Ta掺杂Na0.5 Bi4.5 Ti4O15陶瓷的显微结构和电性能

Microstructure and electrical propertiesof Ta-doped Na 0.5 Bi 4.5 Ti 4O 15 ceramics

采用固相烧结法制备铋层结构Na 0.5 Bi 4.5 Ta x Ti 4-x O 15+0.5 x(NBT-Ta-x)(x=0~0.20)压电陶瓷。采用X射线衍射、扫描电镜和自动控温测试系统研究Ta 5+的B位掺杂对NBT-Ta-x陶瓷的微观结构、电导、介电和压电性能的影响。结果表明:随Ta掺杂量的增加,晶粒尺寸和长径比逐渐减小,表现出沿c轴的取向生长,同时,陶瓷的理论密度和体积密度增加,在掺杂量x=0.05时达到最高的相对密度96.1%,Ta在NBT晶格中的固溶极限在0.10附近。随Ta 5+掺杂量x增加到0.20,陶瓷的居里温度从680℃降至658℃。Ta 5+掺杂使NBT-Ta-x陶瓷的电阻率增加了两个数量级,压电常数d 33从13.8 pC/N增加到23 pC/N。当x=0.04~0.05时,NBT-Ta-x陶瓷的综合电性能良好:T c=670~672℃,d 33=21.8~23 pC/N,k p=7.9%~8.3%。

Bismuth layer structured piezoelectric ceramics,Na 0.5 Bi 4.5 Ta x Ti 4-x O 15+0.5 x(NBT-Ta-x)(x=0-0.20),were fabricated via a solid state sintering process.The effect of Ta 5+doping for B site on the microstructure,electrical conductivity,dielectric and piezoelectric properties of NBT-Ta-x ceramics was investigated by means of XRD,SEM and an automatic temperature control testing system.The results show that Ta doping brings about the decrease in grain size and aspect ratio of grain with a preferable orientation growth along c-axis.Meanwhile,both theoretical density and measured density of the ceramics is increased with increasing tantalum doping content,with the highest relative density of 96.1%at x=0.05,showing that the solid solution limit of tantalum in NBT lattice is in the proximity of x=0.10.The Curie temperature is decreased slightly from 680℃to 658℃with the increase of Ta 5+doping content x to 0.20.The electrical resistivity of NBT-Ta-x ceramics is increased as much as about two orders of magnitude by Ta 5+modification and the piezoelectric constant d 33 values is increased significantly from 13.8 pC/N to 23 pC/N.The x=0.04-0.05 samples exhibit the optimal electrical performance:T c=670-672℃,d 33=21.8-23 pC/N,k p=7.9%-8.3%.