Spatial lithium quantification by backscattered electron microscopy coupled with energy-dispersive X-ray spectroscopy

The quantification of lithium in electron microscopes by energy-dispersive X-ray spectroscopy (EDS) is highly challenging due to the low energy of the characteristic X-rays. Only special windowless detectors can detect Li, yet the sensitivity is suboptimal (i.e., ~20 wt. %). We introduce the use of quantitative backscattered electron microscopy in combination with measurements using a standard EDS sensor to achieve spatially resolved quantification of Li. The method is demonstrated using two Mg-Li alloys with 4 and 20 wt. % Li and good accuracy with a deviation of only ~1.2 wt. % and ~2.5 wt. %, respectively, is achieved.