Low-Voltage Electron-Probe Microanalysis of Fe–Si Compounds Using Soft X-Rays

Gopon, Phillip; Fournelle, John; Sobol, P. E.; Llovet, Xavier

doi:10.1017/s1431927613012695

Cited by 55 publications

(71 citation statements)

References 23 publications

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“…One solution to the quantification problems of Ni-silicides at low voltage is to use the Ni-Ll line, as has already been suggested by [8][9][10]. The Ll-line, with an energy of 742 eV, is far from the L 2,3 -absorption edges, and corresponds to a radiative transition (L 3 -M 1 ) that does not involve the unfilled 3d-shell.…”

Section: K-ratios Using the Ni-ll Line And Conventional Macsmentioning

confidence: 99%

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Electron probe microanalysis of Ni-silicides at low voltage: difficulties and possibilities

Heikinheimo

Pinard

Richter

et al. 2016

IOP Conf. Ser.: Mater. Sci. Eng.

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Section: K-ratios Using the Ni-ll Line And Conventional Macsmentioning

confidence: 99%

“…Gopon et al [8] showed that the use of the less intense Ll (L 3 -M 1 transition) line, which does not involve transitions from the unfilled 3d-shells, may be a suitable alternative for the analysis of Fe-silicides at low voltage. Statham and Holland [9] also used the Ll-lines to analyse a high Cr-Ni steel.…”

Section: Introductionmentioning

confidence: 99%

Electron probe microanalysis of Ni-silicides at low voltage: difficulties and possibilities

Heikinheimo

Pinard

Richter

et al. 2016

IOP Conf. Ser.: Mater. Sci. Eng.

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“…Gopon et al [1] showed that the Fe Ll line had some utility, but its weak intensity was a drawback. Here we investigate the possible utility of Fe Lα and Lβ.…”

mentioning

confidence: 99%

“…Due to the strong absorption of these lines in the high-energy side by the L2 and L3 absorption edges, the peak shapes are not symmetrical and a sum of pseudo-Voigt function is needed to ensure a good fitting. The MACs were obtained by non-linear fitting of the previously obtained L line intensities in relation to the accelerating voltage using the PAP model [1] The variations of the MAC in relation to the photon energy can be evaluated with the self-absorption spectrum which is constructed by comparing the spectrum acquired at 2.5 kV with the spectrum acquired at 30 kV. As seen in Figure 1, the self-absorption spectra measured on pure Fe and on fayalite differ greatly.…”

mentioning

confidence: 99%

Quantitative Electron Probe Microanalysis of Fe at Low Accelerating Voltage Using the Lα and Lβ X-ray Lines

Moy

Fournelle

2017

Microsc Microanal

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For more than six decades, electron probe microanalysis has been employed to determine the composition of unknown samples at ~micron-size domains. The introduction of the field emission gun (FEG) has allowed the reduction of the electron beam size. Electron imaging by microprobe can now reach a sub-micron resolution allowing the clearer imaging of sub-micron features such as inclusions in larger phases. To improve the X-ray lateral spatial analytical resolution, however, the interaction volume of the electrons inside the sample also needs to be reduced. This can only be done by decreasing the accelerating voltage from typically 15 kV to 5-7 kV, reducing the typical size of the electron interaction volume from ~1-2 µm to ~0.2-0.7 µm (depending upon material composition). However, by reducing the accelerating voltage, the commonly utilized X-ray lines (the Kα lines) of many of the elements of the periodic table up to Z=34, cannot be excited and thus cannot be used for analysis. Instead of using the K lines, the L lines of these elements must be used. However, for some elements, these L X-ray lines are not well known and complex chemical and physical effects can occur, making their use difficult in quantitative analysis. This is especially the case for the transition metals with the main L lines (and for many of the rare-earth elements with the main M lines). Several effects can influence the emission of X-rays produced by an electronic transition involving outer electronic shells. In the case of the transition metals, the Lα and Lβ X-ray lines involve a partially filled 3d electron shell which is subject to strong bonding and hybridization with electrons from the neighboring atoms. This results in a change of the state of the outer electronic orbitals and then changes the energy of the electrons and the electronic transition probabilities associated with these shells. Consequently, the value of the different atomic parameters (mass absorption coefficient, fluorescence yield, Coster-Kronig factor, …) not only depend of the studied element but also of the composition and nature of the specific material, both of the unknown and of the standard used to generate the k-ratio.Our work was focused on the transition metal iron as it is a commonly encountered element in many materials of interest. Gopon et al [1] showed that the Fe Ll line had some utility, but its weak intensity was a drawback. Here we investigate the possible utility of Fe Lα and Lβ. The atomic parameters associated with the emission and absorption of the Fe Lα and Lβ X-ray lines were reevaluated on 15 iron-bearing standards of well-known composition (silicates and oxides). Trends are deduced from these measurements in order to predict the value of the atomic parameters in relation to the composition of the material and thus allowing their use for correct quantitative analysis. The mass absorption coefficients (MAC) of the Fe Lα and Lβ X-ray lines were first evaluated. For each standard, the L X-ray spectra of these lines were recorded with three waveleng...

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“…During the initial analysis of Fe-Si [6], it was suggested that carbon (~1-2 wt. %, determined by EPMA) might be present in the Fe-Si, but the possibility of analytical artifacts has not been resolved.…”

mentioning

confidence: 99%

Survey for Fe-Si in Apollo 16 Regolith Sample 61501,22

Gopon¹,

Fournelle²,

Spicuzza³

et al. 2015

Microsc Microanal

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Metallic iron (micron to submicron spherules) is relatively abundant in lunar regolith and is widely believed to have formed by reduction of Fe during space weathering (micrometeorite/ cosmic ray bombardment; [1] During the initial analysis of Fe-Si [6], it was suggested that carbon (~1-2 wt. %, determined by EPMA) might be present in the Fe-Si, but the possibility of analytical artifacts has not been resolved. The presence of carbon was hypothesized to explain the ultra-reduced conditions. In order to determine with certainty the presence of carbon in these phases, a destructive technique (SIMS or atom probe) is necessary. Therefore we sought additional examples of Fe-Si/Si o from 61501,22 to test this hypothesis, increase by an order of magnitude the number of reported grains containing Fe-Si. Moreover, all found instances of Fe-Si were present encapsulated in a glassy matrix of anorthitic composition, referred to as glassy-anorthite (presumed glassy based on textural similarity to that present in [2]). Thus Fe-Si in this lunar regolith sample is relatively common, and may be more common in the lunar regolith in general than previously reported.

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Low-Voltage Electron-Probe Microanalysis of Fe–Si Compounds Using Soft X-Rays

Cited by 55 publications

References 23 publications

Electron probe microanalysis of Ni-silicides at low voltage: difficulties and possibilities

Electron probe microanalysis of Ni-silicides at low voltage: difficulties and possibilities

Quantitative Electron Probe Microanalysis of Fe at Low Accelerating Voltage Using the Lα and Lβ X-ray Lines

Survey for Fe-Si in Apollo 16 Regolith Sample 61501,22

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