Zinc Sulfide

Hmmm

Most inorganic luminescent materials usually need to be calcined for many hours or even days anywhere from 600 to 1300 C. Have a kiln? Consult the US patent office at uspto.gov and do a search for fluorescent or luminous inorganic pigments. The europium doped alkaline earth aluminates fascinate me most.

[Edited on 11/23/2003 by chloric1]

If there's any newer thread, please merge it with this post. (can't believe last posts on this interesting subject are dated 2003 )


I was testing effects of some impurities on zinc sulfide and I found out that silver and strontium (as nitrates) and sodium (as chloride) don't do anything in particular.
My plan was to mix the powder in silicone grease and press it between two microscope slide covers, to make a scintilator.

Copper is the winner, and I used a grinded mixture of chloride, sulfate and the metallic powder itself, in minute quantities.

I've mixed zinc (reagent grade) and sulfur (technical grade) with the copper dopants, put it in a steel can, covered it with an asbestos mat and heated until a vigorous reaction has occured, which made the whole can glow intensively orange. The asbestos mat was to avoid the oxidation of the sulfide, and to catch the product as much as possible. Brilliant flame and smoke oozed beneath the mat and left some interesting bits for analysis.

What I've noticed is that not all of the product in the crucible glows with equal intensity under blacklight tube.
The most striking glow was exactly at the places where that flame and smoke were oozing out, depositing almost white flakes.
Actually, that white smoke is the key. Exactly that aerosol is the precious intensively phosphorescent matter, and it is usually wasted as it billows in the atmosphere.
Residues in the crucible are nothing compared to the stuff that is lost. That's probably the reason why ZnS is neglected by the amateurs - they don't catch the best part, and let it out.
And perhaps additional reaction with oxygen is needed, too.


You can see that the best glowing is around the edge.

The asbestos mat captured at least some of the powder that was flowing outside, and as you can see in this photo, the glow is striking.


I've tweaked the image to appear as I see it with my own eyes after the dust is charged by blacklight tube.
It's obvious that only the lightest particles which flowed outside glow the most.

The product is rather heterogenous. Maybe it has something to do with particle sizes.
Tomorrow I'm capturing the smoke in a long glass tube, calcinating the residues from the crucible in the absence of air and in air, and I'm grinding the rest to check for particle size effect.

So stay tuned...

I've did it. Though it wasn't very sucessful.

Grinding did nothing. It's useless.
Calcinating, whether it was done openly or in an tube reduced the phosphorescent properties. I've let it stay orange-hot and red hot for 5-10 minutes. Still hot compound won't glow at all, and when it cools down, its glow is a lot weaker compared to before.

I've tried to catch the smoke with a 1.5 meter long glass tube (somewhat similar to a very, very crude cromatography), and found out that only parts of it low appreciately, as you can see in this photo.


The colors are a bit messed up because the tube attenuates UV rays a bit, but the parts that glow are obvious.

It's puzzling. My current opinion is that ZnS doped with copper will glow well only if it's "forged in hell", but afterwards cooled at a fast rate. And traces of oxygen might help, too.

Quote: Originally posted by annaandherdad

When I was a teenager (early 1960's) I had a zinc sulfide scintillator as a part of a lab kit on radioactivity. It was a screen inside a plastic container with a lens you could look through. In those same years I took a course in qualitative analysis at the local college. We routinely made hydrogen sulfide and bubbled it through solutions (Pb etc) to get precipitates to identify compounds. I remember the teacher saying that hydrogen sulfide was poisonous, but it smelled so bad that no one had ever been known to be poisoned by it. In any case, we didn't worry about it during the lab, and, apart from that remark, neither did the teacher. The lab smelled bad, but no one died. Amazing how times have changed.

Quote: Originally posted by CrEaTiVePyroScience

http://www.youtube.com/watch?v=5HtNCdz8X3g = ZnS "synthesis" + reaction

Quote: Originally posted by White Yeti

I tried making zinc sulfide with zinc acetate and hydrogen sulfide, complete and utter failure. I did add a little copper acetate to the solution in attempt to "dope" it, so that wasn't the problem. I got a precipitate, but it didn't glow at all. I could try it again, I have a little aluminium sulfide left over.

This is a picture of Zinc Sulfide Phosphorescence. I am currently working on a instructional video of how to make this. Strong phosphorescence lasts for over a minute and the material weakly phosphorescence for hours.

Quote: Originally posted by Squall181

Did you fire the powder after precipitation? When you percipitate zinc sulfide from solution it is in its amorphous form. You have to heat it up to get it to crystallize and become phosphorescent.