Enhanced energy-storage performance and electrocaloric effect in compositionally graded Pb(1-3x/2)LaxZr0.85Ti0.15O3 antiferroelectric thick films

The compositionally graded multilayer Pb((1-3x/2))LaxZr0.85Ti0.15O3 (PLZT) antiferroelectric (APE) thick films were deposited on LaNiO3/Si (100) substrates by using a sol-gel method. The effect of gradient sequence on dielectric properties, energy-storage performance, and electrocaloric effect (ECE) was investigated in detail. It is found that the compositionally graded films exhibited a significant enhancement in dielectric properties, energy-storage performance and ECE, which was, in contrast to the single-composition PLZT film, contributed by the strain and the gradient of polarization near the interfaces between the adjacent layers. A recoverable energy-storage density of 44 J/cm(3) and efficiency of 71% was obtained in the up-graded PLZT APE thick film at 1950 kV/cm. A giant reversible adiabatic temperature change of Delta T=28 degrees C at room temperature at 900 kV/cm was also achieved in the up-graded film. Moreover, all the thick films displayed a small leakage current density below 10(-6) A/cm(2) at room temperature. Thus, the compositionally graded PLZT APE thick films with a large recoverable energy-storage density and a giant ECE could be a potential candidate for the applications in high energy-storage density capacitors and cooling devices. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.