Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNucleation and Growth of CdSe on ZnS Quantum Crystallite Seeds, and Vice Versa, in Inverse Micelle MediaA. R. Kortan, R. Hull, R. L. Opila, M. G. Bawendi, M. L. Steigerwald, P. J. Carroll, and Louis E. BrusCite this: J. Am. Chem. Soc. 1990, 112, 4, 1327–1332Publication Date…
An ac technique for measuring the thermal conductivity of dielectric solids between 30 and 750 K is described. This technique, the 3ω method, can be applied to bulk amorphous solids and crystals as well as amorphous films tens of microns thick. Errors from black-body radiation are calculated to be less than 2% even at…
Abstract Starburst dendrimers are three‐dimensional, highly ordered oligomeric and polymeric compounds formed by reiterative reaction sequences starting from smaller molecules—“initiator cores” such as ammonia or pentaerythritol. Protecting group strategies are crucial in these syntheses, which proceed via discrete “A…
The temperature dependences of the coefficients representing preferential grain-boundary diffusion (PGBD), the dependences of the PGBD parameters on excess charges of atomic probes, and the isotopic effect under the PGBD conditions made it possible to identify the interstitial PGBD mechanism for a number of f.c.c. met…
Abstract CH‐type catalysts were prepared by reacting MgCl 2 · ROH, where ROH is 2‐ethyl hexanol (EH), (R)‐2‐octanol (R‐20), and (S)‐2‐octanol (S‐20), with TiCl 4 in the presence of di‐ i ‐butyl phthalate (BP), di‐ i ‐butyl terephthalate (BT), (‐)‐dimenthyl phthalate (MP), or (‐)‐dimenthyl terephthalate (MT). The MT ca…
Abstract A series of new polyimides containing fluorinated alkoxy side chains are prepared from novel fluorinated alkoxy diamines. The dieletric constant at 1 kHz in the fluorinated polyimides decreases from 3.3 to 2.6 as fluorine content increases. The refractive index also changes from 1.58 to 1.48, dependent on the…
We have determined and refined the X-ray crystal structures of six periplasmic binding proteins that serve as initial receptors for the osmotic-shock sensitive, active transport of L-arabinose, D-galactose/D-glucose, maltose, sulphate, leucine/isoleucine/valine and leucine. The tertiary structures and atomic interacti…
It is shown that Frank's ``saddle'' distortion contribution to the nematic liquid-crystal distortional elastic energy is required, in addition to the splay, twist, and bend energies retained in more recent treatments. ``Normal distortion modes'' for these four distortions are described. Measurement methods and their i…
For the first time the observation of a sharp peak in the broad luminescence spectrum of hydrogenated amorphous silicon (a-Si:H) has been achieved, using erbium as a dopant. Thus, a method of investigating the structure of solid-state systems which previously has only been used with crystals can now be applied to a-Si…
Thin diamond films were deposited on different substrates at temperatures below 500 °C by a microwave plasma-enhanced chemical vapor deposition system. The deposited films were amorphous carbon or diamond films depending on the different gas mixtures used. The addition of oxygen to the gas mixtures was found to be cri…
Single crystals of the new nonlinear optical material 3-methyl-4-methoxy-4′-nitrostilbene (MMONS) have been grown by a seeded solution growth technique and the linear and nonlinear optic and electro-optic properties determined. MMONS is highly birefringent with nz−nx =0.75 (0.532 μm), has large nonlinear optical coeff…
A detailed comparison between molecular dynamics computer simulations and the experimental characterization of molecular motion through deuterium nuclear magnetic resonance (NMR) spectroscopic methods has been carried out for the crystalline phase of nylon 66 (polyhexamethyleneadipamide) at room temperature and just b…
Ceramic superlattices have been produced by electrodeposition with modulation wavelengths in the range from 5 to 10 nanometers. The TlaPbbOc/TldPbeOf superlattices were deposited from a single aqueous solution at room temperature, and the layer thicknesses were galvanostatically controlled. The films showed strong pre…
Nematic liquid crystals (NLCs) are anisotropic molecules which can be oriented to form uniaxial birefringent layers. NLCs aligned between suitably prepared substrates can be used as large aperture retardation plates; furthermore, the retardance of these cells can be tuned by applying an electric field. The ability to…
We have investigated the effects of pressure on the pinned and sliding charge-density-wave states of ${\mathrm{K}}_{0.3}$${\mathrm{MoO}}_{3}$ at 77 and 4.2 K. The application of hydrostatic pressure suppresses the threshold electric field both for the conventional charge-density-wave conduction and for the low-tempera…
New accurate results for the thermopower of Si inversion layers are compared with the calculated screened phonon-drag thermopower. Good agreement is obtained for both the temperature dependence and the magnitude, except at the lowest temperatures, when a change of sign to positive thermopower is observed. This the aut…
The first measurement is reported for the electrical properties of the precursor glasses in the high-temperature superconducting system Bi-Sr-Ca-Cu-O. The phonon-assisted hopping of small polarons is consistent with the DC conductivity in the high temperature region; however, at lower temperatures a variable range hop…
We observed a shear-induced alignment of colloidal particles in a Brownian dynamics simulation carried out in the presence of an oscillating shear flow. As the shear rate \ensuremath{\gamma} is increased for temperatures near the melting point, we first observe shear thinning followed by a transition to a state with t…
A microscopic theory for the long-wavelength dielectric dispersion [\ensuremath{\epsilon}(\ensuremath{\omega})] in a strongly correlated dipolar liquid is presented. The calculated \ensuremath{\epsilon}(\ensuremath{\omega}) is stongly non-Debye if only the orientational mechanism of polarization relaxation is consider…
Layered transition metal dichalcogenides (MoSe2, NbSe2) have been heteroepitaxially grown on (NH4)2 Sx (x≂2) treated GaAs(111)Ga, GaAs(∼(111))As surfaces in spite of the large difference in their crystal structures. The in situ observation of reflection high-energy electron diffraction has shown that the grown film ha…