Thermal conductivity of perovskite KTaO3 and PbTiO3 from first principles

TL;DR

This study uses first principles calculations to compare the thermal conductivity of ferroelectric PbTiO3 and nearly ferroelectric KTaO3, revealing the influence of phonon behavior and ferroelectric mechanisms on heat transport.

Contribution

It provides the first computational analysis of thermal conductivity differences between PbTiO3 and KTaO3, linking phonon properties to ferroelectric characteristics.

Findings

PbTiO3 has significantly lower thermal conductivity than KTaO3.

Low frequency optical phonons in PbTiO3 cause increased phonon scattering.

Ferroelectric mechanism influences phonon dispersiveness and thermal transport.

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.