Newbury Dale E, Ritchie Nicholas W M
Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899 USA.
J Mater Sci. 2015;50(2):493-518. doi: 10.1007/s10853-014-8685-2. Epub 2014 Nov 12.
Electron-excited X-ray microanalysis performed in the scanning electron microscope with energy-dispersive X-ray spectrometry (EDS) is a core technique for characterization of the microstructure of materials. The recent advances in EDS performance with the silicon drift detector (SDD) enable accuracy and precision equivalent to that of the high spectral resolution wavelength-dispersive spectrometer employed on the electron probe microanalyzer platform. SDD-EDS throughput, resolution, and stability provide practical operating conditions for measurement of high-count spectra that form the basis for peak fitting procedures that recover the characteristic peak intensities even for elemental combination where severe peak overlaps occur, such PbS, MoS, BaTiO, SrWO, and WSi. Accurate analyses are also demonstrated for interferences involving large concentration ratios: a major constituent on a minor constituent (Ba at 0.4299 mass fraction on Ti at 0.0180) and a major constituent on a trace constituent (Ba at 0.2194 on Ce at 0.00407; Si at 0.1145 on Ta at 0.0041). Accurate analyses of low atomic number elements, C, N, O, and F, are demonstrated. Measurement of trace constituents with limits of detection below 0.001 mass fraction (1000 ppm) is possible within a practical measurement time of 500 s.
在配备能量色散X射线光谱仪(EDS)的扫描电子显微镜中进行的电子激发X射线微分析是材料微观结构表征的核心技术。硅漂移探测器(SDD)使EDS性能取得的最新进展能够实现与电子探针微分析仪平台上使用的高光谱分辨率波长色散光谱仪相当的准确度和精密度。SDD-EDS的通量、分辨率和稳定性为高计数光谱的测量提供了实际操作条件,这些高计数光谱构成了峰拟合程序的基础,即使对于存在严重峰重叠的元素组合(如PbS、MoS、BaTiO、SrWO和WSi),也能恢复特征峰强度。对于涉及大浓度比的干扰情况,也证明了能进行准确分析:一种主要成分对一种次要成分(质量分数为0.4299的Ba对质量分数为0.0180的Ti)以及一种主要成分对一种痕量成分(质量分数为0.2194的Ba对质量分数为0.00407的Ce;质量分数为0.1145的Si对质量分数为0.0041的Ta)。还证明了能对低原子序数元素C、N、O和F进行准确分析。在500秒的实际测量时间内,能够测量检测限低于0.001质量分数(1000 ppm)的痕量成分。