Preparation And Energy Storage Performance Of PbZr_0.52Ti_0.48O₃-based Composite Thin Films

The Curie temperature of Pb(Zr,Ti)O3 is higher than that of most ferroelectric materials,so its capacitor energy storage Performance has higher temperature stability,especially near the quasi-homophase Phase boundary,Pb Zr0.52Ti0.48O3(PZT)Dielectric and piezoelectric maximums,with excellent ferroelectric properties.Although the PZT film has a very high maximum saturation polarization,the higher remanent polarization and the lower dielectric strength make it difficult to obtain the desired results for the energy density and efficiency of the PZT film.In this paper,on the basis of exploring the process of preparing PZT thin films by sol-gel method,we try to increase the(Pmax-Pr)value and the breakdown field strength of the thin film by means of element doping,introducing seed layer and designing the layered composite structure,futher improve the storage of the thin film.Firstly,PZT thin films were prepared by sol-gel method.The effects of annealing frequency and annealing temperature on the quality,microstructure and energy storage properties of the films were studied.The XRD,SEM and AFM results revealed that the film obtained after annealing at 700°C twice have the largest(111)orientation degree,the smallest surface roughness,and more dense and flat surface.At the same time,the film has the largest breakdown field strength of 1533KV/cm and the maximum energy density.Under the electric field of 1400KV/cm,the energy storage density and energy storage efficiency of the film are 13.5J/cm3 and 50.4%,respectively.The results of XRD and AFM of PZT thin films with La Ni O3(LNO)seed layer show that the PZT thin film has a strong(100)orientation after LNO layer is introduced,and the crystal grains on the surface of the thin film grow uniformly accompanied by a decrease in size.The breakdown field strength of the film increased from 1533 KV/cm to 1867 KV/cm,and the energy storage density of the film reached 16.1J/cm3 at an electric field of 1733 KV/cm,which increased by 2.6J/cm3.The PZT/PZ/PZT sandwich structure was prepared by introducing an Pb Zr O3(PZ)layer with a low remnant Polarization which could reduce the remnant polarization of the composite film to increase the(Pmax-Pr)value.At the same time,the breakdown field strength of the film also can be improved due to the electric field amplification effect.The results show that the composite film with a PZ layer thickness of 180 nm has the largest(Pmax-Pr)value and the maximum breakdown field strength of 1829KV/cm.The energy density and energy storage efficiency of the composite film at the 1676KV/cm electric field are 17.6J/cm3 and 50.6%,respectively.By preparing a(PZT/PZ)multilayer staggered structure film with constant thickness of the entire film,it was found that the breakdown field strength of the film continuously increases as the PZT/PZ interface increases.The breakdown field strength of(PZT/PZ)4 composite film reaches 2095KV/cm.Under the electric field of 1905KV/cm,the energy density and energy storage efficiency of the composite film are 24.6J/cm3 and 57.8%,respectively.The XRD and AFM results of La-doped PZT thin films show that La doping increases the(111)peak intensity of the thin film.With the doping amount increased from 2mol.% to 8mol.%,the(110)diffraction peak intensity of the thin film is gradually weakened.At the same time,the grain size and the surface roughness continuously increased.When the doping amount of La is 8 mol.%,the film has the largest(Pmax-Pr)value of 50.4μC/cm2 and the largest energy storage density of 15.4J/cm3.The XRD and AFM results of Ta doped PZT films show that the Ta doped film is mainly(110)texture.With the doping amount increased from 2mol.% to 8mol.%,the grain size of the film becomes larger,and the surface roughness also increases.The film with 2mol.% doping amount of Ta has the largest energy storage density of 17.1J/cm3 under the electric field of 1333KV/cm,and the energy storage efficiency is 71%.The XRD and AFM results of Ta-doped PZT/LNO thin films show that the LNO layer induces(100)oriented growth of the thin film and the surface roughness of the thin film decreases.Compared to Pb(Zr0.52Ti0.42Ta0.06)O3 thin film without seed layer LNO,the maximum energy density of Pb(Z0.52T0.42Ta0.06)O3/LNO thin film increased by 0.9J/cm3,reaching 16.9J/cm3.The XRD and AFM results of Ta-doped Pb0.92La0.08(Zr0.52T0.48–x Tax)O3 films show that the films have no obvious preferred orientation.The grain size first increases and then decreases.The surface of the film was smooth and uniform.With the increase of the Ta doping amount from 2 mol.% to 8 mol.%,the energy storage density of the film increased gradually.When the Ta doping amount is 8 mol.%,the energy storage density of the film is 24.1J/cm3 at an electric field of 1600 k V/cm,and the energy storage efficiency is 78.6%.