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Abstract  

Triphenyltin(IV) complexes ofN-acetylglycine,N-acetyl-L-leucine,N-acetyl-L-asparagine andN-acetyl-L-tyrosine were prepared by two methods and characterized by means of different spectroscopic methods (FTIR, multinuclear,1H,13C and119Sn NMR and119Sn Mössbauer). The spectroscopic data indicated that theN-acetylglycine complex adopts a trigonal-bipyramidal structure in which the monodentate carboxylate and the amide-C=O group are bound to the same organotin(IV) moiety. The other three complexes are linear oligomers in which the planar Ph3Sn(IV) is coordinated axially by a monodentate carboxylate and an amide-C=O from two different ligands. At theC-terminal end of the oligomer chain there is a tetracoordinated tin(IV) with a monodentate carboxylate as donor group.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: A. Vértes, Z. Klenesár, Gy. Vankó, T. Marek, K. Süvegh, Z. Homonnay, and E. Kuzmann

Abstract  

The paper offers three applications of nuclear methods in the research of chemical structure. First, progress in positron annihilation spectroscopy is illustrated by a positron beamline study, which obtained results that are not available through conventional experiments. The positron beam was used for the study of Langmuir-Blodgett (LB) films containing 4-58 layers of arachidic acid and its salts. These measurements have shown that this emerging technique is capable of characterizing even such elusive systems. Second, the potential of Mössbauer spectroscopy to answer current challenges of solid state chemistry are shown in a study on perovskites of recent interest. 151Eu Mössbauer spectroscopy was used to study the effect of Pr substitution in EuBa2Cu3O7-. It was shown that the introduction of Pr into the rare earth site as well as into the Ba site results in the appearance of extra electrons both in the copper oxide planes and at the 4f shell of Eu cations. The observed effects were explained by the hole filling effect of Pr. Finally, a survey is presented on the recently developed techniques for nuclear resonant scattering of synchrotron radiation, an exciting and very rapidly developing extension to conventional Mössbauer spectroscopy. An interesting new result is that nuclear inelastic scattering experiments performed on solutions of 57Fe complexes show contribution from vibrations rather than from diffusion to the inelastic spectra.

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Abstract  

119Sn conversion electron Mössbauer spectroscopy, X-ray diffractometry and energy dispersive X-ray analysis (EDAX) were employed to investigate microstructure, composition and phases present in as-electroplated Sn-Cr and Sn-Cr-Zn alloys deposited on copper substrates. In the Sn-Cr deposits Cu, -Sn, Cr-Sn phases can be identified by X-ray diffractometry. The phase composition is significantly different between the samples prepared with relatively higher and lower current densities. In the diffractograms of Sn-Cr-Zn deposits Cu, -Sn, Zn phases can be well identified. A small intensity amorphous peak is also present, which can perhaps be associated with the presence of some amorphous Zn and Sn alloy. 119Sn Mössbauer spectra of Sn-Cr deposits exhibit an asymmetric broad main line centered near the isomer shift characteristic of -Sn as well as they contain a small component near the zero velocity which can be attributed to a SnO2 phase based upon its characteristic. 119Sn Mössbauer spectra of Sn-Cr-Zn deposits are roughly similar to those of Sn-Cr deposits although the Mössbauer parameters of the third phase are different and vary with the Zn content. The presence of SnO2 on the surface mainly in the Sn-Cr samples can be attributed to the corrosion process in the air.

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Abstract  

Mössbauer spectroscopy was used to study phlogopites from ultramafic xenoliths derived from alkali mafic rocks of the Transdanubian Midmountains. On the basis of evaluation of the Mössbauer spectra the following iron sites were identified /using the nomenclature published by Dyar1/ in the samples:

\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$Fe_{M1}^{2 + } , Fe_{M2}^{2 + } , Fe_{M3}^{3 + } and Fe_{tet}^{3 + } .$$ \end{document}
Quantitative analysis of all of the iron sites was performed. The Fe2+/Fe3+ ratio was found to be 3.33 for the sample for phlogopite xenolith and 2.05 for the sample from clinopyroxene-phlogopitite xenolith. There are evidences, that Fe3+ can occupy tetrahedral positions in upper mantle phlogopite, even if Si+Al>8. Our data suggest MARID+ glimmerite origin of micas.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: E. Kuzmann, M. Varsányi, L. Korecz, A. Vértes, T. Masumoto, F. Deák, Á. Kiss, and L. Kiss

Abstract  

Neutron, and Mössbauer spectroscopy were used to study the possibility of cold nuclear fusion in Fe90Zr10 amorphous ribbon having high hydrogen absorbing ability. No significant changes in the neutron and in the spectra were found at deuterization performed electrochemically at different cathodic potentials. The observed differences between the Mössbauer spectra of samples deuterized in air and in nitrogen atmosphere can be explained by decrease of deuterium uptake as well as by a small heat effect due to reaction of hydrogen with oxygen dissolved in water in the case of electrolysis carried out in air.

