Large electrical strain in lead-free K_(0.5)Na_(0.5)NbO_(3)-based ceramics by heterovalent doping  

作　　者：Xiangjian Wang Jun Wang Wenping Geng Guohua Dong Brahim Dkhil Xiaojie Lou 

机构地区：[1]Department of Information Engineering,Quzhou College of Technology,Quzhou,324000,China [2]Frontier Institute of Science and Technology,and State Key Laboratory for Mechanical Behavior of Materials,Xi'an Jiaotong University,Xi'an,710049,China [3]Science and Technology on Electronic Test and Measurement Laboratory,North University of China,Taiyuan,030051,China [4]Electronic Materials Research Laboratory,Key Laboratory of the Ministry of Education&International Center for Dielectric Research,Xi'an Jiaotong University,Xi'an,710049,China [5]Applied Physics,Division of Materials Science,Department of Engineering Sciences and Mathematics,LuleåUniversity of Technology,SE-97187,Luleå,Sweden [6]Laboratoire Structures,Proprietes et Modelisation des Solides,Universite Paris Saclay,CentraleSupelec,CNRS-UMR8580,Grande Voie des Vignes,Ch^atenay Malabry,Cedex,92295,France

出　　处：《Journal of Materiomics》2023年第5期959-970,共12页无机材料学学报（英文）

基　　金：supported by National Science Foundation of China(NSFC No.52172125),the CSS project(YK2015-0602006),the Natural Science Foundation of Shandong Province of China(Grant No.ZR2018BA028),Quzhou Science and Technology Plan Project(2022K108)and General Research Project of Zhejiang Provincial Department of Education(Y202249978).

摘　　要：Heterovalent doped(K_(0.48-0.07)xNa_(0.52-0.43)xBi_(0.5)x)(Nb_(0.95-0.95x)Sb_(0.05-0.05x)Zrx)O_(3)ceramics were fabricated using conventional solid-state reaction.Then,the phase structures,dielectric,ferroelectric,and electricstrain properties were investigated.The compositions were tuned to be located at polymorphic phase boundary with increasing heterovalent Bi3t and Zr4t doping levels.A large strain of 0.19%was obtained at relatively low electric fields of 30 kV/cm in the composition of x=0.04.The normalized large-signal d33*values were approximately 633 pm/V under a low driving electric field of 30 kV/cm,which were comparable or larger than the values reported for other lead-free families.The large strains obtained can be attributed to the formation of nanodomains and high-density domain walls,which were confirmed by the observations of domain morphology using transmission electron microscopy(TEM)technique.Excellent temperature stability of the strain properties of the x=0.04 sample could be ascribed to the sluggish behaviour for the local structural heterogeneity in heterovalent-ion doped KNN ceramic.Theoretical simulations revealed that the Zr^(4t)produce the local stress at the BO6 octahedra and Bi3t could yield off-centering of AO12 ployhedron due to the nature of Bi 6s lone pair electrons,which induced lattice expansion and local distortions in the sample.The local displacements are strongly anisotropic in heterovalent-ion doped system.It is believed that random local fields exist in these compositions owing to the eixstence of charge distribution.Such heterovalent doping of Bi^(3t)and Zr^(4t)could destory simultaneously the orthorhombic symmetry and the short-range ferroelecctric order,leading to the formation of complex nanodomains and local structral hetergenenity.Heterovalent doping may,therefore,offer a new avenve to design novel K0.5Na0.5NbO3(KNN)-based materials for their mutifunctional applications.

关 键 词：LEAD-FREE STRAIN Heterovalent doping Local structure Nanodomain 

分 类 号：TQ174.1[化学工程—陶瓷工业]