Multicaloric effect in Pb(Mn1/3Nb2/3)O3-32PbTiO3 single crystals

Enhanced electrocaloric response has been obtained for Pb(Mn1/3Nb2/3)O-3-32PbTiO(3)center dot(PMN-32PT) single crystal by the application of uniaxial compressive pre-stresses. It was observed that an improvement of the electrocaloric effect (Delta T-elec = 0.62 K) to the tune of 200% can be obtained for an applied compressive of 28 MPa against a conventional unstressed peak electrocaloric effect (Delta T-elec = 0.27 K). Furthermore, the accompanying large strain variations and second order structural transition of the single crystal can be used to obtain significantly large values of elastocaloric effect (Delta T-elec 0.36 K) for an operating temperature of 323 K and applied compressive stress of 2-28 MPa (at 1.5 MV m(-1)). The magnitude of elastocaloric response is even larger than the conventional unstressed Delta T-elec of 0.27 K for the same operating temperature. The results indicate that ferroelectric materials possess significant multicaloric potential and can yield better cooling when employed as elastocaloric materials as opposed to conventional electrocaloric effect. Additionally, the two individual caloric effects can be suitably combined to obtain a further enhanced multicaloric Delta T of -0.63 K using a novel electro-mechanical thermodynamic cycle for an optimized operating temperature of 323 K and applied compressive stress of 2-14 MPa. The results of this study are expected to largely benefit the field of ferroelectric solid-state refrigeration and open new horizon for future exploration of multicaloric potential in ferroelectric materials. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.