Research On Ferroelectric Properties Of Lead Zirconate Titanate Based Film

The 21 st century is the era of information.It is an important part of daily life.Storage and processing is the key to social development.With the rapid development of modern society,people's quality of life is also constantly increased,daily life in increasingly high demand,the size of electronic products is smaller and the functions are various.All of these put forward higher requirements for electronic devices,such as greater storage capacity and more effective cooling capacity.Ferroelectric thin film materials with excellent ferroelectric,dielectric,electrocaloric properties and small thickness have been widely considered.In this paper,the lead-based perovskite materials were taken as the main objects,and the thin film was deposited on the conductive substrate of FTO by sol-gel method and modified by doping,the influence of doping on their ferroelectric properties and electrocaloric properties were further revealed.Firstly,PbTiO₃ thin films were prepared by sol-gel method at a relatively low annealing temperature by optimizing the sol,which decrease the volatilization of Pb O caused by high annealing temperature.Cu ions were doped into PbTiO₃ films,detailed investigations were made on the effects of Cu doped on the crystal structure and ferroelectric properties of the thin films.With the Cu doped the crystal structural gradual transition from high tetragonal to low.It is worth noting that Cu doped can induce the superior remnant polarization 25.0?C/cm2 and a relatively low coercive field 124.4 kV/cm when the molar concentration of Cu in the sol is 2.0mol%.It is supposed that the number of oxygen vacancies could be effectively decreased by Cu doping.The experimental research results will hopefully serve as a point for ferroelectric random access memories?Fe RAMS?.Secondly,to obtain more suitable ferroelectric films for Fe RAMS,the uniform and dense PbZr_0.53Ti_0.47O₃ films were successfully fabricated on FTO by facile sol-gel processes.It is confirmed the existence of silver nanoparticles in the film,indicating the composite ferroelectric films are of 0-3 type.UV-vis spectrum confirms the generation of Ag₂ O in the process of mixing the sol.Furthermore,the oxygen vacancies caused by natural evaporation of lead specie are effectively reduced because of the decomposition of Ag₂ O,confirmed by X-ray photoelectron spectroscopy.This work points out the generated Ag₂O as the intermediate product is the key to achieve high remnant polarization in Ag/PZT based film and make it as a promising candidate for memory applications.Last,to improve electrocaloric effect?ECE?,an ECE is obtained in an un-oriented PbZr_0.95Ti_0.05O₃?PZT?95/5??film fabricated on an FTO substrate which was treated in a plasma treatment system,using an improved sol-gel method.Si was doped into the lattice of PZT?95/5?thin film by mixing the suspension of SiO₂ nanosphere with PZT?95/5?sol.ECE was measured by an indirect method.A giant ECE is acquired in the PZT/0.01 Si film,which attribute to the coexistence of antiferroelectric orthorhombic and tetragonal phase in film,the polarization is easy to rotate,it have some contribution to the ECE,hence,a highest ECE is obtained.This work demonstrates that Si is a key component for producing un-oriented PZT antiferroelectric films on FTO substrates and identifies these films as promising candidates for electrocaloric refrigeration.