Experimental and simulation-based understanding of morphology controlled barium titanate nanoparticles under co-adsorption of surfactants

Well dispersed single-crystalline BaTiO3 nanoparticles with controlled morphologies were synthesized using a thermohydrolysis route. The nanoparticles were tuned from spherical to cubic upon changing the NaOH concentration under a critical molar ratio of oleic acid to hydrazine. Density functional theory (DFT) and molecular dynamics (MD) calculations indicated that hydrazine molecules adsorbed preferably on the Ti position of the Ti-O terminated surface; meanwhile, oleic acid molecules tended to adsorb on the Ba position of the Ba-O terminated surface. The added hydrazine changed the formation mechanism of BaTiO3 nanoparticles from an in situ growth to a dissolution-precipitation growth. Excellent dispersibility in aqueous solution was achieved for the BaTiO3 nanoparticles under the assistance of hydrazine. Meanwhile, a high-quality self-assembled film with a stable dielectric constant of 30 in the frequency range from 0 Hz to 1 MHz was prepared using the well dispersed BaTiO3 nanoparticles, providing a novel low-temperature route for the fabrication of perovskite films.