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Author: Subject: Triboluminescent crystals
chemx01
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[*] posted on 5-9-2012 at 10:01
Triboluminescent crystals


Recently I got quite large amounts of europium and dysprosium oxides so I decided to prepare nitrates and then triboluminescent crystals.
I proceeded per instructions in Nurdrage's video but I used methanol instead of ethanol since i have large amounts of that.
But the results weren't very good here's the procedure I used:

In 50ml of sodium dried MeOH was dissolved 1,47g of dibenzoylmethane (at r.t. no need to heat). Than 0,7g of Eu(NO3)3*5H2O and 0,8ml TEA (dried). The solution was left in dewar overnight, small amount of crystals separated, then i put the solution in -18°C freezer for 10 hours and filtered and washed the crystals with ice cold MeOH (2x 3ml) and dried the crystals under vacuum. I obtained 1,16g of needle like crystals. They exhibited strong luminescence under UV, but when smashed the light wasn't very visible.

I guess the crystals were too small, but i found some articles which explores the solvent effect on the synthesis and it was found there is no need for dry or pure solvents, in fact was found there is better luminescent yield in acetone than pure EtOH or MeOH. But I don't have the acces to the full article so I would kindly ask anyone who has acces to it for posting it here.

The free article:
http://ma.ecsdl.org/content/MA2012-02/57/3906.full.pdf

The article I need:
http://pubs.rsc.org/en/content/articlelanding/2012/ce/c2ce06...

[Edited on 5-9-2012 by chemx01]
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unionised
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[*] posted on 5-9-2012 at 10:06


I did that synthesis a long time ago.
I didn't get very good crystals but I found that if you put them between two glass dishes - (the sort that get called watch glasses) and ground them in a totally dark room you could see the luminescence.
You need to let your eyes get fully used to the dark first.
It's hard to be certain after so long, but I think I used acetone or butanone as the solvent.
Another point, are you using TEA
http://en.wikipedia.org/wiki/Triethylamine
or
TEA
http://en.wikipedia.org/wiki/Triethanolamine
?


Can I ask where you got the dibenzoylmethane from?


[Edited on 5-9-12 by unionised]

[Edited on 5-9-12 by unionised]
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mineralman
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[*] posted on 5-9-2012 at 10:20


Can it be extracted from sunscreen? or better still, baught for its UV absorbing properties legaly.
Or is it a listed chemical.

[Edited on 5-9-2012 by mineralman]
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chemx01
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[*] posted on 5-9-2012 at 10:22


Thank you for the watchglass idea I'll try that.
I used triethylamine dried by KOH and distilled from Na.

I prepared the dibenzoylmethane i'm going to post the video, I initially wanted to post together with the triboluminescent crystals, but since they didn't work very well I'll post them separatly. I haven't uploaded any videos in a while.

If I get my hands on the article about solvent effects I'll prepare the triboluminescent crystals according to the procedure.
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MrHomeScientist
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[*] posted on 5-9-2012 at 10:25


I just recently made these crystals following the procedure Nurdrage used, with dry ethanol as the solvent. Everything worked beautifully, no problems at all during synthesis. I recovered 2.6g of crystals, which were very brightly fluorescent and flashed orange when smashed. The flashes can easily be seen in a somewhat dim room, no need for total darkness or to let your eyes adjust at all. It sounds to me like the solvent does indeed play a role in the performance of the crystals, since both of you substituted for different ones.

The really interesting part was recrystallizing. I dissolved my 2.6g of (now mostly powdered) product into 100mL of fresh ethanol, heating to near boiling before everything dissolved, and let it cool slowly by wrapping the flask in styrofoam and placing it in a styrofoam cooler. I harvested the crystals at room temperature, then placed the flask in the fridge to gather a second crop. I only recovered 1.5g of crystals total. That's a 42% loss!

I even tried boiling the solution down to 1/4 the volume and nothing at all precipitated! I took the remaining 25mL and let it evaporate on its own in a Petri dish, and all this produced was a bright yellow "slime" that didn't luminesce at all. What happened to my crystals? The only thing I can think is they get decomposed if the solution is overheated.
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[*] posted on 5-9-2012 at 11:12


@Mr Home Scientist- Clearly you squished them too hard.
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haroldramis
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[*] posted on 6-9-2012 at 09:58


Where did you get large amounts of Eu and Dy Oxides? That is a nice find, they are insanely expensive at the vanishingly few places I know that will sell small amounts.

Did they dissolve easily in the HNO3?

What about the Triethylamine? Any hobby friendly US retailers that have it?

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chemx01
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[*] posted on 8-9-2012 at 00:33


@haroldramis -
I got them from a chemical stockroom which because of REACH and similar laws had to be cleaned. I got many interesting chemicals including large amounts of rare earth metal oxides (samarium, dysprosium, europium, praseodymium Lanthanium etc..) 100g or more of each.

The europium oxide dissolved well, the reaction was very vigorous. On the other hand dysprosium oxide didn't dissolve very well and when I heated the suspension it bumped and sprayed HNO3 (it was only a test batch 5ml of HNO3) so it wasn't very serious.


The promised video about dibenzoylmethane synthesis is here:
http://www.youtube.com/watch?v=qZmAdC9Ln58&feature=plcp
About TEA, I'm not situated in USA so I have no idea.

[Edited on 8-9-2012 by chemx01]
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