Dielectric Property Regulation of Ferroelectric Composites for Electrocaloric Refrigeration

ABSTRACT

Ferroelectric materials are pivotal for advancing room‐temperature flexible portable electrocaloric refrigeration. Ferroelectric ceramic–polymer nanocomposites, which integrate the advantages of both material types, have emerged as a promising solution. The dielectric properties (e.g., dielectric constant and dielectric breakdown strength) of these nanocomposites are key determinants of their electrocaloric performance, and they are highly dependent on microstructural features of the composites. In this study, finite element models of two typical ferroelectric composites, namely Ethylene Vinyl Acetate (EVA)‐Barium Titanate (BaTiO ₃ , BTO) and Poly(vinylidene fluoride‐trifluoroethylene) P(VDF‐TrFE)‐BTO, are established using the electrostatic analysis model. The effects of BTO filler parameters on the dielectric constant and dielectric breakdown strength of the composites are systematically investigated. The results indicate that: (1) provided that the filler loading ratio is kept constant, nanoscale variations in BTO particle size (50–500 nm) have no significant impact on the dielectric properties of the composites; (2) increasing BTO volume fraction, adopting chain‐like particle distribution, or increasing BTO fiber aspect ratio can effectively enhance the dielectric constant of the composites; (3) a trade‐off exists between dielectric constant and dielectric breakdown strength. A 40% BTO volume fraction is experimentally identified as the flexibility‐maintaining upper limit. The improvements in dielectric constant are accompanied by a decrease in dielectric breakdown strength. This research provides a theoretical basis for the microstructural design of high‐performance ferroelectric electrocaloric composites, laying the groundwork for the development of efficient room‐temperature flexible electrocaloric refrigeration devices.