Materials Literature
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Photoluminescence (PL) spectra of undoped and neutron-transmutation-doped InSe samples at 15 K are reported. The undoped InSe PL spectrum clearly shows the free exciton line and an exciton-neutral acceptor complex recombination. A structure of partially resolved transitions is observed between 1.315 and 1.330 eV, whos…
Caesium vanadium(V) selenite contains infinite sheets of distorted vertex-sharing VO6 octahedra, capped by selenite groups [dav(V—O) = 1.927 (4) Å and dav(Se—O) = 1.709 (3) Å]. Interlayer caesium cations complete the structure [dav(Cs—O) = 3.365 (4) Å].
The structure of strained Cu films deposited on Ru(0001) surfaces at 720 K was investigated by x-ray diffraction techniques. Our analysis shows that a single Cu monolayer adopts a pseudomorphic structure with the first three interlayer spacings significantly relaxed. The two-layer structure consists of a commensurate,…
The force constants and elastic properties of some polymers are calculated with a full-electron, crystal-orbital density functional method. Calculations are carried out on single helical chains of polyethylene, polytetrafluoroethylene (teflon), polyglycine (nylon-2), and nylon-3. The longitudinal elastic moduli are ob…
We numerically study morphology of symmetric diblock copolymer films with a thickness smaller than the bulk equilibrium period. These films are cast on either flat or corrugated substrates. Our results show that the formation of uniformly sized lateral domains that appear randomly on a flat surface can be controlled b…
A symmetry-based, nondisplacive mechanism for the first-order $B3\ensuremath{\rightleftharpoons}B1$ phase transition exhibited by many binary semiconductors is proposed. Using a single-molecule $R3m$ unit cell, the energetic and dynamical features of the transformation are disclosed along a transition path characteriz…
It is shown to what extent the phase of a reflection coefficient may be determined from a single x-ray reflectivity experiment. Complex calculus guarantees that the so-called ``phase problem'' is relaxed for certain situations and the reflection coefficient is only determined by its moduls. A procedure to reconstruct…
The instabilities toward orbital ordering are studied for a model of metallic double-exchange ferromagnets. In contrast to previous studies a possibility of octupole ordering is also considered in addition to ordinary orbital ordering (corresponding to quadrupole ordering). The present theory, which is based on the si…
The localization of electrons at ${\mathrm{W}}^{6+}$ sites perturbed by lanthanum in ${\mathrm{PbWO}}_{4}$ is studied by electron spin resonance (ESR) and thermally stimulated luminescence (TSL) measurements. The $({\mathrm{WO}}_{4}{)}^{3\ensuremath{-}}\ensuremath{-}{\mathrm{La}}^{3+}$ centers are created at the ${\ma…
Whereas boron nitride nanotubes have elastic properties similar to those of their carbon counterparts, they can have a very different response to plastic deformation. $(n,n)$ boron nitride nanotubes have comparable plastic limits to those of carbon tubes with similar wrapping angle. $(n,0)$ boron nitride nanotubes, ho…
Measurements of initial adsorption probabilities, S0, as well as the coverage dependence of the adsorption probability, S(ΘCO), of CO on Zn–ZnO [ZnO(0001)] and O–ZnO [ZnO(0001̄)] are presented. The samples have been characterized by He atom scattering, He atom reflectivity measurements, LEED, and XPS. Samples with dif…
Aligned carbon nanotubes were synthesized on Ni-coated Si substrates using microwave plasma-enhanced chemical vapor deposition. The surface morphology of Ni thin films was varied with the rf power density during the rf magnetron sputtering process. It was found that the growth of carbon nanotubes was strongly influenc…
The crystal structures of samarium nitrate Sm(NO 3 ) 3 6H 2 O at temperatures 297, 253 and 193 K±1 K were investigated by single crystal X ray diffraction technique. The crystal symmetry at the temperatures was triclinic with space group P \bar1. The structures were solved by using Fourier techniques. The full matrix…
The photoluminescence properties and quantum efficiency of potential red, green, and blue (RGB) phosphors are measured under near-ultraviolet excitation (380–420 nm). The suitability of several phosphors is discussed for their application in phosphor-liquid crystal displays (LCDs). K5Eu2.5(WO4)6.25, SrGa2S4:Eu, and Ba…
The effect of nonstoichiometry (δ) on the magnetic properties of (Mg0.22Mn0.07Fe0.71)3−δO4 ferrite was investigated. The nonstoichiometry was controlled via a solid state electrochemical method to encompass from δ=+0.005 to −0.006. Initial permeability was found to be affected significantly by nonstoichiometry. From t…
We investigate, through first-principles calculations, the energetics of substitutional carbon and oxygen impurities as well as complexes involving these impurities and vacancies in cubic boron nitride $(c\ensuremath{-}\mathrm{BN}).$ The formation energies and the electronic and structural properties of these defects…
Dynamic electrical analysis shows that at high temperatures (above the glass transition temperature), the electrical properties of polyetherimide are strongly influenced by space charge. In this article we have studied the relaxation of space charge in two commercial varieties of polyetherimide: Ultem 1000 and Ultem 5…
The magnetic properties and structure evolution of CoxC1−x (x=44, 65, 71 at. %) nanocomposite films prepared by pulsed filtered vacuum arc deposition were studied. The as-deposited films consist of amorphous Co clusters in a-C and are soft ferromagnets. The low coercivity in the amorphous films is due to the very low…
We have studied the multiphonon resonant Raman scattering from confined and interface polar optical phonons in spherical nanocrystallites. The intermediate virtual states in the scattering process are taken into account as Wannier-Mott confined excitons in a spherical dot. Fr\"ohlich interaction between excitons and o…
We report synthesis and examination of the electronic properties of an isomorphous series of mixed-stack organic charge-transfer complexes, composed of [bis(ethylenedithio)tetrathiafulvalene] (BEDT-TTF)-based electron donors and electron acceptors of halogen-substituted tetracyanoquinodimethanes (TCNQ's). Single cryst…