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  • Electronic Resource  (9)
  • 2000-2004  (9)
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  • Electronic Resource  (9)
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  • 1
    Electronic Resource
    Electronic Resource
    Study of (Ln,Sr)(Fe,Co)O〈sub〉3-δ〈/sub〉 Type CMR Materials by 〈sup〉57〈/sup〉Co Emission Mössbauer Spectroscopy (2003)
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 90-91 (Apr. 2003), p. 165-170 
    Details
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/26/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.90-91.165.pdf
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  • 2
    Electronic Resource
    Electronic Resource
    Sterical effects of encapsulation on some cobalt complexes built up in zeolite Y – A Mössbauer emission spectroscopy study (2000)
    Springer
    Hyperfine interactions 126 (2000), S. 163-167 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Mössbauer emission spectroscopy revealed effects of encapsulation on 2,2′-bipyridine and 1,10-phenantroline complexes of 57Co2+ synthesized in the supercages of zeolite Y. The tris coordinated phenantroline complex, unexpectedly, did not form in the supercage due to the blocking effect of the cage walls. The spectra of the tris bipyridine complex did not show the high spin state of the nucleogenic iron(II) complex. This is attributed to the very short lifetime of this state destabilized by the misfit to the volume of the zeolite cage. The relaxation rate was estimated and compared with lifetimes measured on the complex embedded in other matrices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012613332761
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  • 3
    Electronic Resource
    Electronic Resource
    Mössbauer Spectroscopy and Preparation of Hg-1223, Tl-1223 and Tl-1212 Superconductors (2000)
    Springer
    Journal of radioanalytical and nuclear chemistry 246 (2000), S. 107-112 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Introduction of the Mössbauer nuclei 57Fe into Hg-1223 phase and that of 57Fe and 151Eu into Tl-1212 and Tl-1223 superconductors were investigated. Samples of high phase purity were obtained. Scanning electron microscopy and optical microscopy in normal and polarized light were employed to study the microstructure of the specimens. Energy dispersive X-ray analysis showed that 57Fe in the Hg-based samples and 57Fe as well as 151Eu in the Tl-based compounds, entered superconducting phases. Incorporation of Eu3+ into the superconducting phase favored the formation of the Tl-1212 phase. Mössbauer spectroscopy showed that Eu3+ entered the Ca-site. Two doublets found in the 57Fe Mössbauer spectra in both the Hg-1223 and the Tl-1223 phase referred to two different micro-environments of Fe3+. The assignment of the 57Fe Mössbauer spectra was made under the assumption that Fe favored the 1223 phase. Fe3+ may replace Cu in both the square pyramidal, five-fold oxygen coordinated Cu sites between the Ca and Ba-(Sr)-O layers, and in the square planar, four-fold oxygen coordinated Cu sites the Ca layers in the superconducting phases in both the Hg- and the Tl-based materials. From the relative areas of the two doublets, we concluded that the Fe3+ preferred the square planar Cu site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006797417970
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  • 4
    Electronic Resource
    Electronic Resource
    57Fe Mössbauer Investigation of the Substitutional Effect of Praseodymium in 1-2-3 Compounds (2000)
    Springer
    Journal of radioanalytical and nuclear chemistry 246 (2000), S. 117-121 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract 57Fe Mössbauer spectroscopy measurements were performed on the perovskite compounds Eu0.7Pr0.3Ba2(Cu0.99 57Fe0.01)3O7-δ, EuBa1.5Pr0.5(Cu0.99 57Fe0.01)3O7-δ and EuBa1.3Pr0.7(Cu0.99 57Fe0.01)3O7-δ. The observed 57Fe Mössbauer spectra provided an evidence for the correct site assignment of subspectra originating from 57Fe in different microenvironments. Apart from a minor component which was assigned to the 57Fe in the Cu(2) site of the copper oxide plane, all the subspectra could be attributed to the 57Fe in the Cu(1) copper oxide chain site with a fourfold (doublet D1), fivefold (doublet D2) or sixfold (doublet D3) oxygen coordination. In contrast, in the compound EuBa2(Cu0.99 57Fe0.01)3O7-δ the 6-coordinated (D3) species has not been observed. The substitution of Pr for Eu or for Ba resulted in an increased occupancy of the O(5) antichain oxygen sites, which was explained by the charge neutrality criterion. Especially, the replacement of Ba2+ with Pr3+ led to an unusually high degree of occupancy of O(5) sites. In the 57Fe Mössbauer spectra the relative area of the 6-coordinated species (D3) increased, and that of the 4-coordinated one (D1) vanished completely in the case when Pr was substituted for Ba. Furthermore, the proportion of the 6-coordinated (D3) species increased at the expense of the 5-coordinated (D2) one with an increasing concentration of Pr at the Ba site. These experimental results are consistent with the variety of Mössbauer results reported so far.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006753719787
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  • 5
    Electronic Resource
    Electronic Resource
    The Influence of Mechanical Treatment on the Absorption of CO2 by Perovskite Oxides (2000)
    Springer
