Sn alloys and on commercial Cu-Ag-Sn dental alloys. Although x-ray diffractograms of aged Ag-Sn showed only γ Ag-Sn and free silver, 119Sn Moessbauer spectra exhibited Sn(IV) oxide also. A low Debye temperature showed the oxide to be in intimate dynamical contact with the metallic matrix. Upon adding mercury, the phases γ1 Ag-Hg and η' Cu-Sn were observed in a commercial specimen. Conversion-electron spectra of a mercury-coated disk showed the presence of γ2 Sn-Hg and a distribution of line positions smaller than that for particulate amalgams. Internal oxidation was found to prevent amalgamation. (orig.)

  4. Radio frequency interference in rf-collapse Moessbauer experiments and application of main-frame computer linked data acquisition system

    International Nuclear Information System (INIS)

    Radio frequency field in Moessbauer experiments of rf-collapse studies poses stringent demands on the setup due to strong radio frequency interference-(RFI). In switched-rf experiments, RFI conditions are more acute. Although screening cage is a standard practice, complete shielding and plugging rf-leaks are difficult. We describe an experimental set-up and procedures for coupling rf power to field coil. This set-up was used in switched rf experiments of collapse. Probable modes of rf pick-up and measures to suppress RFI, are discussed. In second part, data acquisition system linked to main-frame computer is described. Due to the proximity of rf radiation field, demand on system reliability is important. We employed microcomputer based units devoted to smaller dedicated tasks, such as 1) data acquisition, 2) data concentration, 3) serial line link to main-frame computer using UP LOAD and DOWN LOAD subroutine and subsidiary facilities. (orig.)

  5. Moessbauer and XRD study of the Fe{sub 65}Si{sub 35} alloy obtained by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Velez, G. Y., E-mail: giovelez29@gmail.com [Universidad del Valle, Departamento de Fisica (Colombia); Rodriguez, R. R. [Corporacion Universidad Autonoma de Occidente (Colombia); Melo, C. A.; Perez Alcazar, G. A.; Zamora, Ligia E.; Tabares, J. A. [Universidad del Valle, Departamento de Fisica (Colombia)

    2011-11-15

    A study was made on the alloy Fe{sub 65}Si{sub 35} using x-ray diffraction and Moessbauer spectrometry. The alloy was obtained by mechanical alloying in a high energy planetary mill, with milling times of 15, 30, 50, 75 and 100 h. The results show that in the alloys two structural phases are present, a Fe-Si BCC disordered phase and ferromagnetic, and a Fe-Si SC phase, whose nature is paramagnetic and which decreases with milling time. In the temporal evolution of the milling two stages are differentiated: one between 15 and 75 h of milling, in which silicon atoms diffuse into the bcc matrix of iron and its effect is to reduce the hyperfine magnetic field; the other, after 75 h of milling, where the alloy is consolidated, the effect of the milling is only to increase the disorder of the system, increasing the magnetic order.

  6. On the magnetic and Moessbauer spectroscopic characterization of EuPd{sub 2}Sb{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Schellenberg, Inga; Eul, Matthias; Poettgen, Rainer [Inst. fuer Anorganische und Analytische Chemie, Westfaelische Wilhelms-Univ. Muenster (Germany)

    2010-01-15

    The CaBe{sub 2}Ge{sub 2}-type antimonide EuPd{sub 2}Sb{sub 2} (P4/nmm, a = 462.43(7), c = 1056.1(2) pm) was synthesized by induction melting of the elements in a sealed tantalum tube. Temperature-dependent magnetic susceptibility measurements have revealed Curie-Weiss behavior with an experimental magnetic moment of 7.93(1) {mu}{sub B}/Eu atom, indicating stable divalent europium. EuPd{sub 2}Sb{sub 2} orders antiferromagnetically at T{sub N} = 4.5(2) K as is also evident from almost full hyperfine field splitting (B{sub h} = 19.5 T) in the {sup 151}Eu Moessbauer spectrum at 4.2 K. (orig.)

  7. Investigations of Deep-Level Fe-centres in Si by Mössbauer Spectroscopy

    CERN Multimedia

    Dietrich, M

    2002-01-01

    %IS359\\\\ \\\\Electronic, vibrational and diffusional properties of interstitial and substitutional Fe impurities in silicon are studied by $ ^{57} $Fe Mössbauer emission spectroscopy utilizing implanted radioactive $ ^{57}$Mn$^{+} $ parent ions from ISOLDE as probe atoms. Thus the electronic charge density and the impurity mean-square vibrational amplitude shall be determined for substitutional Fe$_{s} $ and for interstitial Fe$_{i}^{0/+} $ in its two different charge states. These quantities are complementary to previously determined hyperfine interaction parameters and are expected to shed light on the nature of the deviations between calculated and measured parameters. The supposedly different diffusivities of interstitial Fe$_{i}^{0} $ and Fe$_{i}^{+} $ shall be measured by the broadening of the Mössbauer lines, i.e. at a temperature where diffusion jumps occur on an atomic scale within the lifetime of the Mössbauer state.

  8. Superconductivity and magnetism in K-doped EuFe2As2

    International Nuclear Information System (INIS)

    Superconductivity is found in 50% K-doped EuFe2As2 samples below 33 K. Our results from electrical resistivity, magnetic susceptibility and 57Fe and 151Eu Moessbauer spectroscopy provide clear evidence that the ordering of the Fe moments observed at 190 K in undoped EuFe2As2 is completely suppressed in our 50% K-doped sample; thus there is no coexistence of the Fe magnetic order and the superconducting state. However, short range ordering of the Eu moments coexists with the superconducting state below 15 K. A bump in the susceptibility well below Tc as well as the broadening of the Fe Moessbauer line below 27 K evidence an interplay between the Eu magnetism and the superconducting state.

  9. Superconductivity and magnetism in K-doped EuFe{sub 2}As{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Anupam; Hossain, Z [Department of Physics, Indian Institute of Technology, Kanpur 208016 (India); Paulose, P L [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Jeevan, H S; Geibel, C [Max Planck Institute for Chemical Physics of Solids, 01187 Dresden (Germany)], E-mail: zakir@iitk.ac.in

    2009-07-01

    Superconductivity is found in 50% K-doped EuFe{sub 2}As{sub 2} samples below 33 K. Our results from electrical resistivity, magnetic susceptibility and {sup 57}Fe and {sup 151}Eu Moessbauer spectroscopy provide clear evidence that the ordering of the Fe moments observed at 190 K in undoped EuFe{sub 2}As{sub 2} is completely suppressed in our 50% K-doped sample; thus there is no coexistence of the Fe magnetic order and the superconducting state. However, short range ordering of the Eu moments coexists with the superconducting state below 15 K. A bump in the susceptibility well below T{sub c} as well as the broadening of the Fe Moessbauer line below 27 K evidence an interplay between the Eu magnetism and the superconducting state.

  10. Iron sites in greigite from the Cypris series''

    Energy Technology Data Exchange (ETDEWEB)

    Zemcik, T. (Inst. of Physical Metallurgy, Academy of Sciences of the Czech Republic, Brno (Czech Republic) Joint Moessbauer Lab., Faculty of Mathematics and Physics, Charles Univ., Prague (Czech Republic)); Cimbalnikova, A. (Inst. of Geology, Academy of Sciences of the Czech Republic, Prague (Czech Republic))

    1994-02-01

    Results of the [sup 57]Fe Moessbauer spectroscopy of greigite from the greigite-rich'' horizon of the middle part of the miocene series (Sokolov Basin, North Bohemia) are reported. From the room-temperature transmission spectra of the powdered samples magnetically separated from claystones, the Moessbauer analyses were performed. Relative abundances of various magnetic and non-magnetic Fe[sup 2+] and Fe[sup 3+] species led to the identification of the two magnetic iron sites in greigite in accordance with its spinel structure having mutually near effective magnetic inductions of 32.1 and 31.3 T, respectively. In addition, three pyrrhotite and two magnetite magnetic sites plus probably two pyrite and/or arsenopyrite iron positions were identified, of which some have been reported in the literature as the greigite iron contributions. (orig.)

