Ssbauer Spectroscopy Research Articles

Antiferromagnetic transition of fayalite under high pressure studied by M�ssbauer spectroscopy

Neel temperature (Tm N of α-Fe2SiO4 (fayalite) was measured as a function of pressure by means of Mossbauer spectroscopy in the pressure range 0–16 Gpa. High pressure was generated using a clamp-type miniature diamond anvil cell which was inserted into a cryostat. The Neel temperature increased linearly with increasing pressure at a rate of dT N /dp=2.2±0.2 K/GPa. The result is discussed on the basis of the model proposed for the magnetic structure of fayalite by Santoro et al. (1966). The observed dT N /dp suggests that the superexchange interactions vary as the −10/3 power of the volume while the volume dependence of the direct exchange interactions is positive and small.

Influence of anionic substitutions on hyperfine interactions and ionic ordering in ferrites

Since M~ssbauer spectrum parameters are quite sensitive to the nearest surroundings variation, the M~ssbauer spectroscopy enables one to obtain information concerning the cation and anion mutual distribution on the atomic level. The magnetic properties of dielectric crystals in relation to the types of the constituting cations and their distribution in nonequivalent sites is studied rather elaborately. But the problem of the anionic influence has been raised rather recently /1-3/. The magnetic ordering is explained by the magnetic ions exchange interaction through diamagnetic ligands. Thus the direct anionic influence on the exchange interactions and on magnetic microstructure formation should be expected. In order to investigate the anionic influence a M6ssbauer study of ferrites with various anionic substitution was carried out

Multilayer Fe/Cu Films

ABSTRACTMultilayer films consisting of alternating Fe and Cu thin films have been made by a twin-gun sputtering device with a rotating substrate platform. Both proportional modulated films and films with a fixed Cu layer have been fabricated, where the Fe layer has been varied between 10 and 150 Å. These films have been studied by x-ray diffraction, Mö;ssbauer spectroscopy and SQUID magnetometry. Thin Fe layers with thicknesses less than 25 Å, exist only as fee α-Fe. Thicker Fe layers contain both bec and fee Fe. The interface between Fe and Cu appears very sharp with no evidence of Fe-Cu alloys. The α-Fe state orders magnetically below 100 K with a small magnetic moment.

Determination of the second order doppler shift of iron in myoglobin by Mössbauer spectroscopy.

We have performed Mössbauer absorption experiments on a sample of deoxygenated myoglobin crystals from 5 K to 280 K. With two series of measurements, one with the source and sample at the same temperature and the other with the source always at 298 K, we are able to extract information from the second-order Doppler effect in the sample. Simple models consistent with a description of myoglobin with low lying electronic states which are thermally populated above 40 K indicate that the Debye temperature of myoglobin is 220 K, in agreement with measurements using the Lamb-Mössbauer factor. The second-order Doppler effect is proportional to the square of the velocity of the motion. We are unable to see any indication of protein specific motion from the second-order Doppler effect, thereby indicating that protein specific motions are relatively slow.

Study of structure of tetranuclear cluster of Fe with fluoroacetic acid by means of M�ssbauer spectroscopy and x-ray structure temperature analysis

This paper presents a reliable assignment that has been made of the partial Mossbauer spectra to two positions of the Fe ions in the structure of Fe/sub 4/O/sub 2/ (CF/sub 3/COO)/sub 8/.(H/sub 2/O).2H/sub 2/O)/sub 6/. To accomplish this, the authors combined analysis of the mean-square displacements of Mossbauer atoms, obtained in the 80-300 degrees K interval by means of Mossbauer spectroscopy and x-ray structure analysis at different temperatures. Th character of the thermal vibrations of the atoms of the cluster indicates a limitation on the application of the model of a solid to this cluster.

Metal/Flame‐Sprayed‐Aluminum Interface as Studied by Emission Mössbauer Spectroscopy

not Available.

Magnetic properties of Cu-Cd ferrite investigated by M�ssbauer spectroscopy

Samples of the copper-cadmium ferrite series Cd x Cu1−x Fe2O4 (x=0 to 1) have been investigated by means of Mossbauer spectroscopy at 77 K. Mossbauer spectra forx=0.0 to 0.7 suggest the existence of two hyperfine fields, one due to the Fe3+ tetrahedral ions (A-sites) and the other due to the Fe3+ octahedral ions (B-sites), while forx=0.8 it shows relaxation behaviour and forx⩾0.9 it exhibits a paramagnetic quadrupole doublet. The systematic dependence of the isomer shifts, line widths, quadrupole interactions and nuclear magnetic fields of57Fe3+ ions in both A and B sites has been determined as a function of cadmium content. The variation of nuclear magnetic fields at the A and B sites is explained on the basis of the A-B and B-B supertransferred hyperfine interactions. Analysis of the average Mossbauer line widths as a function of cadmium concentration suggests that the relaxation spectrum observed atx=0.8 (77 K) is possibly due to domain wall oscillations. It has been found here that QS (B) increases from CuFe2O4to CdFe2O4 as the cadmium concentration is increased.

