Energy Storage And Electrocaloric Effect Of Lead Zirconate Based Antiferroelectric Thin Films In Wide Temperature Range

Lead zirconate(PbZrO₃)is the first compound identified as antiferroelectrics(AFE)in 1951.In the high external electric field,ferroelectric state will be produced in AFE,which is accompanied by large strain and polarization changes.With the development of power electronic systems toward miniaturization and integration,the potential applications of lead-based AFE materials in energy storage capacitors,micro-actuators,pyroelectric safety sensors,cooling devices,pulse power generators,which have attracted more attention.Dielectric capacitors are also used in power systems such as electron beams,directional energy weapons and so on for their excellent energy storage density and low loss.It has been widely studied,there are a number of reports about energy storage properties and electrocaloric effect(ECE)of AFE materials have been reported.Antiferroelectric thin films are considered as potential candidates for solid state refrigeration technology due to their remarkable electrothermal effect(ECE).(1)In this work,Pb_0.97La_0.02ZrO₃(PLZ)thin films that deposited on La NiO₃(LNO)/Pt and LNO electrodes by sol-gel method,respectively.High spontaneous polarization(P_s?91.3?C cm^-2)and low remanent polarization(P_r?7.3?C cm^-2)can be obtained from PLZ/LNO/Pt/TiO₂/SiO₂/Si with energy storage density up to 25.4 J cm^-3,which could be explained by good ohmic contact between films and composite electrodes.Besides,recoverable energy storage of films exhibits outstanding temperature stability(25.9-25.3 J cm^-3)over-60-20?.Giant negative electrocaloric effect(?T?-13.2 K)can observed in wide temperature range(213 K-493 K)that deposited on composite electrode,which can be attributed to better electric conductivity of LNO/Pt composite electrode than LNO electrode.In addition to outstanding negative ECE,positive ECE also can be obtained near curie temperature,which is caused by phase transition from ferroelectric(FE)to paraelectric(PE)state.The optimized ECE property contributed to the phase transition and introduction of composite electrode,which pave the giant prospect considering high-efficiency solid-state refrigeration devices through combination of positive and negative ECE.The obtained results reveal the fact that LNO/Pt composite electrode is benefit for the optimization of energy properties in PLZ thin films,exhibiting giant prospects for the evelopment of wide temperature range energy-storage and refrigerating capacitors.(2)In this paper,four colloid of PLZ-x%Mn(x=0,0.5,1,1.5)were prepared by sol-gel method,and were coated on LNO substrates.The effects of different dopants on the microstructure,electrical properties,energy storage and electrical properties of Mn were studied.The results show that proper amount of Mn ion doping can optimize the energy storage and card performance.The remanent polarization of the films reaches the maximum at x=1,and the P_r is 102?C cm^-2,which is 86.6%higher than that at x=0(?60?C cm^-2).The maximum effective energy storage density at x=1(?19.57 J cm^-3)is also higher than that of the other three samples(16.83,12.9,14.03 J cm^-3).The energy storage efficiency(51.7%)is higher than that of the other three samples(51.1%,51.2%,47.9%).The minimum adiabatic temperatures of PLZ-x%Mn(x=0,0.5,1,1.5)films are-13.7K,-15 K,-30 K and-18.7 K respectively,and the adiabatic temperature is the lowest when x=1.It can been seen that appropriate Mn doping can improve the electrical properties,energy storage properties and electrical card properties of PLZ antiferroelectric films.