Theoretical model of phonon propagation in micro- and nanostructural materials
Peculiarities of the kinetics of weakly nonequilibrium thermal phonons (λph = 10−50 nm) in nanodispersed ceramics are investigated. The features of the phonon spectrum in the wavelength range λph ∼ Rg (where Rg is the average size of a ceramic grain) are studied. The conditions yielding the formation of a gap in the phonon spectrum of nanodispersed materials are analyzed. It is shown that the presence of inclusions with characteristic sizes smaller than the grain size of the parent ceramic material (pores, inclusions of other phases) shifts the gap toward the high-frequency range of the phonon spectrum. Peculiarities of the transport of nonequilibrium phonons during the transition from nano- to microdispersed sizes of the ceramic structure are analyzed.