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Abstract  

Traditional black pottery produced in Nádudvar, E-Hungary, was studied by 57Fe Mössbauer spectroscopy, X-ray diffractometry and microscopy. Quartz, feldspar, clay minerals (kaolinite, smeetite, illite) and calcite were identified in the basic clay material by X-ray diffractometry (XRD). Mössbauer spectroscopy (MS) of the original clay revealed that about 35% of iron compounds were present in goethite while the rest in clay minerals (illite and smectite). After firing the clay in air using an electric furnace (red pottery is prepared in the same way), the Mössbauer spectra showed hematite as the only iron oxide or hydroxide phase, being in good agreement with X-ray diffractometry. In the black product itself, fired in the traditional open-flame furnace, the Mössbauer spectra reflected the presence of iron in magnetite and in sheet silicates with approximately the same relative ratio of oxides and silicates as in the starting material. This can be interpreted as a result of the transformation of goethite to hematite in the first step of firing (in air), and as a reduction of hematite to magnetite in the second step of firing (closed from air). A significant difference was found in the distribution of iron at the Fe2+ and Fe3+ cation sites in the black surface (more Fe2+) and at the dark gray bulk of the fired pottery (less Fe2+), showing that the reduction of Fe3+ occurs in the silicates instead of further reduction of the magnetite (e.g., to wüstite).

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Abstract  

Mössbauer, FTIR and XRD analyses showed that in aqueous medium in air in the presence of L-tryptophan (Trp) or indole-3-acetic acid (IAA) the ambient-temperature ageing of the precipitates formed from ferrous sulphate at pH7 gave composite phases with varying proportions of -FeOOH (a dominating crystalline phase), -FeOOH (both fine-grained, showing superparamagnetic behaviour at 298 K, and relatively better crystallized) and amorphous ferric hydroxide. The experimental data suggested a competition for adsorption sites at the oxyhydroxide surface in the suspension during phase transformations, as well as the transformation of -FeOOH (and/or amorphous ferric hydroxide) to -FeOOH via the dissolution-reprecipitation mechanism. The formation of certain ferric oxyhydroxide phases in the presence of Trp and IAA — released e.g., in the course of bacterial and plant metabolism — can contribute to the regulation of soil mineral composition.

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Abstract  

Sr0.95Ca0.05Fe0.5Co0.5O3- and Sr0.5Ca0.5Fe0.5Co0.5O3- perovskites were studied by 57Fe emission Mössbauer spectroscopy. It was found that Co prefers lower valence and lower coordination number than Fe in both compounds. The comparison of the emission and transmission Mössbauer spectra of the CO2 treated materials revealed a preferred formation of Fe-containing products in reaction with CO2 in Sr0.5Ca0.5Fe0.5Co0.5O3- , and it is proposed that such a reaction can be responsible for phase separation in Sr0.95Ca0.05Fe0.5Co0.5O3– after absorption and partial desorption of CO2 at 950 °C.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: E. Kuzmann, Z. Homonnay, A. Vértes, I. Halász, J. Bánkuti, and I. Kirschner

Abstract  

151Eu,119Sn and57Fe Mössbauer spectroscopy was used to study high Tc superconductors. Mössbauer spectra of Sn substituted EuBa2Cu3O7–y, YBa2Cu3O7–y and TlBaCaCuO4.5+y as well as of Fe Substituted TlBaCaCuO4.5+y were compared. The Sn and Fe ions replace the regular Cu positions in the YBa2Cu3O7–y and in TlBaCaCuO4.5+y materials, fespectively, while the localization of tin atoms in both the119Sn doped EuBa2Cu3O7–y and TlBaCaCuO4.5+y superconductors is different from that of previous cases. Up to our knowledge, this is the first publication on a Mössbauer study of a Tl-containing superconductor.

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