  11. Moessbauer study of the phase distribution of Fe{sub 78-x}Al{sub x}Si{sub 9}B{sub 13} powder

    Energy Technology Data Exchange (ETDEWEB)

    Jesus, D.R. de E-mail: denis@macbeth.if.usp.br; Partiti, C.S.M

    2001-05-01

    In this work, by using X-ray diffraction, magnetization and Moessbauer measurements, magnetic and structural properties of Fe{sub 78-x}Al{sub x}Si{sub 9}B{sub 13} (x=10, 20, 30) have been studied. These three sets of specimens in nominal composition Fe{sub 78-x}Al{sub x}Si{sub 9}B{sub 13} were produced by mechanically processing blended Fe, Al, B and Si powders, using different times in the range from 2 up to 300 h. Moessbauer spectra show a strong line broadening and were fitted by considering Gaussian distributions of hyperfine fields. The crystalline phase present in the spectra was identified as {alpha}-Fe. Magnetic hyperfine data are discussed in conjunction with X-ray diffraction and magnetic measurements.

  12. Moessbauer Studies of Fe{sub 0.7-x}Si{sub 0.3}Mn{sub x} Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Al-Omari, I. A., E-mail: ialomari@yahoo.com; Gismelseed, A.; Rais, A.; Widatallah, H. M.; Al Rawas, A.; Elzain, M.; Yousif, A. A. [Sultan Qaboos University, Department of Physics (Oman)

    2004-12-15

    In this work we present Fe{sup 57} Moessbauer study for the alloy system Fe{sub 0.7-x}Si{sub 0.3}Mn{sub x}, where 0{<=}x{<=}0.3. Moessbauer spectroscopic results show that all the samples studied are magnetically ordered at 77 K, and at room temperature, except for x=0.3 at 300 K where it shows paramagnetic behavior. The average magnetic hyperfine field is found to decrease with increasing the manganese concentration at 77 K and 300 K. The average magnetic hyperfine field is found to increase with decreasing the temperature from 300 K to 77 K for all samples under investigation. The average isomer shift is found to decrease with increasing the manganese concentration.

  13. Moessbauer spectrometry and X-ray diffraction studies of the Fe sub 8 sub 7 Zr sub 6 B sub 6 Cu sub 1 nanocrystallization process

    CERN Document Server

    Bibicu, I; Plazaola, F; Apinaniz, E

    2001-01-01

    Fe sub 8 sub 7 Zr sub 6 B sub 6 Cu sub 1 amorphous ribbon were obtained by the melt spinning technique under a controlled atmosphere. One-hour isothermal treatments at different temperatures were performed in a differential thermal analyzer apparatus in an Ar atmosphere. The Conversion Electron Moessbauer Spectrometry (CEMS) and X-ray diffraction measurements of the Fe sub 8 sub 7 Zr sub 6 B sub 6 Cu sub 1 sample in different steps of the nanocrystallization process have been performed. The results have been compared with those obtained by means of Transmission Moessbauer Spectrometry (TMS) technique. The X-ray diffraction patterns and CEMS spectra of the studied samples present systematically higher crystallized fractions than those corresponding to spectra obtained by transmission geometry. As these techniques offer us information about different regions of the sample, the differences among the obtained results have been related to an inhomogenization of the crystallization process into the sample induced b...

  14. Oxide transformation during preparation of black pottery in Hungary

    International Nuclear Information System (INIS)

    Traditional black pottery produced in Nadudvar, E-Hungary, was studied by 57Fe Moessbauer spectroscopy, X-ray diffractometry and microscopy. Quartz, feldspar, clay minerals (kaolinite, smectite, illite) and calcite were identified in the basic clay material by X-ray diffractometry (XRD). Moessbauer spectroscopy (MS) of the original clay revealed that about 35% of iron compounds were present in goethite while the rest in clay minerals (illite and smectite). After firing the clay in air using an electric furnace (red pottery is prepared in the same way), the Moessbauer spectra showed hematite as the only iron oxide or hydroxide phase, being in good agreement with X-ray diffractometry. In the black product itself, fired in the traditional open-flame furnace, the Moessbauer spectra reflected the presence of iron in magnetite and in sheet silicates with approximately the same relative ratio of oxides and silicates as in the starting material. This can be interpreted as a result of the transformation of goethite to hematite in the first step of firing (in air), and as a reduction of hematite to magnetite in the second step of firing (closed from air). A significant difference was found in the distribution of iron at the Fe2+ and Fe3+ cation sites in the black surface (more Fe2+) and at the dark gray bulk of the fired pottery (less Fe2+), showing that the reduction of Fe3+ occurs in the silicates instead of further reduction of the magnetite (e.g., to wuestite). (author)

  15. Rayleigh Scattering of Moessbauer Radiation (RSMR) data, hydration effects and glass-like dynamical model of biopolymers

    Energy Technology Data Exchange (ETDEWEB)

    Gol' danskii, V.I.; Krupyanskii, Yu.F.; Fleurov, V.N.

    1986-06-01

    Specific features of the Rayleigh Scattering of Moessbauer Radiation (RSMR) technique in the study of biological systems are described. Experimental data show that the temperature and hydration degree are the principal parameters which influence intramolecular mobility in biopolymers. Data on temperature dependencies of elastic fraction, f, and spectrum line-shape do not fit neither Debye or Einstein models of solids nor the free diffusion in liquids and demand for their explanation a multimode approximation (i.e. a wide spectrum of correlation times, at T=293 K from 10/sup -6/s to 10/sup -12/-10/sup -13/s). On the basis of RSMR, low temperature specific heat and X-ray dynamic analysis data and from the general conditions that information macromolecule must be in a non-equilibrium state (an independent confirmation of this fact comes from the kinetic model of protein folding) a glass-like dynamical model of biopolymers is formulated. A possible interpretation of RSMR data shows that fluctuatively prepared tunneling between quasiequilibrium positions (QEP) can prevail activated transitions up to a room temperature.

  16. Mechanosynthesis of supersaturated solid solutions of Sn in near-equiatomic bcc FeCo

    Energy Technology Data Exchange (ETDEWEB)

    Loureiro, J.M. [CEMDRX, Physics Department, University of Coimbra, P-3004-516 Coimbra (Portugal); Costa, B.F.O., E-mail: benilde@ci.uc.pt [CEMDRX, Physics Department, University of Coimbra, P-3004-516 Coimbra (Portugal); Le Caeer, G. [IPR, UMR URI-CNRS 6251, Universite de Rennes I, Campus de Beaulieu, Bat 11A, F-35042 Rennes Cedex (France)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer (Fe{sub 50-x/2}Co{sub 50-x/2})Sn{sub x} mixtures are mechanically alloyed for x {<=} 33 at.%. Black-Right-Pointing-Pointer As-ground powders are studied by X-ray diffraction and {sup 57}Fe and {sup 119}Sn Moessbauer spectroscopy. Black-Right-Pointing-Pointer Supersaturated solutions of Sn in disordered bcc FeCo alloys are formed in our dynamical conditions up to x {<=} 20 at.%. Black-Right-Pointing-Pointer This maximum Sn solubility found is much larger than the equilibrium solubility which is about 0.5 at.%. Black-Right-Pointing-Pointer The mean {sup 119}Sn hyperfine field in the bcc alloys is essentially constant with x and equal to 9.6 T at room temperature. - Abstract: The mechanosynthesis of Fe-Co-Sn ternary alloys from initial powder mixtures of composition (Fe{sub 50-x/2}Co{sub 50-x/2})Sn{sub x} is studied for x {<=} 33 at.%. Disordered nanocrystalline bcc solid solutions are formed in that way up to Sn contents as large as {approx}20 at.%. The dissolution of Sn in near-equiatomic bcc Fe-Co is unambiguously proven by X-ray diffraction and {sup 57}Fe and {sup 119}Sn Moessbauer spectroscopy.