Study of the high iron concentrations in cement clinker by M�ssbauer spectroscopy

Determination par spectrometrie Mossbauer de la teneur en fer de clinkers obtenus a partir de melanges de matieres premieres contenant differentes teneurs en cendres de pyrite

M�ssbauer spectroscopy in cement manufacture

Etude par spectrometrie Mossbauer des etats du fer dans le melange cru a differentes temperatures jusqu'a la temperature de formation du clinker 1500°C

The martensitic transformation in cold-worked Fe-Mn alloys studied by M�ssbauer spectroscopy

The effect of cold-working on 16, 23 and 30 at% Mn iron-manganese alloys (C<0.05 at%) has been examined using Mossbauer spectroscopy and X-ray diffractometry. The induced martensitic transformation γ→e, α′ depends on the composition and on the initial structure. It is found that the γ→α′ transformation in presence of the e phase occurs only at high deformations.

M�ssbauer spectroscopy of implanted sources

A review is given of the field of Mossbauer spectroscopy of ion-implanted sources. After an introduction to the various aspects of the ion-implantation method, the following topics are treated: final site selection of implanted impurities; trapping of defects at implanted ions; on-line implantation; implantation in metals, semiconductors and insulators.

Quantitative determination of goethite and hematite in kaolinitic soils by X-ray diffraction

In the past, two factors have impeded the quantitative estimate of Fe-oxides in soils by X-ray diffraction. First, Fe-oxides are still quite often considered X-ray amorphous, although numerous results, e.g. a low ratio of oxalate- to dithionite-soluble Fe, have indicated the opposite. Second, even if crystalline, the cocentration of Fe-oxides in many soils is low, thereby complicating their identification by XRD. Recently, however, more sensitive methods such as Mössbauer spectroscopy and Differential-XRD (Schulze, 1981) have been introduced, which substantially reduce the lower limit of detection. Because these two methods are not generally available and, especially in the case of M&amp;oum;ssbauer spectroscopy, are rather time consuming, ordinary XRD should be adapted for quantitative estimation of Fe-oxides.Determination can be facilitated by using samples in which the Fe-oxides are concentrated by particle-size separation and a 5 M NaOH boiling treatment (Norrish &amp; Taylor, 1961). The latter treatment is particularly suitable for kaolinitic soils as the Fe-oxides are unaffected―provided certain precautions are taken (Käimpf &amp; Schwertmann, 1982a). This paper gives details of a procedure for the quantitative estimation of goethite (Gt) and hematite (Hm) by XRD.

Application of M�ssbauer spectroscopy to the determination of the phase composition of finely dispersed corrosion products of reactor materials in a water coolant

Application of M�ssbauer spectroscopy to the determination of the phase composition of finely dispersed corrosion products of reactor materials in a water coolant

The use of m�ssbauer spectroscopy of iron in clay mineralogy

The use of m�ssbauer spectroscopy of iron in clay mineralogy

Tribological studies of iron implanted with tin using M�ssbauer spectroscopy

Tribological studies of iron implanted with tin using M�ssbauer spectroscopy

The applied field dependence of TN for RbFeCl3 observed by M�ssbauer spectroscopy

The applied field dependence of TN for RbFeCl3 observed by M�ssbauer spectroscopy

Complexes of impurity atoms with trapped interstitials in molybdenum observed by M�ssbauer spectroscopy

Complexes of impurity atoms with trapped interstitials in molybdenum observed by M�ssbauer spectroscopy

Determination of the thickness of hematite and magnetite layers on oxidized iron by electron reemission M�ssbauer spectroscopy

A reanalysis of earlier electron reemission Mossbauer (ERM) data obtained from iron oxidized in pure oxygen at 150 to 500°C is presented. The new data analysis utilized the same theoretical method used previously, but with significantly altered values for the electron attenuation coefficients determined from recent experimental work by Graham, Mitchell, and Channing. The recalculated oxide-thickness values were found to be in much better agreement with the volumetrically measured oxygen uptake.

M�ssbauer spectroscopy in the phase-composition analysis of corrosion deposits in a nuclear power station

Moessbauer measurements have been made on the phase composition for various corrosion products in various systems in a nuclear power station, and the results are fully explicable in relation to the processes of formation and are in agreement with data obtained by other methods, in particular x-ray spectroscopy. The Moessbauer spectra were recorded with a YaGRS-4M /gamma/-resonance spectrometer. 15 refs.

Crystal field of Dy implanted in Cu single crystals obtained by M�ssbauer spectroscopy

The field dependence of the hyperfine interaction of161Dy impurities in Cu has been studied in external magnetic fields up to 3.21 T by means of Mossbauer spectroscopy. 161Dy was introduced into a single crystal of Cu by means of low temperature ion implantation. From the measurements we determine the parameters of the cubic crystalline electric field acting on the Dy nuclei:A 4 =−28±58 K and $$A_6 \langle r^6 \rangle = 20.6_{ - 0.2}^{ + 3.1} K$$ . The ground state is a $$\Gamma _7 $$ doublet, separated well from a $$\Gamma _8 $$ excited quartet by $$\Delta = 44.8_{ - 13.3 }^{ + 1.8} K$$ .