Reduction of electron channeling in EDS using precession

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.

► PED significantly reduces electron channeling effects under strong diffraction conditions such as zone axis and two-beam conditions.
► For the [0 0 1] zone axis, the Sr/Ti ratio measured using EDS was consistently ∼0.99 when the precession angle greater than 22.54 mRad.
► For ALCHEMI-like experiments, the channeling effects were largely suppressed when at a higher angle of 47.48 mRad.