Materials Literature
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Calculations of the static dielectric response ${\ensuremath{\epsilon}}_{\ensuremath{\infty}}$ of some simple oxide and mixed transition-metal oxide insulators using the weighted density approximation are reported, including in particular the perovskites ${\mathrm{KNbO}}_{3},$ ${\mathrm{KTaO}}_{3},$ and ${\mathrm{BaTi…
The relationship between molecular self-assembly processes and nucleation during crystallization from solution is an important issue, both in terms of fundamental physical chemistry and for the control and application of crystallization processes in crystal engineering and materials chemistry. This contribution examin…
We calculate energies, oscillator strengths for radiative recombination, and two-particle wave functions for the ground state exciton and around 100 excited states in a T-shaped quantum wire. We include the single-particle potential and the Coulomb interaction between the electron and hole on an equal footing, and per…
We predict new forms of carbon consisting of one- and two-dimensional networks of interlinked single-wall carbon nanotubes, some of which are energetically more stable than van der Waals packing of the nanotubes on a hexagonal lattice. These interlinked nanotubes are further transformed with higher applied external pr…
A computational study of the doping of alkali halide crystals (AX: A=Na and K; X=Cl and Br) by ns2 cations (Ga+, In+, and Tl+) is presented. Active clusters of increasing size (from 33 to 177 ions) are considered in order to deal with the large scale distortions induced by the substitutional impurities. Those clusters…
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…