  17. Preparation and characterisation of electrodeposited amorphous Sn-Co-Fe ternary alloys

    International Nuclear Information System (INIS)

    Electrochemical deposition was investigated as a process to obtain alloys of Sn-Co-Fe, which to date have not been reported in the literature. A constant current technique was used to electrochemically deposit tin-cobalt-iron alloys from a gluconate electrolyte. The gluconate system was chosen as an electrolyte, which could potentially provide an environmentally safe process. The effect of plating parameters such as current density, deposition time, temperature and pH are discussed. Results are reported for current density and plating time using an electrolyte temperature of 20-60 deg. C and pH of 7.0 in relation to phase composition, crystal structure and magnetic anisotropy of the deposited alloys. Investigations were conducted using 57Fe conversion electron Moessbauer spectroscopy (CEMS), 119Sn CEMS, transmission Moessbauer Spectroscopy and XRD. The 57Fe and 119Sn CEMS spectra and XRD showed that the dominant phase in the deposits was amorphous Sn-Co-Fe. The relative area of the 2nd and 5th lines of the sextets representing the magnetic iron containing phases was found to decrease continuously with increasing current density while at the same time no significant changes in the magnetic anisotropy was found with plating time. Magnetically split 119Sn spectra reflecting a transferred hyperfine field were also observed. A range of good quality amorphous Sn-Co-Fe ternary alloys was obtained over a range of operating conditions from an environmentally acceptable gluconate electrolyte

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

    Science.gov (United States)

    Munayco, P.; Scorzelli, R. B.

    2013-08-01

    Here we report on a study of samples from fragments of Marajoara ceramics using 57Fe Mössbauer spectroscopy and XRD. The Mössbauer spectra were measured at room temperature (RT) and at liquid helium temperature (4.2 K). Despite a certain variability of the Mössbauer spectra, dominant features could be established, which allowed the samples to be classified into characteristic types (Möss-types) according to their Mössbauer patterns. The different Möss-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.

  19. Test for the influence of relaxation on Moessbauer spectra of (Fe[sub 0. 65]Ni[sub 0. 35])[sub 1-x]Mn[sub x] alloys by the sharpening method

    Energy Technology Data Exchange (ETDEWEB)

    Tsymbal, E.Yu. (Inst. fuer Festkoerperforschung, Forschungszentrum Juelich (KFA) (Germany)); Afanas' ev, A.M. (Inst. of Physics and Technology, Russian Academy of Sciences, Moscow (Russian Federation)); Fricke, M. (Inst. fuer Metallphysik und Nukleare Festkoerperphysik, Technische Univ. Braunschweig (Germany)); Hesse, J. (Inst. fuer Metallphysik und Nukleare Festkoerperphysik, Technische Univ. Braunschweig (Germany))

    1994-11-01

    A mathematical procedure which gives an opportunity to distinguish between relaxation and static mechanisms of the Moessbauer line broadening is developed. It is based on the method of Moessbauer line sharpening developed recently and allows one to answer unambiguously the question whether or not relaxation manifests itself in Moessbauer measurements by examinign the wings of the spectrum. The procedure was applied to the spectra of (Fe[sub 0.65]Ni[sub 0.35])[sub 1-x]Mn[sub x] alloys with x = 0 (INVAR) and x = 0.047, where the mechanism of the line broadening has not been clarified so far. An analysis of the spectra shows that in the temperature range 4 to 300 K no relaxation is observed and the line broadening is mainly caused by the distributions of magnetic hyperfine fields. (orig.)

  20. Terahertz spectroscopy

    DEFF Research Database (Denmark)

    Jepsen, Peter Uhd

    2009-01-01

    In this presentation I will review methods for spectroscopy in the THz range, with special emphasis on the practical implementation of the technique known ad THz time-domain spectroscopy (THz-TDS). THz-TDS has revived the old field of far-infrared spectroscopy, and enabled a wealth of new...... activities that promise commercial potential for spectroscopic applications in the THz range. This will be illustrated with examples of spectroscopy of liquids inside their bottles as well as sensitive, quantitative spectroscopy in waveguides....

  1. A {sup 119}Sn Moessbauer Study of Tin(IV) Complexes of 2- and 4-Benzoylpyridine Thiosemicarbazone and 4-Benzoylpyridine Semicarbazone

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Rebolledo, Anayive [Universidade Federal de Minas Gerais, Departamento de Quimica (Brazil); Ardisson, Jose D., E-mail: jdr@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear, Laboratorio de Fisica Aplicada (LFA/CDTN) (Brazil); Lima, Geraldo M. de [Universidade Federal de Minas Gerais, Departamento de Quimica (Brazil); Macedo, Waldemar A. A. [Centro de Desenvolvimento da Tecnologia Nuclear, Laboratorio de Fisica Aplicada (LFA/CDTN) (Brazil); Beraldo, Heloisa, E-mail: hberaldo@ufmg.br [Universidade Federal de Minas Gerais, Departamento de Quimica (Brazil)

    2005-06-15

    A {sup 119}Sn Moessbauer study was carried out of tin(IV) complexes with 2-benzoylpyridine thiosemicarbazone (H2Bz4DH) and its N(4)-methyl (H2Bz4M) and N(4)-phenyl (H2Bz4Ph) derivatives: [Sn(2Bz4DH)Cl{sub 3}] (1), [Sn(2Bz4DH)PhCl{sub 2}] (2), [Sn(2Bz4M)Cl{sub 3}] (3), [H{sub 2}2Bz4M]{sub 2}[Ph{sub 2}SnCl{sub 4}] (4), [Sn(2Bz4Ph)PhCl{sub 2}] (5), [Sn(2Bz4Ph)Ph{sub 2}Cl] (6), in which H2Bz4R stands for the neutral ligand and 2Bz4R stands for the anionic thiosemicarbazone. In addition, {sup 119}Sn Moessbauer studies of the tin(IV) complexes [Sn(H4Bz4DH){sub 2}Cl{sub 4}H{sub 2}O] (7), [Sn(H4BzPS){sub 2}Cl{sub 4}H{sub 2}O] (8) with 4-benzoylpyridine thiosemicarbazone (H4Bz4DH) and the correspondent semicarbazone (H4BzPS) were performed. The isomer shifts decrease upon coordination due to the variation in the percentage of s character as tin changes from approximately sp{sup 3} hybridization in the tin salts to sp{sup 3}d{sup 2} in the octahedral or sp{sup 3}d{sup 3} in the heptahedral complexes. The Moessbauer parameters of compound (4) showed the existence of two tin(IV) sites, which have been attributed to the presence of the cis and trans isomers.

  2. Anomalous broadening of the Moessbauer spectrum lines of oxygen-depleted HTSC ceramic YBa2(Cu(1-x)Fe(x))3O(y) in the structural transition region

    Energy Technology Data Exchange (ETDEWEB)

    Chuev, M.A.; Cherepanov, V.M.; Iakimov, S.S.; Tsymbal, E.IU.; Bush, A.A.; Sauer, CH.; Zinn, W. (Inst. Atomnoi Energii, Moscow (Russian Federation) Inst. Radiotekhniki, Elektroniki i Avtomatiki, Moscow (Russian Federation) Forschungszentrum Juelich GmbH (Germany))

    1992-07-01

    A sharp peak in the temperature dependence of the width of the Moessbauer spectrum lines of Fe-57 nuclei has been detected in the superconducting ceramic YBa2(Cu(0.983)Fe(0.017))3O(6.8) at around 110 K. In view of the Lorentz nature of the observed line broadening, it is suggested that the characteristic charge fluctuation frequency of the nearest oxygen neighbors of the Fe impurity atoms in Cu(1) positions corresponds to the Moessbauer time window (10 exp 7 - 10 exp 9/s) in the temperature range 140-90 K. 7 refs.

