Materials Literature
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Anomalous lattice expansions have been measured for the first time in monodisperse CeO2-x nanoparticles and in BaTiO3 single nanoparticles by electron diffraction. X-ray photoelectron spectroscopy studies on CeO2-x nanoparticles and ab initio computer simulation on BaTiO3 clusters show that the origin of expansion is…
Hydrogen-terminated diamond exhibits a high surface conductivity (SC) that is commonly attributed to the direct action of hydrogen-related acceptors. We give experimental evidence that hydrogen is only a necessary requirement for SC; exposure to air is also essential. We propose a mechanism in which a redox reaction i…
A simple and effective method is presented for producing light-emitting porous silicon (PSi). A thin (d<10 nm) layer of Au, Pt, or Au/Pd is deposited on the (100) Si surface prior to immersion in a solution of HF and H2O2. Depending on the type of metal deposited and Si doping type and doping level, PSi with di…
We have found that near the metal-insulator transition of Al 70 Pd 22.5 Re 7.5 quasicrystal, the conductivity σ( T ) obeys σ( T )=σ(0)+ m T 1/3 between 1.5 K and ∼10 K on both sides of the metal-insulator transition, as found in disorder systems. This indicates that the conductivity near the metal-insulator transition…
beta-Lactams inhibit a range of enzymes via acylation of nucleophilic serine residues. Certain gamma-lactam analogues of monocyclic beta-lactams have also been shown to be reversible inhibitors of porcine pancreatic elastase (PPE), forming acyl-enzyme complexes that are stable with respect to hydrolysis. Crystallograp…
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…