Spectral heat flux redistribution upon interfacial transmission

Area of Science:

• Solid-state physics
• Thermal transport phenomena

Background:

• Heat in nonmetallic crystals is carried by phonons of various frequencies.
• Each phonon frequency contributes uniquely to the total heat flux spectrum.

Purpose of the Study:

• To investigate heat flux redistribution among phonon frequencies at interfaces between dissimilar solids.
• To explore how interface structures affect phonon frequency distributions.

Main Methods:

• Analysis of phonon frequency redistribution across material interfaces.
• Examination of heat flux spectra in bulk materials, superlattices, and sandwich structures.

Main Results:

• Significant redistribution of heat flux among phonon frequencies occurs at dissimilar solid interfaces.
• In superlattices with layer thicknesses below phonon mean free paths, heat flux spectra of dissimilar solids become nearly identical.
• Phonon frequency redistribution to bulk characteristics develops over distances comparable to phonon mean free paths.

Conclusions:

• Interface interactions significantly alter phonon frequency contributions to heat transport.
• Superlattice structures can homogenize heat flux spectra despite material dissimilarities.
• The development of bulk-like phonon distributions is a distance-dependent process, not instantaneous at the interface.