Materials Literature
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The optical properties of nanographite ribbons are studied within the gradient approximation. The spectral function exhibits rich peak structures due to the divergencies in its density of states. Whether there are prominent peak structures is mainly determined by the geometric structure, the edge structure and the wid…
Extended x-ray absorption fine structure spectra of monoclinic zirconia (m-ZrO2) and of amorphous zirconia (a-ZrO2) in form of a thin film are analyzed by reverse Monte Carlo simulations. Partial pair distribution functions (PDF, gZr–O and gZr–Zr) are extracted. Coordination numbers and distances determined for m-ZrO2…
The crystal structures of M10(PO4)6X2, where M = Ca or Pb and X = OH¯, F¯, Cl¯ or Br¯, have been determined by Rietveld refinement of powder synchrotron X-ray and neutron diffraction data. All the compounds are hexagonal with space group P 63/ m . For the calcium compounds, the lattice parameters are a = 9.4302(5), 9.…
The low-frequency optical properties of single-wall carbon nanotube bundles are studied within the gradient approximation. The nanotube geometry (diameter and chiral angle) and the polarization direction strongly affect the optical absorption function, the dielectric function, the loss function, and the reflectance. T…
A general theory of the electronic relaxation of an S state complexed paramagnetic metal ion (Mn2+, Gd3+) in solution is developed. Contrarily to the usual assumption, the electronic relaxation is not only due to the effects of the transient zero field splitting, but is strongly influenced by the static crystal field…
When using electron-energy-loss spectroscopy (EELS) to quantify the ${\mathrm{sp}}^{2}{/sp}^{3}$ bonding fraction in thin film carbon, the spectrum taken from the film must be compared to that of a suitable known standard. In contrast to the work of Berger [S. D. Berger and D. R. McKenzie, Philos. Mag. Lett. 57, 285 (…
The work function of tetrahedral amorphous carbon (ta-C) has been measured by Kelvin probe to lie in the range 4–5 eV, irrespective of its sp3 content or nitrogen addition. This implies that the surface barrier to emission is dominant and that emission changes caused by sp3 bonding or nitrogen addition are not directl…
The structural and magnetic evolution in magnesium ferrite (MgFe2O4) caused by high-energy milling are investigated by Mössbauer spectroscopy. It is found that the nanostructural state of the milled MgFe2O4 is characterized by a mechanically induced cation redistribution between tetrahedral (A) and octahedral [B] site…
Different types of electrochromic devices for thermal emittance modulation were developed in the spectral region from mid- to far-infrared (2–40 μm). In all devices polycrystalline and amorphous tungsten oxide have been used as electrochromic and ion storage layer, respectively. Two types of all-solid-state devices we…
The solubility and diffusion coefficient of carbon dioxide in the biodegradable polymers poly(butylene succinate) and poly(butylene succinate- co -adipate) were measured at temperatures from 323.15 to 453.15 K and pressures up to 20 MPa. The solubilities in the polymer's molten state increased linearly with pressure a…
Polarized resonant Raman and optical spectroscopy of aligned single-wall carbon nanotubes show that the optical transitions are strongly polarized along the nanotubes axis. This behavior is consistent with recent electronic structure calculations.
A detailed quantum chemical analysis of the underlying principles of hyperfine coupling in 3d transition metal complexes has been carried out. The explicit evaluation of one- and two-electron integrals for some atomic systems has been used to understand the spin polarization of the core shells. While spin polarization…
Aligned multiwall carbon nanotubes have been grown on silicon substrates by microwave plasma enhanced chemical vapor deposition using methane/ammonia mixtures. Scanning electron microscopy shows that the nanotubes are well aligned with high aspect ratio and growth direction normal to the substrate. Transmission electr…
This paper proposes to survey a good part of the research work accomplished to date on the atmospheric icing of conductors and insulators in the presence of high voltage, with emphasis laid on the studies carried out at the University of Quebec in Chicoutimi. The review covers laboratory testing and mathematical model…
Calculations of the static dielectric response ${\ensuremath{\epsilon}}_{\ensuremath{\infty}}$ of some simple oxide and mixed transition-metal oxide insulators using the weighted density approximation are reported, including in particular the perovskites ${\mathrm{KNbO}}_{3},$ ${\mathrm{KTaO}}_{3},$ and ${\mathrm{BaTi…
The relationship between molecular self-assembly processes and nucleation during crystallization from solution is an important issue, both in terms of fundamental physical chemistry and for the control and application of crystallization processes in crystal engineering and materials chemistry. This contribution examin…
We calculate energies, oscillator strengths for radiative recombination, and two-particle wave functions for the ground state exciton and around 100 excited states in a T-shaped quantum wire. We include the single-particle potential and the Coulomb interaction between the electron and hole on an equal footing, and per…
We predict new forms of carbon consisting of one- and two-dimensional networks of interlinked single-wall carbon nanotubes, some of which are energetically more stable than van der Waals packing of the nanotubes on a hexagonal lattice. These interlinked nanotubes are further transformed with higher applied external pr…
A computational study of the doping of alkali halide crystals (AX: A=Na and K; X=Cl and Br) by ns2 cations (Ga+, In+, and Tl+) is presented. Active clusters of increasing size (from 33 to 177 ions) are considered in order to deal with the large scale distortions induced by the substitutional impurities. Those clusters…
Heavily phosphorus-doped Si nanocrystals several nanometers in diameter are studied by photoluminescence (PL) and optical absorption spectroscopy. It is demonstrated that P doping results in the quenching of the PL. The quenching is accompanied by the appearance of the optical absorption in the infrared range. The abs…