Molten salt synthesis of BaTiO3 nanorods: Dielectric, optical properties, and structural characterizations

Single-crystalline perovskite BaTiO3 (BTO) nanorods were synthesized by (BaTi2O5-template) molten salt synthesis (MSS) methods. The effects of process parameters (eg, calcination temperature, reaction time, molten salt content, as well as different phase structures of TiO2 and barium oxides) on the formation of BTO nanorods and their structural characteristics were systematically investigated. The BTO nanorods synthesized at 800 degrees C for 5 hours by MSS method with the molar salt ratios of BaCO3:TiO2 (anatase):NaCl:KCl equal to 1:1:60:60, exhibited smooth and clean surfaces through their lengths. Their diameters were in the range of 130-200 nm with average length of 5 mu m. Large-scale amount of BTO nanorods was synthesized by BaTi2O5-template MSS method at 650 degrees C with molar salt ratios of BaC2O4:BaTi2O5 (template):NaCl:KCl equal to 1:1:60:60. The BTO nanorods successfully retained the one-dimensional morphology of the BaTi2O5 templates and their lengths were in the range of 5-10 mu m with an average diameter of similar to 300 nm. The single-crystalline nature of individual BTO nanorod was revealed by its selected area electron diffraction patterns and high-resolution TEM images. The BTO nanorods exhibited good optical properties with optical bandgaps in the range of 2.5-2.6 eV. Such optical bandgaps make the present BTO nanorods promising candidates for ferroelectric photovoltaic devices. Dielectric properties of the BTO nanorods synthesized by MSS method were comparatively investigated with the BTO nanorods synthesized by the BaTi2O5-template MSS method. It is found that the later BTO nanorods exhibit better dielectric properties and their synthesized temperature is also much lower than the former ones.