Origin of Pyroelectricity in LiNbO3

TL;DR

This study uses molecular dynamics simulations to elucidate the primary mechanisms behind pyroelectricity in lithium niobate, highlighting the roles of anharmonic structural changes and effective charges, and suggests new experimental and optimization routes.

Contribution

It demonstrates that pyroelectricity in LiNbO3 is mainly due to anharmonic structural changes and effective charges, providing a new perspective and experimental approach for studying pyroelectric materials.

Findings

Primary pyroelectric effect dominates in LiNbO3.

Pyroelectricity can be understood from anharmonic structural changes and Born effective charges.

Pressure influences pyroelectricity and electrocaloric effects near Tc.

Abstract

We use molecular dynamics with a first-principles based shell model potential to study pyroelec- tricity in lithium niobate. We find that the primary pyroelectric effect is dominant, and pyroelec- tricity can be understood simply from the anharmonic change in crystal structure with temperature and the Born effective charges on the ions. This opens a new experimental route to studying py- roelectricity, as candidate pyroelectric materials can be studied with X-ray diffraction as a function of temperature in conjunction with theoretical effective charges. We also predict an appreciable pressure effect on pyroelectricity, which could be used to optimize materials pyroelectricity, and the converse electrocaloric effect, peak as Tc is approached.