Radioluminescence and differing zinc sulfide preparations?

  • Thread starter Positronix
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Summary:
I know zinc sulfide products are "doped" or "activated" with copper and/or silver, but how do some avoid afterglow after light exposure (and other considerations)?
It's all over the internet, the epidermis-deep explanation of radioluminescent zinc sulfide, "doped" or "activated" with copper (green) and/or silver (blue), being the phosphor that people mixed with radium salts (perhaps radium-doped barium or something with a bit more bulk for managability and safety) in order to produce glowing digits and things that perpetually fluoresced without need for a light source or "charging".

What I don't understand, though, is when you look at different copper and/or silver-activated phosphors (afterglow type, electroluminecent, radioluminescent etc.), they differ in behavior but not really in their basic description such as "cu-doped ZnS".

For example, electroluminescent devices might have a tiny bit of afterglow after you turn out the lights for a minute, but nothing substantial when compared to vintage glow in the dark halloween decorations (before the age of strontium aluminate or whatever) yet both products say they contain the same thing: copper-doped or activated zinc sulfide.

I just bought some copper-doped zinc sulfide and it has a ton of afterglow for many minutes after exposure to even weak, indoor lighting.
Yet United Nuclear sells a more expensive zinc sulfide (they activated it with both copper and silver for maxiumum radioluminescent performance) which reportedly has essentially zero afterglow after exposure to sunlight.

Question 1: What is the difference in how these are prepared? The temperature at which they are quenched with the activators? The method by which they are introduced?

Question 2: Should one or the other perform better as a radioluminescent phosphor?

Notes:
I can certainly see the convenience of having no afterglow if you are strictly trying to build a spinthariscope or detect scintillation, but I did notice an americium-treated pellet causing the cheap kind of halloween cu-doped ZnS to fluoresce a little. It took letting my eyes adjust to the darkness and a magnification lens (and shield!) to see it, but I'm told it's similar in that way even if you buy the expensive activated ZnS (you just don't have to handle it in the dark to prevent the light-charged afterglow).

But I'm yet to test them side by side to see which works better -- activated ZnS that has afterglow vs. premium stuff meant strictly for radioluminescence. The stuff activated with both silver and copper has an unfair advantage; I know ZnS activated with just copper and not silver was widely used with radium, and/but there was no worry about afterglow since it was just added luminosity in a clock.

*** Also -- United Nuclear says the non-afterglowing, radioluminescent activated ZnS they sell responds to alpha radiation. I would hope it also responds to beta. Tritium illuminates whatever phosphor used in exits signs purely with beta emissions -- and very low-energy ones at that!

Thank you for your time and attention!
Positronic Jeff
"I was injected with antimatter and wasn't annihilated (I shot it back at the scientists)!"#PET scan
 
Last edited:

Answers and Replies

  • #2
DrDu
Science Advisor
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Are you familiar with the concepts Fluorescence and Phosphorescence?
 

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