Materials Literature
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Heavily phosphorus-doped Si nanocrystals several nanometers in diameter are studied by photoluminescence (PL) and optical absorption spectroscopy. It is demonstrated that P doping results in the quenching of the PL. The quenching is accompanied by the appearance of the optical absorption in the infrared range. The abs…
Half-Heusler compounds containing Ni of the form NiMP, where M is a trivalent (Sc) or tetravelent (Ti, Zr, Hf) ion and P is a pnictide or stannide ion (Sb, Sn), are known to form semiconducting phases for $M=\mathrm{Sc}$ and $P=\mathrm{Sb}$ as well as when M=Ti,Zr,Hf and $P=\mathrm{Sn}.$ However, the electronic struct…
The strain energies in straight and bent single-walled carbon nanotubes (SWNT's) are calculated by taking account of the total energy of all the occupied band electrons. The obtained results are in good agreement with previous theoretical studies and experimental observations. Young's modulus and the effective wall th…
Transparent conducting indium tin oxide (ITO) thin films (40–870 nm) were grown by pulsed laser deposition on amorphous substrates and the structural, electrical, and optical properties of these films were investigated. Films were deposited using a KrF excimer laser (248 nm, 30 ns FWHM) at a fluence of 2 J/cm2, at sub…
The potential energies of interaction between two parallel, infinitely long carbon nanotubes of the same diameter, and between ${\mathrm{C}}_{60}$ and a nanotube in various arrangements, were computed by assuming a continuous distribution of atoms on the tube and ball surfaces and using a Lennard-Jones (LJ) carbon-car…
The flow of a polypropylene in a self-wiping corotating twin-screw extruder was characterized by measuring the pressure, temperature, and residence time along the screw profile. The influence of the operating conditions (feed rate, screw speed, barrel temperature) and screw profile was studied. Flow modeling was perfo…
Rh(por)H, where por is an octaethyl- or meso−tetraphenylporphyrin dianion, reacts with triethylphosphine to form stable mononuclear paramagnetic formally-Rh II complexes, Rh(OEP)(PEt 3 ) and Rh(TPP)(PEt 3 ) 2 . The former adduct is also obtained as the sole product of the reaction between Rh 2 (OEP) 2 and PEt 3 . The…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSum Frequency Generation on Surfactant-Coated Gold NanoparticlesTakeshi Kawai, David J. Neivandt, and Paul B. DaviesView Author Information Department of Chemistry, University of Cambridge Lensfield Road, Cambridge CB2 1EW, UK Cite this: J. Am. Chem. Soc. 2000, 122, 48…
Vanadium-containing polyoxometalates, such as PV2Mo10O40, are shown to act as oxygen-donating compounds and catalyze the oxygenation of hydrocarbons in a liquid homogeneous phase by a Mars–van Krevelen type mechanism [Eqs. (1) and (2)].
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTAn Efficient Ketone-Catalyzed Epoxidation Using Hydrogen Peroxide as OxidantLianhe Shu and Yian ShiView Author Information Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523 [email protected]Cite this: J. Org. Chem. 2000, 65, 25, 8807–8810Publicati…
Nearly monodisperse CdSe quantum dots of 1.8 nm in size were synthesized and capped with a surface monolayer of 1-thioglycerol. The optical properties of thin films made from these matrix-free close-packed quantum dots were studied at different temperatures and electric field strengths and compared with isolated quant…
We demonstrate that polarization-related quantities in semiconductors can be predicted accurately from first-principles calculations using the appropriate approach to the problem, the Berry-phase polarization theory. For III-V nitrides, our test case, we find polarizations, polarization differences between nitride pai…
Complementary to the experimental studies on magic Ba clusters [Rayane et al., Phys. Rev. A 39, 6056 (1989)], it is theoretically found that magic Ba clusters with 13, 19, 23, 26, 29, and 32 atoms have icosahedral or polyicosahedral structures, which are induced by $5d$-electron bonding. As the cluster grows, the aver…
Ferroelectric/metal composites have been characterized for their electric field dependence of the dielectric and ferroelectric properties. The composites show an interesting change of dielectric properties with increasing metal concentration. A relatively high dielectric constant, up to four times as high as that of m…
Utilizing the containerless electrostatic levitation facility at NASA/MSFC, we were able to undercool the Ni59Nb41 (atomic) alloy by 210 K which was 160° farther than the results of previous flight experiments. Undercoolings were clustered around 200 K during the repeated melting–freezing cycles on a single sample. Pr…
SiO 2 / Ge:SiO 2 / SiO 2 sandwiched structure was fabricated for exploring efficient light emission. After annealed in N2 (O2<1%), this structure shows three photoluminescence (PL) bands at 293, 395, and 780 nm. The intensity of the 395 nm band is largely enhanced in comparison with that from the monolayered Ge…
Stress-free and two-way thermoelastic shape memory, with 1.2% strain and 6 K temperature hysteresis, has been found in single crystalline Ni52Mn24Ga24. The deformation can be enhanced more than three times, up to 4.0% shrinkage with a bias field 1.2 T applied along the measurement direction, or changed to 1.5% expansi…
By applying a transverse magnetic field ${B}_{\ensuremath{\perp}}$ of sufficient strength to the uniaxial molecular magnets ${\mathrm{Fe}}_{8}$ and ${\mathrm{Mn}}_{12}$, the tunneling splitting ${\ensuremath{\Delta}}_{t}$ of their $S\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ifmmode\pm\else\textpm\fi{}10$ mag…
The time-dependent relaxation of the remanent polarization in epitaxial lead zirconate titanate (PbZr0.2Ti0.8O3) ferroelectric thin films, containing a uniform two-dimensional grid of 90° domains (c axis in the plane of the film), is examined using piezoresponse microscopy. The 90° domain walls preferentially nucleate…
We show that the crystal growth rate of a very long-chain n-alkane C C(198)H(398) from solution can decrease with increasing supersaturation and follow strongly negative order kinetics. The experimental behavior can be well represented by a theoretical model which allows the molecule to attach and detach as either ext…