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First we studied the kinetics of the formation of Ba monoferrite by means of Mossbauer spectroscopy. The most important result is the considerable portion of hexaferrite existing after treatment of the starting materials between 800 and 900°C, caused by a higher rate of diffusion of the Ba2+ ions in comparison to the Fe3+ ions. Second we report susceptibility measurements recorded in a temperature range of 4.3 K to 280 K and Mossbauer spectra at room temperature and at 4.2 K without and in the presence of an applied magnetic field of 6 T. The experimental data demonstrate that the magnetic behaviour of Ba monoferrite deviates to some extent from a simple antiferromagnetic.

Electrochemically hydrogenated ASTM 310 and ASTM 316 austenitic steels were investigated by means of57Fe Mossbauer spectroscopy. Starting with non-hydrogenated materials, freshly hydrogenated ones and one-day room temperature aged hydrogenated samples were studied. The resultant spectra were analysed with a modified Hesse-Rubartsch method [1] adopted to the case of isomer shift distribution.

Etude des structures magnetiques de BaFe 12 O 19 et de BaCo 0.8 Ti 0.8 Fe 10.4 O 19 par spectroscopie Mossbauer de Fe 57 . Analyse de la variation du spectre Mossbauer avec la temperature et le champ magnetique applique. Interpretation des resultats en termes d'inversion du spin du reseau, du a l'influence des ions Co 2+

Magnetic and Mossbauer effect studies have been reported for new UFe10Si2, UCo10Si2 and UFe10Mo2 compounds crystallizing with tetragonal structure of the ThMn12-type. The magnetization measurements have been performed for the magnetic field preoriented sample of UFe10Si2 and bulk sample of UCo10Si2, in high fields up to 140 kOe. The 57Fe Mossbauer spectra for UFe10Si2 and UFe10Mo2 have been recorded below the corresponding Curie temperatures.

The 57 Fe Mossbauer resonance has been applied to study polyacetylene films doped chemically and electrochemically to different doping levels. Both methods lead to the insertion of a high spin Fe III complex with Mossbauer parameters characteristic of FeCl − 4 . Degradation of [CH(FeCl 4 ) y ] x in air leads to gradual transformation of Fe III into a high spin Fe II .

Mesure de la susceptibilite magnetique du monoferrite Ba (BaFe 2 O 4 ) entre 4,3 et 280K, et des spectres Mossbauer a l'ambiance et a 4,2K avec et sans champ magnetique applique. Existence d'une contribution ferrimagnetique a l'ordre magnetique de BaF 2 O 4 a basse temperature due aux couches cristallographiques magnetiquement differentes de la structure

Several Mossbauer studies of Ti-Fe spinels have been reported in the literature for x ≦ 0.8 (BANERJEE et al.; VANLEERBERGHE et al.) or for x ≦ 0.05 (UMEMURA et al.). BHADURI measured the Mossbauer spectra of the whole system (0 ≦ x ≦ 1) and suggested that TixFe3−xO4 samples with x 0.6 may be regarded as n-type semiconductors with localized electrons. We present measurements of electrical properties and Mossbauer spectra of synthetic TixFe3−xO4 single crystals with x = 0; 0.24; 0.5; 0.72. It is seen that the electronic behaviour strongly depends on the content of titanium. At a composition of approximately x = 0.65 a transition from n- to p-type of electrical conductivity occurs. 57Fe Mossbauer data of the samples for different temperatures obtained of the spectrum computer analysis using a least squares fit program are given. The Mossbauer spectra below and above the Neel temperature demonstrate the distinct decrease in mobility of electrons in dependence on the Ti content. It is evident from the Mossbauer spectrum of the sample Ti0.72Fe2.28O4 recorded above the Neel temperature that Titanium is incorporated into the spinel structure of this system only in a four valent state.

The hyperfine interaction parameters at the 161Dy and 57Fe nuclei in Dy2Fe17−yAly compounds (0 ⩽ y ⩽ 8) have been determined from the Mossbauer effect measurements at 4.2 K. The excess of the hyperfine magnetic field at the 161Dy nuclei is discussed according to the 5d electron transfer model.

The x-ray and Mossbauer measurements of both57Fe and161Dy in Dy2Fe17−y Al (y=0, 1,5 and 3) compounds and their hydrides are reported.

Mőssbauer effect experiments in scattering geometry were performed for gauging plates and bearings in order to measure the retained austenite content. The results, obtained from numerical calculations of Mossbauer spectra are compared with the X-ray diffraction measurements. A simple three point Mossbauer effect technique is applied in order to decrease the time of measurements in the industrial use.

Doping of polyacetylene with iron chloride complexes has been studied by MBssbauer spectroscopy. It was proved that the doped polymer undergoes degradation in air manifested by the formation of FeOlxaE^O with the simultaneous chlorination of the double bond.

Very active catalysts can be prepared from FeCl3-GIC precursors through a two-step reduction and washing with HCl. Mossbauer spectrometry during the first (H2) reduction step indicates that Fe0 in the form of α-Fe is obtained together with two non-equivalent FeII sites. This α-Fe is catalytically inactive and can be readily removed from the system treatment with HCl. The second reduction with potassium vapour transforms the remaining FeII into catalytically active Fe0 which is strongly resistant to the HCl treatment.

The compounds Dy 2 Fe 17− y Co y (O⩽ y ⩽17) have been investigated using the Mossbauer resonances at the 161 Dy and 57 Fe nuclei (at 4.2 K). The changes of the hyperfine interaction parameters have been determined as a function of the Co content. The dependence of the hyperfine field at the 57 Fe nuclei on y is quite different from that for the 161 Dy nuclei. The 5d electron model is proposed to explain this behaviour.

The hyperfine interaction parameters at the 161Dy and 57Fe nuclei in Dy2−yYyFe17 compounds (0⩽y⩽2) have been determined from the Mossbauer effect measurements at 4.2 K. The dysprosium atoms are substituted by the yttrium atoms across the series and then the 5d electrons of Dy are replaced by the 4d electrons of Y. The hyperfine interaction parameters for both nuclei remain constant versus Y content. The full equivalency between 5d and 4d electrons has been deduced. The excess of the hyperfine magnetic field at the 161Dy nuclei and the reduction of the magnetic hyperfine field at the 57Fe nuclei can be explained as a result of the presence of the magnetically polarized 5d (or 4d) electrons in these compounds.