Characterization of single-crystalline PbTiO3 nanowire growth via surfactant-free hydrothermal method

In this work, we present the results obtained in fabrication and characterization of single-crystalline lead titanate nanowires synthesized by surfactant-free hydrothermal method at 200 degrees C. The as-prepared samples were characterized by means of x-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, selected-area electron diffraction, x-ray photoelectron spectroscopy (XPS), thermogravimetry and differential thermal analysis, Fourier transformation infrared spectroscopy, Raman spectroscopy, photoluminescence spectroscopy, and ultraviolet-visible spectroscopy. The results show that the products have a tetragonal perovskite structure without any other impurity phase, which are made up of a large quantity of nanowires with uniform diameters of about 12 nm and lengths reaching up to 5 mu m, and the growth of nanowires is generally along the [001] direction. XPS result shows that the binding energy of Ti2p((3/2)) core level peak for PbTiO3 nanowires is larger than that of the corresponding ceramics and leads to the larger spin-orbit splitting (Delta[2p((3/2))-2p((1/2))]) for Ti2p. Raman studies show that the vibration modes of nanowires redshifted and broadened, which have shorter phonon lifetime compared to that of bulk materials. A blue light emission peaking at about 471 nm (2.63 eV) is observed at room temperature, oxygen vacancies are responsible for the luminescence in PbTiO3 nanowires. The band gap energy for PbTiO3 nanowires was about 4.15 eV. (c) 2007 American Institute of Physics.