  3. Moessbauer and magnetoelastic investigations of the surface effects in Fe72Cu1.5Nb4Si13.5B9 nanocrystalline alloy

    International Nuclear Information System (INIS)

    An existence of effects connected with the surface of grains in nanocrystalline FINEMET-like Fe72Cu1.5Nb4Si13.5B9 alloy was verified by investigation of hyperfine and magnetoelastic properties. In the Moessbauer spectra (collected both at room temperature and close to Tc of amorphous matrix) a broad, high field component was found, which could be attributed to the grains surface and interface region. Such interpretation is confirmed in magnetostrictive experiment pointing to a high value of surface magnetostriction constant

  4. Iron Doped SBA-15 Mesoporous Silica Studied by Mössbauer Spectroscopy

    Directory of Open Access Journals (Sweden)

    Łukasz Laskowski

    2016-01-01

    Full Text Available Mesoporous silica SBA-15 containing propyl-iron-phosphonate groups were considered to confirm their molecular structure. To detect the iron-containing group configuration the Mössbauer spectroscopy was used. Both mesoporous silica SBA-15 containing propyl-iron-phosphonate groups and pure doping agent (iron acetylacetate were investigated using Mössbauer spectroscopy. The parameters such as isomer shift, quadrupole splitting, and asymmetry in 57Fe Mössbauer spectra were analyzed. The differences in Mössbauer spectra were explained assuming different local surroundings of Fe nuclei. On this base we were able to conclude about activation of phosphonate units by iron ions and determinate the oxidation state of the metal ion. To examine bonding between iron atoms and phosphonic units the resonance Raman spectroscopy was applied. The density functional theory (DFT approach was used to make adequate calculations. The distribution of active units inside silica matrix was estimated by comparison of calculated vibrational spectra with the experimental ones. Analysis of both Mössbauer and resonance Raman spectra seems to confirm the correctness of the synthesis procedure. Also EDX elemental analysis confirms our conclusions.

  5. Chemical spectroscopy

    International Nuclear Information System (INIS)

    The purpose of chemical spectroscopy with neutrons is to utilize the dependence of neutron scattering cross-sections on isotope and on momentum transfer (which probes the spatial extent of the excitation) to understand fundamental and applied aspects of the dynamics of molecules and fluids. Chemical spectroscopy is divided into three energy ranges: vibrational spectroscopy, 25-500 MeV, for which much of the work is done on Be-filter analyzer instruments; low energy spectroscopy, less than 25 MeV; and high resolution spectroscopy, less than 1 MeV, which typically is performed on backscattering spectrometers. Representative examples of measurements of the Q-depenence of vibrational spectra, higher energy resolution as well as extension of the Q-range to lower values at high energy transfers, and provisions of higher sensitivities in vibrational spectroscopy are discussed. High resolution, high sensitivity, and polarization analysis studies in low energy spectroscopy are discussed. Applications of very high resolution spectroscopy are also discussed

  6. Laser spectroscopy

    CERN Document Server

    Demtröder, Wolfgang

    Keeping abreast of the latest techniques and applications, this new edition of the standard reference and graduate text on laser spectroscopy has been completely revised and expanded. While the general concept is unchanged, the new edition features a broad array of new material, e.g., ultrafast lasers (atto- and femto-second lasers) and parametric oscillators, coherent matter waves, Doppler-free Fourier spectroscopy with optical frequency combs, interference spectroscopy, quantum optics, the interferometric detection of gravitational waves and still more applications in chemical analysis, medical diagnostics, and engineering.

  7. Dynamics of Rhodobacter capsulatus [2Fe-2S] Ferredoxin VI and Aquifex aeolicus Ferredoxin 5 Via Nuclear Resonance Vibrational Spectroscopy (NRVS) and Resonance Raman Spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Yuming; Tan, Ming-Liang; Ichiye, Toshiko; Wang, Hongxin; Guo, Yisong; Smith, Matt C.; Meyer, Jacques; Sturhahn, Wolfgang; Alp, E. E.; Zhao, Jiyong; Yoda, Yoshitaka; Cramer, Stephen P.

    2008-06-24

    We have used (57)Fe nuclear resonance vibrational spectroscopy (NRVS) to study the Fe(2)S(2)(Cys)(4) sites in oxidized and reduced [2Fe-2S] ferredoxins from Rhodobacter capsulatus (Rc FdVI) and Aquifex aeolicus (Aa Fd5). In the oxidized forms, nearly identical NRVS patterns are observed, with strong bands from Fe-S stretching modes peaking around 335 cm(-1), and additional features observed as high as the B(2u) mode at approximately 421 cm(-1). Both forms of Rc FdVI have also been investigated by resonance Raman (RR) spectroscopy. There is good correspondence between NRVS and Raman frequencies, but because of different selection rules, intensities vary dramatically between the two kinds of spectra. For example, the B(3u) mode at approximately 288 cm(-1), attributed to an asymmetric combination of the two FeS(4) breathing modes, is often the strongest resonance Raman feature. In contrast, it is nearly invisible in the NRVS, as there is almost no Fe motion in such FeS(4) breathing. NRVS and RR analysis of isotope shifts with (36)S-substituted into bridging S(2-) ions in Rc FdVI allowed quantitation of S(2-) motion in different normal modes. We observed the symmetric Fe-Fe stretching mode at approximately 190 cm(-1) in both NRVS and RR spectra. At still lower energies, the NRVS presents a complex envelope of bending, torsion, and protein modes, with a maximum at 78 cm(-1). The (57)Fe partial vibrational densities of states (PVDOS) were interpreted by normal-mode analysis with optimization of Urey-Bradley force fields. Progressively more complex D(2h) Fe(2)S(2)S'(4), C(2h) Fe(2)S(2)(SCC)(4), and C(1) Fe(2)S(2)(Cys)(4) models were optimized by comparison with the experimental spectra. After modification of the CHARMM22 all-atom force field by the addition of refined Fe-S force constants, a simulation employing the complete protein structure was used to reproduce the PVDOS, with better results in the low frequency protein mode region. This process was then repeated

  8. Moessbauer effect and X-ray distribution function analysis in complex Na{sub 2}O-CaO-ZnO-Fe{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-SiO{sub 2} glasses and glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Romero, M.; Rincon, J.M.; Musik, S.; Kozhukharov, V.

    1999-05-01

    Moessbauer spectroscopy at room temperature was carried out to determine the state of iron ions in complex glasses and glass-ceramics in the SiO{sub 2}-CaO-ZnO-Na{sub 2}O-Fe{sub 2}O{sub 3}-Al{sub 2}O{sub 3} system. Isomer shift values of the glasses suggest that Fe{sup 3+} and Fe{sup 2+} are in tetrahedral and octahedral coordination, respectively. The spectrum of the glass-ceramic shows that about 60 wt% total iron is in the magnetite phase. The Fe{sup +3}/Fe{sup +2} ratio varies with the total iron oxide content of the glasses, indicating that the vitreous network is more distorted when the iron content is greater. X-ray diffraction measurements were carried out to obtain the radial distribution function (RDF). The interatomic distances for Si-Si and Si-O have been determined. The complex composition of these glasses does not allow the estimation of Al-O and Fe-O distances.

