Lithium Detection in a Binary Al-20 wt% Li Alloy Powder with a New Windowless SDD EDS Detector and EELS

Experimental Evaluation of Lithium Detection Limits by Windowless SDD EDXS and EELS in a Binary Al-Li Alloy Powder

“…In this work, we report on identification of lithium detection limits evaluated by windowless SDD EDXS and electron energy-loss spectroscopy (EELS) in a commercial Al-Li alloy (Li mass fraction of 20 %) powder [2]. Prior to EDX analyses with a windowless SDD EDXS detector installed on a dual beam focused ion beam scanning electron microscope (FIB)/SEM), the microstructure and local chemical compositions of the powders were characterized using low-voltage field-emission SEM, conventional and phase-contrast high-resolution transmission EM (CTEM/HRTEM), and high-angle annular dark-field scanning TEM (HAADF STEM).…”

“…1d). The challenge for EDXS analysis is that, in X-ray spectra of the powders, the analyzed peaks are not resolved since the Li Ka (55 eV) X-ray peak and Al L2,3 (72 eV) X-ray peak are only separated by 17 eV [1,2]. In the EDX spectra acquired from fresh cross-sections of the Al-Li alloy microparticles milled in the FIB, the unresolved asymmetric Li Kα + Al L2,3 peak is centered at ~70 eV, while the Li Kα peak is centered at 59 eV ( Fig.…”

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Spatially-resolved nanoscale detection and quantification of lithium in emerging materials are critical for such key technology application areas as renewable energy, transportation, aerospace, organic synthesis and pharmacy. Li is the lightest element that can generate characteristic X-rays by electron interaction, but >99% of Li X-ray photons are expected to be absorbed in a 0.3 µm thick polymer window [1,2]. Windowless silicon drift (SDD) energy-dispersive X-ray (EDX) detectors with low-noise electronics and more efficient geometry designed to collect X-rays under low-kV conditions down to 20 eV have advanced ultra-soft X-ray light element analysis by eliminating the absorption of Li Ka and other soft X-rays.

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“…Windowless silicon drift (SDD) energy-dispersive X-ray (EDX) detectors with low-noise electronics and more efficient geometry designed to collect X-rays under low-kV conditions down to 20 eV have advanced ultra-soft X-ray light element analysis by eliminating the absorption of Li Ka and other soft X-rays. Although lithium detection in Li metal foils by SDD EDXS was demonstrated recently [1, 2], detection challenges remain [2,3]. Li and its compounds are often highly reactive and, upon being exposed to air, readily react with it.…”