Mössbauer study of electrodeposited Fe−Cr−Ni alloys

Mössbauer spectroscopy was used to compare Fe?Cr?Ni alloys prepared by different electrochemical as well as thermal methods. The main phase of the electrodeposits was ferromagnetic contrary to the thermally prepared alloys of same composition, which were paramagnetic. Obvious differences can be observed among the spectra of electrodeposited samples of different composition. Narrower line width and smaller paramagnetic contribution can be observed in samples electrodeposited onto A1 substrate compared to those in samples plated onto graphite with modified electrochemical parameters. Changes in hyperfine field distribution of as-deposited and aged samples indicate a precipitation process due to the heat treatment.     

Mössbauer study of Fe−Zr amorphous alloys hydrogenated at different cathodic potentials

Mössbauer spectroscopy was used for studying the effect of hydrogenation on amorphous Fe₉₀Zr₁₀ and Fe₈₉Zr₁₁ alloys electrolytically charged to high hydrogen content. The differences observed between the room temperature Mossbauer spectra of uncharged and hydrogenated amorphous alloys can be attributed to a change in the Curie temperature. Up to a certain hydrogen content the Curie temperature increases with the hydrogen concentration while the Curie temperature goes thorough a maximum as the hydrogen content increases.     

Une nouvelle méthode de relaxation pour les équations de Navier–Stokes compressibles

We consider the compressible Navier–Stokes equations for gas flows endowed with general pressure and temperature laws as long as they are compatible with the existence of an entropy and Gibbs relations. We extend the relaxation method introduced for the Euler equations by Coquel and Perthame. Keeping the same “sub-characteristic” conditions for the hyperbolic fluxes and using a consistent splitting of the diffusive fluxes based on a global temperature, we prove the stability of the relaxation system via the sign of the production of a suitable entropy. A first order asymptotic analysis around equilibrium states confirms the stability result. Finally, we present a numerical implementation of the method. To cite this article: E. Bongiovanni et al., C. R. Acad. Sci. Paris, Ser. I 336 (2003).     

DCEMS Study of Thin Oxide Layers and Interface of Stainless Steel Films Deposited by Sputtering Austenitic AISI304

Hyperfine Interactions - Thin stainless steel films were deposited on surface oxidized Si plate using austenitic AISI304 stainless steel as target with a RF magnetron Ar sputtering method. The...     

Mössbauer study of Fe70Cr10C10P10 rapidly quenched alloys

Mössbauer spectroscopy was used to study rapidly quenched Fe₇₀Cr₁₀C₁₀P₁₀ amorphous alloys in order to get information about the effect of some preparation parameters on the structure and properties of the alloys. The results indicate that the Mössbauer spectroscopy can sensitively detect changes with quenching rate in these amorphous alloys. The average magnetic field decreases with increasing thickness of the samples. This cooling rate effect was compared with low temperature relaxation changes of the aged thin samples.     

119Sn and151Eu Mössbauer study of EuBa2(Cu1-xSnx)3O7-y perovskites

Eu and Sn Mössbauer spectroscopy was used to study EuBa₂(Cu_1-xSn_x)₃O_7-y metallic oxides. The spectra are characteristic for Eu^III and Sn^IV states in all cases. The existence of at least two different Sn states was determined by decomposition of the Sn Mössbauer spectra. These Sn sites can be associated with nonequivalent Cu sites replaced by Sn atoms in the perovskite type lattice. Anomalous changes were observed in the isomer shifts and area fractions in the spectra measured at room temperature and at 77 K. It can be interpreted assuming low temperature phase transformation and phonon softening. Time dependent changes were found in the Sn spectra recorded at 77 K in the case of highest Sn concentration. The observed changes are consistent with a transitional stage of the low temperature phase transformation.     

Mössbauer investigation of Fe−Zr amorphous alloys hydrogenated after annealing

Transmission and conversion electron Mössbauer spectroscopy were used in order to get further information bout thé effect of hydrogenation in Fe₈₉Zr₁₁ amorphous alloys in connection with the observation that the magnetically split spectrum appearing at room temperature due to a moderate hydrogenation gradually collapses with increasing hydrogen content. The Mössbauer measurements were performed on differently hydrogenated amorphous samples aged at 150 °C 300 °C and 600 °C before the hydrogenation. The time dependence of hydrogenation has also been measured. From the changes of Mössbauer parameters depending on the annealing temperature as well as on the cathodic potential of hydrogenation (compared with the hydrogen concentration measured by gas chromatography) we can conclude that relaxation processes and structural changes, taking place in these amorphous alloys, influence the hydrogen uptake, already at relatively low temperatures.     

Determination of the drug content of pharmaceuticals containing phenothiazine compounds by triangle programmed flow titration

Summary A flow-through triangle programmed coulometric titration technique is worked out for the determination of phenothiazine compounds. The oxidation reaction of phenothiazines with hypobromite ion served as titration reaction. A biamperometric detector cell has been used for following the titration process. The titration technique has been used for the determination of the drug content (average and individual) of chlorpromazine, promethazine, diethazine and trifluoperazine in pharmaceutical preparations. The relative standard deviation was in the range of 2.0 to 3.5%.

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Bestimmung des Wirkstoffgehaltes von Phenothiazin-haltigen Pharmazeutica mit Hilfe einer Dreieck-programmierten Durchflu\-Titration

     

Oxygen separation induced by Xe ion beam upon electrodeposited oxygen-nickel and oxygen-chromium systems on iron substrate studied by conversion electron Mössbauer spectroscopy

Nickel was electrodeposited on one side and chromium on the other side of a sheet of α-iron enriched (∼85%) with⁵⁷Fe. The electrodeposited Ni and Cr contained oxygen and it could be separated by 500 keV xenon implantation. The separated oxygen formed an amorphous metal-oxide interphase at the interface of iron substrate and electrodeposited Ni or Cr.     

Mössbauer study of amorphous alloys irradiated with energetic heavy ions

The Mössbauer spectroscopy was applied to study radiation damage in metal-metalloid amorphous alloys irradiated with⁴⁰Ar/E=225 MeV/ or¹³²Xe/E=120 MeV/ ions at room temperature. The observed dose dependent changes in the intensity of the Mössbauer lines and of the hyperfine field distributions can be associated with structural changes in short-range order of the irradiated amorphous alloys.