M?ssbauer study of FINEMET type nanocrystalline ribbons irradiated with swift heavy ions

As-quenched and stress field annealed FINEMET ribbons were irradiated with 246?MeV energy Kr, 470?MeV energy Xe and 720?MeV energy Bi ions and investigated by ⁵⁷Fe M?ssbauer spectroscopy and XRD methods. The change in relative areas of the 2nd and 5th lines in the M?ssbauer spectra indicated significant changes in the magnetic anisotropy of both as-quenched and stress annealed FINEMET due to irradiation with swift heavy ions. Differences were observed between the effect of irradiations with various ions having different energy and fluence. The effect of irradiation on the magnetic orientation in FINEMET was explained in terms of radiation induced defects. The swift heavy ion irradiation can be applied to produce FINEMET ribbons with more favorable soft magnetic properties for technological applications.     

Approximation of Mössbauer spectra of metallic glasses

Mössbauer spectra of iron-rich metallic glasses are approximated by means of six broadened lines which have line position relations similar to those of -Fe. It was shown via the results of the DISPA lineshape analysis that each spectral peak is broadened owing to a sum of Lorentzian lines weighted by a Gaussian distribution in the peak position. This paper presents the Mössbauer parameters of amorphous metallic Fe₈₃B₁₇ and Fe₄₀Ni₄₀B₂₀ alloys derived from the fitted spectra.We would like to thank Dr. P. Duhaj for the preparation of amorphous samples.     

Mössbauer and EPR study of nitrosyl hemoglobin

Nitrosyl hemoglobin was prepared by bubbling fresh⁵⁷Fe-enriched rat hemoglobin with NO. S- and X-band EPR spectra at 77 K are typical for anS=1/2 system with an anisotropicg-tensor and exhibit hyperfine interactions of¹⁴N with the electronic spin. Mössbauer spectra at 4.2 and 100 K consist of a superposition of spectra from high- and low-spin Fe(III), deoxygenated hemoglobin and a component corresponding toS=1/2,g=2, hyperfine constantsA _xx /g _{n n} =A _yy /g _{n n} =–19.6 T,A _zz /g _{n n} =6.8 T, quadrupole splitting E _Q=1.5 mm s^–1, isomer shiftI _s=0.42 mm s^–1 and linewidth 0.4 mm s^–1. The spin-lattice relaxation rate at 100 K is <2×10⁶ s^–1.     

Mössbauer study of sediment alteration produced by heat treatment

Pincenvent (France) cooking-place silt-like sediments have been studied by using Mössbauer spectroscopy and characterized by using X-ray diffraction (XRD). The sediments were treated at 400, 600, 800 and 1000°C under oxidizing conditions. We discuss the results and we suggest a Mössbauer thermometer to be used to recognize the temperatures and atmosphere ancient people used in their cooking-places.Fellow of CONICET, Argentina, on leave, Laboratoire d'Ethnologie Prehistorique, 44 Rue de L'Almiral Mouchez, 75014 Paris, France.     

Mössbauer study of Fe-Re alloys prepared by mechanical alloying

The room temperature Mössbauer spectra of ⁵⁷Fe were measured for nanocrystalline iron-based solid solutions Fe _1?x Re _x , prepared by mechanical alloying with x in the range 0.01 ≤ x ≤ 0.04. The obtained data were analysed in terms of the binding energy E _b between two rhenium atoms in the Fe-Re system. The extrapolated value of E _b for x = 0 was used for computation of enthalpy of solution of rhenium in iron. The result was compared with that resulting from the cellular atomic model of alloys by Miedema as well as with value, derived from proper data for Fe-Re solid solutions obtained by melting in an arc furnace. From the comparison it follows that our findings are in agreement with the Miedema’s model predictions and previous Mössbauer studies.     

Mössbauer effect study of Y(Fe0.022 Co0.978)2 at temperatures between 0.15 and 4.2k

A³He-⁴He dilution refrigerator was constructed to perform Mössbauer measurements well below 4.2K. Results are reported here on the pseudobinary Laves-Phase system Y (Fe_1-x Co_x)₂ for x=0.978. We found that at low temperatures, the Fe ions undergo a disordered magnetic phase transition, with a Curie temperature of approximately 4K and a saturation field of 96K0e. The easy axis of magnetization appears to be the [111] direction. This study is an extension to very low temperatures of previous work on the system with 0X0.978.Supported by the NSF Grant No. DMR 73-07665 AO 3     

Mössbauer study of the dynamics of iron ions in bipyramidal positions of strontium hexaferrite

The dynamics of Fe³⁺ ions in bipyramidal 2b positions of a type M hexaferrite are studied on single-crystal and polycrystalline SrFe₆Ga₆O₁₉ samples in the paramagnetic temperature range. We show that when the angle between the c axis of the crystal and the direction of -ray emission varies from 0 to 32 the area under the resonance lines corresponding to Fe³⁺ ions in 2b positions increases by a factor of roughly 1.5. The effect is more pronounced upon passing from a single-crystal sample (=0) to a polycrystalline sample. A comparison of the line intensities under different experimental conditions served as a basis for an evaluation of the difference between the mean-square displacements of the Fe³⁺ ions in 2b positions along the c axis in the perpendicular plane.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 5–8, January, 1991.     

