Topological Vortex Structure And Conductance Information Storage In Ferroelectric Ceramics Were Investigated Via Phase Field Method

The perovskite crystal structure determines the appearance of ferroelectricity and the polarization direction of ferroelectric ceramics.When the polarization direction has a certain order,different domain structures will combine to form a multiparticle system with a specific morphology,i.e.,the topological structure existing in ferroelectrics.However,at present,the relevant classification of topological structures in ferroelectrics and the description of the specific switching process are not clear,which also limits the wide application of topological structures in ferroelectrics as functional structures.In this study,the domain structures of potassium sodium niobate(K0.5Na0.5Nb O3)thin films under different hysteresis electric fields and thickness are simulated and observed by the phase field method According to the different switching paths of the domain structure under the electric field,the domain is divided into fast and slow switching process.Based on this,a method is proposed to first determine the domain switching state of the desired experiment and then conduct directional observation.Through the analysis of the domain structures combined with the polarization vector,a clear multi-domain combined with vortex-antivortex pair topological structure is observed for the first time in K0.5Na0.5Nb O3 film.The vortex structure is further analyzed for its switching process,and it is observed that this vortex topological microstructure can make the domain more likely to switch,so that more small-scale polarization vectors can be ordered,forming the desired multiparticle system topology.The mechanism of improving the dielectric properties of ferroelectric material by this polarization vector ordering is similar with that of the microscopic phase boundary formed by the specific polarization directions on both sides of the quasi morphotropic phase boundary.Then,based on the study of domain structure and eddy domain flipping in ferroelectric materials,the special order formed under pulsed electric field was simulated by using the phase field method,and the domain walls formed between domains in vortices were analyzed.The changes of conductance characteristics of domain walls in vortex topology were calculated and discussed.A further connection with conductance information storage is proposed for the first time in potassium sodium niobate for multi-processional information storage,which may be applied to non-volatile ferroelectric domain wall memory.Different from traditional binary storage,the conductance state design of multi-base storage can store information with higher density in unit area,thus solving the storage capacity problem of non-volatile ferroelectric information memory to a certain extent,and providing a new idea and method for the application and research of ferroelectric memory.