Prediction of giant elastocaloric strength and stress-mediated electrocaloric effect in BaTiO3 single crystals

An applied stress field σ3 can reversibly change the temperature of an elastocaloric material under adiabatic
conditions, and the temperature change Tσ3 is usually maximized near phase transitions.Using a thermodynamic
approach, we demonstrate that an elastocaloric strength α = | Tσ3
|/|σ3| of 0.016 K/MPa can be achieved
benefiting from the full first-order phase transition in BaTiO3 single crystals, which is comparable with typical
elastocaloric materials reported in the literature. The elastocaloric temperature change is found to be giant
(3.2 K) under a stress of 200 MPa with a temperature span of over 50 K, which can be significantly larger than
its electrocaloric counterpart (∼1 K). Moreover, it is found that the elastocaloric strength can be remarkably
enhanced (2.32 K/MPa) as long as the phase transition is triggered even by a modest stress near the sharp
first-order phase transition, which is two orders of magnitude larger than those accomplished by full transition.
Therefore, even a low stress (<30 MPa) can induce a modest elastocaloric effect (1.3 K) comparable with the
electrocaloric counterpart, which is accompanied by a reduction of the working temperature span. In addition, it
is found that the electrocaloric peak under tensile stresses moves towards higher temperatures with its magnitude
slightly enhanced. Hopefully, our study will stimulate further investigations on elastocaloric and stress-mediated
electrocaloric effects in ferroelectrics.