Lattice dynamics in the paraelectric phase of PbHfO$_3$ studied by inelastic X-ray scattering

TL;DR

This study investigates the lattice dynamics of PbHfO$_3$ in its paraelectric phase using inelastic X-ray scattering, revealing phonon mode interactions and susceptibility changes relevant to its antiferroelectric properties.

Contribution

It provides new insights into phonon interactions and susceptibility behavior in PbHfO$_3$, comparing its lattice dynamics with PbZrO$_3$ using advanced scattering techniques.

Findings

Avoided crossing between transverse acoustic and optic phonons.

Susceptibility increases with cooling along the $ ext{Γ}$-M direction.

Differences and similarities with PbZrO$_3$ lattice dynamics.

Abstract

We report the results of an inelastic X-ray scattering study of the lattice dynamics in the paraelectric phase of the antiferroelectric lead hafnate PbHfO$_3$. The study reveals an avoided crossing between the transverse acoustic and transverse optic phonon modes propagating along the [1 1 0] direction with [1 -1 0] polarization. The static susceptibility with respect to the generally incommensurate modulations is shown to increase on cooling for the entire $\Gamma$-M direction. We consider different approaches to the data analysis that correspond to different models for the temperature evolution of the dynamic susceptibility function. A number of similarities and differences between the lattice dynamics of PbHfO$_3$ and PbZrO$_3$ are described.