Low temperature molten salt synthesis of SrTiO_3 submicron crystallites and nanocrystals in the eutectic NaCl-KCl

摘要

An eutectic NaCl-KCl molten salts method has been developed for the synthesis of SrTiO_3 submicron crystallites and nanocrystals from SrO_2 and two kinds (submicron and nano-sized) of TiO_2 powders at 700 ℃. which was much lower than that (generally>1000℃) 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 SrTiO_3 without any contamination of Na, K, and Cl ions. The scanning electronic microscopy and transmission electron microscopy images disclosed that the starting TiO_2 played an important role in the morphology and size of the obtained SrTiO_3: while the product derived from TiO_2 submicron crystallites comprised faceted submicron crystallites of about 95-184 nm, that derived from TiO_2 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 TiO_2, the possible formation mechanism of SrTiO_3 submicron crystallites and nanocrystals was proposed.