    Journal of radioanalytical and nuclear chemistry 246 (2000), S. 69-77 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Perovskite oxides of composition (Sr1-x Ca x )(Fe0.5Co0.5)O3-δ were investigated for CO2 absorption properties and were proved to be useful as materials for CO2 absorption in the temperature range from 550 to 850 °C. The absorption rate of CO2 increased with Ca doping. The mechanical treatment of perovskite oxides for several minutes, especially for the oxides containing a small amount of Ca, was found to be effective for activating the oxides for CO2 absorption and for reducing the starting temperature of CO2 absorption by about 80 °C. However, it was not less effective to treat the oxides for a long time. The site distortion due to Sr and Ca ions at site A and the mixed valence states at site B were confirmed to be effective for CO2 absorption at high temperatures. During the absorption of CO2, a spinel compound was formed according to the following reaction: 2(Sr,Ca)(Fe,Co)O2.5 + CO2 → (Sr,Ca)CO3 + (Sr,Ca)(Fe,Co)2O4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006772812518
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of AP-CITROX Decontamination Procedure on the Surface Oxide Layer Composition of Stainless Steel Originating from the Primary Circuit of a VVER-Type Nuclear Reactor (2000)
    Springer
    Journal of radioanalytical and nuclear chemistry 246 (2000), S. 131-136 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A real specimen originating from the primary circuit of a VVER-440 type pressurized water cooled nuclear reactor has been studied by Conversion Electron Mössbauer Spectroscopy (CEMS) in order to find out how the AP-CITROX decontamination procedure modifies the structure and composition of the surface oxide layer of stainless steel which is used in the steam generator. Other methods like voltammetry, gravimetry, and SEM-EDAX were also applied to characterize the samples and to help the interpretation of CEMS results. It was found that, in contradiction with expectations, the presence of the surface magnetite layer could not be convincingly identified even on the non-decontaminated sample. This finding together with the relatively weak Mössbauer signals indicated that the surface oxide layer is strongly Fe-depleted. It was also concluded that the upper layer of the bulk steel (under the oxide layer) has an altered composition probably due to irradiation-enhanced diffusion of the metallic constituents. It was established that the AP-CITROX decontamination procedure does not exert detrimental effects on the thickness and composition of the surface oxide layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006761921604
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  • 7
    Electronic Resource
    Electronic Resource
    Mössbauer Spectroscopy and Radiofrequency Absorption Investigations of Pr Substituted 1-2-3 Type Compounds (2000)
    Springer
    Journal of radioanalytical and nuclear chemistry 246 (2000), S. 313-316 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract 57Fe and 151Eu Mössbauer spectroscopy as well as RF susceptibility measurements were applied to study the effects of Pr substitution either into the rare earth or into the Ba site in Eu1−x Pr x Ba2Cu3O7−δ and EuBa2−x Pr x Cu3O7−δ, respectively. Site mixing of Pr between the rare earth and Ba sites could be excluded by the utilization of 57Fe Mössbauer spectroscopy. It was found that there exists a correlation between the 151Eu isomer shift and the onset temperature of the superconducting transition independent of the location of Pr. RF susceptibility measurements provide an evidence for a difference in the magnetic moment of Pr substituted for the Eu or Ba sites. The obtained results can be explained by hole filling as the dominant effect of Pr substitution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006770407434
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  • 8
    Electronic Resource
    Electronic Resource
    Nuclear Techniques in the Elucidation of Chemical Structure (2000)
    Springer
    Journal of radioanalytical and nuclear chemistry 243 (2000), S. 241-253 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: 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-δ. 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006716708476
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  • 9
    Electronic Resource
    Electronic Resource
    Mössbauer Investigation of Characteristic Distribution of Iron Oxides in Sediments from the Antarctica (2000)
    Springer
    Journal of radioanalytical and nuclear chemistry 246 (2000), S. 61-68 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Sediments from the Admiralty Bay, King George Island, Antarctica, were investigated by 57Fe Mössbauer spectroscopy, X-ray diffractometry, and radiometry. Quartz, feldspar, chlorite, calcite, dolomite, mica, kaolinite, hematite and magnetite were identified as constituent minerals in the sediment samples. The phase composition and the iron distribution among the crystallographic sites of iron-bearing minerals (silicates, magnetite and hematite) of samples from different location have been derived from the complex Mössbauer spectra. At different locations sediments had significant characteristic differences in the mineral composition, in the iron distribution among the crystallographic site of silicates, and in the specific radioactivity of Cs radionuclides. These results indicate differences in the rock formation and alteration by the sediments in this maritime part of Antarctica. There is a much higher amount of iron oxides in the sediments from south part of the geological fault across the Admiralty Bay than in the north part. This can be associated with much more alteration in the rocks in the south part compared to the northern one. This finding can contribute to the question of the history of the formation and alteration of volcanic rocks in the border of Antarctica.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006768628448
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