Preparation And Properties Of BiFeO₃ Group And Its Composite Ferroelectric Materials

With the continuous progress and development of global information technology,many traditional single functional materials have been unable to meet the needs of various industries in the society.People are constantly exploring new green multi-functional materials with excellent performance and wide range of applications,hoping to replace these backward traditional materials through scientific research.BiFeO₃?BFO?films have been widely studied for many years due to their unique properties in the application of new multi-functional intelligent devices such as sensors and photovoltaic cells.Due to the existence of oxygen vacancy and other defects in BFO materials and the large leakage current flow caused by the change of Fe³⁺ion price,the further application is hindered,and the improvement of preparation process and doping modification is an important method to improve BFO ferroelectric materials.In this paper,BFO based ferroelectric materials with different content of Zn and different preparation processes are prepared by sol-gel method.The following three conclusions are drawn from the study of BFO based ferroelectric materials:1?The B-bit Zn doping is beneficial to the performance improvement of BFZO films.When the content of Zn was 1mol%,the ferroelectric performance of BFZO film was better,the grain development was better,the concentration of Fe²⁺and oxygen vacancy was lower,and the leakage current density was smaller.At this time,the conduction mechanism is Space-Charge-Limited Conduction.It shows that appropriate Zn doping is beneficial to the grain development of BFZO film,reduces the concentration of oxygen vacancy,and reduces the leakage current density of the film,so as to improve the performance of the film.2?O₂ annealing atmosphere is beneficial to the improvement of BFZO film properties.BFZO films have high crystallinity,good grain development,low concentrations of Fe²⁺and oxygen vacancy,good ferroelectric and dielectric properties and low leakage current density under the atmosphere of O₂ annealing.At this time,the conduction mechanism is the mechanism of F-N tunneling effect.The aging model of thin films was established from the perspective of volume effect,and the effect of annealing atmosphere on the aging of samples was deeply explored.3?In 0.5BFO-0.5CSBT ceramic samples,BFO was inserted into the CSBT perovskite layer to form a composite 6-layer bismuth-layered perovskite structure?BLFS?.The relative content of Ti³⁺and the oxygen vacancy concentration of the ceramic sample in the sintering atmosphere of O₂ were small.The conductance activation energy of ceramic samples with different sintering atmospheres at high temperature were close to that of second-order ionization of oxygen vacancy.No matter at high or low temperature,the conductance activation energy of ceramic samples with O₂ sintering atmosphere is larger,and oxygen vacancy and other defects are less.At high temperature,the relaxation phenomenon of ceramic samples was related to the concentration of oxygen vacancy.The relaxation activation energy of sintered samples in O₂ atmosphere was greater than 0.733ev,and the oxygen vacancy concentration was smaller.