Optimization of an indirect method for electrocaloric effect in BT-based ceramics validated through the Rayleigh relationship and direct method

Abstract

Efforts to enhance refrigeration efficiency and environmental friendliness are underway, focusing on the electrocaloric effect (ECE) as an alternative to traditional compression methods. Maintaining a substantial adiabatic temperature change (ΔT) across a broad temperature span (T_span) induced by ECE is a significant challenge in achieving efficient, zero-emission ferroelectric refrigeration. This study introduces a stacked composite ceramic (SCC) with broad dielectric peaks, achieved by stacking ceramics with a specific ferroelectric–paraelectric phase transition. The interlayer synergies optimize between layers and amplify polarization changes due to flip domains and lattice distortion, enhancing ECE properties. Notably, SCC exhibits a substantial ΔT_max of 1.198 K and a wide T_span of 64 °C at 50 kV cm⁻¹, surpassing the cumulative properties of individual components. The study proposes an effective composite design strategy for developing high-performance electrothermal materials with exceptional ECE properties for practical refrigeration applications.