Abstract
Flux-grown Fe3+-bearing spinel s.s.–hercynite solid-solution crystals, (Mg 1-y Fe2+ y )Al2O4 (0 < y≤ 1), have been investigated by means of electron microprobe technique and Mössbauer and electronic spectroscopy. Obtained results show that different electronic processes cause intense optical absorption bands in the near-infrared spectral region. In addition to an electronic d–d transition in single-ion IVFe2+, observed at 5200 cm−1, intense and broad bands at 9500 and 14 500 cm−1 are assigned to exchange-coupled pair (ECP) and intervalence charge-transfer (IVCT) transitions in VI Fe 2+ VIFe3+clusters, respectively. The net linear extinction coefficients of these bands (α) were calibrated against Fe2+ and Fe3+ concentrations and site distributions previously defined by combined microchemical, Mössbauer, and XRD structural refinement data. The following expressions were obtained:
where α is measured in cm−1 and concentrations are expressed in mol l−1.
The present results show that optical absorption spectroscopy may be used as a probe to obtain high spatial resolution (∅∼ 10 μm) information on Fe2+ ordering as well as on Fe3+ concentrations in minerals belonging to the spinel group.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
Author information
Authors and Affiliations
Additional information
Received: 30 August 2001 / Accepted: 18 December 2001
Rights and permissions
About this article
Cite this article
Hålenius, U., Skogby , H. & Andreozzi , G. Influence of cation distribution on the optical absorption spectra of Fe3+-bearing spinel s.s.–hercynite crystals: evidence for electron transitions in VIFe2+–VIFe3+ clusters. Phys Chem Min 29, 319–330 (2002). https://doi.org/10.1007/s00269-002-0240-z
Issue Date:
DOI: https://doi.org/10.1007/s00269-002-0240-z