  9. Innovative instrumentation for mineralogical and elemental analyses of solid extraterrestrial surfaces: The Backscatter Moessbauer Spectrometer/X Ray Fluorescence analyzer (BaMS/XRF)

    Science.gov (United States)

    Shelfer, T. D.; Morris, Richard V.; Nguyen, T.; Agresti, D. G.; Wills, E. L.

    1994-01-01

    We have developed a four-detector research-grade backscatter Moessbauer spectrometer (BaMS) instrument with low resolution x-ray fluorescence analysis (XRF) capability. A flight-qualified instrument based on this design would be suitable for use on missions to the surfaces of solid solar-system objects (Moon, Mars, asteroids, etc.). Target specifications for the flight instrument are as follows: mass less than 500 g; volumes less than 300 cu cm; and power less than 2 W. The BaMS/XRF instrument would provide data on the oxidation state of iron and its distribution among iron-bearing mineralogies and elemental composition information. This data is a primary concern for the characterization of extraterrestrial surface materials.

  10. A Moessbauer investigation of non-bridging oxygens in Na2O-Fe2O3-B2O3 glasses

    International Nuclear Information System (INIS)

    Moessbauer measurements of sodium borate glasses 4Fe2O3 . xNa2O . (96-x)B2O3 (x = 6, 10, 15, 20, 25, 30) have been carried out. It was found that Fe3+ is present in both octahedral and tetrahedral sites, whereby the tetrahedral sites are preferred. In the range of Na2O contents higher than about 15 mol%, the isomer shifts and quadrupole splittings for Fe3+ decrease continuously with increasing Na2O concentration. These changes could be attributed to the formation of non-bridging oxygens (NBO) in the neighborhood of ferric ions. Increasing Na2O content thus gives rise to more NBO increasing the symmetry of the iron polyhedra. (Auth.)

  11. Nuclear spectroscopy

    CERN Document Server

    Ajzenberg-Selove, Fay

    1960-01-01

    Nuclear Spectroscopy, Part A deals with the experimental and theoretical techniques involved in nuclear spectroscopy.This book discusses the interactions of charged particles with matter, gaseous ionization detectors, and particular mass attenuation coefficients. The magnetic gamma-ray spectrometers for photo or internal-conversion electrons, general characteristics of cross-section variation with energy, and measurement of fast neutron spectra are also elaborated. This text likewise covers the elastic scattering of photons by nuclei and measurement of widths of gamma-radiating levels.This pub

  12. Optogalvanic spectroscopy

    International Nuclear Information System (INIS)

    Laser induced optogalvanic spectroscopy in a hollow cathode-produced plasma has been used to resolve the isotopic structure of some absorption lines in uranium. We have shown that the optogalvanic signal associated with any isotope can be related to the concentration of that isotope in a multi-isotopic sample. From the results we have obtained, optogalvanic spectroscopy of sputtered samples appears to be an interesting approach to the isotopic analysis of both natural and enriched uranium and could easily be applied to the analysis of other fissile elements, such as the plutonium isotopes

  13. Dynamics of ferrocene in molecular sieves probed by Mossbauer spectroscopy and nuclear resonant scattering

    International Nuclear Information System (INIS)

    A detailed study on the slow dynamics of ferrocene in the unidimensional channels of the molecular sieves SSZ-24 and AlPO4-5 has been carried out, using Moessbauer spectroscopy (MS), nuclear forward scattering (NFS) and synchrotron radiation-based perturbed angular correlations (SRPAC). In both host systems, anisotropic rotational dynamics is observed above 100 K. For SSZ-24, this anisotropy persists even above the bulk melting temperature of ferrocene. Various theoretical models are exploited for the study of anisotropic discrete jump rotations for the first time. The experimental data can be described fairly well by a jump model that involves reorientations of the molecular axis on a cone mantle with an opening angle dependant on temperature.

  14. Bioimpedance Spectroscopy

    DEFF Research Database (Denmark)

    Klösgen, Beate; Rümenapp, Christine; Gleich, Bernhard

    2011-01-01

    causes relaxation processes with characteristic contributions to the frequency-dependent complex dielectric constant. These dipolar relaxations were initially described by Debye (Polare Molekeln 1929). They are the basis of impedance spectroscopy (K’Owino and Sadik Electroanalysis 17(23):2101–2113, 2005...

  15. PLASMA SPECTROSCOPY

    NARCIS (Netherlands)

    Jaspers, R. J. E.

    2010-01-01

    A brief introduction into the spectroscopy of fusion plasmas is presented. Basic principles of the emission of ionic, atomic and molecular radiation is explained and a survey of the effects, which lead to the population of the respective excited levels, is given. Line radiation, continuum radiation,

  16. 50 MeV Li{sup 3+} ion irradiation induced modifications in structural and magnetic properties of Ti{sup 4+}-substituted Li-Al and Li-Cr ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Chhantbar, M. C. [Saurashtra University, Department of Physics (India); Yousif, Ali [Sultan Qaboos University, Department of Physics (Oman); Kumar, Ravi [Inter University Accelerator Centre (India); Joshi, H. H., E-mail: ferrites@rediffmail.com [Saurashtra University, Department of Physics (India)

    2008-06-15

    Using 50 MeV Li{sup 3+} ion irradiation, the change induced in polycrystalline ferrites Li{sub 0.5(1+x)}Ti{sub x}Al{sub 0.1}Fe{sub 2.4-1.5x}O{sub 4} (x = 0.0 to 0.3, step-0.1)[LTAF] and Li{sub 0.5(1+x)}Ti{sub x}Cr{sub 0.1}Fe{sub 2.4-1.5x}O{sub 4} (x = 0.0 to 0.3, step-0.1; LTCF) in the electronic stopping power regime is studied. Both the systems were irradiated with the same fluence of 5 x 10{sup 13} ions/cm{sup 2}. The modifications of the structural and magnetic properties are studied by means of X-ray diffraction (XRD), magnetization, {sup 57}Fe Moessbauer spectroscopy and low field a. c. susceptibility. The contrast in the role of Ti{sup 4+} in the presence of Al{sup 3+} and Cr{sup 3+} causing the formation of paramagnetic centres through Swift Heavy Ion Irradiation (SHII) induced cation rearrangement has been revealed through the comparative Moessbauer signatures of both the systems. The hyperfine interaction parameters deduced through Moessbauer spectra are also discussed before and after irradiation. The observed reduction in the saturation magnetic moment and Curie temperature after irradiation supports the partial formation of paramagnetic centres and rearrangement of cations in the lattice.

  17. Optical Spectroscopy

    DEFF Research Database (Denmark)

    Thyrhaug, Erling

    containing systems using simple instrumentation and well-known and understood theoretical concepts. Overall it is attempted to achieve this goal by presenting five research projects that I have been involved in during my Ph.D. studies which collectively demonstrate some of the many possibilities of gaining...... containing systems and are characterized using techniques in optical spectroscopy. Of the standard techniques in optical spectroscopy, particular attention has been paid to those based on time-resolved measurements and polarization, which is reflected in the experiment design in the projects. Not all...... solution. In project 2 the intramolecular excited state association reaction between aniline and anthracene is characterized by both steady-state and time-resolved techniques, where the time resolved fluorescence measurements in particular allowed for the determination of the reaction rate constants...

