Abstract: Ferric ferrocyanides synthesized from different sources of ferric cations and ferrocyanide anions and those derived from ferrous ferricyanide, ferrous ferrocyanide and ferric ferricyanide have been studied using Mossbauer and XRD techniques. Structural information of the effect of the provenance on the properties of the final compound is obtained. Significant correlations between isomer shift and quadrupole splitting of inner and outer iron cations have been observed.

Abstract: Metastable Fe1−xAlx alloys over the entire composition range have been investigated by X-ray diffraction and Mossbauer effect measurements. Alloys with x less than 0.55 are bec, whereas those with x>0.9 are fce, in between, the samples are amorphous. The Mossbauer spectra at 300 K for the bce alloys with x<0.5 consist of a broadened sextet and the spectra for the alloys with x≥0.5 are quadrupole-split doublets with a slight asymmetry. The magnetic hyperfine field at 4.2 K decreases monotonically with Al concentration from 340 kOe in pure Fe to zero at x=0.7. The isomer shift increases essentially linearly with Al concentration, and reaches a maximum at x=0.75. It is noted that at the boundary of x=0.55 separating the bce and the amorphous states, there is no discernible change in elther hyperfine field or lsomer shift.

Abstract: Perovskite-type nanocrystalline materials LaFeO3 with different crystal size were synthesized. These samples with different compacted pressure were investigated by Mossbauer spectroscopy at room temperature. The results showed that the LaFeO3 crystal in size of 70nm possessed an antiferromagnetic structure, that of 12nm was the superposition of the weaker antiferromagnetic structure and the stronger superparamagnetic structure. The rate of interface atoms to crystal atoms and the hyperfine field in nanocrystals varied with the compacted pressure.

Abstract: The hyperline parameters of relatively well crystallized grelgite (Fe3S4) have been determined by Mossbauer spectroscopy on a natural greigite-smythite sample. Applied-field measurements confirm the ferrimagnetic behavior. Saturation values of the magnetic hyperfine fields are 31.8 and 33.0 T for the tetrahedral and octahedral Fe respectively. The temperature dependence implies a Curle temperature of at least 800K. In addition, the analyses of the spectra provide some information about smythite for which the spectra seem to be composed of at least three sextets.

Abstract: A Mossbauer spectrometer is included in the preliminary payload of a rover to be placed on the surface of Mars in the Soviet mission to the planct in 1996/1,2/. In counection with the American planctary program it has also been suggested to construct a Mossbauer spectrometer to be landed on Mars /3, 4/. The objective is to study the iron compounds of the Martian soil and rocks by backscattering Mossbauer spectroscopy. The paper describes the significance of the element iron in the study of the evolution of the planetary system and what we might expect to learn from Mossbauer spectroscopy of the surface materials of Mars. The study of Mars is expected to expand substantially in the coming decades, probably culminating with a manned flight to the planet. The international Mossbauer community may contribute significantly to the preparation of these events.

Abstract: A Mossbauer study of magnetically enriched samples of loess and associated, palaeosol from a section in Jixian (China) reveals that the iron-bearing magnetic components are predominantly hematite and magnetite, exhibiting to a large extent similar features in loess and soil. The only important difference observed is the presence of a substantial amount of maghemite in the soil, indicating an advanced stage of weathering of magnetite in the latter. It is therefore concluded that the enhanced remanence observed in the soil can mainly be explained by a dilution of the primary non-magnetic loess minerals and the acquisition of chemical remanence.

Abstract: The present work reports measurements of isotope shifts and hyperfine structure in the optical spectra of two high-Z elements: Hf and U. The experiments are based on the observation of the resonance fluorescence in a well collimated atomic beam, excited by a tunable dye laser. The chains of the stable Hf isotopes and of233–236, 238U have been investigated and changes in ms nuclear charge radii have been deduced. The results have been discussed from the point of view of nuclear structure in the investigated regions.

Abstract: It is now well established that, as with amorphous alloys, the Mossbauer spectra of icosahedral alloys exhibit QSD's. This is evidence for intrinsic local disorder present in icosahedral structures. The shapes of the QSD's have not been unambiguously established and, as a result, it has been difficult to link these shapes with other physical properties of these novel and complex alloys. We apply a recently developed arbitrary shape static hyperfine parameter distribution method to the case of a new icosahedral alloy series: Al65Cu20Cr15-xFex. The method proves to be a powerful and useful tool in this application. It enables us to evaluate several robust features and to identify other features that are subject to large uncertainties due to extreme sensitivity to details.

