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Introducing sp3 bonds in carbon nanotubes can significantly modify their electronic properties but need high pressure at room temperature. Here we show by molecular dynamics simulations that sp2 to sp3 bond transition can be realized through bending manipulation at the buckling location, resembling that of nanoindented carbon nanostructures but with more convenient operation technique. The capability of sp3 bond formation is sensitive to the thickness and diameter of the carbon nanotubes. This bending induced sp3 structures can serve as tunneling junction for electrons, thus bending manipulation could be a route to tailoring nanocircuits. [ABSTRACT FROM AUTHOR]

In sharp contrast to the prevailing view that electric fields promote water freezing, here we show by molecular dynamics simulations that monolayer ice confined between two parallel plates can melt into liquid water under a perpendicularly applied electric field. The melting temperature of the monolayer ice decreases with the increasing strength of the external field due to the field-induced disruption of the water-wall interaction induced well-ordered network of the hydrogen bond. This electromelting process should add an important new ingredient to the physics of water. [ABSTRACT FROM AUTHOR]

The size dependence of the piezoelectricity in ZnO nanofilms is investigated using ab initio density-functional theory calculations. The effective piezoelectric constant of ZnO nanofilms increases monotonically with increasing film thickness in the nanoscale simulated in the present work, and surprisingly, exceeds that of the bulk ZnO when the thickness is greater than 2.4 nm. The enhancement over the bulk value reaches 11% when the film thickness is 2.9 nm. [ABSTRACT FROM AUTHOR]

Uniform single-crystalline pearl-necklace-shaped PbTe nanowires with an average diameter of about 30 nm, smaller than its average excitonic Bohr radius of 46 nm, were successfully synthesized by a hydrothermal process using tellurium nanowires as templates and Pb(NO 3) 2as a precursor at a molar ratio of 1:1. It is shown that the reaction temperature, duration, and concentration of Pb(NO 3) 2play important roles in the formation of the PbTe nanowires. The growth process of the pearl-necklace-shaped PbTe nanowires can be reasonably explained by an oriented attachment mechanism. Thermoelectric transport measurement indicates that the film composed of the obtained PbTe nanowires has a Seebeck coefficient of about 307 μV/K, up to about 16% higher than that of the state-of-the-art bulk PbTe at room temperature. The synthetic route can be applied to obtain other low-dimensional semiconducting telluride nanostructures and optimization of the thermoelectric properties through nanowire alignment and doping may lead to practical applications. [ABSTRACT FROM AUTHOR]