Materials Literature
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The transformation of a chemisorbed O layer on the Al(111) surface into Al2O3 under electron impact has been monitored by high-resolution electron energy-loss and x-ray photoelectron spectroscopies. Electron irradiation (100 eV) of chemisorbed O was observed to cause spectroscopic changes in the surface layer indicati…
A significant breakthrough in the nitride chemistry of main group elements has been achieved: Surprisingly Sn(3)N(4), for which there had been no proof of existence until now, as well as the isotypic high-pressure polymorphs gamma-Si(3)N(4) and gamma-Ge(3)N(4) have been synthesized. All three compounds crystallize in…
Yttrium sodium oxalate tetrahydrate, [Y(H 2 O)]Na-(C 2 O 4 ) 2 .3H 2 O, was obtained from hydrothermal synthesis and its structure determined from single-crystal X-ray diffraction data. The structure consists of corrugated layers of ninefold-coordinated Y atoms linked together by oxalate groups. Na atoms and water mol…
High-quality ZnO crystals have been grown by vapor-phase techniques and by the hydrothermal method. Depending on the surface preparation technique, some hydrothermally grown crystals contain strain. These strains result in energy shifts of the free excitons as well as relaxation of the selection rules. The Γ6 unallowe…
Domain structures arising as a result of pulsed electric fields are investigated in Pb(Zn1/3Nb2/3)O3–PbTiO3 (PZN-PT) 〈001〉 single crystals by means of etching and environmental scanning electron microscope. It is shown that randomly orientated dendritic domain patterns were created under a pulsed electric field condit…
A series of crystalline oligomers from α-D-cellobiose octaacetate through α-D-cellohexaose eicosaacetate were prepared by homogeneous acetylation of the corresponding cellooligosaccharides and characterized by cross-polarization and magic angle sample spinning (CPMAS) carbon-13 nuclear magnetic resonance (13C NMR) spe…
Polymerizable styrenic surfactants (surfmers) and nonreactive analogs, have been applied in emulsion copolymerization of acrylic monomers in a seeded semibatch process. Stable core-shell latexes with low levels of coagulum and controlled particle size have been obtained; some of them, with either steric or electroster…
We present molecular dynamics simulations of the flow of macromolecules from a bulk melt into a slit of nanometer dimension with strongly attracting walls. Such flow is central to the formation of polymer-layered silicate nanocomposites by direct melt intercalation. In this process, polymer molecules flow from a melt…
Scanning tunneling microscopy results show that irradiation with electrons of primary energies of 90--2000 eV created single-layer deep vacancies on GaAs(110), Si(100), and Si(111). The removal yield was linear with dose during the initial stages of surface modification, but it increased as the surface damage increase…
Cadmium selenide nanocrystals have been made in a transparent polymer matrix by synthesis at room temperature. Particle size is controlled by reaction time or reagent concentration. Larger nanocrystals (≳3 nm) show near-band-edge photoluminescence. Smaller ones have a broad emission extending across the visible region…
In situ, real-time, mass selective energy analysis of the incoming ions has been carried out during bias enhanced nucleation for diamond chemical vapor deposition. The dependence of ion energies and fluxes as a function of the bias voltage and CH4 concentration was measured. The main ionic species that strike the subs…
The analysis of the dielectric relaxation spectrum at percolation was used for the determination of the dimensions of pore fractals and porosity of silica glasses. The percolation phenomenon in the porous glasses is related to the transfer of the electric excitation within the developed network of open pores due to mi…
The strain state of epitaxial ${\mathrm{C}\mathrm{u}(50\mathrm{}\mathrm{\AA{}})/\mathrm{N}\mathrm{i}(\mathrm{t}}_{\mathrm{Ni}})/\mathrm{C}\mathrm{u}(2000\mathrm{}\mathrm{\AA{}})/\mathrm{S}\mathrm{i}(001)$ films as a function of the nickel film thickness $(30\AA{}<~{t}_{\mathrm{Ni}}<~2000\AA{})$ has been studied…
The mechanisms by which carbon nanotubule (CNT) proximal probe tips deform during the indentation of surfaces are explored using classical molecular-dynamics simulations. The forces acting on the atoms in the simulations are calculated using the Brenner empirical bond-order potential for hydrocarbons. The results show…
Both optical reflectivity and ellipsometry data obtained from freestanding films in the $\mathrm{Sm}\ensuremath{-}{C}_{\ensuremath{\alpha}}^{*}$ phase of one liquid-crystal compound display characteristic oscillations as a function of temperature. A model for the film consisting of surface anticlinic layers and an int…
This study concerns a hitherto unknown bcc→fcc allotropic transformation in Nb induced by the mechanical alloying of Nb80Al20. This metastable transformation is preceded by a gradual increase in the lattice parameter of bcc–Nb. The stored excess energy in nanocrystalline bcc–Nb may be responsible for the bcc→fcc phase…
The formation of a vibrationally excited photoproduct of nickel octaethylporphyrin (NiOEP) upon (π, π*) excitation and its subsequent vibrational energy relaxation were monitored by picosecond time-resolved resonance Raman spectroscopy. Stokes Raman bands due to the photoproduct instantaneously appeared upon the photo…
We report results on domain retention in preferentially oriented PbZr0.53Ti0.47O3 (PZT) thin films on Pt and on LaNiO3 (LNO) electrodes. Domain images are obtained by detecting an electrostatic force exerted on the biased conductive probe. We demonstrate that polarization loss of PZT domains on LNO electrodes occurs l…
Diamond films were grown on silicon by microwave chemical-vapor deposition using a CH4–H2 gas mixture. The crystalline quality of the films was assessed through their α-particle detection performance, a property highly sensitive to film quality, by using a 5.5 MeV Am241 source. A maximum collection efficiency η of 70%…
An explanation, using the logarithmic derivative method, is given for some previously unexplained features of the temperature dependence of the conductivity for barely insulating Si:As for $10\mathrm{K}<T<78\mathrm{K}.$ The results and analysis suggest an important high-temperature correction to the prefactor of…