Materials Literature
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Neutral poly(3,4-ethylenedioxythiophene) (PEDOT) thin films can be switched to an electronically conducting form either by oxidation (p-doping) or reduction (n-doping) in anhydrous organic solvents. The maximum attainable n-conductivity is ca. 1% of the maximum p-conductivity. However, based on spectroelectrochemical…
In order to develop new dry phantom materials that can simulate the effect of electromagnetic wave on human tissues, the dielectric properties of the phantom materials composed of dielectrics, carbon black, and epoxy resin were investigated. For dielectrics/epoxy composite, the dielectric constants increased with the…
Colour separation gratings designed to separate three wavelengths into different diffraction orders are computed. Nonlinear phase transformation by the law of colour separation grating is used in an analytical design of diffractive optical elements that produce different domains of focusing for two or three different…
The purpose of this chapter is to provide the background needed for subsequent chapters on toughened plastics. This chapter introduces the topic of fracture mechanics, describes the methods used to quantify toughness, discusses the origin of toughness in terms of toughening mechanisms, briefly reviews the factors infl…
Many normally ductile semi-crystalline polymers such as polyamide-6 (or 66) (nylon), high density polyethylene, (HDPE), and isotactic polypropylene (iPP) are known to be brittle under impact loading. Here we present some general principles for improvement of toughness that rely on the reduction of plastic resistance o…
Complex dielectric susceptibility (χ' + jχ'') has been studied at f = 10 -2 -10 5 Hz in the relaxor ferroelectric 0.75Pb(Mg 1/3 Nb 2/3 )O 3 -0.25PbTiO 3 . In addition to the well known relaxor dispersion observed at temperatures around and below the temperature of permittivity maximum T m , a new and comparatively wea…
InNH 3 has been studied with single-photon zero electron kinetic energy (ZEKE) spectroscopy and density functional theory and ab initio calculations. The ZEKE spectrum reveals vibrational structures of the cation and neutral complexes. The comparison of the experiment and theory establishes that the indium-ammonia com…
Infrared spectra of tropolone(OH) and tropolone(OD) obtained from vapor phase, solvated, and rare gas matrix-isolated samples, and from fluorescence dip infrared spectroscopy experiments by Frost et al. on jet-cooled samples, are analyzed with the guidance of high level ab initio molecular orbital (MO) computations. I…
The purpose of this chapter is to provide the background needed for subsequent chapters on toughened plastics. This chapter introduces the topic of fracture mechanics, describes the methods used to quantify toughness, discusses the origin of toughness in terms of toughening mechanisms, briefly reviews the factors infl…
The minimum energy pathway leading between the tautomers of tropolone was calculated using molecular orbital (MO) methods. This, with various 1D and 2D cuts of the potential energy surface (PES) topography, reveals the {tunneling skeleton}/{tunneling H atom} mechanism for tautomerization. In the zero-point states the…
We propose a detailed description of the structural and electronic properties of neutral and charged TinO2n+m clusters (n=1–3 and m=0,1), through simulations based on the density functional theory in the local spin density approximation. In all the isomers studied, strongly bound titanyl groups are found. The order of…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTStrong Ferromagnetic and Antiferromagnetic Exchange Coupling between Transition Metals and Coordinated Verdazyl RadicalsRobin G. Hicks, Martin T. Lemaire, Laurence K. Thompson, and Tosha M. BarclayView Author Information Department of Chemistry, University of Victoria…
The treatment of dipole moments (μ), polarizabilities (α), and hyperpolarizabilities (β, γ) in push−pull systems using electric field simulation for the substituents is reanalyzed and tested by comparison with ab initio Hartree−Fock calculations on representative donor−acceptor (D/A) polyenes. Both vibrational and ele…
We calculate the electronic states of Al$_x$Ga$_{1-x}$As/GaAs/Al$_x$Ga$_{1-x}$As double heterojunctions subjected to a magnetic field parallel to the quasi two-dimensional electron gas. We study the energy dispersion curves, the density of states, the electron concentration and the distribution of the electrons in the…
We compare the models that have been proposed in the literature for the atomic structure of the 90-degree partial dislocation in the homopolar semiconductors, silicon, diamond, and germanium. In particular, we examine the traditional single-period and our recently proposed double-period core structures. Ab-initio and…
Carbon and nitrogen austenites, modeled by Fe8N and Fe8C superstructures are studied by full-potential LAPW method. Structure parameters, electronic and magnetic properties as well as hyperfine interaction parameters are obtained. Calculations prove that Fe-C austenite can be successfully modeled by ordered Fe8C super…
The spectroscopic characteristics of systems with adsorbed d impurities on noble metal surfaces should depend on the number and geometric arrangement of the adsorbed atoms and also on their d band filling. Recent experiments using scanning tunneling microscopy have probed the electronic structure of all 3d transition…
In a recent Letter [N. Lehto and S. Oberg, Phys. Rev. Lett. 80, 5568 (1998)], Lehto and Oberg investigated the effects of strain fields on the core structure of the 90-degree partial dislocation in silicon, especially the influence of the choice of supercell periodic boundary conditions in theoretical simulations. We…
We investigate theoretically the spatial dependence of the linear absorption spectra of single and coupled semiconductor quantum dots, where the strong three-dimensional quantum confinement leads to an overall enhancement of Coulomb interaction and, in turn, to a pronounced renormalization of the excitonic properties.…
An analysis of the transport properties data on established thermoelectric materials indicates that the ratio of the electrical power factor to optimum electrical conductivity appears constant. This result, when combined with the previously proposed concept of a minimum thermal conductivity, enables realistic maximum…