The unusual Mössbauer spectrum of beryl.
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2001
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Resumo
The Mössbauer spectra of several aquamarine samples have been obtained in the temperature
range of 4.2–500 K. A common feature observed in all room-temperature spectra is the
presence of an asymmetric Fe2+ doublet ( EQ ∼ 2.7 mm/s, δ ∼ 1.1 mm/s), with a very broad lowvelocity
peak. This asymmetry is not caused by preferred orientation since the spectrum collected
under the magic angle did not show any difference in the line intensities, nor is it caused by the
superposition of a Fe3+ doublet. At 4.2 K the spectrum of a deep-blue beryl could be well fitted with
three symmetrical doublets, with the major Fe2+ doublet accounting for 87% of the total spectral
area. At 14 K the symmetry remains, but at 30 K the low-velocity peak is again broad. Surprisingly,
the spectrum at 500 K also shows a broad, but symmetrical doublet, with a clear splitting of the lines
indicating the presence of at least two Fe2+ components. The room-temperature spectrum obtained
after the 500 K run shows the same features as before the heating. A meaningful fit for the roomtemperature
spectrum, as well as an explanation for the temperature dependence of the Mössbauer
spectra, are discussed.
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Beryl, Mössbauer spectroscop
Citação
VIANA, R. R. et al. The unusual Mössbauer spectrum of beryl. Hyperfine Interactions, v. 134, p. 193-197, 2001. Disponível em: <https://link.springer.com/article/10.1023/A:1013814217476>. Acesso em: 20 de jun. 2017.