Microwave synthesis of nano-sized barium titanate

Nano-sized barium titanate powders have been synthesized by microwave processing at 2.45 GHz. Using barium titanyl oxalate (BTO) as a precursor, microwave processing was carried out by heating the precursor to a temperature between 600 degrees C and 750 degrees C with different heating rates from 10 degrees C/min to 20 degrees C/min without isothermal holding. X-ray diffraction analysis indicates that the decomposed product at 680 degrees C was pure cubic BaTiO3. The BET specific surface area of barium titanate powder, after microwave heating to 680 degrees C, was 14.2 +/- 0.5 m(2)/g, corresponding to an average particle size of 70 nm. This particle size was confirmed by the scanning electron microscopy (SEM). Parallel study shows that the conventional heating in a regular resistance furnace using a similar heating schedule did not result in complete conversion of BTO. This study shows that the microwave processing significantly accelerated the decomposition of barium titanyl oxalate and reduced the temperature of barium titanate nano-powder formation, resulting in nano-sized pure cubic barium titanate powder. (C) 2007 Elsevier B.V. All rights reserved.