利用标准曲线法测定绿泥石中不同价态铁的电子探针定量分析方法

A New Technique for Determining the Percentages of FeO and Fe_2O_3 in Chlorite with Electron-Probe Microanalyzer (EPMA)

本文建立了一种可利用电子探针对绿泥石矿物中的FeO和Fe_2O_3进行定量分析的工作曲线方法。 实验表明,实验条件对分析结果具有非常重要的影响。对于全铁含量大于10％的样品,应选用15kV的加速电压、20nA的激发电流和20μm的束斑尺寸;而对于全铁含量小于10％的样品,则选用10kV的加速电压、100nA的激发电流和20μm的束斑尺寸。 利用电子探针进行定量分析所得结果与利用化学分析方法进行分析所得结果进行对比后可得出如下结论,即对于全铁含量大于10％或小于10％的绿泥石分别选用两种不同实验条件下的工作曲线,均可使FeO和Fe_2O_3的相对误差小于7％。

The determination of percentages of FeO and Fe2O3 in chlorite is a basical work in chlorite classification, diagenesis environment interpretation and formation damage investigation. A working curve technique for determining the percentages of FeO and Fe2O3 in chlorite with electron - probe microanalyzer (EPMA) has been developed in this paper.The experiments conducted in the paper show that the experimental conditions have a great influence on the results. 15kV of accelerating voltage, 20nA of exciting current and 20μm of beam size should be selected for the samples in which the total iron content is over 10%. And 10kV,100nA and 20μm should be selected for the samples in which the total iron content is less than 10%.The comparisons with the results of chemical analysis indicate that with the suitable working curves developed under different conditions, the relative errors of both FeO and Fe2O3 for two kinds of samples are all less shan 7 % .