Materials Literature
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In real metals with interacting conduction electrons a Fermi surface (FS) can no longer be defined as separating occupied from unoccupied one-electron states in k space, but is rather given by the location of discontinuities in the momentum distribution function n(k). Here we show that this many-body theoretical defin…
A comparative study of photoluminescence (PL) and photoluminescence excitation (PLE) spectra of porous silicon (PS) and Si oxide, both emitting blue light, is reported. The PLE spectrum of Si oxide monitored at 460 nm displays a three-peak structure with peak wavelengths around 265, 300, and 360 nm. The PLE intensity…
Extended x-ray-absorption fine structure (EXAFS), Fourier-transform infrared absorption (FTIR), and elemental analysis were used on a variety of CdSe nanocrystallites (NC's) to study surface structure. All CdSe NC's were grown by standard inverse micelle techniques. Two sets of NC's samples were made. One set was made…
The interaction of a Cl2 plasma with a Si(100) surface has been investigated by angle resolved x-ray photoelectron spectroscopy (XPS). It was found that the amount of chlorine incorporated into the near-surface region of Si increases with ion energy, and does not change with long exposure to the plasma. Chlorine is pr…
By employing a deep level transient spectroscopy (DLTS) technique, this work investigates the deep trap levels of rf-sputtered (Ba0.4Sr0.6)TiO3 (BST) thin films deposited at various temperatures. Arrhenius plots of DLTS spectra detect a single trap located at 0.45 eV in 450 °C deposited films, whereas two traps locate…
Strontium silicon trioxide has been synthesized for the first time and its structure solved. It is isostructural with the germanium analogue SrGeO3 reported by Hilmer [Sov. Phys. Crystallogr. (1963). 7, 573–576], but the true symmetry is monoclinic, rather than hexagonal as reported earlier. The structure has alternat…
The first stages of the oxidation process of titanium thin films deposited on top of Cu(100) substrates have been studied by means of Auger electron spectroscopy. Using principal component analysis we found different oxidation regimes for Ti films depending on their thickness. While for a film thickness up to 1 ML onl…
Dielectric dispersion measurements have been performed on CH 3 NH 3 PbX 3 (MAPbX 3 , X = Cl and Br) single crystals at frequencies between 50 Hz and 1 MHz. Significant dielectric dispersion was observed in the cubic and tetragonal II phases for MAPbCl 3 and in the cubic, tetragonal I and tetragonal II phases for MAPbB…
The carrier transport mechanism through the p-diamond/metal interface was studied by measuring specific contact resistances (ρc) using a transmission line method for Ti, Mo, and Cr (carbide forming metals) and Pd and Co (carbon soluble metals) metals contacting to the boron-doped polycrystalline diamond films. Schottk…
We determine the electronic structure of single-wall, multiwall, and filled carbon nanotubes using the local-density-functional formalism. In order to handle these extremely inhomogeneous systems of nested graphene cylinders with ${10}^{3}$--${10}^{4}$ valence electrons, we adopt a technique that discretizes the eigen…
The influence of n-type doping CdO with In or Y has been investigated by high-resolution ultraviolet and x-ray photoemission spectroscopy. It is found that core levels and valence band features suffer a shift to high binding energy due to doping. However this shift is less than the change in the width of the occupied…
The local electric fields in a semicontinuous metal film are shown to exhibit giant fluctuations in the visible and infrared spectral ranges, when the dissipation in metallic grains is small. The field fluctuations result in significantly enhanced Raman scattering from semicontinuous metal films. The scaling analysis…
A reproducible process for fabricating Ba1−xKxBiO3/Nb-doped SrTiO3 (BKBO/STNO) all-oxide-type Schottky junctions has been established, and the electrical properties of the junctions have been investigated at room temperature. Improving the STNO surface conditions by high-temperature oxygen-annealing made it possible t…
Narrow-band conductors may turn insulating and magnetic as a consequence of strong electron-electron correlation. In molecular conductors, the concomitance of a strong Jahn-Teller coupling may give rise to the alternative possibility of a nonmagnetic insulator, with or without a static cooperative Jahn-Teller distorti…
The Verwey transition in magnetite, ${\mathrm{Fe}}_{3}$${\mathrm{O}}_{4}$, has been studied using temperature-dependent high-resolution photoemission spectroscopy. On heating through the transition temperature ${\mathrm{T}}_{\mathrm{V}}$ the band gap is not collapsed, but is merely reduced by \ensuremath{\sim}50 meV,…
Thin solid films of closely packed CdS nanocrystals with sizes between 1.5 and 1.8 nm have been prepared and sandwiched between indium–tin–oxide (ITO) and silver contacts. At room temperature, these CdS nanocrystals start to emit light visible to the unaided eye at a bias above 15 V. The spectral characteristics are v…
The potential of the production of polyhydroxyalkanoates (PHA), consisting of medium-chain-length (MCL) hydroxyfatty acids (C5-C14), in recombinant Escherichia coli was investigated. E. coli mutants affected in fatty acid degradation and fatty acid de novo synthesis were employed. We established the functional express…
A new method for the synthesis of inroganic—organic composites with promising properties is the incorporation of polyoxometalates into well-ordered organic films by the Langmuir–Blodgett (LB) method. The structure of such an LB film is depicted schematically on the right.
The magnetic structure of antiferromagnetically ordered phases of quasi-one-dimensional organic conductors is studied theoretically at absolute zero based on the mean field approximation to the quarter-filled band with on-site and nearest-neighbor Coulomb interaction. The differences in magnetic properties between the…
Femtosecond nonlinear transmission techniques are applied to study mechanisms for optical nonlinearities and ultrafast carrier dynamics in CdS nanocrystals (NC's). The obtained data indicate the change in a dominant hole relaxation channel at high pump levels where nonlinear recombination effects start to play a signi…