Electrocaloric temperature change constrained by the dielectric strength

We have analyzed the correlations between the electrocaloric (EC) temperature change and the EC coefficient, both obtained with experimental characterization of the materials in different forms: as thin films, thick films, single crystals and ceramics. We showed that higher EC temperature change has been obtained for the materials with lower EC coefficients as a result of very high applied electric fields that these materials can withstand due to their high dielectric strength. Based on that the dielectric strength has been shown to be one of the key parameters for the high-performance EC materials. The materials microstructural characteristics, required for the high dielectric strength, have been identified. We propose a number of future research and development directions towards the new EC materials with the high dielectric strength and high EC coefficient, which could result in the breakthrough in the EC refrigeration technology.

► Controversial relationship between EC effect and EC temp. change (ΔT) is explained.
► Low dielectric strength was recognized as the limiting factor for achieving high ΔT.
► Cooling power of the bulk EC materials is required for refrigeration applications.
► Improvement of dielectric strength through better material processing is proposed.
► New research directions in the field of electrocaloric materials are identified.