Seminars and Events

Seminars and Events

Energy, Environment and Health

 


14 November 2017, 12:00 h. Sala de Seminarios, 182

Mössbauer transmission method and its analytical application into the study of Fe-containing carbon nanotubes, metal hydrides and perovskite oxides

Crisanto García Ramos
Dpto. de Energía, Medio Ambiente y Salud, ICMM

A discovery made by R. Mössbauer in 1957 allowed a more detailed structure of a number of materials to be known. Mossbauer spectroscopy as a very important analytical and valuable tool was used extensively in various sciences, besides physical and chemical sciences, such as mining and geology. It can provide us information about the oxidation state of active isotopes such as iron, gold, and so on, which are contained in the samples. Mossbauer spectroscopy can provide information about the magnetic arrangement, the orientation of this arrangement with respect to the crystallographic axes, the ratio of different magnetic phases.

We will describe three paradigmatic types of Fe containing materials: Fe-filled carbon nanotubes, Mg2FeH6 hydride and a series of oxyfluoride Fe perovskites. Fe-filled multiwall carbon nanotubes (Fe-MWCNTs) were grown by chemical vapor deposition with ferrocene as precursor. The data show that Fe phases encapsulated within the carbon nanotubes comprise alpha-Fe, gamma-Fe, and Fe3C in different percentage ratio depending on the sample preparation. In Mg2FeH6, Mossbauer data helped to determine that the oxidation state of Fe is close to zero, in accordance with neutron diffraction and XAS data. The 57Fe Mossbauer spectra of the Sr1-xBaxFeO2F, indicate that TN (magnetic order temperature) variation with the contents (x) has an exponential dependence on x2 and TN’s are significantly higher than those precedently reported.



       

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