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Electrical resistivity and Fe-57 Mossbauer spectra of Fe-bearing calcic amphiboles

Schmidbauer, E., T. Kunzmann, T. Fehr, and R. Hochleitner (2000), Electrical resistivity and Fe-57 Mossbauer spectra of Fe-bearing calcic amphiboles, Physics and Chemistry of Minerals, 27(5), 347-356.

Abstract
Electrical resistivity and Fe-57 Mossbauer spectra are reported for three calcic amphiboles with different Fe concentrations. AC measurements (20 Hz - 1 MHz) were performed, applying impedance spectroscopy between 100 and 785 degrees C in an N-2 gas atmosphere. It was found that up to three semiconducting charge transport processes call be distinguished, which in part changed slightly when several runs were carried out to higher temperatures. The extrapolated DC resistivity is much smaller for an amphibole with high Fe content than for the two with lower Fe concentrations. The derived activation energies are between similar to 0.48 and similar to 1.06 eV. For temperatures less than or equal to 600 degrees C the results are compatible with a charge transport mechanism due to electron hopping between Fe2+ and Fe3+. Above 600 degrees C, dehydrogenation and/or beginning amphibole decomposition obviously alter the conduction mechanism. From Mossbauer spectra it was established that in all amphibole samples Fe2+ and Fe3+ are simultaneously present. Mossbauer parameters were derived by fitting the observed spectra to models taking the occupation of various M sites into account.
BibTeX
@article{id179,
  author = {E. Schmidbauer and T. Kunzmann and T. Fehr and R. Hochleitner},
  journal = {Physics and Chemistry of Minerals},
  number = {5},
  pages = {347-356},
  title = {{Electrical resistivity and Fe-57 Mossbauer spectra of Fe-bearing calcic amphiboles}},
  volume = {27},
  year = {2000},
  language = {en},
}
EndNote
%0 Journal Article
%A Schmidbauer, E.
%A Kunzmann, T.
%A Fehr, T.
%A Hochleitner, R.
%D 2000
%N 5
%V 27
%J Physics and Chemistry of Minerals
%P 347-356
%T Electrical resistivity and Fe-57 Mossbauer spectra of Fe-bearing calcic amphiboles
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