A quantitative study of electrocaloric performance differences between bulk and MLCC-structured PMN-PT ferroelectric ceramics

Abstract

Solid-state cooling technology based on electrocaloric effect (ECE) has attracted worldwide attention due to its high efficiency, environmental benign nature, and cost effectivity. Although different forms of EC materials, i.e., ceramic bulk, multilayer ceramic capacitor, thin film, etc., have applied for EC applications, the impact of different structures on EC performance has not been thoroughly determined. In this study, ceramic bulks and multilayer ceramic capacitor (MLCC)-structured EC materials are directly compared with the same composition of 0.92Pb(Mg_1/3Nb_2/3)O₃-0.08PbTiO₃(PMN-8PT). In order to further figure out the performance improvement caused by geometric design, the dielectric layer thicknesses and layer numbers of MLCC structures were varied, while the same effective working volume was maintained. Both indirect and direct measurements were utilized for comparative EC performance analysis of ceramic bulk and multilayer structures. It was observed that MLCC samples with 6 dielectric layers exhibited an enhanced breakdown strength of 142 kV cm⁻¹, achieving enhanced electrocaloric performance of ΔS = 0.979 J kg⁻¹ K⁻¹ and ΔT = 1.285 K. These results indicate that when the effective cooling volume maintains equivalent in ferroelectric materials, the MLCC samples with reduced dielectric layer thickness exhibit an enhancement in the EC performance. It could be concluded that the MLCC structure would be beneficial for high EC performance, especially in terms of practical applications.