Mössbauer study of EUROFER and VVER steel reactor materials

⁵⁷Fe Mössbauer spectroscopy and X-ray diffractometry were used to study EUROFER or VVER ferritic reactor steels mechanically alloyed with TaC or NbC. Significant changes were found in the Mössbauer spectra and in the corresponding hyperfine field distributions between the ball milled pure steel and that alloyed with TaC or NbC. Spectral differences were also found in the case of use of same carbides with different origin, too. The observed spectral changes as an effect of ball milling of the reactor material steels with carbides can be associated with change in short range order of the constituents of steel.     

Mössbauer and XRD study of intercalated CaFe-layered double hydroxides

N-containing fully saturated (L-prolinate) or aromatic (indole-2-carboxylate) heterocyclic anions were immobilised in CaFe-layered double hydroxide with the dehydration-rehydration method from aqueous ethanol or acetone. The structure of the resulting organic-inorganic hybrids was characterised mainly with powder X-ray diffraction and ⁵⁷Fe Mössbauer spectroscopy, and as supplementary analysis scanning electron microscopy, energy dispersive X-ray spectroscopy with elemental mapping and molecular modelling were also applied. It was found that the solvent mixture used for the synthesis caused enormous difference in the interlayer spacings of the obtained inorganic-organic hybrids.     

Mössbauer and XRD study of hot dip galvanized alloy

Mössbauer spectroscopy has been used to investigate the nature of the Zinc-Iron alloys present within the Hot Dip Galvanized (HDG) layers of steel with a silicon content of 0.35 %. The investigation also studied the impact of the powder coating pretreatment on the nature of the alloy layers. The acid etching process within the pretreatment process in particular would be expected to have a significant impact on the HDG layer. This study utilized ⁵⁷Fe Mössbauer spectroscopy to examine identically processed samples prior to and post pre treatment. XRD and ⁵⁷Fe CEMS measurements were performed on hot galvanized S355J2 + N samples, forming sandwiched structure. Both XRD and CEMS reveal the presence of dominant steel phase in accordance with its estimated occurrence on the surface of the sandwiched samples. Minor Γ-Fe3Zn10, ζ-FeZn15 and solid solution Fe-Zn as well as minor Fe-Si phases could also be identified.     

Mössbauer and magnetic study of silicon substituted cobalt ferrite

Silicon substituted cobalt ferrites have been investigated for improved performance as stress sensing materials. A series of samples with the formulae CoSi _x Fe_2???x O₄ were prepared using conventional powder ceramic technique. X-ray diffraction patterns were taken to examine spinel crystal structures and energy dispersive spectrometry was done to confirm Si segregations at the grain boundaries. Magnetic and magneto-strictive measurements were carried out to evaluate the material performance. Mössbauer spectra were taken on selective samples to understand the cationic distribution responsible for the modification of properties. The variations are explained on the basis of the strength of the exchange interactions between cations, and anisotropy contributions of cobalt ions. The results demonstrate the possibility of controlling magnetic and magneto-mechanical properties such as Curie temperature and strain derivative through Co and Si substitutions.     

Mössbauer study of pure illite and its firing products

Eight illites with an iron content between 0.8% and 8.4%, which X-ray diffraction indicated to be free from interference from other iron-bearing minerals, were studied by Mössbauer spectroscopy at room temperature and 4.2 K. The Fe³⁺ quadrupole splitting varied from 0.59 mm/s for the iron-rich illites (>5 wt.% Fe) to 0.73 mm/s for those poor in iron (wt.% Fe). A distinction of iron sites in the illites with cis- and trans-OH coordination was not possible. The products of firing one illite at temperatures up to 1300 C were also studied and revealed the disappearance of Fe²⁺, the gradual dehydroxylation of illite, and characteristic features of the products formed at higher temperatures.     

119Sn-mössbauer,IR, and DSC study of tin oxyfluoride glasses

The¹¹⁹Sn-Mössbauer spectra ofxSnO·(70–x)SnF₂·30P₂O₅ glasses (0 x70) measured at 78 K comprised a doublet due to Sn²⁺ (=3.30–3.36 mm s^–1, = 1.70–1.72 mm s^–1) and a weak singlet due to Sn⁴⁺ located at –0.23 mm s^–1 with respect to BaSnO₃. The and of Sn²⁺ were comparable to those of Sn₂P₂O₇. Small Debye temperatures (146 and 155 K) were obtained from the low-temperature measurements. These results indicate that Sn²⁺ and Sn₄₊ occupied interstitial sites, being loosely and ionically bonded to distorted PO_4–x F _x tetrahedra.     

