Materials Literature
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An all-optical ultrafast switch which operates at a wide wavelength range has been demonstrated based on photoinduced changes of real and/or imaginary parts of complex refractive index in a composite thin film of silver and polymer containing photochromic spiropyran dye. Very fast switching ON and OFF of a reading bea…
The geometric structure of the toroidal carbon nanotubes (TCN's) determines the electronic structure and thus the characteristics of the persistent current. Such current is caused by the magnetic flux \ensuremath{\varphi} through TCN's. The semiconducting TCN's exhibit diamagnetism at small \ensuremath{\varphi}, which…
The electronic structure of $p$-type ${\mathrm{SrTiO}}_{3}$ has been studied by photoemission spectroscopy (PES). Comparing with the PES of $n$-type ${\mathrm{SrTiO}}_{3},$ the Fermi level of $p$ type is lower by about 0.7 eV and a prominent feature of Ti $3d$ character within the band gap, which is formed in the $n$-…
Dielectric investigations of the (PMN)(1−x)(PT)x crystalline solution have been performed for various electrical histories. For x<0.3, relaxor behavior was observed, however the degree of diffuseness in the dielectric maximum and degree of relaxor characteristics were decreased with increasing x. Application of…
We report local-density-approximation calculations of the electronic structure and thermoelectric properties of $\ensuremath{\beta}\ensuremath{-}{\mathrm{Zn}}_{4}{\mathrm{Sb}}_{3}$. The material is a low carrier density metal with a complex Fermi-surface topology and a nontrivial dependence of the Hall concentration o…
A consistent approach to the calculation of the surface energy valid for all crystal systems is presented. Voronoi polyhedra are introduced and used in conjunction with the energy-density formalism of Chetty and Martin [Phys. Rev. B 45, 6074 (1992); 45, 6089 (1992)] to provide a methodology for the determination of su…
We have measured the Seebeck coefficient and electric conductivity in the air-stable conducting polymers polyaniline and polypyrrole at different doping levels. We find, at 300 K, the general correlation that the logarithm of the electrical conductivity varies linearly with the Seebeck coefficient on doping, but with…
Temperature-dependent resistivity of single-wall carbon nanotubes, C. L. Kane, E. J. Mele, R. S. Lee, J. E. Fischer, P. Petit, H. Dai, A. Thess, R. E. Smalley, A. R. M. Verschueren, S. J. Tans, C. Dekker
The use of ferroelectric ceramics and thin films in microwave devices requires that they possess frequency-stable, low-loss dielectric properties. At microwave frequencies, ferroelectric polycrystalline ceramic materials typically exhibit a large dielectric relaxation, characterized by a decrease in the relative permi…
We report ab initio calculations of the structural and quasiparticle properties of ${\mathrm{ZrO}}_{2}$, otherwise known as zirconia. The plane-wave pseudopotential method is used to compute the structural properties of the cubic, tetragonal, and monoclinic phases of zirconia. Oxygen vacancies in the cubic phase are a…
Kinetics of polymerization of l, l -lactide (LA) initiated with aluminum isopropoxide (Al(O i Pr) 3 ) trimer (A 3 ) or tetramer (A 4 ) was followed by polarimetry and by gel permeation chromatography (GPC). Results of the kinetic measurements show that A 3 and A 4 react with LA with different rates; namely, the k i(A…
The large magnetic-field-induced strains observed in martensitic phases based on Ni2MnGa and in other magnetic shape memory alloys are believed to arise from a process of twin-boundary motion rather than magnetostriction. The dependence of strain on magnetization, e(M), generally shows a large component that is linear…
Using high-resolution laser photoelectron spectrometry we have determined absolute cross sections and the electron angular distribution parameter for one-photon ionization of metastable and atoms to the resolved ion states near threshold -244 nm). For comparison with the experimental data we have carried out many-elec…
The development of cellulose acetate blend membranes using a commercial grade Mycell cellulose acetate and cellulose diacetate with suitable pore structure is discussed. These membranes were characterized in terms of resistance of the membrane, pure water flux, the molecular weight cutoff, water content, pore size, an…
Based on experiments conducted, it has been found that bacterial cellulose, like spruce cellulose, is soluble in an aqueous NaOH solution with the concentration of 8.5% at a temperature of −5°C if the polymerization degree of the cellulose does not exceed 400. When 1% of urea is added to the NaOH solution, the solubil…
Within an ab-initio HF scheme, we use both Berry-phase calculations and supercell calculations in order to compute the dynamical charges for lattice dynamics and the electronic dielectric constant for KNbO_3 and BaTiO_3. Comparison with experimental data indicates that HF provides a description of the electronic prope…
The Pd catalysts were prepared by impregnating Pd(CH 3 COO) 2 in Al 2 O 3 supports. To investigate the influence of mass transfer on the catalytic performance, the catalysts and the polystyrene- block -polybutadiene- block -polystyrene thermoplastic elastomers (SBS rubber) were prepared with average pore size ranging…
Calculations on [Ag(NHCHNH)] 2 and [Ag(dmtp)(NO 3 )] 2 complexes have been performed at RHF, DFT (B3LYP), and MP2 levels. Geometry optimizations have been performed on both compounds comparing the result obtained with the different levels of theory and basis set against the available experimental X-ray data. The exist…
The synthesis, X-ray crystal structures, and ESR and magnetic properties of the anhydrous salt Na 3 [Cr(OH) 6 Mo 6 O 18 ]·6(CH 3 ) 2 SO ( CrDMSO ) containing the Anderson−Evans polyanion, of two new molecular compounds based on this polyanion ([Fe(C 5 Me 5 ) 2 ] 3 [Cr(OH) 6 Mo 6 O 18 ]·20H 2 O [ FeCr(1) ], Na[Fe(C 5 H…
Experiments and ab initio calculations have been performed to study the catalytic activity of calcium oxide and magnesium oxide toward N 2 O decomposition. The experiments were carried out in a fixed-bed quartz reactor in the temperature range 773−1223 K. The decomposition of N 2 O appeared to be a first-order reactio…