  18. Moessbauer study on the CMR double perovskite AFe0.5Mo0.5O3 with A = (Ba,Sr) or (Sr,Ca). Chemical pressure effect

    International Nuclear Information System (INIS)

    The double perovskites, AFe0.5Mo0.5O3 with A = (Ba,Sr) or (Sr,Ca), were prepared by a sol-gel method, and the substitution effect at site A was studied by Moessbauer spectrometry. In the Moessbauer spectra of the double perovskite (Ba, Sr)Fe0.5Mo0.5O3, the isomer shifts decreased from δ = 0.72 mm/s to δ = 0.4 mm/s and the internal magnetic fields increased with the increase of the Sr content. The Ba-rich samples were shown to contain superparamagnetic components under the same preparation conditions. Better crystallinity and larger hyperfine fields were obtained when 5% of the Sr-content of SrFe0.5Mo0.5O3 was substituted by Ca as compared with substitution by Ba. Phonon density of states (DOS) of SrFe0.5Mo0.5O3 substituted with Ca or Ba were obtained by nuclear inelastic scattering. The peaks of phonon DOS were shifted, depending on chemical compression/expansion of the lattice. The chemical pressure effect could be observed in the Moessbauer spectra and the phonon DOS spectra. (author)

  19. Laser spectroscopy

    CERN Document Server

    Demtröder, Wolfgang

    2008-01-01

    Keeping abreast of the latest techniques and applications, this new edition of the standard reference and graduate text on laser spectroscopy has been completely revised and expanded. While the general concept is unchanged, the new edition features a broad array of new material, e.g., frequency doubling in external cavities, reliable cw-parametric oscillators, tunable narrow-band UV sources, more sensitive detection techniques, tunable femtosecond and sub-femtosecond lasers (X-ray region and the attosecond range), control of atomic and molecular excitations, frequency combs able to synchronize independent femtosecond lasers, coherent matter waves, and still more applications in chemical analysis, medical diagnostics, and engineering.

  20. Characterization of transition metal-containing oxide systems by Mössbauer Spectroscopy

    Directory of Open Access Journals (Sweden)

    Z. Homonnay

    2004-12-01

    Full Text Available High-temperature (high-Tc superconductors and colossal magnetoresistant (CMR materials belong to the most promising materials of the past 2-3 decades for technical applications. Most of them are oxides and the crucial element which determines their useful physical properties is often a transition metal (Cu, Co, Fe, Mn. 57Fe Mössbauer Spectroscopy can be used to characterize the electronic and structural properties of transition metal-containing oxides by providing information on the local electronic structure of the lattice site where the Mössbauer probe is accommodated. By reviewing several Mössbauer studies, it is demonstrated how the layered (2D electronic structure of high-Tc superconductors can be deduced from the analysis of the Mössbauer isomer shift and quadrupole splitting. We also show how the Mössbauer isomer shift indicates metallicity of the ferromagnetic phase in the CMR material LaxSr1-xCoO3.

  1. Moessbauer studies of single crystal Pr sub 1 sub / sub 3 Sr sub 2 sub / sub 3 FeO sub 3

    CERN Document Server

    Uhm, Y R; Kim, C S; Tomioka, Y; Tokura, Y

    2000-01-01

    Single crystal Pr sub 1 sub / sub 3 Sr sub 2 sub / sub 3 FeO sub 3 was synthesized by using the floating zone method and the relation of magnetic properties and charge ordering transition with lattice dynamics was systematically investigated. Moessbauer spectra of Pr sub 1 sub / sub 3 sub S r sub 2 sub / sub 3 FeO sub 3 were taken at various temperatures ranging from 20 K to room temperature. The charge disproportionation, in which iron with valence states Fe sup 3 sup + and Fe sup 5 sup + was found in a ratio of 2:1, was detected in Pr sub 1 sub / sub 3 Sr sub 2 sub / sub 3 FeO sub 3 below 190+-3 K. Iron with valence state Fe sup 4 sup + coexisted in Pr sub 1 sub / sub 3 sub S r sub 2 sub / sub 3 FeO sub 3 at and above 150 K, and its ratio increased from 13 to 66 % with increasing temperature. This result means that charge-ordered and -disordered phases co-exist in Pr sub 1 sub / sub 3 Sr sub 2 sub / sub 3 FeO sub 3.

  2. Moessbauer and magnetic studies of the ternary compound FeIn{sub 2}Se{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Bodnar, I. V., E-mail: chemzav@bsuir.by; Pauliukavets, S. A. [Belarussian State University of Informatics and Radioelectronics (Belarus); Trukhanov, S. V. [National Academy of Sciences of Belarus, Scientific-Practical Materials Research Center (Belarus); Fedotova, Yu. A. [Belarus State University (Belarus)

    2012-05-15

    Single crystals of the ternary compound FeIn{sub 2}Se{sub 4} are grown by directional crystallization of the melt. The composition and structure of the single crystals are determined. The local states of iron ions in this compound are studied by nuclear {gamma}-resonance spectroscopy in transmission configuration. The temperature and field dependences of a specific magnetic moment for the ternary compound FeIn{sub 2}Se{sub 4} are measured in the temperature range 4-310 K in magnetic fields of 0-140 kOe. The reasons and mechanisms for magnetic state formation in single crystals of the obtained compound are discussed.

  3. Superparamagnetic bimetallic iron-palladium nanoalloy: synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Nazir, Rabia; Mazhar, Muhammad [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Akhtar, M Javed; Nadeem, M; Siddique, Muhammad [Physics Division, PINSTECH, PO Nilore, Islamabad 44000 (Pakistan); Shah, M Raza [HEJ Research Institute of Chemistry, University of Karachi, Karachi 75270 (Pakistan); Khan, Nawazish A [Material Science Laboratory, Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Mehmood, Mazhar [National Centre for Nanotechnology, PIEAS, Islamabad 45650 (Pakistan); Butt, N M [Pakistan Science Foundation, Islamabad 44000 (Pakistan)], E-mail: mazhar42pk@yahoo.com

    2008-05-07

    Iron-palladium nanoalloy in the particle size range of 15-30 nm is synthesized by the relatively low temperature thermal decomposition of coprecipitated [Fe(Bipy){sub 3}]Cl{sub 2} and [Pd(Bipy){sub 3}]Cl{sub 2} in an inert ambient of dry argon gas. The silvery black Fe-Pd alloy nanoparticles are air-stable and have been characterized by EDX-RF, XRD, AFM, TEM, magnetometry, {sup 57}Fe Moessbauer and impedance spectroscopy. This Fe-Pd nanoalloy is in single phase and contains iron sites having up to 11 nearest-neighboring atoms. It is superparamagnetic in nature with high magnetic susceptibility, low coercivity and hyperfine field.

  4. Induced magnetic moment on Rh in the (Fe{sub x}Rh{sub 1-x}){sub 100-y}B{sub y} amorphous system

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, Sarbari; Paulose, P.L. E-mail: paulose@tifr.res.in

    2003-01-01

    The magnetic properties of the (FeRh){sub 100-y}B{sub y}(y=20,25) amorphous system have been investigated by AC susceptibility, DC magnetization and {sup 57}Fe Moessbauer spectroscopy. The experimental data give strong evidence for the presence of a sizable moment on Rh. Our data suggest that the moment on Rh evolves discontinuously, existing only when it has at least four Fe nearest neighbours. While the condition for the appearance of the moment on Rh is identical in both the a-(FeRh){sub 75}B{sub 25} and a-(FeRh){sub 80}B{sub 20} systems, the magnitude of the induced moment decreases despite an enhancement in the average ferromagnetic exchange in the Boron-rich system. We show that the induced Rh moment is correlated to the Fe-Rh exchange and there are indications of induced moment on Rh even in the paramagnetic state.

