Correlation between multi-factor phase diagrams and complex electrocaloric behaviors in PNZST antiferroelectric ceramic system

Ferroelectric (FE) phase transition with a large polarization change benefits to generate large electrocaloric (EC) effect for solid-sate and zero-carbon cooling application. However, most EC studies only focus on the single-physical factor associated phase transition. Herein, we initiated a comprehensive discussion on phase transition in Pb0.99Nb0.02[(Zr0.6Sn0.4)(1-x)Ti-x](0.98)O-3 (PNZST100x) antiferroelectric (AFE) ceramic system under the joint action of multi-physical factors, including composition, temperature, and electric field. Due to low energy barrier and enhanced zero-field entropy, the multi-phase coexistence point (x = 0.12) in the composition-temperature phase diagram yields a large positive EC peak of maximum temperature change (Delta T-max) = 2.44 K (at 40 kV/cm). Moreover, the electric field-temperature phase diagrams for four representative ceramics provide a more explicit guidance for EC evolution behavior. Besides the positive EC peaks near various phase transition temperatures, giant positive EC effects are also brought out by the electric field-induced phase transition from tetragonal AFE (AFE(T)) to low-temperature rhombohedral FE (FER), which is reflected by a positive-slope boundary in the electric field-temperature phase diagram, while significant negative EC responses are generated by the phase transition from AFE(T) to high-temperature multi-cell cubic paraelectric (PEMCC) with a negative-slope phase boundary. This work emphasizes the importance of phase diagram covering multi-physical factors for high-performance EC material design.

Automated summary

This study discusses the phase transition in the PNZST100x antiferroelectric ceramic system under the joint action of multi-physical factors, including composition, temperature, and electric field. The results show that the composition-temperature phase diagram and electric field-temperature phase diagrams provide guidance for high-performance electrocaloric material design.