Structural and chemical characterization of BaTiO3 nanorods

An electron-microscopy investigation was performed on BaTiO3 nanorods that were processed by sol–gel electrophoretic deposition (EPD) into anodic aluminium oxide (AAO) membranes. The BaTiO3 nanorods grown within the template membranes had diameters ranging from 150 to 200 nm, with an average length of 10–50 μm. By using various electron-microscopy techniques we showed that the processed BaTiO3 nanorods were homogeneous in their chemical composition. The BaTiO3 nanorods were always polycrystalline and were composed of well-crystallized, defect-free, pseudo-cubic BaTiO3 grains, ranging from 10 to 30 nm. No intergranular phases were observed between the BaTiO3 grains. A low-temperature hexagonal polymorph that is coherently intergrown with the BaTiO3 perovskite matrix was also observed as a minor phase. When annealing the AAO templates containing the BaTiO3 sol in an oxygen atmosphere the presence of the hexagonal polymorph was diminished.