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

Abstract

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°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 12nm and lengths reaching up to 5μm, 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 (Δ[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 471nm (2.63eV) is observed at room temperature, oxygen vacancies are responsible for the luminescence in PbTiO3 nanowires. The band gap energy for PbTiO3 nanowires was about 4.15eV.

Phase transition and phonon characteristics of PbTiO3 single-crystal nanorods prepared in NaCl flux

“…The remarkable cell shrinking and tetragonality decreasing induced by size effect have also been observed in the BaTiO 3 and SrTiO 3 nanostructures prepared through surfactant system [2,7]. In contrast, the PT nanorod by surfactant-free method shows less change in lattice than crystal, though the size effect was observed as well [6]. Therefore, we suggest that the both the point-initiated growth kinetics of nanorods and the surfactants used in synthesis process contribute to the enhancing of the size effect.…”

“…Variety of techniques, such as solution-phase decomposition [1,3], hydrothermal [5,6], flux [2], template [4,7], microemulsion [8] and electro-spinning [9] methods, have been developed to synthesize them. And many further researches are directed towards the detailed experimental investigations on their size-dependent properties [3,4,6,10]. As an important perovskite oxide of excellent ferroelectric and optoelectronic characters, PT has been studied theoretically and experimentally in the past decades.…”

Structural and dielectric properties of Pb(1−x)(Na0.5Sm0.5) x TiO3 ceramics

“…Pure PbTiO 3 is known to have a sharp ferroelectric to paraelectric transition around 763 K (Curie temperature) accompanied by a structural transition from polar tetragonal to non-polar cubic phase [28]. This structural phase transition manifests as a sharp and frequency independent peak in dielectric permittivity versus temperature plot.…”

Photoluminescence in Low-Dimensional Oxide Ferroelectric Materials

“…Gu, et al reported characterization of single-crystalline lead titanate nanowires using photoluminescence spectroscopy, and ultraviolet-visible spectroscopy [26,27]. The nanowires were synthesized by surfactant-free hydrothermal method at 200 o C. The nanowires with uniform diameters of about 12 nm and lengths up to 5 um, exhibit a tetragonal perovskite structure without impurity phases.…”