| 电子探针多道波谱仪同时测试同一个元素的方法：以石英中Al 和Ti 含量的测试为例 |
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| 引用本文： | 崔继强,郭晟彬,张若曦,谢 静,杨水源.电子探针多道波谱仪同时测试同一个元素的方法：以石英中Al 和Ti 含量的测试为例[J].高校地质学报,2021,27(3):340-348. |
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| 作者姓名： | 崔继强 郭晟彬 张若曦 谢 静 杨水源 |
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| 作者单位： | 1. 中国地质大学（武汉）地质过程与矿产资源国家重点实验室，武汉 430074；
2. 中国科学院青藏高原研究所大陆碰撞与高原隆升重点实验室，北京 100101 |
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| 摘 要： | 电子探针显微分析是常用的原位分析矿物中各种主量元素含量的技术方法，但是对于微量元素的分析，提高测试精确度和准确度长期以来面临着各种挑战。常用的提高精确度方法有改变加速电压、加大电流和增加计数时间，但是这些方法容易使样品遭到破坏，发生元素迁移从而造成测试结果的不准确，增加计数时间还会降低测试效率。文章提出了一种利用电子探针多道波谱仪同时测试同一个元素的方法来提高待测元素特征X射线的强度值。该方法利用电子探针不同波谱仪同时测试同一个待测元素，通过测试标准样品中待测元素的总净计数和待测样品中待测元素的总净计数，结合标准样品中待测元素的浓度计算待测样品中待测元素的含量。该方法在同等测试条件下可以有效的提高待测元素特征X射线的强度值，从而提高了测试的精确度，降低了测试的检测限。文章以石英中Al和Ti含量的测试为例，验证了多道波谱仪同时测试同一个元素的方法在微量元素测试中的应用。测试Al元素时使用一个TAP晶体和一个TAPL晶体，测试Ti元素时使用三个PETL晶体，结合多点背景测试法准确测试了石英中Al和Ti的含量，在20 kV电压、500 nA束流和20 μm束斑直径的条件下可将Al的检测限降低至2.6×10-6 (3σ)，将Ti的检测限降低至2.1×10-6 (3σ)，测试获得石英参考标样中Al和Ti的含量分别为163.8×10-6±5.8×10-6 (3σ)和56.5×10-6±2.0×10-6 (3σ)，皆在参考值区间(Al：154×10-6±15×10-6；Ti：57×10-6±4×10-6)内，并且具有较好的长期稳定性。
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| 关 键 词： | 电子探针 微量元素 多道波谱仪 同时测试 石英 |
EPMA Simultaneous Determination of An Element byMulti-spectrometer: A Case Study of the Determination ofAl and Ti Contents in Quartz |
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| CUI Jiqiang,GUO Shengbin,ZHANG Ruoxi,XIE Jing,YANG Shuiyuan.EPMA Simultaneous Determination of An Element byMulti-spectrometer: A Case Study of the Determination ofAl and Ti Contents in Quartz[J].Geological Journal of China Universities,2021,27(3):340-348. |
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| Authors: | CUI Jiqiang GUO Shengbin ZHANG Ruoxi XIE Jing YANG Shuiyuan |
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| Institution: | 1. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China;
2. Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; |
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| Abstract: | Electron probe microanalysis (EPMA) is a method for in-situ analysis of major element contents in minerals. However, it is a challenge to improve precision and accuracy for the analysis of trace elements by EPMA. Changing accelerating voltage, increasing beam current, and increasing counting time are the common methods to improve the precision. However, these methods are easy to destroy the samples and cause element migration, resulting in the inaccuracy of the analytical results. Increasing the counting time will also reduce the analytical efficiency. In this paper, a method of simultaneous determination of an element by multi-spectrometer is proposed to improve the intensity of characteristic X-ray. In this method, multi-spectrometer is used to measure the characteristic X-ray intensity of an element simultaneously. The total characteristic X-ray intensity of standard and unknow are obtained by multi-spectrometer. Then, combined the content of the element in the standard, the content of the element in unknows can be calculated. This method can significantly improve the characteristic
X-ray intensity, leading to high precision and low detection limit. In this study, the contents of Al and Ti in a reference quartz standard were measured by the method of simultaneous determination of an element by multi-spectrometer, to verify the application of this method in trace element analysis. Two wavelength dispersive spectrometer with one TAP crystal and one TAPL crystal were used to measure Al simultaneously, and three wavelength dispersive spectrometer with three PETL crystals were used to measure Ti simultaneously. The multipoint background method, and the condition of 20 kV accelerating voltage, 500 nA beam current, and 20 μm beam diameter were used. The detection limit of Al and Ti in this study were 2.6×10-6(3σ) and 2.1×10-6(3σ), respectively. The analyses result of Al and Ti in this reference standard were
163.8×10-6±5.8×10-6 (3σ) and 56.5×10-6±2.0×10-6 (3σ) respectively, which are all close to the reference values (154×10-6±15×10-6 for Al and 57×10-6±4×10-6 for Ti), and show a good long-term stability. |
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| Keywords: | EPMA trace element multi-spectrometer simultaneous determination quartz |
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