Optimizing TiO2 through Water-Soluble Ti Complexes as Raw Material for Controlling Particle Size and Distribution of Synthesized BaTiO3 Nanocubes

• Published in: ACS omega Vol. 6; no. 48; pp. 32517 - 32527
• Main Authors: Nakashima, Kouichi, Hironaka, Kouta, Oouchi, Kazuma, Ajioka, Mao, Kobayashi, Yoshio, Yoneda, Yasuhiro, Yin, Shu, Kakihana, Masato, Sekino, Tohru
• Format: Journal Article
• Language: English
• Published: American Chemical Society 07.12.2021
• ISSN: 2470-1343; 2470-1343
• DOI: 10.1021/acsomega.1c04013

Barium titanate (BaTiO3) nanocubes with a narrow particle size distribution were synthesized using a three-step approach. First, a water-soluble Ti complex was synthesized using a hydrolysis method. Next, the titanium dioxide (TiO2) raw material was synthesized via a hydrothermal method using various water-soluble titanium (Ti) complexes. The TiO2 exhibited various particle sizes and crystal structures (anatase, rutile, or brookite) depending on the water-soluble Ti complex and the hydrothermal conditions used in its synthesis. Finally, BaTiO3 nanocubes were subsequently created through a hydrothermal method using the synthesized TiO2 particles and barium hydroxide octahydrate [Ba­(OH)2·8H2O] as raw materials. The present study clarifies that the particle size of the BaTiO3 nanocubes depends on the particle size of the TiO2 raw material. BaTiO3 particles with a narrow size distribution were obtained when the TiO2 particles exhibited a narrow size distribution. We found that the best conditions for the creation of BaTiO3 nanocubes using TiO2 involved using lactic acid as a complexing agent, which resulted in a particle size of 166 nm on average. This particle size is consistent with an average of the width of the cubes measured from corner to corner diagonally, which corresponds to a side length of 117 nm. In addition, surface reconstruction of the BaTiO3 was clarified via electron microscopy observations, identifying the outermost surface as a Ti layer. Electron tomography using high-angle annular dark-field (HAADF)-scanning transmission electron microscopy (STEM) confirmed the three-dimensional (3D) structure of the obtained BaTiO3 nanocubes.