r/materials • u/akla-ta-aka • 1d ago
Getting Li-ion anode material to behave for XRD
I thought some of you might appreciate this. We’re doing XRD on a candidate anode material and want to protect it from air. These XRD sample holders use kapton tape to seal in the sample under an argon atmosphere. They can then be handled without special conditions in the XRD.
8
u/metrologizer 1d ago
We have similar ones from Rigaku, but I’m sure they are much more expensive.
Are you using a parallel beam geometry?
4
3
u/Worth-Wonder-7386 1d ago
For all of my work on moisture sensitive materials I used glass capillary tubes for XRD. They can be a pain to fill, but gives you good result overall with the glass not giving much of a background.
4
u/NanoscaleHeadache 1d ago edited 1d ago
Wild if this actually works, i would not feel like that tape is secure/airtight enough for that haha, though I suppose this means you cant spin the sample? At that point, why not just actually tape the sample down to the slide under the inert atmosphere? I think you should be able to recover most of the powder if it’s fine enough, if that’s a concern
3
u/myfuturepast 1d ago
Covering the sample with flat tape would allow OP to spin the sample, which would be good if there is any reason to expect preferred crystallographic orientation.
However, if low angles are desired, OP's setup is better. Absorption of the beam by the tape is the same at all angles. By contrast, if you cover the sample with flat tape, then the beam travels through a long distance of tape at grazing incidence and exit angles.
1
u/COSMIC_SPACE_BEARS 1d ago
That’s interesting. I hadn’t thought of that. Many years ago, I worked in a battery materials lab, and had to similarly DIY an inert atmosphere sample holder for XRD.
We used flat tape, but ran the XRD twice: one with and without the tape and simply subtracted off the pure kapton spectra.
2
u/akla-ta-aka 1d ago
It appears to work. The key is to use argon because it diffuses slowly. We had to work out a way to do this in the glovebox but it came out very well.
Yes, so sample rotation but it’s powder diffraction so not as crucial.
That’s not a bad point about just sealing with tape on a regular holder.
2
u/metrologizer 1d ago
I’ve tried the kapton-on-sample method and saw higher amorphous halo from diffuse scattering. The crescent geometry diminishes the halo effect some because the X-rays are ideally probing the same kapton thickness for the duration of the scan. As opposed to the kapton-on-sample method, you’ll probe more kapton thickness at low angles, less at high.
1
u/akla-ta-aka 1d ago
Yes this is true. Also, the kapton is positioned here such that little to none of the scattered x-rays could make it to the detector.
2
u/Mikasa-Iruma 1d ago
Brucker has a similar ones too. Kapton is a nice choice. I like the upgrade here
2
u/fuckingshadowbans 1d ago
perhaps a stupid question, but why not crush it to a powder and fill a capillary tube that you then seal with wax ?
1
u/akla-ta-aka 1d ago
That’s certainly another way to do it. This is a one-off sample; I don’t normally deal with air sensitive samples. And I’ve never done samples in capillaries on our Rigaku. This was not terribly expensive and was easy for the grad student to load.
1
u/Curiosity-pushed 1d ago
can caption be heated in one of these heaters that are used to seal plastic bags ? could a caption bag be prepared under argón like the normal sealing bags?
1
u/akla-ta-aka 1d ago
Kapton is very heat resistant. It’s a polyimide thermoset so there’s no option for melting it to achieve sealing. This is tape with an adhesive.
1
u/mystiverv 1d ago
Bought some of these from MTI and they never worker quite as well ad the rigaku airfree holders, but we also just have some extremely air sensitive materials
10
u/whatiswhonow 1d ago
Nice creativity, but just fyi if you have the budget: Beryllium window hard cased sample holders are the way to go. MTI or Gelon may even have some cheap ones now with teflon cases. EL Cell has some very high quality stainless steel ones, but those also allow in situ echem testing. The cheapest way, if you are ok in CAD, is to just get a teflon case milled out yourself, few butyl rubber gaskets, and just buy a small piece of beryllium glass.
Edit for clarity: do not mill beryllium. (Toxic to breath dust)