Abstract: We have made preliminary measurements of positronium (Ps) formation cross sections for 9 to 452 eV positrons scattered from Ar atoms and for 1 to 20 eV positrons scattered from K atoms. Our experimental approach involves setting lower and upper limits on Ps formation cross sections using a combination of (1) the detection of the coincidences of 511 keV annihilation gamma rays produced by the decay of para-Ps and by the interaction of ortho-Ps with the wall of the scattering cell in which the Ps is formed, and (2) the determination of scattering cross sections associated with the measured transmission of the positron beam through the gas in our scattering cell with the angular discrimination of our apparatus deliberately made as poor as possible. The constraints placed by these lower and upper limits are used to check for consistency with prior experimental and theoretical results for Ar and to provide the first measurements of Ps formation cross sections for K, which are compared with available theoretical results.

Abstract: Mossbauer spectroscopy and X-ray diffraction analysis allow to detect the presence of green rust 2, the ferrous-ferric sulfated compound of composition, 4Fe(OH)2,2FeOOH,FeSO4,nH2O, mixed with magnetite at the surface of steel sheets corroded in a harbour area where the presence of sulfate reducing bacteria are also detected.

Abstract: Addition of 5%Ni to an Fe−28%Cr alloy causes a transition of the aging behavior from the nucleation and growth to the spinodal decomposition. Very rapid increase in the average internal magnetic field and a broadening of the internal magnetic field distribution occur in the spinodal decomposition. Mossbauer spectra are synthesized by assuming a rectangular and a sinusoidal wave for the composition fluctuation, and the internal magnetic field distributions obtained from those are compared with the experimental results to estimate a time evolution of the amplitude of the composition wave.

Abstract: Recent developments in the field of beams of positronium (Ps) atoms formed in charge-exchange reactions of slow positrons with gaseous targets are reported. The beam production efficiencies with respect to target species and density have been measured, together with a determination of the population of the quantum states of the atoms in the beam. Estimates of the total scattering cross section of Ps with He and Ar targets, at intermediate projectile velocities, have been obtained.

Abstract: We review and discuss the information provided by some low-energy nuclear processes on physics beyond the standard model of the fundamental interactions. We focus on probes where nuclear orientation is either essential or helpful.

Abstract: Mossbauer spectra were recorded of tissue from β-thalassaemia/haemoglobin E spleen, liver, pancreas and heart and of crude haemosiderins (insoluble iron fractions) isolated from the organs. Iron in the crude haemosiderins from the spleen and heart remains paramagnetic below 4.2K indicating that the iron is in a non-crystalline form. Superparamagnetic behaviour of the crude haemosiderins from the pancreas and liver indicate the presence of ferrihydrite cores with some cores with a structure based on defect-goethite.

Abstract: 57Fe Mossbauer and X-ray diffraction measurements have been performed on a perovskite CaFeO3 under external high pressure upto 50 GPa at room temperature using a diamond anvil cell. Above 29 GPa the57Fe magnetic hyperfine splitting appears superimposing with usual paramagnetic pattern of CaFeO3. Magnitude of hyperfine field is 16 T and much smaller than 33 T of typical Fe4+ in SrFeO3 suggesting a transition from high-spin S=2 to low-spin S=1 state in CaFeO3.

Abstract: A laser ion source based on resonance photo ionization in a gas cell is proposed. The gas cell, filled with helium, consists of a target chamber in which the recoil products are stopped and neutralized, and an ionization chamber where the atoms of interest are selectively ionized by the laser light. The extraction of the ions from the ionization chamber through the exit hole and skimmer is similar to the ion-guide system. The conditions to obtain an optimal system are given. The results of a two-step one-laser resonance photo ionization of nickel, and the first results of laser ionization in a helium buffer gas cell are presented.

Abstract: The temperature variation in the range 8–760K of the hyperfine parameters of the Fe−Ni phases in the Santa Catharina meteorite has been determined. It is suggested that the disordered 50–50 Fe−Ni phase actually consists of two distinct fractions, i.e. a completely disordered phase and one with intermediate long-range ordering parameter. The single-line subspectrum of the 28%-Ni phase was found to display magnetic ordering below approximately 25K.

Abstract: We have calculated the Mossbauer absorption integral for symmetrical quadrupole doublets as a function of the effective thicknessT of the sample and of the ratioQS/⇏ (quadrupole splitting/natural width); the resulting absorptionA can be well approximated by a simple expressionA≈T/(1+αT), where α is a function of the resolutionQS/⇏ of the absorption lines. A convenient analytical expression is given for α(QS/⇏). As an example, the thermal variation of the absorption area of a spin crossover system is analysed.

Abstract: The effect of a dry-hot period on the SO2 corrosion of weatherig steel and pure iron under wet-dry cycling was investigated. Corrosion products were identified by Mossbauer spectroscopy and X-ray powder diffraction. The formation of an intermediate corrosion layer of spm α-FeOOH only on weathering steel was the most significant result.

