Experimental observation of nanojets formed by heating PbO-coated Pb clusters

Phase Separation of Dirac Electrons in Topological Insulators at the Spatial Limit

In this work we present unique signatures manifested by the local electronic properties of the topological surface state in Bi₂Te₃ nanostructures as the spatial limit is approached. We concentrate on the pure nanoscale limit (nanoplatelets) with spatial electronic resolution down to 1 nm. The highlights include strong dependencies on nanoplatelet size: (1) observation of a phase separation of Dirac electrons whose length scale decreases as the spatial limit is approached, and (2) the evolution from heavily n-type to lightly n-type surface doping as nanoplatelet thickness increases. Our results show a new approach to tune the Dirac point together with reduction of electronic disorder in topological insulator (TI) nanostructured systems. We expect our work will provide a new route for application of these nanostructured Dirac systems in electronic devices.

Observation of infrared-active modes in Raman scattering from topological insulator nanoplates

Two infrared (IR)-active vibrational modes, observed at 93 and 113 cm(-1) in Raman scattering, are evidence of an inversion symmetry breakdown in thin (~10 nm) nanoplates of topological insulator Bi(2)Te(3) as-grown on SiO(2). Both Raman and IR modes are preserved after typical device fabrication processes. In nanoplates transferred to another SiO(2) substrate via contact printing, however, the IR modes are absent, and the Raman spectra are similar to those from bulk samples. The differences between as-grown and transferred nanoplates may result from nanoplate-substrate interactions.

Structure and stability of nickel/nickel oxide core-shell nanoparticles

The results of a combined x-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HR-TEM) study of Ni nanoparticles (NP), before and after oxidation, are presented. An experimental set-up was realized for the preparation and study of pre-formed NP films, concentrating the attention on Ni NP in the diameter range between 4 and 8 nm. The XPS data were taken in situ from NPs after different stages of oxidation, including controlled dosing of O(2) gas in the experimental system and exposure to the atmosphere. The Ni 2p structure is a combination of spectra from metallic Ni in the NP core and from the oxide shell. The signal from the NP core was observed even for samples after exposure to air. From the comparison of HR-TEM experimental images with theoretical simulations, it was found that the Ni NP core has a regular multitwinned icosahedral structure, composed of single-crystal tetrahedra with (111) faces. The NiO phase is clearly observed forming islands on the NP surface.

Obvious temperature difference along a pb cluster-decorated carbon nanowire

Pb nanoclusters were deposited onto a suspended carbon nanowire (CNW), where in situ temperature variable observation was carried out by a transmission electron microscope. The heating temperature was up to 450 °C. Both the melting and evaporation of the Pb nanoparticles on the CNW were retarded when compared to the particles on the support frame. The obvious temperature difference of up to 10 K along the CNW of less than 1 μm was demonstrated. It was attributed to the irradiating dissipation-dependent on the surface area of the decorating Pb particle by calculation.(See supplementary material 1).

Molecular dynamics of a water jet from a carbon nanotube

A carbon nanotube (CNT) can be viewed as a molecular nozzle. It has a cylindrical shape of atomistic regularity, and the diameter can be even less than 1 nm. We have conducted molecular-dynamics simulations of water jet from a (6,6) CNT that confines water in a form of single-file molecular chain. The results show that the water forms nanoscale clusters at the outlet and they are released intermittently. The jet breakup is dominated by the thermal fluctuations, which leads to the strong dependence on the temperature. The cluster size n decreases and the release frequency f increases at higher temperatures. The f roughly follows the reaction kinetics by the transition state theory. The speed of a cluster is proportional to the 1/sqrt[n] because of the central limit theorem. These properties make great contrast with the macroscopic liquid jets.

Cluster-assembled Tb-Fe nanostructured films produced by low energy cluster beam deposition

Cluster-assembled Tb-Fe nanostructured films were prepared by the low energy cluster beam deposition method. The microstructure, magnetization and magnetostriction were investigated for the films. It is shown that the film is assembled by monodisperse spherical nanoparticles with average diameter of ∼30 nm which are distributed uniformly. The cluster-assembled Tb-Fe nanostructured films exhibit good magnetization and possess giant magnetostriction with saturation value of ∼1060 × 10(-6), much higher than that of the common Tb-Fe films. The origin of good magnetization and giant magnetostriction for the cluster-assembled Tb-Fe nanostructured film was discussed. The present work opens a new avenue to produce the nanostructured magnetostrictive alloy in application of a nano-electro-mechanical system.

Growth mechanisms of SnO(2)/Sn nanocables

SnO(2)/Sn nanocables have been grown on single-crystal Si substrates by metal catalyst assisted thermal evaporation of SnO powders. The morphologies and structures of the prepared nanocables were determined on the basis of field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), x-ray diffraction (XRD), Raman and photoluminescence (PL) spectra analyses. The microstructures and compositions of the top and bottom regions of the SnO(2)/Sn nanocables were identified by HRTEM in detail, which revealed some basic physical and chemical processes involved in the formation of the nanocables. A growth model was proposed to address the formation of SnO(2)/Sn nanocables on the basis of the vapour-liquid-solid (VLS) process.