Study On Microscopic Polarization And Relaxation Of Ferroelectric Domains In Piezoelectric Ceramics

Widely used in industry and daily life,piezoelectric materials are strongly related to the progress of human society.A large number of experiments are applied in order to improve the properties of piezoelectric materials,while the key is the research on domain activities of the materials.In this article,piezoresponse force microscopy?PFM?,a multi-functional instrument for domain detection,is used to study the domain growth and relaxation in different piezoelectric materials.Their structure and properties are analyzed according to the results.The relaxation of a CaZrO₃-doped?K,Na?NbO₃ ceramic sample with abnormal grain growth is studied using PFM.It is found that large grains relax slowly,while small grains and grain boundary hold higher piezoelectric properties.According to that,the macroscopic piezoelectric properties could be promoted by eliminating abnormal grain growth and lessening grains.The domain growth process of a?K,Na?NbO₃ thin-film sample is studied by PFM.The domain size is linear with the polarization voltage,and logarithmic with the polarization time.The relationship of domain growth speed and domain size is ln?=ln?₀-aD^?,where?=0.10,representing a large amount of point defect in the sample.The domain growth of once annealing and twice annealing Pb?Mg,Nb?O₃-PbTiO₃?PMN-PT?thin-film samples are studies by PFM.In once annealing PMN-PT thin-film,?=1,which means defect in the sample is mainly random field type.Local piezoelectric properties are pretty weak in twice annealing PMN-PT samples,which cannot perform macroscopic piezoelectric properties.In conclusion,once annealing is the better method in preparing PMN-PT thin-films.