Enhancing the Elastocaloric Strength by Combining Positive and Negative Elastocaloric Effects

Solid-state refrigeration has received widespread attention recently because of its high refrigeration efficiency and environmental protection. Compared with other solid-state refrigeration technologies, elastocaloric effects have great application potential. However, the current temperature change of elastocaloric effects is still low. This work explores the change law of phase transition temperature of ferroelectric materials by applying the external stress based on the thermodynamic calculation. It can be found that ferroelectric materials’ positive and negative elastocaloric effects can peak at the same temperature, so here a device to combine the positive and negative elastocaloric effects of Ba_0.7Sr_0.3TiO₃ and BaZr_0.015Ti_0.085O₃ is designed. This device can achieve a ΔT of 3.18 K near room temperature under applied stress of 200 MPa, which is twice as large as that of 1.4 K in BCZTO-Fe under the same stress condition. And it can be raised to 4.1 K after applying an electric field of 10 MV m⁻¹. It is the first time to combine positive and negative elastocaloric effects to achieve high cooling near room temperature, which provides a new solution for efficient cooling near room temperature.