Simultaneous enhancement of the electrocaloric effect and electrostrain via exploiting the reversible polarization rotation

Self-actuating ferroelectric cooling technology have drawn increasing attention for its extensive application prospect, where simultaneous enhancement of electrocaloric effects (ECE) and electrostrain (ES) in ferroelectric materials is necessary prerequisites for the efficient operation of the cooling system. In this work, we proposed a self-actuating dual cooling cycle system combining the positive and negative ECE/ES effect, and further confirmed its feasibility in 0.7 Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-30PT) single crystal via bipolar electric field regulation. A suitable reverse electric field can generate negative ECE and ES simultaneously due to the reversible polarization rotation, whereas a high reverse electric field will lead to a serious perform loss as a result of emergent irreversible polarization jumping. The optimal reverse electric field (-Eop) can enhance the total ECE and ES by 31% and 17% respectively, whose effective combination can significantly improve the cooling capacity of the self-actuating cooling system. Moreover, compared to traditional P-E and/or I-E measurements, we pro-posed a more applicable and precise method to determine the-Eop under square-wave DC electric field, i.e. capacitance-voltage measurement. Our work not only provides new ideas for improving the ECE and ES of the ferroelectric materials, but also promotes the design of ferroelectric cooling systems.

Automated summary

In this study, a self-actuating dual cooling cycle system was proposed, combining the positive and negative electrocaloric effects (ECE) and electrostrain (ES) in a 0.7 Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-30PT) single crystal. It was found that a suitable reverse electric field can generate negative ECE and ES simultaneously, enhancing the cooling capacity of the system. The optimal reverse electric field (-Eop) can improve the total ECE and ES by 31% and 17% respectively.