paper

Thermal conductivity of perovskite KTaO3 and PbTiO3 from first principles

arXiv:1809.03936 · doi:10.1103/PhysRevMaterials.2.094408

Abstract

The low thermal conductivity of piezoelectric perovskites is a challenge for high power transducer applications. We report first principles calculations of the thermal conductivity of ferroelectric PbTiO $_{3}$ and the cubic nearly ferroelectric perovskite KTaO $_{3}$ . The calculated thermal conductivity of PbTiO $_{3}$ is much lower than that of KTaO $_{3}$ in accord with experiment. Analysis of the results shows that the reason for the low thermal conductivity of PbTiO $_{3}$ is the presence of low frequency optical phonons associated with the polar modes. These are less dispersive in PbTiO $_{3}$ , leading to a large three phonon scattering phase space. These differences between the two materials are associated with the $A$ -site driven ferroelectricity of PbTiO $_{3}$ in contrast to the $B$ -site driven near ferroelectricity of KTaO $_{3}$ . The results are discussed in the context of modification of the thermal conductivity of electroactive materials.