Materials Literature
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The synthesis, characterization, and self-assembly in butanol of a series of well-defined alpha,alpha'-linked quinqui-, sexi-, and septithiophenes substituted, via ester links at their termini, by chiral oligo(ethylene oxide) chains carrying an alpha, beta, delta, and epsilon methyl, respectively, are reported. Studie…
Patterning technologically important semiconductor interfaces with nanoscale metal films is important for applications such as metallic interconnects and sensing applications. Self-assembling block copolymer templates are utilized to pattern an aqueous metal reduction reaction, galvanic displacement, on silicon surfac…
The electric-field-induced evolution of the recently discovered periodic 180 degree nanostripe domain structure is predicted in epitaxial Pb(Zr0.5Ti0.5)O3 ultrathin films from first principles. This evolution involves (1) the lateral growth of majority dipole domains at the expense of minority domains with the overall…
We have fabricated field-effect transistors from carbon nanotubes using a novel selective placement scheme. We use carbon nanotubes that are covalently bound to molecules containing a hydroxamic acid functionality. The functionalized nanotubes bind strongly to basic metal oxide surfaces, but not to silicon dioxide. Up…
Using a model of Frenkel excitons coupled to a bath of acoustic phonons in the host medium, we study the temperature dependence of the dephasing rates and homogeneous line width in linear molecular aggregates. The model includes localization by disorder and predicts a power-law thermal scaling of the effective homogen…
Magnetization reversal mechanisms and impact of magnetization direction are studied in square arrays of interconnected circular permalloy nanorings using MOKE, local imaging, numerical simulations and transport techniques.
Interface effects on the ferroelectric behavior of PbTiO3 ultrathin films deposited on a SrTiO3 substrate are investigated using an interatomic potential approach with parameters fitted to first-principles calculations. We find that the correlation of atomic displacements across the film-substrate interface is crucial…
We investigated the size-dependent high-pressure phase transition behavior of nanocrystalline anatase TiO2 with synchrotron x-ray diffraction and Raman spectroscopy to 45 GPa at ambient temperature. Pressure-induced amorphization results in a high-density amorphous (HDA) form when the starting crystallite size is < 10…
A quantitative assessment of the homogeneity of particle coordination in green bodies is achieved by addressing pore structures. Avoiding a coarser tail of the pore size distribution is important but insufficient for optimum sintering. Instead, the steepest slope of the main body of the distribution is responsible for…
Using the Rietveld refinement, we analyze the structural evolution under thermal treatment of silica xerogel samples prepared by the sol–gel method with molar ratio (R) of water to TEOS of R = 5 and R = 11.66. We refine the structure of compounds using the Maud program and we found the unit cell parameters and atomic…
We present a first-principles description of anisotropic materials characterized by having both weak (dispersionlike) and strong covalent bonds, based on the adiabatic-connection fluctuation-dissipation theorem with density functional theory. For hexagonal boron nitride the in-plane and out-of-plane bonding as well as…
Carbon nanotube (CNT) is expected for much more important and broader applications in the future, because of its amazing electrical and mechanical properties. However, today, the prospect is detained by the fact that the growth of CNTs cannot be well controlled. In particular, controlling the chirality of CNTs seems f…
We theoretically analyze the excitation energy transfer between two closely spaced linear molecular J-aggregates, whose excited states are Frenkel excitons. The aggregate with the higher (lower) exciton band edge energy is considered as the donor (acceptor). The celebrated theory of Förster resonance energy transfer (…
In the interaction of PVP with Pt nanoparticles <7 nm in size, charge transfer is from carbonyl groups in PVP to Pt nanoparticles, whereas in the interaction of PVP with bulk Pt or Pt nanoparticles >25 nm in size, charge transfer is from Pt metal to the polymer side chain of PVP. There exists a critical nanoparticle s…
Silver nanodendrites are synthesized by a simple surfactant-free method using a suspension of zinc microparticles as a heterogeneous reducing agent. Structural characterizations suggest the preferential growth along 100 and 111 directions by oriented attachment of silver nanocrystals in the diffusion limit, leading to…
We study the nematic structure of a liquid crystal confined within a plan-parallel cell following the temperature driven isotropic-nematic phase transition quench. The Lebwohl-Lasher lattice model is used. The kinetics of the system is followed via Brownian molecular dynamics, enabling us to reach macroscopic time sca…
The presented study deals with pattern forming phenomena in electrohydrodynamic convection (EHC) under superimposed rectangular wave forms. An effect of re-stabilization is observed experimentally, i.e., with changing of one control parameter of the excitation wave form, the system undergoes transitions from the conve…
${\mathrm{Gd}}_{5}{\mathrm{Si}}_{4}$, ${\mathrm{Gd}}_{5}{\mathrm{Ge}}_{4}$, and ${\mathrm{Gd}}_{5.09}{\mathrm{Ge}}_{2.03}{\mathrm{Si}}_{1.88}$ compounds were studied by electron spin resonance. The arc-melted samples were initially characterized by optical metallography, x-ray diffraction, and static magnetization mea…
A finite element technique for computer simulation of transient electromagnetic fields, eddy currents density and power losses distributions due to negative sequence currents in synchronous generator rotors at various operational conditions is developed. Time-varying electromagnetic field calculation is performed in t…
In several mesophases of bent-core liquid crystals, stable freely suspended filaments can be prepared. In this paper, we report a study of smectic liquid-crystal filaments formed by bent-shaped molecules in different mesophases, focused on a mechanical and structural characterization of the filaments.