Comparison of two electron probe microanalysis techniques to determine ferric iron in synthetic wüstite samples
Comparison of two electron probe microanalysis techniques to determine ferric iron in synthetic wüstite samples
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两种电子探针微量分析技术测定合成方铁矿样品中三价铁的比较
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
G. Brey
中科院分区：
文献类型：
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作者：
H. Höfer;S. Weinbruch;C. McCammon;G. Brey
比较了用电子探针测定FexO中铁含量的两种方法：一种是直接法(Hofer等人，1994年)，这种方法是基于Fe Lα和Fe LβX射线发射线的强度比和波长随Fe2+/Fe3+的伴随变化而变化的；该法测定Fe3+/∑Fe的精密度和准确度为±0.0 2(1s)。用间接法测定铁和氧含量得到相似的结果，而单独测定铁和计算氧含量从差值到100%就不那么准确了。结果仅对这一相对简单的双组分系统有效，不能在没有进一步校准的情况下转移到多组分系统。目前，只要已知样品的整体化学成分和晶体结构，并建立了类似材料的校准曲线，就可以采用侧边法。间接法仅限于Fe为唯一多价阳离子的样品。侧边法的精度在很大程度上受光谱仪位置精度的影响。为此，提出了一种利用Fe-K-α1.9级发射线对光谱仪进行定标的优化方法。
Two techniques are compared for determining the ferric iron content in Fe x O using the electron microprobe: (i) a direct method termed the flank method (Hofer et al., 1994), which is based on the concomitant changes of both the intensity ratio and the wave length of the Fe Lα and Fe Lβ X-ray emission lines with Fe 2+ /Fe 3+ , and (ii) an indirect method by calculating Fe 2+ /Fe 3+ from elemental microprobe analyses which may include oxygen. The precision and accuracy of Fe 3+ /∑Fe determined with the flank method is ± 0.02 (1s). Similar values are achieved with the indirect method by determining the Fe and O contents, while measurement of iron alone and calculation of the oxygen content from the difference to 100% is less accurate. The results are valid only for this relatively simple two component system and cannot be transferred to multiple component systems without further calibration. At present, the flank method can be applied if the bulk chemical composition and crystal structures of the samples are known and calibration curves with similar materials have been established. The indirect method is restricted to samples with Fe as the only multivalent cation. The precision of the flank method is largely affected by the accuracy of the spectrometer position. Thus, a method is developed to optimize the spectrometer calibration using the Fe Kα 1 9th order emission line.