Li Jinhui, Inukai Koji, Takahashi Yosuke, Tsuruta Akihiro, Shin Woosuck
Department of Frontier Materials, Nagoya Institute of Technology, Nagoya 466-8555, Japan.
Inorganic Functional Material Research Institute AIST, Nagoya 463-8560, Japan.
Materials (Basel). 2017 Dec 29;11(1):51. doi: 10.3390/ma11010051.
Nano-sized tetragonal BaTiO₃ (BT) particles that are well dispersed in solution are essential for the dielectric layer in multilayer ceramic capacitor technology. A hydrothermal process using TiCl₄ and BaCl₂, as source of Ti and Ba, respectively, or the precursor TiO₂ as seed for the formation of BT, and poly(vinylpyrrolidone) (PVP) as a surfactant, was employed in this study to enhance both the dispersibility and tetragonality (c/a) simultaneously in a single reaction process. The process parameters, i.e., the ratio of TiO₂ substitution of TiCl₄, the reaction time, and PVP content were systematically studied, and the growth mechanism and relation between the tetragonality and the particle size are discussed. Dynamic light scattering (DLS) analysis was used to show that truncated pseudo-tetragonal BT-PVP particles with an average size of 100 nm, having a narrow size distribution and a coefficient of variation (CV) as low as 20% and being mono-dispersed in water, were produced. The narrow particle size distribution is attributed to the ability of PVP to inhibit the growth of BT particles, and the high c/a of BT-PVP to heterogeneous particle growth using TiO₂ seeds.
在多层陶瓷电容器技术中，溶液中分散良好的纳米级四方相钛酸钡（BT）颗粒对于介电层至关重要。本研究采用水热法，分别使用TiCl₄和BaCl₂作为Ti和Ba的来源，或以前体TiO₂作为形成BT的晶种，并使用聚乙烯吡咯烷酮（PVP）作为表面活性剂，以在单一反应过程中同时提高分散性和四方度（c/a）。系统研究了工艺参数，即TiCl₄中TiO₂替代比例、反应时间和PVP含量，并讨论了生长机理以及四方度与粒径之间的关系。动态光散射（DLS）分析表明，制备出了平均尺寸为100 nm的截顶伪四方相BT-PVP颗粒，其粒径分布窄，变异系数（CV）低至20%，且在水中呈单分散状态。窄粒径分布归因于PVP抑制BT颗粒生长的能力，而BT-PVP的高c/a则归因于使用TiO₂晶种的异质颗粒生长。