  5. Distribution of inorganic and organic substances in the hydrocyclone separated Slovak sub-bituminous coal

    Energy Technology Data Exchange (ETDEWEB)

    Anton Zubrik; Slavomir Hredzak; Ludmila Turcaniova; Michal Lovas; Ingo Bergmann; Klaus Dieter Becker; Maria Lukcova; Vladimir Sepelak [Slovak Academy of Sciences, Kosice (Slovakia). Institute of Geotechnics

    2010-08-15

    A low-rank Slovak sub-bituminous coal from the Handlova deposit was physically treated by washing in a water-only cyclone with the goal to find the separation effect for inorganic (mainly Fe-bearing minerals) and organic substances (humic acids, diterpanes). A high-quality coal product with the ash content in the dry matter of 9.02% and carbon content of C{sup d} = 68.12% at a mass yield of 29.51% was obtained using the water-only cyclone processing. At first, the physically treated coal samples were detailed characterized by XRD, {sup 57}Fe Moessbauer spectroscopy, FT-IR and HR-TEM. In addition to non-crystalline organic coal components, inorganic compounds belonging to silicate minerals (kaolinite, muscovite and quartz) as well as to Fe-bearing sulphide minerals (pyrite) were identified in the sub-bituminous coal by XRD. {sup 57}Fe Moessbauer spectroscopy detected the presence of iron carbonate (siderite), iron-containing clay mineral and two sulphur-containing minerals (pyrite, jarosite) in the untreated coal. On the other hand, only one Fe-bearing mineral, (pyrite) was found in the washed coal. Effect of the physical separation is also demonstrated in FT-IR spectra, where the peak at 1040 cm{sup -1} representing the silicate component in the untreated sample is not detectable in the washed coal sample. Presence of extractive organic substances, i.e. humic acids and tetracyclic diterpane (16a(H)-phyllocladane), in the hydrocyclone products is also evidenced. It was confirmed that the isolated diterpenoic compound is attendant in the washed product with the lowest ash content and it is assimilated with the organic part of coal. Surprisingly, humic acids were found in the highest concentration in the slurry that has the highest content of ash (63.14%). 54 refs., 8 figs., 5 tabs.

  6. Planetary spectroscopy

    International Nuclear Information System (INIS)

    The main goal of the research is charge coupled device (CCD) spectroscopic and imaging studies of the solar system in support of spacecraft investigations. Studies include the physical behavior of comets, the atmosphere of the gaseous planets, and the solid surfaces of satellites and asteroids. The major observing program consisted of approximately 50 nights of photometry of Comet Halley in order to resolve the controversy over this comet's rotation period. This data is presently being analyzed. Additional observing projects included the spectroscopic occultation of Charon by Pluto, reflection spectroscopy of Mercury, and a spectrum of the satellite Oberon. Mercury data does not corroborate the Fe(++) absorption feature reported by McCord and Clark at 8800 A but instead potentially shows a weaker feature at longer wavelengths. This position is in much closer accord with expectations for Mercury since a band center near 8800 A implies too little Fe(++) on Mercury, especially if band shifts with temperature are considered. The Pluto project proved that the deep methane absorptions visible in their combined specta are due soley to Pluto with Charon showing a flat and featureless spectrum. It appears that if Charon ever contained a substantial methane component, the satellite's low surface gravity could not hold it and the methane evaporated and escaped

  7. MHD Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Heeter, R F; Fasoli, A; Testa, D; Sharapov, S; Berk, H L; Breizman, B; Gondhalekar, A; Mantsinen, M

    2004-03-23

    Experiments are conducted on the JET tokamak to assess the diagnostic potential of MHD active and passive spectroscopy, for the plasma bulk and its suprathermal components, using Alfv{acute e}n Eigenmodes (AEs) excited by external antennas and by energetic particles. The measurements of AE frequencies and mode numbers give information on the bulk plasma. Improved equilibrium reconstruction, in particular in terms of radial profiles of density and safety factor, is possible from the comparison between the antenna driven spectrum and that calculated theoretically. Details of the time evolution of the non-monotonic safety factor profile in advanced scenarios can be reconstructed from the frequency of ICRH-driven energetic particle modes. The plasma effective mass can be inferred from the resonant frequency of externally driven AEs in discharges with similar equilibrium profiles. The stability thresholds and the nonlinear development of the instabilities can give clues on energy and spatial distribution of the fast particle population. The presence of unstable AEs provides lower limits in the energy of ICRH generated fast ion tails. Fast ion pressure gradients and their evolution can be inferred from the stability of AEs at different plasma radial positions. Finally, the details of the AE spectrum in the nonlinear stage can be used to obtain information about the fast particle velocity space diffusion.

  8. Effect of uniaxial tensile stress on the isomer shift of 57Fe in fcc stainless steels

    Science.gov (United States)

    Ratner, E.; Ron, M.

    1982-05-01

    The electron wave-function response to uniaxial tensile stress in fcc steels (SS310 and SS316) was investigated through the isomer shift of the Mössbauer effect. Stresses up to 12 kbar (the ultimate tensile stress is approximately 14 kbar) were applied at room temperature. The isomer shift changes linearly in these circumstances. It is concluded that, as in the case of hydrostatic pressure, the paramount factor here is the volume strain of the wave functions of 4S electrons.

  9. Time-dependent modulation of moessbauer resonance: Experiments on gamma echo and double resonance phenomena. Doctoral thesis

    Energy Technology Data Exchange (ETDEWEB)

    Tittonen, I.

    1992-11-27

    In the present work, temporal aspects of nuclear recoil-free transitions are studied. Some of the results are analogous to those encountered earlier in Nuclear Magnetic Resonance and laser spectroscopy with some special features in the gamma ray regime. The main attention was focused on the interference effects of the classical gamma radiation field of the source and the field developed and emitted by a resonant absorber. The concept of classical phase modulation of gamma radiation was applied to develop a novel gamma echo phenomenon by causing a constructive rather than a destructive interference by a single phase change of the source radiation. When a periodical magnetic modulation was used with a frequency comparable to the natural linewidth, so called transient oscillations were observed. The experimental results were analyzed with high accuracy using the phase modulation theory. By increasing the frequency of the modulating magnetic field even further to match the resonance frequencies of the hyperfine split states, it was possible to establish conditions for another novel phenomenon, the double resonance in the gamma ray regime.

  10. Chiroptical Spectroscopy

    Science.gov (United States)

    Gurst, Jerome E.

    1995-09-01

    A brief review of the literature, and Chemical and Engineering News in particular, reveals that the determination and use of optical activity is of increasing importance in today's commercial and research laboratories. The classical technique is to measure [alpha]D using a manual or recording polarimeter to provide a single value, the specific rotation at 589 nm. A spectropolarimeter can be used to determine optical activity through the UV-Visible spectrum (Optical Rotatory Dispersion [ORD]). At wavelengths far removed from electronic absorption bands, optical activity arises from circular birefringence, or the difference in the refractive index for left- and right-circularly polarized light; i.e., nL - nR does not equal zero for chiral materials. If the optical activity is measured through an absorption band, complex behavior is observed (a Cotton Effect curve). At an absorption band, chiral materials exhibit circular dichroism (CD), or a difference in the absorption of left- and right-circularly polarized light; epsilon L minus epsilon R does not equal zero. If the spectropolarimeter is set for the measurement of CD spectra, one observes what appears to be a UV-Vis spectrum except that some absorption bands are positive while others may be negative. Just as enantiomers have specific rotations that are equal and opposite at 589 nm (sodium D line), rotations are equal and opposite at all wavelengths, and CD measurements are equal and opposite at all wavelengths. Figure 1 shows the ORD curves for the enantiomeric carvones while Figure 2 contains the CD curves. The enantiomer of carvone that has the positive [alpha]D is obtained from caraway seeds and is known to have the S-configuration while the R-enantiomer is found in spearmint oil. Figure 1. ORD of S-(+)- and R-(-)-carvones Figure 2. CD of S-(+)- and R-(-)-carvones While little can be done to correlate stereochemistry with [alpha]D values, chiroptical spectroscopy (ORD and/or CD) often can be used to assign

  11. An evaluation of least-squares fitting methods in XAFS spectroscopy: iron-based SBA-15 catalyst formulations.

    Science.gov (United States)

    Huggins, Frank E; Kim, Dae-Jung; Dunn, Brian C; Eyring, Edward M; Huffman, Gerald P

