Facile Synthesis of BaTiO₃ Nanocubes with the Use of Anatase TiO₂ Nanorods as a Precursor to Titanium Hydroxide

We report a solvothermal method for the facile and reproducible synthesis of BaTiO₃ nanocubes by employing anatase TiO₂ nanorods as a precursor to titanium hydroxide. The TiO₂ nanorods were, in turn, synthesized in advance through another solvothermal process. We could obtain high-quality BaTiO₃ nanocubes by reacting the TiO₂ nanorods with Ba(NO₃)₂ under solvothermal conditions in the presence of oleic acid and acetic acid as dual capping agents, followed by a purification process involving chemical washing and physical filtration. The addition of acetic acid alongside oleic acid was critical to the formation of well-defined {100} facets on the nanocrystals and also increased batch-to-batch reproducibility without the use of a glove box or similar air-free experimental design. Using this method, BaTiO₃ nanocubes crystallized in the cubic phase could be readily obtained with an average edge length around 8 nm.