I work at a university. Shortly after a major terror incident, long ago, we needed a phosphor for an experiment. At the time, sales of certain items was highly restricted (quietly) until further notice and we could not get a short persistence phosphor by any commercial means. Common ZnS:cu was out the question for the prof's experiment. So I requested a text on the production of phosphors by intra-library loan. Knowing that there might come a day when I might need to make a batch, I photocopied some of the materials that looked easy to produce and did not need exotic dopants. Below data is from my notes. This sounds easy, in reality results are only as good as your materials and techniques, but you need a lab furnace to pull it off..
Prep of these materials, from what I have read, (and tried!) require very pure starting materials and extremely hot ovens filled with hard to make gas mixtures. For example, the book method of purifying the sulfur goes like this: Ideally you would dissolve the Sulfur in Carbon Disulfide, precipitate it using acetone, and wash that incredibly toxic mess using a filter paper lined funnel, etc... If you really want this to work well, you would start with semiconductor grade chemicals... etc..
So here is the method for one that fires at a mere 900'C, uses fairly common stuff, and according to the book, works with short UV, long UV, and e-beam excitation. Broadband green emission centered around 500 nm with no sidebands according to the spectrum.
900'C is good, because most of these "easy" materials ls do not start to fuse until 1100'C or higher, which is above the limits you can hit with Nichrome based ovens. Note that you need 900'C final temperature with no more then 20'C overshoot for an hour or more. This one is unique because of its high dopant concentration, making it less of a hit or miss proposition for home brew.
As your using Sulfur and a tiny bit of Carbon Monoxide to make this, its an outdoor project, not to be cooked inside unless your at work with a fume hood. This will smell nasty during fabrication. In other words, kids don't try this at home or indoors..
Zinc Oxide is used in Sun Screen, is very inert, which is why I selected this methodology for posting here. Most of the other materials you can use are very toxic and hard to get.
The raw materials need ball milled in a alcohol slurry or in a mortar and pestle for a very long time. The author suggests ceramic balls for milling to avoid trace metals that may poison the emission.
You need a Quartz furnace tube open at one end, one quartz boat for said furnace tube, two quartz test tubes, one that slides into the other. a proper high temperature cork , a thin quartz tube with a closable rubber feed tube, and tank O2... You'll also need finely powdered activated charcoal to make the CO environment.
ZnO:S phosphor
Zinc Oxide 81 Grams
Sulfur 0.064 grams
After mixing, grinding, slurry process, and drying, place the mixture in the very clean small diameter quartz test tube. Slide the small tube into the larger test tube to form a loosely sealed capsule. Push the loaded tube assembly down to the end of the furnace tube with a quartz rod.
Fill the quartz boat with a few tens of grams of carbon powder, then place a plug of quartz wool in the cold end of the tube to slow or block gas diffusing into the hot zone as much as possible.
Stick the thin quartz tube into the stopper and seal the furnace tube with the stopper. Back fill and flush the furnace tube with Oxygen using the thin tube, to displace Nitrogen, which blocks the reaction.
Cap the fill tube with rubber tubing and close it off with a tubing clamp. Make sure there is a tiny hole in the stopper for a little air to diffuse in and to prevent pressure buildup.
The O2 flow is OFF once the oven starts to heat up, the idea being that the charcoal dust slowly burns away to create a reducing atmosphere of Carbon Monoxide in the tube... If you leave the O2 on, you will just have a burnt mess or a possible risk of fire due to hot O2 escaping the furnace.
Fire for one hour at 900'C ... Cool slowly. Book says if you want to shift emission towards the blue, replace 20% of the ZnO with Magnesium Oxide, but I have not tried that version.
UV efficiency is supposed to be ~60%. Persistance is 1 to 10 microseconds....
According to the book, you can fire this one, check its uniformity, and if needed, re-fire it in the reducing atmosphere after another grinding.
DISCLAIMERS AND WARNINGS:
Quality production of the material using these 1940s techniques is a bit of hit or miss. Your mileage may vary.... High temperature ovens and Oxygen are a bit dangerous if you have never worked with them together... Buying raw sulfur will put you on the "radar" of certain government groups. Carbon Disulfide is poisonous and nasty, and dissolves most containers.. Unless I worked in a chemistry lab, I'd skip that step. Never use Carbon Disulfide at home, if you can even get it.
Nurdrage has a video on home made phosphors, and so does Ms. Ellsworth...
https://www.youtube.com/watch?annotation_id=annotation_732376&feature=iv&src_vid=pmQqdYrn9g8&v=veOiHb-KuSEREF:
Zink Oxide and Zinc Cadmium Oxide Phosphors, Journal of the Electrochemistry Society, Lehmann, W, Volume 115, Page 538, (1968)
Steve