School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798.
ACS Appl Mater Interfaces. 2010 Nov;2(11):3037-42. doi: 10.1021/am1004865. Epub 2010 Oct 14.
Truncated nanocubes of barium titanate (BT) were synthesized using a rapid, facile microwave-assisted hydrothermal route. Stoichiometric composition of pellets of nanocube BT powders was prepared by two-stage microwave process. Characterization by powder XRD, Rietveld refinement, SEM, TEM, and dielectric and polarization measurements was performed. X-ray diffraction revealed a polymorphic transformation from cubic Pm3̅m to tetragonal P4mm after 15 min of microwave irradiation, arising from titanium displacement along the c-axis. Secondary electron images were examined for nanocube BT synthesis and annealed at different timings. Transmission electron microscopy showed a narrow particle size distribution with an average size of 70 ± 9 nm. The remanence and saturation polarization were 15.5 ± 1.6 and 19.3 ± 1.2 μC/cm(2), respectively. A charge storage density of 925 ± 47 nF/cm(2) was obtained; Pt/BT/Pt multilayer ceramic capacitor stack had an average leakage current density of 5.78 ± 0.46 × 10(-8) A/cm(2) at ±2 V. The significance of this study shows an inexpensive and facile processing platform for synthesis of high-k dielectric for charge storage applications.
采用快速简便的微波辅助水热法合成了钛酸钡（BT）的截断纳米立方体。通过两步微波工艺制备了纳米立方体 BT 粉末压坯的化学计量组成。通过粉末 XRD、Rietveld 精修、SEM、TEM 以及介电和极化测量进行了表征。X 射线衍射表明，在微波辐照 15 分钟后，立方 Pm3̅m 相到四方 P4mm 相发生了多晶型转变，这是由于钛原子沿 c 轴的位移引起的。对纳米立方体 BT 的合成和不同退火时间的二次电子图像进行了检查。透射电子显微镜显示出具有 70 ± 9nm 平均粒径的窄粒径分布。剩余极化和饱和极化分别为 15.5 ± 1.6 和 19.3 ± 1.2μC/cm(2)。获得了 925 ± 47 nF/cm(2)的电荷存储密度；Pt/BT/Pt 多层陶瓷电容器堆叠在 ±2V 时的平均漏电流密度为 5.78 ± 0.46×10(-8)A/cm(2)。这项研究的意义在于为电荷存储应用提供了一种用于合成高介电常数的廉价且简便的处理平台。
