Quantitative electron microprobe analysis of Fe3+/ΣFe: Basic concepts and experimental protocol for glasses
-
Michel Fialin
,
Antoine Bézos
Abstract
The presence of an unfilled 3d electron shell in the transition metals of the first series is manifested in X-ray self-absorption effects that cause distortions in the L emission spectra. In particular, one observes peak shape changes and peak position shifts toward lower energies that are attributed to X-ray photon self-absorption in the specimen. Self-absorption corresponds to partial overlap of both L-emission and absorption transitions in the region of the Fermi level. Such an overlap is related to relaxation effects that follow the creation of the core hole in the studied ions. For Fe, the overlap between the FeLα emission peak and the corresponding FeLIII absorption band is clearly higher for Fe2+ than for Fe3+, leading to an enhanced self-absorption induced shift of the FeLα peak for Fe2+. The shift of the Lα peak between Fe2+ and Fe3+ can be measured with the electron microprobe and hence exploited to determine the Fe3+/ΣFe ratios in silicates and glasses. For that purpose, an empirical method has been established based on working curves constructed from reference materials. A complete set of working curves is presented for glasses as well as an original experimental protocol.
Most glasses are electron beam sensitive and suffer especially from beam-induced oxidation-reduction mechanisms that are related to the implanted charge. The flux of Na+ ions from the surface the depth in the glass (driven by the electric field induced by the electrostatic charge) tends to oxidize the surface whereas, concurrently, the counterflux of electrons produced by excitonic mechanisms and trapped at Fe3+ sites tends to reduce the surface. Therefore operating conditions should be set to minimize these phenomena, as they are a source of large discrepancies in Fe3+/ΣFe. The application of the current protocol gives uncertainties of about ±5% absolute for specimens with nominal total Fe concentrations ranging from 6 to 9 wt% (accuracy and precision on Fe3+/ΣFe dramatically depend on the total Fe wt% concentration). Results obtained from a suite of basaltic glasses exhibit errors higher than ±5% absolute. Improved performances are expected for the method after the method can be used with promising new high resolution and high sensibility X-ray optics.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
- A zero-damage model for fission-track annealing in zircon
- Unoccupied states of pyrite probed by electron energy-loss spectroscopy (EELS)
- Tugtupite: High-temperature structures obtained from in situ synchrotron diffraction and Rietveld refinements
- SIMS microanalyses for Au in silicates
- Geochemistry of oxide minerals of Nb, Ta, Sn, and Sb in the Varuträsk granitic pegmatite, Sweden: The case of an “anomalous” columbite-tantalite trend
- An X-ray and electron microprobe study of Fe, Ni, Ga, and Ge distribution and local structure in a section of the Canyon Diablo iron meteorite
- Mineralogical approaches to fundamental crystal dissolution kinetics
- Cu L3X-ray absorption spectroscopy and the electronic structure of minerals: Spectral variations in non-stoichiometric bornites, Cu5FeS4
- A new nondestructive X-ray method for the determination of the 3D mineralogy at the micrometer scale
- Dissolution rates and pit morphologies of rhombohedral carbonate minerals
- The effect of TiO2on Pd, Ni, and Fe solubilities in silicate melts
- X-ray absorption spectroscopic study of Fe reference compounds for the analysis of natural sediments
- A survey of hydrous species and concentrations in igneous feldspars
- Structure and crystallization behavior of the (Ba,Sr)HAsO4·H2O solid-solution in aqueous environments
- The crystal structure of painite CaZrB[Al9O18] revisited
- Model pyroxenes II: Structural variation as a function of tetrahedral rotation
- Mn-rich fluorapatite from Austria: Crystal structure, chemical analysis, and spectroscopic investigations
- Isothermal equation of state and compressional behavior of tetragonal edingtonite
- Synthesis and crystal-chemistry of Na(NaMg)Mg5Si8O22(OH)2, a P21/m amphibole
- A single-crystal study on the pressure behavior of phlogopite and petrological implications
- Quantitative electron microprobe analysis of Fe3+/ΣFe: Basic concepts and experimental protocol for glasses
Articles in the same Issue
- A zero-damage model for fission-track annealing in zircon
- Unoccupied states of pyrite probed by electron energy-loss spectroscopy (EELS)
- Tugtupite: High-temperature structures obtained from in situ synchrotron diffraction and Rietveld refinements
- SIMS microanalyses for Au in silicates
- Geochemistry of oxide minerals of Nb, Ta, Sn, and Sb in the Varuträsk granitic pegmatite, Sweden: The case of an “anomalous” columbite-tantalite trend
- An X-ray and electron microprobe study of Fe, Ni, Ga, and Ge distribution and local structure in a section of the Canyon Diablo iron meteorite
- Mineralogical approaches to fundamental crystal dissolution kinetics
- Cu L3X-ray absorption spectroscopy and the electronic structure of minerals: Spectral variations in non-stoichiometric bornites, Cu5FeS4
- A new nondestructive X-ray method for the determination of the 3D mineralogy at the micrometer scale
- Dissolution rates and pit morphologies of rhombohedral carbonate minerals
- The effect of TiO2on Pd, Ni, and Fe solubilities in silicate melts
- X-ray absorption spectroscopic study of Fe reference compounds for the analysis of natural sediments
- A survey of hydrous species and concentrations in igneous feldspars
- Structure and crystallization behavior of the (Ba,Sr)HAsO4·H2O solid-solution in aqueous environments
- The crystal structure of painite CaZrB[Al9O18] revisited
- Model pyroxenes II: Structural variation as a function of tetrahedral rotation
- Mn-rich fluorapatite from Austria: Crystal structure, chemical analysis, and spectroscopic investigations
- Isothermal equation of state and compressional behavior of tetragonal edingtonite
- Synthesis and crystal-chemistry of Na(NaMg)Mg5Si8O22(OH)2, a P21/m amphibole
- A single-crystal study on the pressure behavior of phlogopite and petrological implications
- Quantitative electron microprobe analysis of Fe3+/ΣFe: Basic concepts and experimental protocol for glasses
