| Autor: |
Lerf, Anton, Wagner, Friedrich E., Poyato, Juan, Pérez-Rodríguez, José Luis |
| Předmět: |
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| Zdroj: |
Journal of Solid State Electrochemistry; Feb2011, Vol. 15 Issue 2, p223-229, 7p, 2 Charts, 5 Graphs |
| Abstrakt: |
lthough the intercalation of Fe into layered phyllosicilicates-especially into smectites-attracted much attention in the past two decades, the information about Fe loaded phyllosilicates is sparse. Here we present an investigation of the Fe exchanged vermiculites from Santa Olalla and Ojén (Andalusia, Spain) by means of Mössbauer spectroscopy. The room temperature Mössbauer spectra are very similar to those of the starting compounds (Na forms) except for a decrease of the contribution of structural Fe and a concomitant increase of the contribution of Fe sites, indicating an internal redox process. The extent of this redox reaction is different for the two vermiculites. Thus, the intercalated Fe acts as an electron mediator from the external medium to the structural Fe ions. A new component attributable to intercalated Fe is practically invisible in the room temperature Mössbauer spectra, but increases strongly and continuously during cooling to 4.2 K, where it is the dominant feature of the Mössbauer patterns. At 4.2 K, its quadruple splitting amounts to 3.31 mm/s, which is in excellent agreement with the quadrupole slitting of Fe coordinated to six water molecules in a highly symmetric octahedral arrangement. The strong decrease of the Mössbauer-Lamb factor of this component with increasing temperature indicates a weak bonding of the Fe in the interlayer space. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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