Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA.
Ultramicroscopy. 2013 Mar;126:19-22. doi: 10.1016/j.ultramic.2012.11.007. Epub 2012 Nov 23.
We demonstrated that EDS measurement can be significantly improved by precessing the electron beam, thereby reducing electron channeling effects. For a SrTiO3 specimen orientated along the [001] zone axis, the measured strontium to titanium atomic ratio was 0.74-0.80 using conventional EDS methods, and the ratio was improved to ~0.99 by precessing the electron beam for angles greater than 22.54 mRad. In ALCHEMI-like experiments in which the specimen was tilted to near two-beam condition, the strontium to titanium ratio was insensitive to the deviation from the Bragg condition using a precessed electron beam. Similar reduction of electron channeling effects was also observed in precession-assisted EDS measurements for an L21-ordered Fe2MnAl intermetallic alloy tilted to the [011] zone axis as well as near two-beam conditions.
我们证明了通过使电子束进动，可以显著提高 EDS 测量的精度，从而减少电子通道效应。对于沿[001]晶带轴取向的 SrTiO3 样品，使用常规 EDS 方法测量的锶钛原子比为 0.74-0.80，而通过使电子束进动大于 22.54 mRad 的角度，比值提高到约 0.99。在类似于 ALCHEMI 的实验中，当样品倾斜至接近双束条件时，使用进动电子束时，锶钛比对偏离布拉格条件不敏感。在倾斜至[011]晶带轴以及接近双束条件的 L21 有序 Fe2MnAl 金属间化合物合金的进动辅助 EDS 测量中，也观察到类似的电子通道效应的减少。
