织构化(Na_(1/2)Bi_(1/2))TiO_3-BaTiO_3无铅压电陶瓷晶粒定向生长机制

Mechanism of grain orientation growth on textured (Na_(1/2)Bi_(1/2))TiO_3-BaTiO_3 lead-free piezoelectric ceramics

以熔盐法合成的片状SrTiO3晶粒为模板,利用模板晶粒生长(TGG)技术制备晶粒沿[001]方向为取向的0.94(Na1/2Bi1/2)TiO3-0.06BaTiO3(简写为BNBT6)无铅压电陶瓷,采用X线衍射仪(XRD)、扫描电子显微镜(SEM)对陶瓷试样进行表征,采用透射电子显微镜(TEM)观察SrTiO3与BNBT6基体界面的微观结构.结果表明,BNBT6陶瓷晶粒定向生长过程分为2个阶段:首先是异质外延生长阶段,即在片状模板晶粒的诱导下,BNBT6基体粉体在SrTiO3模板晶粒表面外延生长,形成与模板取向完全一致的单晶生长层的过程;其次是同质外延生长阶段,即单晶生长层生成后吞噬BNBT6基体粉体逐步生长得到各向异性的高取向BNBT6陶瓷的过程.

The grain-oriented 0.94（Na1/2Bi1/2）TiO3-0.06BaTiO3（BNBT6） lead-free piezoelectric ceramics were fabricated by templated grain growth（TGG） method,using plate-like SrTiO3 as template prepared by a molten salt method.Characterization techniques,such as X-ray powder diffractometer（XRD） analysis,scanning electron microscope（SEM） were used to investigate the products.The microstructures of SrTiO3-BNBT6 interface were studied by transmission electron microscope（TEM）.The results showed that the process of grain growth within the BNBT6 ceramics included two steps：the first was heteroepitaxial growth,the BNBT6 matrix was epitaxially grown on the surface of SrTiO3 template at the induction of plate-like template,and the grown layer was a single crystal with the same orientation to the template;the second was homoepitaxially growth,the single crystal layer was grown to an anisotropic textured BNBT6 ceramics at the expense of matrix grains.