# Electrocaloric effects in the lead-free Ba(Zr,Ti)O$_{3}$ relaxor ferroelectric from atomistic simulations

## TL;DR

This study uses atomistic simulations to explore the electrocaloric effects in lead-free Ba(Zr,Ti)O$_{3}$ relaxor ferroelectrics, revealing non-monotonic behavior and introducing a Landau-based model for broader application.

## Contribution

It presents the first atomistic simulation analysis of electrocaloric effects in BZT relaxor ferroelectrics and develops a simple model applicable to other materials.

## Key findings

- EC coefficient varies non-monotonically with field
- A Landau-based model reproduces EC behavior
- Indirect measurements differ from direct evaluations at low temperatures

## Abstract

Atomistic effective Hamiltonian simulations are used to investigate electrocaloric (EC) effects in the lead-free Ba(Zr$_{0.5}$Ti$_{0.5}$)O$_{3}$ (BZT) relaxor ferroelectric. We find that the EC coefficient varies non-monotonically with the field at any temperature, presenting a maximum that can be traced back to the behavior of BZT's polar nanoregions. We also introduce a simple Landau-based model that reproduces the EC behavior of BZT as a function of field and temperature, and which is directly applicable to other compounds. Finally, we confirm that, for low temperatures (i.e., in non-ergodic conditions), the usual indirect approach to measure the EC response provides an estimate that differs quantitatively from a direct evaluation of the field-induced temperature change.