Giant barocaloric effects over a wide temperature range in superionic conductor AgI

Araceli Aznar,Claudio Cazorla,María Barrio,Daniel Errandonea,Josep-Lluís Tamarit,Xavier Moya,Michela Romanini,Lluís Mañosa,Antoni Planes,Neil D Mathur,Pol Lloveras

doi:10.1038/s41467-017-01898-2

Abstract

Current interest in barocaloric effects has been stimulated by the discovery that these pressure-driven thermal changes can be giant near ferroic phase transitions in materials that display magnetic or electrical order. Here we demonstrate giant inverse barocaloric effects in the solid electrolyte AgI, near its superionic phase transition at ~420 K. Over a wide range of temperatures, hydrostatic pressure changes of 2.5 kbar yield large and reversible barocaloric effects, resulting in large values of refrigerant capacity. Moreover, the peak values of isothermal entropy change (60 J K−1 kg−1 or 0.34 J K−1 cm−3) and adiabatic temperature changes (18 K), which we identify for a starting temperature of 390 K, exceed all values previously recorded for barocaloric materials. Our work should therefore inspire the study of barocaloric effects in a wide range of solid electrolytes, as well as the parallel development of cooling devices.

Highlights

Current interest in barocaloric effects has been stimulated by the discovery that these pressure-driven thermal changes can be giant near ferroic phase transitions in materials that display magnetic or electrical order
Giant BC effects have only been experimentally demonstrated near room temperature in a polymer[10], a small number of relatively expensive magnetic materials[11,12,13,14,15,16], a number of fluorites[17,18,19,20], a hybrid perovskite[21] and a small number of ferro/ferrielectric materials[22, 23]
Following the recent prediction of giant BC effects in fluoride-based superionic conductors at very high temperatures[24], we demonstrate here giant BC effects nearer to room temperature in a powder of AgI, which is the prototypical solid electrolyte that was shown to display fast ionic conduction over one century ago[25, 26]

Summary

Introduction

Current interest in barocaloric effects has been stimulated by the discovery that these pressure-driven thermal changes can be giant near ferroic phase transitions in materials that display magnetic or electrical order. We show that AgI displays peak isothermal entropy changes of |ΔS| ~ 60 J K−1 kg−1, corresponding to adiabatic temperature changes of |ΔT| ~ 18 K, due to moderate changes of applied pressure |Δp| ~ 2.5 kbar (where we assume ambient pressure to be zero such that |Δp| ~ p).

Results

Conclusion