Low temperature molten salt synthesis of SrTiO3 submicron crystallites and nanocrystals in the eutectic NaCl-KCl

An eutectic NaCl-Cl molten salts method has been developed for the synthesis of SrTiO3 submicron crystallites and nanocrystals from SrO2 and two kinds (submicron and nano-sized) of TiO2 powders at 700 degrees C, which was much lower than that (generally> 1000 degrees C) of the conventional solid state reactions. The characterization results from X-ray diffraction and X-ray photoelectron spectroscopy revealed that the obtained products were pure perovskite phase SrTiO3 without any contamination of Na, K, and Cl ions. The scanning electronic microscopy and transmission electron microscopy images disclosed that the starting TiO2 played an important role in the morphology and size of the obtained SrTiO3: while the product derived from TiO2 submicron crystallites comprised faceted submicron crystallites of about 95-184 nm, that derived from TiO2 nanocrystals comprised quadrate nanocrystals of about 20-61 nm. Besides, based on the experiments without the molten NaCl-KCl eutectic, at different temperatures and times, and using different kinds of TiO2, the possible formation mechanism of SrTiO3 submicron crystailites and nanocrystals was proposed. (C) 2009 Elsevier B.V. All rights reserved.