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

Abstract

Enhanced electrocaloric response has been obtained for Pb(Mn1/3Nb2/3)O3-32PbTiO3·(PMN-32PT) single crystal by the application of uniaxial compressive pre-stresses. It was observed that an improvement of the electrocaloric effect (ΔTelec=0.62K) to the tune of 200% can be obtained for an applied compressive of 28MPa against a conventional unstressed peak electrocaloric effect (ΔTelec=0.27K). 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 (ΔTelas 0.36K) for an operating temperature of 323K and applied compressive stress of 2–28MPa (at 1.5MVm−1). The magnitude of elastocaloric response is even larger than the conventional unstressed ΔTelec of 0.27K 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 ΔT of −0.63K using a novel electro-mechanical thermodynamic cycle for an optimized operating temperature of 323K and applied compressive stress of 2–14MPa. 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.