Department of Advanced Materials Science, Faculty of Engineering, Kagawa University , 2217-20 Hayashi-cho, Takamatsu-shi, 761-0396 Japan.
Inorg Chem. 2013 Sep 16;52(18):10542-51. doi: 10.1021/ic4015256. Epub 2013 Aug 26.
Ferroelectric mesocrystals of Bi0.5Na0.5TiO3 (BNT) with [100]-crystal-axis orientation were successfully prepared using a topotactic structural transformation process from a layered titanate H1.07Ti1.73O4·nH2O (HTO). The formation reactions of BNT mesocrystals in HTO-Bi2O3-Na2CO3 and HTO-TiO2-Bi2O3-Na2CO3 reaction systems and their nanostructures were studied by XRD, FE-SEM, TEM, SAED, and EDS, and the reaction mechanisms were given. The BNT mesocrystals are formed by a topotactic structural transformation mechanism in the HTO-Bi2O3-Na2CO3 reaction system and by a combination mechanism of the topotactic structural transformation and epitaxial crystal growth in the HTO-TiO2-Bi2O3-Na2CO3 reaction system, respectively. The BNT mesocrystals prepared by these methods are constructed from [100]-oriented BNT nanocrystals. Furthermore, these reaction systems were successfully applied to the fabrication of [100]-oriented BNT ferroelectric ceramic materials. A BNT ceramic material with a high degree of orientation, high relative density, and small grain size was achieved.
具有[100]晶轴取向的 Bi0.5Na0.5TiO3（BNT）铁电微晶通过从层状钛酸盐 H1.07Ti1.73O4·nH2O（HTO）的拓扑结构转变过程成功制备。通过 XRD、FE-SEM、TEM、SAED 和 EDS 研究了 HTO-Bi2O3-Na2CO3 和 HTO-TiO2-Bi2O3-Na2CO3 反应体系中 BNT 微晶的形成反应及其纳米结构，并给出了反应机制。在 HTO-Bi2O3-Na2CO3 反应体系中，BNT 微晶通过拓扑结构转变机制形成，在 HTO-TiO2-Bi2O3-Na2CO3 反应体系中，BNT 微晶通过拓扑结构转变和外延晶体生长的组合机制形成。通过这些方法制备的 BNT 微晶由[100]取向的 BNT 纳米晶构成。此外，这些反应体系成功应用于[100]取向的 BNT 铁电陶瓷材料的制备。获得了具有高取向度、高相对密度和小晶粒尺寸的 BNT 陶瓷材料。
