Structure study of single crystal BaTiO3 nanotube arrays produced by the hydrothermal method.

High aspect ratio BaTiO(3) nanotube arrays with single crystal structure were fabricated by the hydrothermal method at low temperature (150 degrees C). Numerous structure study methods, including x-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), electron paramagnetic resonance (EPR), and x-ray photoelectron spectroscopy (XPS), were used to investigate the structure of single crystal BaTiO(3) nanotube arrays. TEM observation shows that BaTiO(3) nanotubes have identical crystallographic orientation through their growth directions. EPR and XPS studies show that the obtained BaTiO(3) nanotubes contain perceptible oxygen vacancies. Those oxygen vacancies are responsible for the observed green emission band at 545 nm (2.27 eV) detected by photoluminescence study.