Emergent Enhanced Electrocaloric Effect within Wide Temperature Span in Laminated Composite Ceramics

An outstanding challenge for high-efficient and zero-emissions ferroelectric refrigeration is to maintain a large adiabatic temperature change (Delta T) over a wide temperature span (T-span) resulting from the electrocaloric effect (ECE). A multilayer ferroelectric structure with interlayer synergistic phase transitions as a means to address this problem is proposed. BaTi0.89Sn0.11O3, BaTi0.85Zr0.15O3, and BaTi0.89Hf0.11O3 were selected as the components of each layer, the compositions of which are fixed at the tricritical point (TP) in each system and where the transition temperatures increase sequentially. Ferroelectrics near TP have a high sensitivity to external fields and the good co-firing adhesion leads to strong electrical and stress interface coupling between adjacent layers. The electric-field-induced phase transition in one layer then synergistically induces a phase transition in the near interface part of the adjacent layer, which is close to but is not at the transition point yet. As a result, the enhanced ECE performance, including both a large Delta T-max = 0.63 K and a wide T-span = 57 degrees C (Delta T >= 80% Delta T-max), exceeds that associated with the sum of the individual components. An efficient composite materials design strategy to develop high-performance electrocaloric materials with excellent ECE properties for practical refrigeration applications is thus proposed.

Automated summary

A multilayer ferroelectric structure with interlayer synergistic phase transitions is proposed to enhance the electrocaloric effect in ferroelectric materials, resulting in improved cooling performance for practical refrigeration applications.