Simultaneous shifts in pressure and electric field boost the caloric response in ferroelectrics.

Abstract

Solid-state caloric effects driven by external fields promise sustainable cooling and heating but their implementation requires performance enhancement. Multicaloric effects, induced by multiple fields, offer unique avenues for improvement. Here, the unexplored multicaloric potential of ferroelectrics driven simultaneously by electric field and pressure is investigated. For this purpose, unprecedented experiments of dielectric spectroscopy and calorimetry under these two fields are conducted on the archetypal electrocaloric material lead scandium tantalate ceramics. This allows analysis of the pressure-electric field phase space and the cross-coupling response of this multivariable system. More importantly, the multicaloric response offers opportunities unachievable with one field: caloric effects on decompression from 250 MPa triple if an electric field of ∼6 kV cm^-1 is simultaneously applied. Conversely, reversible caloric effects, unrealizable under low electric fields, reach 2 J K^-1 kg^-1 if a decompression from 250 MPa is simultaneously performed. Also, tuning pressure between 0 and 300 MPa shifts the caloric response to span over 20 K below room temperature, meeting household requirements. Our study not only demonstrates the viability and novelty of multivariate calorimetry and dielectric spectroscopy; more importantly, it also reveals the impact of the multicaloric response in ferroelectrics, promising new opportunities and physical insights in this broad material family.