Journal of the Korean Physical Society, Vol. 65, No. 3, August 2014, pp. 404∼407 Effects of the Processing Parameters in the Synthesis of BaTiO 3 Nanoparticle by Using the Co-precipitation Method Xin He Engineering Ceramic Center, Korea Institute of Ceramic Engineering and Technology, Korea and Department of Bionano Technology, Gachon University, Korea Hwa-Jun Lee and Sung-Soo Ryu ∗ Engineering Ceramic Center, Korea Institute of Ceramic Engineering and Technology, Korea Youn-Kyu Choi AMRI, Samsung Fine Chemicals Co., Ltd., Korea Heongkyu Ju Department of Bionano Technology, Gachon University, Korea, Department of Nanophysics, Gachon University, Korea and Neuroscience Institute, Gil Hospital, Incheon, Korea (Received 14 January 2014, in final form 15 March 2014) In this study, BaTiO3 powder was synthesized by using the co-precipitation of BaCl2 and TiOCl2 in a highly-alkaline solution at ambient pressure and a heating temperature lower than 100 ◦ C. Control of both the pH of the sodium hydroxide (NaOH) solution and the concentrations of the starting raw materials was studied to evaluate their effects on the grain size and the homogeneity of the powder. Under the condition of a solution pH of 14 and a reaction temperature of 80 ◦ C, an average particle size of 80 nm was estimated. X-ray diffraction, field-emission scanning electron microscopy, and transmission electron microscopy analyses showed that with high-energy ball milling in a bead mill, the uniformity and the dispersion of BaTiO3 particles could be enhanced. PACS numbers: 81.20.Ev Keywords: BaTiO 3 , Co-precipitation, Bead milling, Nanosized particle DOI: 10.3938/jkps.65.404 I. INTRODUCTION Barium titanate (BaTiO 3 ) is a perovskite-type dielec- tric ceramic material that has been widely used owing to its dielectric and ferroelectric properties [1,2]. BaTiO 3 is mainly used to fabricate multilayer ceramic capacitors (MLCCs), which are essential components in modern electronic devices such as smartphones. Intense market competition in the field of electronic devices has led to the miniaturization of MLCCs, which requires high volu- metric efficiency, by reducing their thickness and employ- ing a large number of layers [3]. However, each dielectric layer needs at least five grains to ensure the reliability of the MLCC [4]. In this light, this study investigated BaTiO 3 with small particle size and high tetragonality. To the best of our knowledge, BaTiO 3 can be synthe- sized by various methods such as the solid-state reac- ∗ E-mail: ssryu@kicet.re.kr tion method [5], the sol-gel method [6,7], and hydrother- mal method [8]. All of these aim to obtain BaTiO 3 powder with good dispersion, narrow particle size dis- tribution, and high dielectric constant so that it can be adapted to recent developments in MLCCs. How- ever, the above-mentioned synthesis methods have draw- backs that restrict their application and decrease their price-to-performance ratio. In contrast, the proposed co- precipitation method requires neither harsh conditions such as high temperature and high pressure, nor compli- cated preparation of the precursor. The entire process is implemented at low temperatures below 100 ◦ C and at ambient pressure; in addition, precursors can easily be prepared from an aqueous solution [6]. The particle size and uniformity are strongly affected by the nucleation rate and the crystallite growth, which can be controlled by the reaction temperature, the Ba/Ti ion concentra- tion, and the pH value [9]. A high-energy bead milling is introduced in this study -404-