tin pest, transformation of beta tin into alpha modification (grey tin)
Why Chemistry Stack Exchange recommends it
Chemistry Stack Exchange answerers link it as a quick visual demonstration of the beta-to-alpha tin phase change, in answers about tin allotropes, seed-crystal phase transitions and expansion on cooling.
Recommended by 1 people across 1 different months, 2015 to 2025.
What it is
A 23-second time-lapse of a tin sample held at -40 C, showing beta (white) tin crumbling into alpha (grey) tin, a process known as tin pest. Each second of video equals one hour of real time, shot against a 1 cm grid, and it comes from the periodictable.ru channel.
What people said
Recommends Jason Patterson · 2015-02 · Chemistry Stack Exchange · on “Can powdered beta-tin be made from raising the temperature of alpha-tin?”
I'd love to know; this seems like it would make an amazing demonstration. All I can find is that reheating will convert the tin back into its beta form. I imagine that would happen below its melting point at 231 C, but I don't know for sure. As long as it did, you'd wind up with tin powder. Really cool 20 second video of this, for anyone interested. [this video]
Cites Dale · 2015-02 · Chemistry Stack Exchange · on “Can powdered beta-tin be made from raising the temperature of alpha-tin?”
Phase changes are fickle. Much like supersaturated solutions. Add a crystal to a supersaturated solution and it will precipitate rapidly. Bring a crystal of the thermodynamically favorable phase into contact with a "supersaturated" phase and it may just do this: [this video] I am not sure how exactly the proceedure in the video was done, so do not take it as evidence that my statement is true. Also, Diamond is stable well below its phase transition temperature. Surely there are other compounds like that.
Cites Nicolau Saker Neto · 2015-09 · Chemistry Stack Exchange · on “Freezing all the water on earth with a seed crystal”
A precise physical argument against the existence of an Ice-9 -like state of water is probably not trivial ( ab initio methods required?). However, there is a simple but powerful argument against it; we haven't found anything like it yet. Water is a very common substance, and humans have been applying the scientific method to it for hundreds of years, humans have manipulated it for hundreds of thousands of years, but most importantly, the entire Earth has been churning massive amounts of water around for billions of years. If an Ice-9 -like state of water did exist, we should have seen it by now. To be clear, superficially this argument may seem to be a fallacious argument from ignorance [LI
Cites Kevin Kostlan · 2025-07 · Chemistry Stack Exchange · on “Does water expand on freezing more than any other known substance?”
Tin Tin may win hands down if you generalize this question: What is the most expansion possible for any chemical substance(s) when cooled two between any two given temperatures. Allowing for reversible phase changes, chemical equilibria, conformation isomerism, or any similar process at a fixed pressure. Water freezing from 4C to -0.0 C very slightly beats out freezing itself since water starts expanding slightly once it's cooled below 4C. Silicon is still better and is best for small $\Delta T$ values across it's melting point. But tin is in a league of this own . Tin expands from 7.28 to 5.74 g/cm^3 as temperature is lowered past 13C. A 20% drop with dramatic [this video] results. It requires h