Some processes like diffusion or conductivity can be phonon assisted. Discussing this in the light of the Meyer-Neldel (compensation) rule, which is due to multi-phonon processes according to the description by Yelon and Movaghar, how do I determine in which case the multi-phonon processes are predominantly due to optical or acoustic phonons?
Dear Albert
As you may know the thermal conductivity of non-metals also carbon base materials like CNTs, graphene, ... and semiconductors is dominated by phonons. Among the acoustic and optical phonons, the acoustic one (because of their greater group velocity) are responsible for thermal conductivity in the mentioned materials. It is plausible to say that the contribution of optical phonons in the thermal conductivity increases as temperature rises.
Hi Sayyed,
Thank you. Do you in which cases acoustic phonons could participate in electron conductivity, and how does one determine this?
I can not understand you on "electron conductivity", do you mean electron thermal conductivity or electrical conductivity? However the phonons have zero contribution both in electron thermal conductivity or electrical conductivity, just in lattice thermal conductivity.
Dear Ehsan
I totally agree with your Complementing talk, but as you know better than me phonon assisted electrical conductivity in semiconductors is significant at the present of an external field. However thank you for your helpful comment.
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