Synthesis Of KNbO₃ And BaTiO₃ One-Dimensional Nanostructures By Self-Sacrificing Templates

nanostructure by self-scrificing templates based on molten salt and hydrothermal method. KNbO₃ nanowires and BaTiO₃ nanorods made of small particles are synthesized successfully.The composition, morphologies and structures of the prepared samples were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Raman spectroscopy and high-resolution transmission electron microscope (HRTEM).First, using the molten salt method, we synthesize a lot of KNb₃O₈, Na₂Ti₃O₇ and Na₂Ti₆O₁₃ nanowires, and use it as the templates in the later reaction.Using KNb₃O₈ nanowires as the template, we synthesized KNbO₃ nanowires by hy hydrothermal method at 200°C, when adding 5mol/L KOH. The nanowires are 100nm in diameter, and 1²Î¼m in length. KNbO₃ nanowires are single-crystalline and the growth direction is along [001] axis. Hydrothermal temperature and the concentration of KOH have important influence on the products.When The product is cube-shaped particles about several micronsin at 120°C; At 150°C, when the concentration of KOH was below 5M, K₂Nb₈O₂₁ microwires were got ,the products were step grown KNbO₃ particles when the concentration of KOH was 10M; When the temprature was 200°C, the product turned from cube-shaped particles to K₂Nb₈O₂₁ microwires and then the nanowires.Using Na₂Ti₆O₁₃ nanowires as the template, BaCl₂ providing Ba, we synthesized BaTi4O9 nanowires and BaTi5O11 nanoflakes by molten salt method.We aslo studied the influence of BaCl₂/NaCl mass ratio on the products. When adding a little BaCl₂, we got BaTi5O11 nanoflakes with thickness of about 400nm. The products turned to nanowores along with the increase of BaCl₂/NaCl mass ratio.When the value is 2.5/0.5, wo got pure BaTi4O9 nanowires with diameter about 300nm, and length several micrometers. Using Na₂Ti₃O₇ nanowires as the template, we sythesized the BaTiO₃ nonotubes made of small particles by adding the ethanol in the hydrothermal reaction. The size of the particles is about 200nm, and the diameters of tube are about several hundred nanometers. We analyse the nanowires with particles on it by TEM, [001] axis of BaTiO₃ and [020] axis of Na₂Ti₃O₇ nanowires were nearly in line, they had certain orientation relationship. We proposed the mechanism for BaTiO₃ nanotubes made of particles is Kirkendall effect.