Application de la RPE à la localisation des substitutions isomorphiques dans les micas: Localisation du Fe3+ dans les muscovites et les phlogopites |
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Authors: | D. Olivier J.C. Vedrine H. Pezerat |
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Affiliation: | Université Pierre et Marie Curie, Laboratoire de Chimie des Solides, 4, Place Jussieu, 75230 Paris Cedex 05, France |
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Abstract: | Electron spin resonance spectra attributed to four Fe3+ centers designated Oa, Ob, Ta, Tb have been observed in crystals of muscovite and phlogopite. The results are discussed using the spin Hamiltonian with ge ~ 2.002. The angular variation of the resonance lines is used to determine the ESR axes of the four different sites. Two species are octahedrally coordinated (Oa and Ob) and are assigned to two different surroundings of Fe3+ in the octahedral sheet. The remaining two species (Ta and Tb) may be assigned to the tetrahedral FeO4. The Ta sites have a symmetry axis lying along one of the FeO bonds. The symmetry axis is created by an excess of negative charge on the oxygen bound to the neighboring tetrahedral substitution. Rhombic symmetry of the Tb sites is due to the presence of fluorine anions substituting some hydroxyl ions. One of the ESR axes is directed toward the fluorine ion. |
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