A novel, controlled, and high-yield solvothermal drying route to nanosized barium titanate powders

In this report, we describe a novel solvothermal procedure for the synthesis of nanosized particles of barium titanate (BaTiO₃). We have been able to synthesize large amounts of nearly uniform sized BaTiO₃ nanocrystals in the size range of 5-37 nm. The advantages of our technique over other previously reported hydrothermal/ solvothermal approaches are the high yield and the simple but precise control of the size of the particles, which is very conveniently achieved by changing the water content of the reaction mixture in a measured way. The particles are systematically characterized by powder X-ray diffraction (XRD), Raman scattering, scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED), high-resolution TEM (HRTEM), disc centrifugation, thermogravimetric and differential thermal analyses (TGA-DTA), infrared spectroscopy (IR), and inductively coupled plasma-optical emission spectrometer (ICP-OES). The as-synthesized BaTiO₃ nanopowders contain BaCO₃ byproduct as well as internal OH^- groups and residual solvent species that can be removed by acid washing following heating. However, it is shown that this procedure results in the substantial change of the chemical composition and strong degradation of real microstructure of nanosized BaTiO₃ particles.