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KarlSethMoran t1_j9ab9tm wrote on February 20, 2023 at 1:38 PM

Reply to comment by nerdguy1138 in When something is bent (a metal ruler for example) and returns to its original shape, what is happening on the molecular level? Where is the information of the original shape stored and what forces do the unbending? by JewNugget2525

At low temperatures the thermal energy is too low to overcome the activation energy barrier required for the defect to migrate.

Coomb t1_j9avh94 wrote on February 20, 2023 at 4:10 PM

It's more fundamental than that. A crystal with a defect has higher entropy than a crystal without any defects. For defects up to a particular number N (variable based on the crystal material and temperature and crystal size and so on), the Gibbs free energy released by defect formation (usually for simplicity's sake taken to be a vacancy) is larger than the energy consumed to generate the vacancy and the defects form spontaneously.

Only at absolute zero can a crystal be perfect.

KarlSethMoran t1_j9b56m6 wrote on February 20, 2023 at 5:14 PM

Thanks for the correction.