Highly pure, stoichiometric, nanometer-sized, and fairly monodispersed anhydrous crystalline BaTiO3 particles are synthesized under hydrothermal conditions in a single process step without further heat treatment by reacting titanium isopropoxide [Ti(OC3H7)4] precursor in aqueous solutions of Ba(OH)2 at 80°C. Traditional considerations of solution hydrolysis, solute condensation, and nucleation only partly explain the generation of the “raspberry-like” BaTiO3 particles composed of 5∼10 nm primary crystalline particles. Consequently, the colloidal interaction of the precipitating particles and, therefore, controlled aggregation of freshly nucleated particles must be taken into account. Our TEM studies show aggregation growth of small subunits to form uniform, rounded polyhedral particles, suggesting colloidal stability may play a key role in controlling precipitate size and shape.In order to investigate the evidence supporting the aggregation growth, Ti(OC3H7)4 precursor (Aldrich) has been added to l.OM Ba(OH)2 solution and hydrothermally reacted at 80°C in polyethylene bottles. Four molecules of water and two hydroxyl ions attach through their oxygen atoms to the titanium of Ti(OC3H7)4 in a nucleophilic process.
Experimental study of interactions between uranium and n-alkanes in hydrothermal conditions (500 bar, 200 °C)
