Alkaline metal ion free organosol synthesis of monodispersed BaTiO۳ nanoparticles

The organosol synthesis method is a high-yield and simple method to produce various nanoparticles. A strong inorganic base such as caustic soda or caustic potash is usually used in this method which increases the risk of the presence of undesirable metal ions. Therefore, several washing steps will be required to remove the contaminants. However, here, an alkaline metal ion free organosol method is developed for the fabrication of fine monodispersed BaTiO۳ nanoparticles (BTO-NPs) from alkoxide precursors. Oleic acid is used as the capping agent. In contrast to previous approaches, an absolute organic base such as methylamine or ethylenediamine is used. The innovative point of this approach is that no inorganic compound is used so, the risk of the presence of undesirable metal cations in the synthesized ferroelectric material is avoided. Consequently, only one washing step is required which decreases the processing time and increases the efficiency of the process significantly. Also, a negligible amount of BaCO۳ is produced during the synthesis stage which is entirely etched away upon washing. The effect of the synthesis temperature on the capping efficiency of oleic acid for titanium isopropoxide as well as the size and morphology of the produced NPs is determined. It is found that, at room temperature, a very broad discrete distribution of NP size is achieved because capping efficiency of oleic acid of titanium isopropoxide with oleic acid is weak. So, many of the formed clusters are not effectively capped, and the grown NPs may enlarge during the growth stage. However, at elevated temperatures, oleic acid will cap effectively the titanium precursor. So, all the formed clusters are effectively capped which results in the formation of fine NPs with uniform size. Consequently, monodispersed NPs of few nanometers in diameter with excellent dispersibility in organic solvents are achieved. The prepared NPs can be easily re-dispersed in different organic nonpolar solvents without adding any surfactant. The method offers an alternate low-cost route to perovskite nanopowders. The mechanism of powder formation is discussed in detail.

کلیدواژه ها:

Nanomaterials ، Organosol Synthesis ، Ferroelectrics ، BaTiO۳.