Study On Dielectric,Ferroelectric And Electrostrain Properties Of Sodium Bismuth Titanate-Barium Titanate Based Ceramics

With increasing attentions to the environmental issues,development of lead-free ceramics has become an urgent task in the research field of piezoelectric materials,and in recent decades,lead-free piezoelectric ceramics have been widely studied and remarkable research results have been obtained.Barium titanate（BaTiO₃,BT）,sodium bismuth titanate(Bi_0.5Na_0.5TiO₃,BNT)and potassium sodium niobate(K_0.5Na_0.5NbO₃,KNN)are the most widely studied perovskite lead-free piezoelectric ceramics,and it is considered that excellent dielectric,ferroelectric,electrostrictive properites can be obtained in their solid solutions due to plenty of morphotropic phase boundary（MPB）in the BNT-BT-KNN systeim.In this work,0.94BNT-0.06BT（abbreviated as BNT-BT）was selected as the basic ceramic composition,and KNN was introduced to form a ternary solid solution system,i.e.（1-x）BNT-BT)-xKNN（abbreviated as（BNT-BT）-xKNN）,where the content of KNN is x mol.%,and is selected as 0,2,4,6,8.10,12,14,16,18,24,28,32,36 mol.%.The（BNT-BT）-xKNN cermaies were fabricated using a typical solid-phase reaction process,and the effects of KNN content on the phase structure,microstructure morphology and electrical properties（dielectric,ferroelectric,electrostrictive and energy storage）were studied systematically.Furthermore,based on the experimental results of the（BNT-BT）-xKNN ceramics in this work,BNT-BT and(BNT-BT-8KNN were selected as basic compositions,and SiO₂ was coated the above two kinds of cermic powders hy a chemical ccoating process.The dielectric,fcrroelectric,electrostrictive and energy storage properties of these ceramics fabricated using the SiO₂ coated pwoders were systematically studied.The research results obtained in this work have scientific value for fully understanding the relationship between the structure and properties of BNT-BT based ceramics,have practical significance for how to improve the performance of BNT-BT based ceramics and for the application of BNT-BT based ceramics in dielectric capacitor,electrostriction,dielectric energy storage.