Elementary excitation in the quantum mechanical treatment of vibrations in a crystal lattice. An energy bundle that behaves as a particle of energy \(h\ \nu \), with \(\nu \) the vibration frequency and \(h\) the @P04685@.
- A phonon can be considered as an acoustic @M03958@ of thermal vibration of a crystal lattice (or liquid helium II).
- Every harmonic vibration can be decomposed in phonons, which are the elementary vibrations. The total number of phonons in a system that has internal vibrations (e.g., a crystal) is related to the temperature of the system.
- The concept of phonons provides a simplification in the theories of thermal and electrical conduction in solids.
- For example, interactions between phonons and electrons are thought to be responsible for such phenomena as 'superconductivity'.