Single wall carbon nanotube (SWNT) bundles protruding from the SWNT layers on self-aligned Sn apexes were brought to a distance of 30 nm by a scanning tunneling microscope inside a transmission electron microscope. A straight bundle on the tip could be observed in situ in contact electrostatically with a looped bundle on the sample by applying tip bias voltages above 2.0 V. The bundles were welded at the nanometer size contact area by local Joule heating.
Pd nanoparticles exhibit the abnormal behavior of the Pd lattice expanding as the size of the Pd nanoparticles decreases. We measured extended X-ray absorption fine structure of poly(N-vinyl-2-pyrrolidone)-protected Pd nanoparticles and confirmed that the Pd–Pd bond distance in small Pd nanoparticles with a diameter of less than 3 nm was elongated by 2% compared with that in Pd foil. The origin of the unusual bond elongation was discussed.
Noble metal nanoparticles always show bond length contraction with the decrease in particle size. PVP-protected small Pd metal nanoparticles (MNPs) were reported to have the unique characteristic of expanding Pd-Pd bond lengths with decreases in particle size. To investigate the origin of this phenomenon in more detail, this work examined Pd MNPs supported on SiO2 (Pd MNPs/SiO2) via extended X-ray absorption fine structure (EXAFS) analysis, where the SiO2 support was used to stabilize the MNPs to prevent unexpected aggregation at higher temperatures. EXAFS data showed that each sample had a face-centered cubic (fcc) structure and that the smallest particles had the longest Pd-Pd bonds. Temperature dependent EXAFS measurements also revealed significant static disorder in the bond-elongated Pd MNPs/SiO2 samples. The XAFS spectral features of these bond-elongated Pd MNPs on SiO2 are in good agreement with those for palladium carbide, and we conclude that the lattice expansion in Pd MNPs can be attributed to the formation of palladium carbide.
We fabricated a nanoincandescent consisting of a single multiwalled carbon nanotube filament on the tip of a sharpened quartz fiber with a diameter of less than 300 nm. The nanoincandescent emits light by Joule heating in the visible to near-infrared region according to the Planck's black-body radiation law, where the nanotube filament reached a temperature of around 2000 K. Nanoprocessing was demonstrated using the nanoincandescent as a nanoheater operating at temperatures higher than 1000 K.
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