Formation Of One-dimensional Structures Research Articles

Enhanced dielectric properties and energy storage density of Mg-doped SrTiO3 nanowire films

To improve dielectric properties of SrTiO3-based materials and meet their development requirements in various scientific and technology fields, Mg-doped SrTiO3 nanowire films (with 0, 0.5, 1, 1.5 and 2mol% Mg) were fabricated by liquid phase deposition (LPD) process. The results showed that structural and dielectric properties of the prepared samples can be effectively affected by Mg doping. Thus, the SrTiO3 nanowire film doped with 1.5mol% Mg has high dielectric constant of 594.2, a low dielectric loss of 0.0167 and the highest breakdown strength of 463.1 kV/cm at 1 kHz, therefore resulting in a high energy density of 5.64 J/cm3, which is about 3.9 times higher than that of the pure SrTiO3 nanowire films (1.44 J/cm3). Based on findings in this research, it was shown that improvement of dielectric properties of SrTiO3 ceramic systems can be obtained with formation of one-dimensional structures and selecting reasonable Mg content for doping.

Template-free electrochemical synthesis of Cd/CdTe core/shell nanowires and CdTe nanotubes

Template-free electrodeposition was utilized to prepare Cd/CdTe nanowires and CdTe nanotubes for the first time, where the formation of one-dimensional structures was due to the highly anisotropic crystal structure and the Kirkendall effect.

STM and DFT study on formation and characterization of Ba-incorporated phases on a Ge(001) surface

We characterize the incorporation of Ba adatoms into the Ge(001) surface, resulting in the formation of one-dimensional structures with an internal 2×3 periodicity, after the deposition of Ba atoms at 970 K or at room temperature followed by a 770 K anneal. Scanning tunneling microscopy (STM) data were compared with theoretically simulated STM images generated by density functional theory electronic structure calculations. Excellent agreement between experiment and simulation was found when using an adopted structural model that assumes partial removal of the surface Ge dimers in the [1–10] surface direction and subsequent addition of a single Ba atom to the substrate second layer. Structural assignments for a number of defects observed within regions of the 2×3 reconstruction were also obtained.

High Surface Area Ceria Nanoparticles via Hydrothermal Synthesis Experiment Design

Hydrothermal synthesis of CeO2was optimized on two reactant concentrations and synthesis temperature and duration, in order to achieve material having the greatest specific surface area (SSA). Taguchi method of experimental design was employed in evaluation of the relative importance of synthesis parameters. CeO2nanoparticles were characterized using X-ray diffraction, nitrogen adsorption-desorption isotherms, and scanning electron microscopy. Optimum conditions for obtaining particles with greater SSA were calculated according to Taguchi’s model “the-higher-the-better.” Synthesis temperature was found to be the only parameter significant for enabling nanoparticles with greater SSA. Mesoporous nanocrystalline ceria with SSA as great as 226 m2 g−1was achieved, which is unprecedented for the hydrothermally synthesized ceria. The reason for this achievement was found in temperature dependence of the diffusion coefficient which, when low, favors nucleation yielding with fine particles, while when high it favors crystal growth and formation of one-dimensional structures. The occurrence of 1D-structure in sample exhibiting the smallest SSA was confirmed. Very fine crystallites with crystallite size as low as 5.9 nm have been obtained being roughly inverse proportional to SSA. Selected samples were tested as catalyst for soot oxidation. Catalyst morphology turned out to be decisive factor for catalytic activity.

Synthesis of pyrene-1-carbaldehyde nanorods and emission tuning by the fluorescent ratiometric change

Pyrene-1-carbaldehyde (PyCHO) nanorods were prepared by a simple reprecipitation method. The morphologies and the structures of the as-prepared PyCHO nanorods were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Unlike pyrene, PyCHO has a preferable packing direction due to the hydrophilic group (CHO), facilitating the formation of one-dimensional structures. The photophysical properties of the as-prepared aqueous dispersions of PyCHO nanorods were investigated, and it is found that the aggregates and the solvated PyCHO coexist in the aqueous dispersion system. Upon increasing the concentration of PyCHO, the emission of the solvated PyCHO was quenched while the emission of the nanostructures gradually increased. Thus, an emission tuning was achieved by the fluorescent ratiometric change in the aqueous suspension and in the polymer film blended with PyCHO nanostructures, which may provide an alternative way to achieve tunable emission.

Synthesis and structure of InP nanowires and nanotubes

An experimental procedure was developed for the synthesis of InP nanowires through reacting InP and In 2O 3 at high temperature. In situ formed vapors containing indium and phosphor were transported to a low-temperature deposition area and, then, recrystallized in the presence of an oxide vapor, resulting in the formation of one-dimensional structures. Both deposition temperature and concentration of the oxide played an important role in determining the diameter and morphology of InP nanowires. InP nanotubes could also be synthesized when excess oxide was used. Structural analysis of the synthesized nanowires was carried out and the possible growth mechanism was proposed.