The Room-Temperature Sodium-Free Organosol Precipitation of Barium Titanate Nanocrystals

The purpose of this research was to produce high-purity monodisperse barium titanate nanocrystals (BTO-NCs). To this end, a modified and very high-yield organosol precipitation method was developed. The novelty of this method was its purely organic approach, which stoped the application of inorganic bases such as caustic soda (NaOH) and avoided the risk of the presence of undesirable ions in the synthesized dielectric material. Results showed that an absolutely-organic base, such as the methylamine aqueous solution could ensure the basic condition required for high-yield organosol precipitation. X-ray diffraction, scanning electron microscopy, dynamic light scattering, and high-resolution transmission electron microscopy analyses were utilized to ensure the formation of monodisperse NCs. It was also found that monodisperse precursor crystals of about 3 nm have been achieved. Using oleic acid as the capping agent allowed generating uniformly small size and excellent dispersibility of the precipitate in the nonpolar solvents. Thus, the synthesized NCs could be easily redispersed in different nonpolar solvents to produce various suspensions of nm-size BTO-NCs without adding any surfactant. The obtained transparent suspensions, which include well-dispersed nm-size crystals, are promising for many applications in nanotechnology such as advanced electro-optic devices.