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Author: Subject: Rare earth flash powders!
Brain&Force
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[*] posted on 23-6-2015 at 14:01
Rare earth flash powders!


I shot a video for Dornier 335A's channel, with dysprosium, samarium, and ytterbium-PTFE flash powders. To my knowledge this is the first time they have been publicly uploaded to YouTube.

<iframe sandbox width="560" height="315" src="https://www.youtube.com/embed/O3lHX-ayzDQ" frameborder="0" allowfullscreen></iframe>

However, one question sticks out to me: how does the ytterbium metal flash end up being so green? From what I have seen most metal powders burn a yellowish color, including most of the rare earths. Only samarium comes somewhere close, with a rosy spark color, and so does zinc, which has a bluish-green flame (though the individual sparks are yellowish). Ytterbium sparks, in contrast, are truly green - but not all of the time.




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blogfast25
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[*] posted on 23-6-2015 at 14:11


Nice. But I don't see a great point to it, sorry.



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[*] posted on 23-6-2015 at 14:18


According to the attached paper, the green combustion color is due to the emission of both ytterbium fluoride (YbF) and ytterbium hydroxide (YbOH) formed in the combustion products.

Dany.

Attachment: 4f metals as flare fuels.pdf (1.4MB)
This file has been downloaded 779 times

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Fulmen
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[*] posted on 23-6-2015 at 14:25


I'm guessing gaseous ytterbium fluoride. Most metals produce solid oxides in air, producing black body radiation. The fluorine in teflon has the same effect as chlorine donors in other pyrotechnics.



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j_sum1
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[*] posted on 23-6-2015 at 15:07


This has come up before in the "bad habits in the lab" thread. There are quite a few of us who set fire to things on the lab floor.

As for blogfast's comment: Maybe this is not the most practical thing to do, but it ain't bad. I would never have thought of Ytterbium as having green sparks. And now I know. And thanks to Dany, have a paper to back it up. It is what experimenting and learning is about. Don't be a wet blanket, bloggers.
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violet sin
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[*] posted on 23-6-2015 at 15:12


nice work there :) always a fan of Dornier 335A's work my self, and I bet it's rewarding to add content to youtube instead of just posting better/worse vids of the same 'ole stuff. the colors are pretty cool, though honestly, I don't know enough about the metals to be surprised or not.

I wanted to work with him on some stuff in the past, but cali laws aren't too friendly on pyro + REALLY hot/dry summers + vid proof posted = nope. years back, but iirc we were discussing dragons egg compositions and ferrocerium flash. (dragons egg https://en.wikipedia.org/wiki/Dragon%27s_egg ). I wasn't good enough of an amateur chemist to do it all by paper chasing, and experimenting at home was no good after a loud report from less than half a gram flash powder woke some neighbors. probably under a quarter gram, but I lacking any equipment to test this, rough estimation on the heavy side seemed prudent. that was just standard permanganate/Al, so I disposed of the other ferrocerium samples with out testing. learning is great, but freedom is more important. one thing I liked was his small scale tests, something I couldn't do. crossed pyro off the list long ago for better or worse. sorry for the descent into random.

you have any more vids coming up? I'll keep an eye out. what source of teflon did you use, and how was it prepared? just out of curiosity, I have heard of people grinding up plumbers tape, but wondered if you used a more standardized source. also, what size did your test samples range in?

* just noticed in the comments, you had some more ideas ahead. cool beans
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[*] posted on 23-6-2015 at 15:39


Quote: Originally posted by j_sum1  
Don't be a wet blanket, bloggers.


You calling me a wet blanket, Squire?!

Daggers or pistols? :D




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Brain&Force
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[*] posted on 23-6-2015 at 19:09


Quote: Originally posted by blogfast25  
Nice. But I don't see a great point to it, sorry.


I never had a point to this :P

Quote: Originally posted by Dany  
According to the attached paper, the green combustion color is due to the emission of both ytterbium fluoride (YbF) and ytterbium hydroxide (YbOH) formed in the combustion products.

Dany.


Thanks for the paper! I've been looking for something like this, as I've been meaning to work with other rare earth metals.

violetsin, I used filed ytterbium, samarium, and dysprosium wrapped in plumber's tape (use an excess of the metal for optimum results).




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[*] posted on 23-6-2015 at 19:49


Quote: Originally posted by blogfast25  
Daggers or pistols? :D

Both.

At dawn.


And I rest assured in the knowledge that dawn for you is at an entirely different time from my dawn.
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