分凝对0.80Na1/2Bi1/2TiO3-0.20BaTiO3铁电单晶电学性能的影响  

EFFECTS OF SEGREGATION ON DIELECTRIC AND PIEZOELECTRIC PROPERTIES OF 0.80Na1/2Bi1/2TiO3-0.20BaTiO3 FERROELECTRIC SINGLE CRYSTAL

作　　者：陈超[1,2] 江向平[1] 林迪[2] 刘洪[1] 张钦辉[2] 罗豪甦[1] 

机构地区：[1]景德镇陶瓷学院材料学院,江西景德镇333001 [2]中国科学院上海硅酸盐研究所,高性能陶瓷和超微结构国家重点实验室,上海201800

出　　处：《硅酸盐学报》2009年第8期1322-1327,共6页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金50562002,50862005;教育部新世纪优秀人才支持计划NCET–06–0576;江西省自然科学基金2008GZC0009;上海市科委基金08JC1420500资助项目

摘　　要：采用坩埚下降法生长了尺寸为2mm×70mm的0．80Na1／2Bi1／2TiO3-0．20BaTiO3（0．80NBT-0．20BT）无铅铁电单晶。通过X射线荧光分析研究了晶体中的分凝现象。结果表明：该单晶沿其纵向生长方向由顶部至底部，BaTiO3（BT）含量逐渐增加，晶体棒底部BT含量为32．15坂摩尔分数，下同），而顶部BT含量为14．26％。XRD分析表明：室温下晶体棒为四方相钙钛矿结构。随着BT含量增加，室温下晶体[001]方向的介电常数减小，去极化温度升高。位于晶体棒中间部位的晶体样品0．81NBT-0．19BT的压电性能最佳，室温下该样品在[001]方向的电学性能指标分别为：压电系数d33=158pC／N，机电耦合系数ki=0.463。A 0.80Na1/2Bi1/2TiO3-0.20BaTiO3（0.80NBT-0.20BT） lead-free ferroelectric single crystal 12 mm in diameter and 70mm in length was successfully grown by the Bridgman technique. The segregation phenomenon in the crystal along the growth direction was investigated by X-ray fluorescence analysis. The results show that the BT content in the crystal increases along the growth direction. The BT contents in the crystal are 32.15% （in mole, the same below） in the top and 14.26% in the bottom, respectively. X-ray diffraction shows that the grown crystal has a pure perovskite structure with tetragonal symmetry in both the bottom and top parts. The permittivity at room temperature decreases and the depolarization temperature increases with the increase of BT content. The 0.81NBT-0.19BT crystal derived from the middle part of the crystal boule has optimized ferroelectric properties, and the permittivity d33 and electromechanical coupling factor kt of the crystal in the [001] direction are 158 pC/N and 0.463 at room temperature, respectively.

关 键 词：铁电单晶 分凝 介电弛豫 压电性能 坩埚下降法 

分 类 号：O738[理学—晶体学] O782