Publication details
The electron microprobe flank method: A fresh approach to Fe³⁺ quantification in tourmalines
| Title in English | The electron microprobe flank method: A fresh approach to Fe3? quantification in tourmalines |
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| Authors | |
| Year of publication | 2025 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
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| Description | We present a methodology for quantifying the Fe3+/?Fe ratio in tourmalines using the flank method with an electron probe microanalyzer (EPMA). This method is based on the measurement of the X-ray intensities at specific spectral positions (FeL?, FeLß flanks) using a TAP monochromator, where the largest differences between emission X-ray spectra of Fe2+ and Fe3+ phases occur, was calibrated using well-characterized natural Fe2+ tourmalines and their oxidized Fe3+ counterparts. The relationship among X-ray intensity at the flank position, known Fe3+/?Fe ratios, and FeOtot content was used to derive an equation for calculating Fe3+/?Fe in unknown samples. The results are consistent with Mössbauer spectroscopy data, and the method is applicable to tourmaline samples with >5 wt.% FeOtot. The absolute error decreases with increasing FeOtot content, from ?6 rel.% Fe3? at ~10 wt.% FeOtot to ?1 rel.% Fe3? in samples with ~20 wt.% FeOtot. The standard deviation ranges from ±0.01 to ±0.09, following the same trend. |
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