Materials Literature
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Sintering of Si 3 N 4 nanoclusters is investigated with the molecular-dynamics approach. At 2000 K thermally rough nanocrystals develop an asymmetric neck in 100 picoseconds. The neck contains more fourfold than threefold coordinated Si atoms. Amorphous nanoclusters develop a symmetric neck which has nearly equal numb…
The amplitudes of electric-field-induced translational vibrations of 90\ifmmode^\circ\else\textdegree\fi{} domain walls formed in a tetragonal ferroelectric thin film grown on a cubic substrate are calculated theoretically. The domain wall contribution to the dielectric response of an epitaxial film is evaluated and s…
We apply density functional theory to study the influence of polydispersity on the stability of columnar, smectic, and solid ordering in the solutions of rodlike macromolecules. For sufficiently large length polydispersity (standard deviation $\ensuremath{\sigma}>0.25$) a direct first-order nematic-columnar transit…
We present the results of a total-energy pseudopotential simulation of the sliding process at a $\ensuremath{\Sigma}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}5$ (001) twist grain boundary in germanium. Sliding involves a stick-slip mechanism with local rebonding among a few atoms, accompanied by the clearance…
The influence of N2 additions (5%–40% N2/CH4) on various features of hot-filament chemical vapor deposition (CVD) of diamond layers is presented and discussed using experimental results and calculations of the thermodynamic equilibrium. Small N2 additions (5%–10% N2/CH4) improved the diamond phase purity but led surpr…
Conductive RuO2 thin films have been heteroepitaxially grown by pulsed laser deposition on Si substrates with yttria-stabilized zirconia (YSZ) buffer layers. The RuO2 thin films deposited under optimized processing conditions are a-axis oriented normal to the Si substrate surface with a high degree of in-plane alignme…
Kincs and Martin [Phys. Rev. Lett. 76, 70 (1996)] have recently discovered a ubiquitous non-Arrhenius temperature dependence of the ionic conductivity in glassy fast ionic conductors when the conductivity exceeds the high level of ${10}^{\ensuremath{-}3}$ to ${10}^{\ensuremath{-}2}{\ensuremath{\Omega}}^{\ensuremath{-}…
It has been suggested [D. L. Koch and E. S. G. Shaqfeh, J. Fluid Mech. 224, 275 (1991)] that the long-range hydrodynamic interactions in sedimenting suspensions of non-Brownian spheres are screened by changes in the pair correlation function. However, a large-scale numerical simulation, using more than 32 000 spheres,…
Organic field-effect transistors (FETs) which employ two carefully selected active materials can function as n channel, p channel, or both n- and p-channel devices. It is shown that under an appropriate set of bias conditions the channel current in FETs with α-hexathienylene (α-6T) and C60 active layers consist of ele…
Raman scattering and far-infrared absorption spectra of PbS nanocrystals with radii of 2 nm are presented. The experimental results are consistent with theoretical calculations which account correctly for the mechanical boundary conditions at the nanocrystal-host interface, and include the first observation of the mix…
We study the combined influence of spin double exchange and Jahn-Teller lattice coupling to holes in the ${\mathrm{La}}_{1\ensuremath{-}x}{A}_{x}{\mathrm{MnO}}_{3}$ perovskites ( $A\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\mathrm{C}\mathrm{a},\phantom{\rule{0ex}{0ex}}\mathrm{S}\mathrm{r},\phantom{\rule{0ex}{…
A qualitatively different character of de Haas--van Alphen oscillations has been found in a multiband (quasi)two-dimensional Fermi liquid with a fixed fermion density ${n}_{e}$ (canonical ensemble) compared with an open system where the chemical potential $\ensuremath{\mu}$ is kept fixed (grand canonical ensemble). A…
We find spatial anisotropy in the asymptotic correlations of two-dimensional Ising models under non-equilibrium phase-ordering. Anisotropy is seen for critical and off-critical quenches and both conserved and non-conserved dynamics. We argue that spatial anisotropy is generic for scalar systems (including Potts models…
Pollen grains made conductive for SEM by coating in a series of osmium and thiocarbohydrazide solutions (OTOTO) show charging artifacts when nonconductive detritus (sand grains, plant fragments, etc.) is present in the immediate sample area of the SEM scanning probe. Standard sputter coating of the sample makes the de…
The crystal structure of triammonium hydrogen diselenate (NH4)3H(SeO4)2 in phase V is studied by single-crystal X-ray diffraction. The space group symmetry (Cc) and structure parameters are determined at −130 °C. The difference of the structure between phase IV and phase V is discussed. The origin of the spontaneous p…
The optical parameters of optically uniaxial γ1-(GaxIn1−x)2Se3 single crystals are systematically measured and analyzed. The optical rotatory power along the optical c-axis is determined in visible spectral region at 77 K and at room temperature and complemented with theoretical estimates for other crystallographic di…
Clusters are an important state of matter, consisting of aggregates of atoms and molecules that are small enough not to have the same properties as the bulk liquid or solid. Quantum states in clusters are size-dependent, leading to new electronic, optical, and magnetic properties. Clusters offer attractive possibiliti…
Luminescent properties of Eu2+ or Ce3+ doped SrGa2S4 powder samples are investigated over the temperature range 30 to 300 K. Up to 300 K the lifetime remains constant (τ0 = 480 and 24 ns for Eu2+ and Ce3+, respectively) showing that the probability of non-radiative transitions is negligible at room temperature. The de…
Abstract Der Sehvorgang sowie andere durch Licht ausgelöste biochemische Umsetzungen in Pflanzen und Lebewesen sind ausgeklügelte biologische Vorgänge, in denen optische Signale registriert und in (physiko)chemische umgesetzt werden. Photoschaltbare Biomakromoleküle sind eine neue Klasse von Substanzen, in denen optis…
Electrochromic vanadium pentoxide (V2O5) thin films are prepared by the physical vapour deposition method using an electron beam gun. The transmission spectra of V2O5 thin films are measured and studied before and after UV irradiation. It is observed that the optical transmission minimum which occurs at 320 nm does no…