Field-induced phase transitions and enhanced double negative electrocaloric effects in (Pb,La)( Zr,Sn,Ti)O-3 antiferroelectric single crystal

Field-induced phase transitions and electrocaloric effect have been studied in (Pb,La)(Zr,Sn,Ti)O-3 (PLZST) antiferroelectric single crystal. Temperature dependent dielectric, Raman spectra, as well as in situ domain evolution demonstrated that the order of phase transitions during heating is in the sequence of orthorhombic antiferroelectric -> tetragonal antiferroelectric -> cubic paraelectric. Enhanced negative electrocaloric effect value of -3.6 degrees C and electrocaloric strength of 0.3K mm/kV at 125 degrees C have been achieved. Double negative effects (-0.7 degrees C at 45 degrees C and -3.6 degrees C at 125 degrees C) and a relatively large positive effect (1 degrees C) near Curie temperature (190 degrees C) have been found in the PLZST single crystal. Moreover, microscopic dipoles and a phenomenological Landau-type model were employed to understand these unusual electrocaloric effects. Enhanced negative effect and the coexistence of both negative and positive effects in one material are promising for us to develop practical solid-state cooling devices with high efficiency. Published by AIP Publishing.