Phonon thermal conduction near perfect and extended edge dislocations in strontium titanate

Abstract

Modifications of phonon thermal conduction by perfect and extended edge dislocations in SrTiO₃ have been numerically analyzed. SrTiO₃ has a unique feature that Ti and O atoms, which form optical phonon modes at intermediate and high frequencies, dominates thermal conduction rather than Sr atoms. Dislocations reduce thermal conductivity through introducing spatial inhomogeneity, that is, nonuniform Ti–O bond strains in the network of TiO₆ octahedra. Due to the different spatial distributions of Ti–O bond strains, an extended dislocation with partial dislocations and stacking faults has a different mechanism of phonon scattering compared with perfect dislocations. The dislocations scatter phonons, most significantly for acoustic phonons, almost eliminating their contributions to thermal conduction. Consequently, optical phonons of Ti and O atoms at intermediate frequencies dominate thermal conduction when dislocations are present in SrTiO₃.