Characterization of Argentine Loess and Paleosols by Mössbauer Spectroscopy

Hyperfine Interactions - We have used Mössbauer spectroscopy to investigate iron-bearing mineral samples of loess and paleosols from a geologic section at La Plata, Argentina, 34°...     

Comparative Mössbauer study of the aging of Fe-C and Fe-N martensites

The clustering-ordering synergy which forms Fe₆C precipitates by aging Fe-C martensite is compared to the long-range ordering which forms Fe₁₆N₂ by aging Fe-N martensite.     

Mössbauer and XRD study of Al-Sn linished steel bimetal alloy

Aluminium alloy free CS1 type steel (0.06 wt% C, 0.45 wt% Mn) and samples of cold roll bonded steel bimetal alloys (MAS15 and MAS16) were fabricated and investigated by X-ray diffraction (XRD), ⁵⁷Fe conversion electron Mössbauer spectroscopy (CEMS) at room temperature. XRD has revealed only the existence of the alpha iron solid solution (steel) phase in the steel only sample, while identified steel and metallic Al and Sn constituent phases in the bimetallic alloys. ⁵⁷Fe Mössbauer spectroscopy revealed the presence of 4 % secondary iron-bearing phase attributed mainly to iron oxide/ oxyhydroxides (ferrihydrite) besides the steel matrix on the surface of the steel sample. A significant difference between the occurrences of the secondary phase of differently prepared bimetal alloys found in their ⁵⁷Fe CEM spectra allowed to identify the main phase of debris as different iron oxide/ oxyhydroxides.     

A Mössbauer and X-ray diffraction study of nonstoichiometry in magnetite

The paper deals with the applicability of Mössbauer spectroscopy and X-ray diffraction methods for the determination of the deviation of magnetite from stoichiometry. The results show that among the data obtainable by both methods, the ratio of intensities of two partial spectra composing the Mössbauer spectrum of magnetite enables to evaluate the deviation of magnetite from stoichiometry quantitatively.The authors express their gratitude to Prof. Dr. Ing. J.Cirák who enabled them to perform all measurements of Mössbauer spectra at the Department of Nuclear Physics and Technics, Slovak Technical University, Bratislava. The authors are also indebted to Ing. P.Holba (Institute of Solid State Physics, Czechoslovak Academy of Sciences) and to Ing. Z.Drbálek (Research Institute of Sound and Picture) for the preparation of magnetite samples, and to Mr. P.Chaloupek (Faculty of Mathematics and Physics, Charles University, Praha) for computer calculation of lattice constants. The aid provided by members of the G. V. Akimov State Research Institute for the Protection of Materials, Dipl. Chem. K.Jendelová who carried out chemical analysis of the samples and Ing. K.Turecká who took part in X-ray diffraction measurements, is gratefully acknowledged.     

Mössbauer and XRD study of novel quaternary Sn-Fe-Co-Ni electroplated alloy

Constant current electrochemical deposition technique was used to obtain quaternary alloys of Sn-Fe-Co-Ni from a gluconate electrolyte, which to date have not been reported in the literature. For the characterization of electroplated alloys, ⁵⁷Fe and ¹¹⁹Sn Conversion Electron Mössbauer Spectroscopy (CEMS), XRD and SEM/EDAX were used. XRD revealed the amorphous character of the novel Sn-Fe-Co-Ni electrodeposited alloys. ⁵⁷Fe Mössbauer spectrum of quaternary deposit with composition of 37.0 at% Sn, 38.8 at% Fe, 16.8 at% Co and 7.4 at% Ni displayed a magnetically split sextet (B = 28.9T) with broad lines typical of iron bearing ferromagnetic amorphous alloys. Magnetically split ¹¹⁹Sn spectra reflecting a transferred hyperfine field (B = 2.3T) were also observed. New quaternary Sn-Fe-Co-Ni alloys were successfully prepared.     

Mössbauer study of Al and Cr co-substituted Yttrium iron garnets

The Mössbauer spectra of Y₃Al _x Cr _X Fe_5???2x O₁₂ (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 (ΔE_Q) indicate the presence of high spin Fe³⁺ ions in the tetrahedral (d) and octahedral (a) sites, typical of yttrium of yttrium iron garnet structure. Mössbauer results have shown that Al³⁺, enters a-sites only but Cr³⁺ enters both a-and d-sites.