Abstract: The method of “in-beam Mossbauer spectroscopy (IBMS)” as presently performed at heavy-ion accelerators is presented and reviewed. Experimental aspects are outlined and special features of this technique in comparison with more conventional radioactive ion implantation are stressed. The review is centered on the fate of57Fe atoms implanted in metals and semi-conductors in which very limited or vanishing solubility for Fe exists. Under these conditions Fe takes up to a rather large extent interstitial positions. These can be characterized by the Mossbauer parameters, in particular by the isomer shift. Already at rather low temperatures one observes in several materials a dynamic behaviour of the Fe interstitial which can be described in some cases as localized motion and in others as onset of long-range interstitial diffusion. Additional information on the dynamic behaviour and the electronic structure in some of the systems presented comes from Perturbed Angular Distribution of γ-rays (PAD). which also is an “in-beam” technique working with a 10+ isomeric state of54Fe.

Abstract: The interaction of ozone with Prussian Blue has been studied by Mossbauer, infrared and XRD techniques. All spectral results reveal a reversible conversion of ferrocyanide to ferricyanide with preservation of the crystal skeleton. Ferric ferricyanide obtained by ozonization of ferric ferrocyanide has Mossbauer parameters different to those of an ordered Prussian Brown, which has been attributed to secondary reaction products located at the zeolite voids of the former compound.

Abstract: Fe/Tb multilayers (ML) have been prepared in UHV. The layer thickness for Fe was varied from 10 to 80 A with Tb-layer thicknesses of 3.5, 7, 14 and 26 A. Different substrate temperatures Ts between Ts=130 K and RT have been used. The magnetic spin texture was studied by57Fe-Mossbauer spectroscopy from T=4.2 K to 670 K. The ferrimagnetic coupling between Fe and Tb moments was observed by Mossbauer studies in external fields up to 5 T.

Abstract: At compositions C<45 at. %Fe, Fe−Ni has a well-known collinear ferromagnetic ground state with no deviation from the Slater-Pauling curve and saturation moments on Fe and Ni of 2.8 and 0.6 μβ′, respectively. At these compositions and at all temperatures T<295 K, the HFD's extracted from the Fe-57 Mossbauer spectra by a new method are shown to be in excellent agreement with predicted HFD's calculated with no free parameters. The calculation assumes that the transferred hyperfine fields are from near neighbours only and uses parameters that are uniquely determined by the behaviour of the average hyperfine field versus composition. This proves the validity of the underlying physics in both the extraction procedure and the calculation.

Abstract: Permanent magnets, composition Nd4Fe96−x B x (x=10–21), were made by rapid quenching followed by crystallization. The effects of B concentration and annealing time on the magnetic properties and phase compositions were studied by Mossbauer spectroscopy and magnetic measurements. The stripping method was adopted to obtain the subspectral area of each Fe phase. Optimum magnetic properties are obtained for the composition Nd4Fe77B19 annealed at 670°C for 3 minutes. Then the remanence is 12.0 kGs, the intrinsic coercivity 3.2 kOe, and the maximum energy product 12.6 MGOe. The crystalline phases are Fe3B, Nd2Fe14B and α-Fe with volume percentages of 60%, 36%, and 4%, respectively.

Abstract: A new detector for CEMS has been built and optimized with respect to the statistical quality of spectra obtained. The optimization has been performed by measuring Mosbauer and pulse height spectra at in- and off-resonance. Single channel analyzer settings were calculated by a new optimization routine. A comparison of different detector designs has been performed using the statistical utility rate of spectra obtained from a stainless steel foil. A procedure for determining optimal operating parameters for ICEMS gas flow proportional counters is proposed.

Abstract: Thickness effects have been studied extensively, both numerically and analytically, only for the case where the intrinsic absorber cross-section, σa, is an elemental

Abstract: Experiments of nuclear Resonant scattering carried out at PF and TRISTAN-AR of KEK are described, which include nuclear Bragg scattering in time domain as well as energy domain, time-resolved nuclear resonant forward scattering, and interferometric studies.

Abstract: The disordered antiferromagnetic γ-FeMn alloys in the range of Mn concentration from 0 up to 50 at.% Mn were investigated by means of X-ray diffraction analysis (XRD), differential scanning calorimeter (DSC) and Mossbauer spectroscopy (ME) at room temperature and at 80 K. The lattice parameter is constant for Mn contents below 27 at.% and increases linearly for higher Mn concentration. The RT Mossbauer spectra for the alloys with less than 20 at.% Mn were fitted with quadrupole splitting (QS) distribution, and above 20 at.% Mn they were fitted with magnetic hyperfine field (HF) distribution. The averageQS decreases, while the HF maintain a constant value by increasing the Mn concentration. At 80 K, the HF increases linearly up to 30 at.% Mn and then maintains a constant value at about 38 kOe. The peak of the specific heat (c p) at the Neel temperature changes from broad to sharp as the Mn content increases. The Neel temperature increases with Mn concentration.