Sciencemadness Discussion Board

Can anything reasonably be done to improve Strontium Aluminate phosphorescense?

Junk_Enginerd - 21-8-2021 at 13:58

I bought a small amount of phosphorescent strontium aluminate off eBay, and I'm a little disappointed. I got the aquamarine color emitting sort, which supposedly has the longest duration of phosphorescense of the differently doped kinds. Up to 14 hours is what I've been reading. Even after charging with high power UV at 380 nm, reality is more like 10 minutes of rapidly fading intensity, and after 30-40 minutes nothing is visible even in pitch black darkness. Pretty underwhelming.

I know some basics about phosphors, like how minute amounts of contaminants can ruin them entirely. Is there anything I can do to make the best of what I have? Purify it? Recrystallize in some way? I'm guessing no, but it doesn't hurt to ask and hope for the best...

clearly_not_atara - 21-8-2021 at 19:28

Sorry you got burned, but the short answer is that purifying this stuff is the worst, because the major contaminant poison is iron, and as you might guess iron is fucking everywhere, including in many common varieties of lab glass. Basically get ready to do some serious process engineering if you want to get anything resembling a useful product. At that point you're basically making it from scratch anyway, so you might as well make more and send me some :D

UC235 - 21-8-2021 at 19:41

Phosphoresence isn't magic. You can only absorb so much energy. If it actually glowed uniformly for 8 hours, you wouldn't be able to see shit. Probably it has detectable phosphorescence for 14hrs using a photomultiplier tube. Apparently larger particles glow brighter as well, but it's produced with a thermal process and reheating it strongly will just destroy the properties.

This gives you an idea what to expect: https://cdn.shopify.com/s/files/1/1244/6186/files/Luminosity... They lose about 80% of initial intensity by the 10min mark and by an hour, they all drop off 20-40-fold from the intial brightness.

Junk_Enginerd - 22-8-2021 at 12:16

Quote: Originally posted by clearly_not_atara  
Sorry you got burned, but the short answer is that purifying this stuff is the worst,


Yeah I suspected as much. I watched NileRed or was it Nurdrage maybe make some ZnS and even with the very very thorough job he did purifying it, it was definitely inferior to commercial ZnS.
Quote: Originally posted by UC235  
Phosphoresence isn't magic. You can only absorb so much energy. If it actually glowed uniformly for 8 hours, you wouldn't be able to see shit. Probably it has detectable phosphorescence for 14hrs using a photomultiplier tube. Apparently larger particles glow brighter as well, but it's produced with a thermal process and reheating it strongly will just destroy the properties.

This gives you an idea what to expect: https://cdn.shopify.com/s/files/1/1244/6186/files/Luminosity... They lose about 80% of initial intensity by the 10min mark and by an hour, they all drop off 20-40-fold from the intial brightness.


No, I guess you're right. I do know better stuff exists though. My reference is some decent quality pacifiers our kids had, which glow in the dark. (Best thing ever btw, makes it easy to find them in the middle of the night.) In a dark room they have a decent glow for an hour or so, and it's definitely visible 4 hours later. Green phosphorescense on those, and I read that the blue glowing phosphor is the longest lasting.

Twospoons - 22-8-2021 at 12:31

Seems like you really did luck out - or you got scammed by the seller. I bought some many years ago from China and its glow time was amazing - the glow from the blue-green one was clearly visible at least 6 hours in the dark.