Elemental Analysis ofContaminated Nuts
Jeffrey W. ElamArgonne National Laboratory
Ossy performed a high-temp vacuum bake of a frit-sealed glass base and sidewall
After the bake, there was contamination in the chamber – black deposits.
Ossy shipped contaminated nuts, along with clean nuts, to ANL for analysis
Jeff did EDAX (energy dispersive analysis of X-rays) in the SEM.
Background:
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Clean Contaminated with black residue
Nuts mounted to SEM stage using carbon tape
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SEM images of clean nut:
This entire field of view used for EDAX in the following slide
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EDAX of clean nut
Detail showing nice fit to Ag, Sn region (blue line) indicating we have only the elements indicated
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EDAX of clean nut
Neglecting the surface carbon contamination (I see this on virtually every sample unless I plasma clean) the clean nut is almost entirely Ag. Makes sense since it’s been silver coated.
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SEM images of dirty nut:
This entire field of view used for EDAX in the following slide
This patch is covered with white spots – I think this is one of the dark regions in the photo on slide 2
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EDAX of dirty nut
We see new elements on the dirty nut: Cu, Bi, Sn, Cr, Fe.We don’t see any Pb.The Cr and Fe might come from the steel.To me, the Bi is the most suspicious.
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More SEM, EDAX of dirty nut
Zoom in SEM so one of the white spots in slide 7 is now the entire field of view
Bi
Neglecting carbon, the white spots are mostly Bi9
Conclusion: the white spots in SEM (which are the black residue observed by eye) are mostly bismuth.
Is there bismuth in the frit?
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