Nanocrystallites of non-stoichiometric copper sul®des were synthesized via the reaction between [Cu(NH 3 ) 4 ] 2z and thiourea in sealed autoclaves at the low temperature of 60 ³C for 3 h. Thiourea played a key role in the process of Cu 9 S 8 nanocrystal formation. Through adjusting the redox atmosphere, Cu 7 S 4 and CuS were obtained from the freshly formed Cu 9 S 8 nanocrystals. The products were characterized by means of X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), FT-IR spectroscopy and transmission electron microscopy (TEM) techniques. The Cu : S atomic ratios for Cu 9 S 8 and Cu 7 S 4 were 9 : 8.08 and 7 : 4.05, respectively, analyzed by inductively coupled plasma (ICP) spectroscopy. The possible mechanism of phase transformation among copper sul®des (Cu 9 S 8 , CuS, and Cu 7 S 4 ) was discussed. The optical properties of the products were also recorded by means of UV±vis absorption, and photoluminescence spectroscopy.
Semiconductor ZnS nanowires were synthesized by a direct templating route in an inverted
hexagonal liquid crystal formed by oligo(ethylene oxide)oleyl ether amphiphiles, n-hexane,
n-hexanol/i-propanol (2:1), and water. The final product consists of ordered nanowires with
a diameter of ca. 5 nm. Most importantly, seven or more close-packed nanowires aggregate
to form a regularly shaped bundle with a width of ca. 10−30 nm, duplicating the hexagonal
structure of close-packed inverted micelles formed by amphiphiles. We propose a novel
simultaneous in situ formation (SISF) technique to synthesize ordered ZnS nanowires by
γ-irradiation at room temperature. The reaction is worth noting in that its occurrence is
homogeneous and simultaneous. The structures of the inverted hexagonal liquid crystal phase
and the final product were characterized by means of polarized optical microscopy (POM),
XRD, XPS, TEM and EDX techniques. UV−vis and PL spectra recorded the optical properties
of the ZnS nanowires. The amount of amphiphiles passivated with ZnS nanowires is ∼3.4
wt %, as determined by thermal gravimetric analysis (TGA).
Single-molecular-layer (SML) MoS2 and MoSe2 were synthesized by a hydrothermal method at 150–180 °C. XPS, XRD, ICP, and TEM were used to characterize the samples, and BET study indicated that the SML MoS2 has very large surface area. And it was found that the SML MoS2 has strong ability to catalytically decompose hydrazine monohydrate, just like platinum black.
We investigate electronic transport properties of the squashed armchair carbon nanotubes, using tight-binding molecular dynamics and Green's function method. We demonstrate a metal-tosemiconductor transistion while squashing the nanotubes and a general mechanism for such transistion. It is the distinction of the two sublattices in the nanotube that opens an energy gap near the Fermi energy. We show that the transition has to be achieved by a combined effect of breaking of mirror symmetry and bond formation between the flattened faces in the squashed nanotubes.
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