Latent Heat of Phase Transition: Origin & Explanation

[g_mogni]

Hello,

We often hear about latent heat of vaporisation for a liquid, which basically corresponds to the energy required to break the hydrogen inter-molecular bonds in the liquid phase to form the gas. I was wondering, what is the equivalent physical explanation for the latent heat of a first-order solid-solid polymorphic pressure-induced phase transition between two solid phases (allotropes) of a crystal? Does it correspond to the difference in energy of the bonds in the two solid phases involved in the phase transition?

Many thanks,Gabriele

 

[DrDu]

Yes. Beside this I would expect a contribution from the phonons. This may be estimated using the Debye model. It will reflect the change in stiffness of the material