    2009-06-01

    A detailed comparison has been made of determinations by (57)Fe Mössbauer spectroscopy and four different XAFS spectroscopic methods of %Fe as hematite and ferrihydrite in 11 iron-based SBA-15 catalyst formulations. The four XAFS methods consisted of least-squares fitting of iron XANES, d(XANES)/dE, and EXAFS (k(3)chi and k(2)chi) spectra to the corresponding standard spectra of hematite and ferrihydrite. The comparison showed that, for this particular application, the EXAFS methods were superior to the XANES methods in reproducing the results of the benchmark Mössbauer method in large part because the EXAFS spectra of the two iron-oxide standards were much less correlated than the corresponding XANES spectra. Furthermore, the EXAFS and Mössbauer results could be made completely consistent by inclusion of a factor of 1.3+/-0.05 for the ratio of the Mössbauer recoilless fraction of hematite relative to that of ferrihydrite at room temperature (293K). This difference in recoilless fraction is attributed to the nanoparticle nature of the ferrihydrite compared to the bulk nature of the hematite. Also discussed are possible alternative non-least-squares XAFS methods for determining the iron speciation in this application as well as criteria for deciding whether or not least-squares XANES methods should be applied for the determination of element speciation in unknown materials. PMID:19185532

  12. Search for canted spin arrangement in Er2−xTbxFe14B with Mössbauer spectroscopy

    Directory of Open Access Journals (Sweden)

    Kurzydło Piotr M.

    2015-03-01

    Full Text Available The materials studied were polycrystalline compounds Er2−xTbxFe14B (x = 0.1, 0.2, 0.3, 0.4 which crystallize in a tetragonal lattice and display a variety of spin arrangements. The compounds have been measured with 57Fe Mössbauer spectroscopy over the temperature range 80–320 K in order to investigate the spin reorientation processes. Each compound was studied in a wide temperature range, with precise Mössbauer scanning in the vicinity of the transition. The set of spectra obtained for a given compound was analyzed using simultaneous fitting procedure to investigate the influence of the transition on the shape of the spectra. The fitting program was specified to analyze the transition according to the ‘two state model’: spins flip abruptly from initial angle to final arrangement (90° angle. Obtained results suggest that spin reorientation process cannot be described using only the mentioned above model. Additional computer simulations based on the Yamada–Kato model were conducted to determine temperature range and the type of spin alignments in the vicinity of the transition. These theoretical results supported by spectra analysis suggest the existence of intermediate (canted spin arrangements in the studied compounds. The spin arrangement diagram was constructed.

  13. Spectroscopy studies of NiFe2O4 nanosized powders obtained using coconut water

    International Nuclear Information System (INIS)

    High-quality NiFe2O4 nanosized powders were prepared by a new route using a natural proteic solution of coconut water and metal ions. The transition from the superparamagnetic to the ferrimagnetic state was observed with the increase of the heat-treatment temperature from 400 deg. C to 800 deg. C. In this work, Electron Paramagnetic Resonance (EPR), a.c. magnetic susceptibility (χa.c.) measurements, infrared (FT-IR) and Raman spectroscopy have been employed to obtain additional information about the structural evolution of the NiFe2O4 nanoparticles, with the increase of the heat-treatment temperature. The obtained results show that the heat-treatment temperature makes remarkable changes in the structure of the samples. The NiFe2O4 nanocrystallite samples, treated at 1200 deg. C, exhibit a large a.c. magnetic susceptibility which was related with the formation of a mixed spinel phase. This is in agreement with the Moessbauer spectroscopy results. The increase of the volume of the nickel ferrite leads to an increase of the magnetic susceptibility. The magnetic properties of these nanoparticles are clearly size dependent.

  14. Magnetic and Moessbauer study of Mg{sub 0.9}Mn{sub 0.1}Cr{sub x}Fe{sub 2-x}O{sub 4} ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Elzain, M., E-mail: elzain@squ.edu.om; Widatallah, H.; Gismelseed, A.; Bouziane, K.; Yousif, A.; Al Rawas, A.; Al-Omari, I.; Sellai, A. [Sultan Qaboos University, Department of Physics, College of Science (Oman)

    2006-02-15

    The ferrites Mg{sub 0.9}Mn{sub 0.1}Cr{sub x}Fe{sub 2-x}O{sub 4} (0x0.9) were prepared using the conventional double sintering method. The XRD showed that the samples maintain a single spinel cubic phase. The Moessbauer measurements were carried out at room and liquid nitrogen temperatures. From the area ratios of the A and B sites, it was found that the Fe cation population of the A and B sites decreases in proportion to Cr concentration. The contact hyperfine fields at the A and B sites were found to decrease with increasing Cr contents. This was found to be in approximate agreement with the results of magnetization measurement. The distributions of Mg and Mn cations versus Cr concentration were also determined using the Moessbauer and magnetization results. The Curie temperatures were determined and found to agree with the reported values. As the Cr contents increases the relative magnetization, was found to increase at low temperatures and decreases at higher temperatures.

  15. Pseudo-discontinuities in the isomer shift near magnetic transitions

    Energy Technology Data Exchange (ETDEWEB)

    Kolk, B.; Hall, D.B.; Zheng, Y.; Lumetta, J.T. (Boston Univ., MA (USA). Dept. of Physics)

    1983-12-01

    It is shown that a relatively small non-linear behaviour of the velocity drive system used in Moessbauer effect studies yields pseudo-discontinuities in the isomer shift near the critical temperature of a magnetic-paramagnetic transition. The anomaly of the /sup 57/Fe isomer shift in iron is attributed to this effect.

  16. Basic molecular spectroscopy

    CERN Document Server

    Gorry, PA

    1985-01-01

    BASIC Molecular Spectroscopy discusses the utilization of the Beginner's All-purpose Symbolic Instruction Code (BASIC) programming language in molecular spectroscopy. The book is comprised of five chapters that provide an introduction to molecular spectroscopy through programs written in BASIC. The coverage of the text includes rotational spectra, vibrational spectra, and Raman and electronic spectra. The book will be of great use to students who are currently taking a course in molecular spectroscopy.

  17. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    1997-01-01

    This series describes selected advances in the area of atomic spectroscopy. It is primarily intended for the reader who has a background in atmoic spectroscopy; suitable to the novice and expert. Although a widely used and accepted method for metal and non-metal analysis in a variety of complex samples, Advances in Atomic Spectroscopy covers a wide range of materials. Each Chapter will completely cover an area of atomic spectroscopy where rapid development has occurred.

  18. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    1995-01-01

    This series describes selected advances in the area of atomic spectroscopy. It is promarily intended for the reader who has a background in atmoic spectroscopy; suitable to the novice and expert. Although a widely used and accepted method for metal and non-metal analysis in a variety of complex samples, Advances in Atomic Spectroscopy covers a wide range of materials. Each Chapter will completely cover an area of atomic spectroscopy where rapid development has occurred.

  19. Symposium on atomic spectroscopy

    International Nuclear Information System (INIS)

    Topics covered by the conference include: fast beam spectroscopy; astrophysical and other spectra; highly ionized spectroscopy; complex spectra; rydberg levels; fine structure, hyperfine structure and isotope shift; lineshapes; lifetimes, oscillator strengths and Einstein coefficients; and spectroscopy with lasers. Abstracts of the conference papers are presented

  20. Symposium on atomic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    1979-01-01

    Topics covered by the conference include: fast beam spectroscopy; astrophysical and other spectra; highly ionized spectroscopy; complex spectra; rydberg levels; fine structure, hyperfine structure and isotope shift; lineshapes; lifetimes, oscillator strengths and Einstein coefficients; and spectroscopy with lasers. Abstracts of the conference papers are presented. (GHT)