# Negative electrocaloric effect in nonpolar phases of perovskite over wide range of temperature

## TL;DR

This study reveals extensive negative electrocaloric effects in nonpolar phases of perovskite materials across a wide temperature range, driven by octahedral tilting entropy, with potential for high-efficiency refrigeration.

## Contribution

It uncovers the microscopic mechanism of negative ECE in nonpolar perovskites and demonstrates a giant negative ECE at room temperature using first-principles Monte Carlo simulations.

## Key findings

- Negative ECE observed in multiple perovskite phases.
- Negative ECE driven by octahedral tilting entropy change.
- Giant negative ECE of 8.6 K at room temperature.

## Abstract

The electrocaloric effect (ECE) offers a promising alternative to the traditional gas compressing refrigeration due to its high efficiency and environmental friendliness. The unusual negative electrocaloric effect refers to the adiabatic temperature drops due to application of electric field, in contrast with the normal (positive) ECE, and provides ways to improve the electrocaloric efficiency in refrigeration cycles. However, negative ECE is unusual and requires a clear understanding of microscopic mechanisms. Here, we found unexpected and extensive negative ECE in nonpolar orthorhombic, tetragonal, and cubic phases of halide and oxide perovskite at wide range of temperature by means of first-principle-based large scale Monte Carlo methods. Such unexpected negative ECE originates from the octahedral tilting related entropy change rather than the polarization entropy change under the application of electric field. Furthermore, a giant negative ECE with temperature change of 8.6 K is found at room temperature. This giant and extensive negative ECE in perovskite opens up new horizon in the research of caloric effects and broadens the electrocaloric refrigeration ways with high efficiency.