Materials Literature
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We report an investigation of the properties of CdSe nanocrystal dispersions using small-angle x-ray scattering. These nanocrystals are prepared from organometallic precursors using high-temperature solution chemistry. The study provides direct and accurate measures of the nanocrystal size and size distribution. The l…
The electronic structures of the narrow ${t}_{2g}$ band systems ${\mathrm{YTiO}}_{3}$ and ${\mathrm{YVO}}_{3}$ are studied using the generalized gradient approximation (GGA) and local-density approximation (LDA)+U method. GGA fails in reproducing the insulating nature of ${\mathrm{YTiO}}_{3}$ and the correct magnetic…
We report on experimental evidence of hydrogen-boron interactions in boron-doped diamond from hydrogen diffusion investigations. Original deuterium diffusion studies in homoepitaxial B-doped diamond films reveal that hydrogen diffusion is limited by the B concentration with a low effective diffusion activation energy.…
A comprehensive study of leakage conduction in Pb(ZrxTi1−x)O3films with Pt electrodes is carried out. The conduction properties of films prepared in different ways (sol–gel coating, metalorganic chemical vapor deposition, sputtering) were studied by using different experimental techniques including variation of the ap…
The tetracalcium dialuminum hydroxide carbonate pentahydrate Ca4Al2(OH)12CO3.5H2O is a layered compound constituted by positively charged [Ca4Al2(OH)12]2+ main layers and negatively charged [CO3, 5H2O]2− interlayers. The Al3+ and Ca2+ ions are six- and sevenfold coordinated by O atoms, respectively. Water molecules oc…
We analyze from a theoretical point of view the optical properties of arrays of carbon nanotubes filled with silver. Dependence of these properties on the different parameters involved is studied using a transfer matrix formalism able to work with tensorlike dielectric functions and including the full electromagnetic…
We study the size dependence of electron and hole quantum size levels in spherical semiconductor nanocrystals. An analytical theory of the quantum size levels within a spherical eight-band Pidgeon and Brown model has been developed, which takes into account both the coupling of conduction and valence bands and the com…
Using time-resolved photoluminescence spectroscopy we have measured the lifetime of the F-center luminescence from α-Al2O3:C. The measurements reveal a lifetime of 35–36 ms at room temperature, decreasing to <2 ms over the temperature range from 370 to 500 K. The decrease in the lifetime is shown to follow a cl…
We have succeeded in observing the size dependent photoluminescence (PL) from Ge nanocrystals (nc-Ge) with 0.9--5.3 nm in average diameter ${(d}_{\mathrm{ave}})$ in the near-infrared region. The nc-Ge were fabricated by rf cosputtering of Ge and ${\mathrm{SiO}}_{2}$ and post annealing at $800\ifmmode^\circ\else\textde…
We have studied the surfaces of zirconia $({\mathrm{ZrO}}_{2})$ by first-principles calculations using density functional theory. We predict surface energies and relaxations for the principal surfaces of different bulk phases of zirconia. We find that the stoichiometric tetragonal(111) and monoclinic(1\ifmmode\bar\els…
We have made electrical measurements on a system using carbon nanotubes as the dopant material. A semiconjugated, organic polymer was mixed with carbon nanotubes to form a wholly organic composite. Composite formation from low to high nanotube concentration increases the conductivity dramatically by ten orders of magn…
This paper present a novel low cost, high performance readout integrated circuit (ROIC) for bolometer uncooled detector applications. The array is designed to offer better than 80mK NEdT using f/1.8 optics. The design incorporates advanced on-ROIC signal processing electronics that allows bolometer element non-uniform…
The Raman study of a single crystal has been performed in a 150-360 K temperature range. Three modes below at 150 K show remarkable softening as the temperature increases. The extrapolated values of these modes still exhibit finite frequency at the Curie point and they seem to be associated with the antiferro- to para…
<div class="htmlview paragraph">Cavitation is the dynamic process of gas cavity growth and collapse in a liquid. These cavities are due to the presence of dissolved gases or volatile liquids and they are formed at the point where the pressure is less than the saturation pressure of the gas (gaseous cavitation) o…
The ferromagnetic system Gd(0001) has been studied by spin-polarized photoelectron diffraction, using the highly spin-polarized $^{7}S$ and $^{9}S$ multiplet peaks in Gd $4s$ and $5s$ spectra. Temperature-dependent spin asymmetries derived from the $^{7}S$-to- $^{9}S$ peak intensity ratios exhibit pronounced changes o…
The structure of the ${\mathrm{TaB}}_{2}(0001)$ surface has been investigated by using impact-collision ${\mathrm{Li}}^{+}$ ion-scattering spectroscopy and three-dimensional three-atom computer simulation. We found for the first time that a graphitic boron layer is formed on the ${\mathrm{TaB}}_{2}(0001)$ surface and…
Neutron scattering experiments have been performed on the Zn-Mg-Ho icosahedral quasicrystal using powder and single-crystalline samples. In contrast to a previous Letter [Charrier et al., Phys. Rev. Lett. 78, 4637 (1997)], the magnetic long-range order could not be detected in the icosahedral quasicrystal. It instead…
The electrical conductivity of and perovskite-type oxides converted by vacuum annealing into states with weak and strong compensation between donors and acceptors has been measured. It was shown that the reduced samples had both shallow and comparatively deep levels which were attributed to the neutral and singly-char…
In the present work, we report self-assembling bismuth-containing nano-electroded cells of layered perovskite ferroelectric thin films that are about 200 nm in size, that is 50 times smaller than the smallest cell reported to date. Heteroepitaxial Bi-rich Bi4Ti3O12 films were grown by pulsed laser deposition (PLD) on…
The application of strain to yttria-stabilized zirconia (YSZ), which can be realized by sandwiching a thin YSZ film epitaxially between layers of a material with larger lattice constants, is proposed as a means to enhance oxygen ion mobility. The possible mechanism of such an enhancement was investigated by molecular…