So we were analyzing Polymers using DSC and calibrated the system using Indium. I expected it to be a single transition only as Indium only has 1 known crystal structure and as I never worked with DSC nor seen a real thermogram before I was quite surprised to a relatively large hysteresis between metling and recrystallizing. I expected it to be a big gap for polymers but for something as uniform as a metal with only one crystal structure it forms I thought the point of melting and crystallizing should be quite close together.
I remember the lecture on solid state chemistry about DSC's of crystals where Ehrenfest and displacive/reconstructive changes in for example quartz-phases had hysteresis and I think displacive ones didn't have any but it was never really explained what caused this gap. I always imagined that it takes more time to form a symmetry like going against entropy and this is why more energy has to be taken out of the system.
But is there a better explanation for pure metals? Does this gap tell me anything about the structure in the end? I imagine that structures which tend to me rather amorphous might have a smaller gap because it's not so much symmetry involved in the process which would then also imply why it is big (relatively, I haven't compared it to any other compound yet) for Indium.