Materials Literature
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We report an observation of holographic gratings recorded exposing a homogeneous mixture of pre-polymer and liquid crystal to a polarization light pattern. This polarization pattern is obtained by a superposition of two waves with orthogonal linear polarization. The idea to use this technique to realize holographic gr…
Chromium-doped aluminum nitride (AlN:Cr) films were grown on p-doped silicon (111) by rf magnetron sputtering in a nitrogen atmosphere at a pressure of 10−4 Torr. Film thickness was typically 200 nm. After growth, the films were “activated” at ∼1300 K for 30 min in a nitrogen atmosphere. Films activated in this manner…
Hydrogen passivation of Si nanocrystals is shown to result in a redshift of photoluminescence (PL) emission spectra, as well as the more commonly observed intensity increase. The shift is reversible, with spectra returning to their unpassivated values as hydrogen is removed from the samples by annealing. The magnitude…
We report on waveguiding properties in epitaxial Er:Y2O3 films grown by pulsed-laser deposition on sapphire [0001] substrate. Characterization of the as-grown films by x-ray diffraction, atomic force microscopy, and Rutherford backscattering revealed that the films were highly crystalline and textured along the [111]…
1.6 μm emission originated from Pr3+: (3F3,3F4)→3H4 transition in Pr3+- and Pr3+/Er3+-doped selenide glasses were investigated under an optical pump of a conventional 1480 nm laser diode. The measured peak wavelength and full width at half maximum of the fluorescent emission were ∼1650 and >100 nm, respectively…
Improved dielectric properties of lead zirconate titanate (PZT) films deposited on a variety of foils using buffer layers are reported. Foils include titanium, stainless steel, and nickel with LaNiO3(LNO) buffer layers which were prepared by sol–gel processing. High dielectric constant (330 for stainless steel, 420 fo…
The magnetic ground state of ${\mathrm{CuB}}_{2}{\mathrm{O}}_{4}$ is incommensurate at $T\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{K}$ and undergoes a continuous phase transition to a noncollinear commensurate antiferromagnetic state at ${T}^{\ensuremath{\star}}\ensuremath{\sim}10\mathrm{K}$. Close…
Atomic and electronic structures of the SrTiO3(100)-(square root of 5 x square root of 5) - R26.6 degrees surface are studied by using scanning tunneling microscopy (STM) and noncontact atomic force microscopy (NC-AFM). Instead of the well established oxygen vacancy model, it is found that a structural model, consisti…
A flat panel display prototype has been fabricated using gated carbon nanotubes as electron emission source. The gate structure is made by a self-aligned method. The pixels are turned “on” and “off” by controlling the gate electrode with a 50 V source. The operating properties of the display show much promise for furt…
The optical absorption spectra of Si(n)H(m) nanoclusters up to approximately 250 atoms are computed using a linear response theory within the time-dependent local density approximation (TDLDA). The TDLDA formalism allows the electronic screening and correlation effects, which determine exciton binding energies, to be…
We explore the electric-field effect of carbon nanotubes (NTs) in electrolytes. Due to the large gate capacitance, Fermi energy (EF) shifts of order ±1 V can be induced, enabling to tune NTs from p to n-type. Consequently, large resistance changes are measured. At zero gate voltage, the NTs are hole-doped in air with…
Recent low-temperature scanning tunneling experiments have challenged the generally accepted picture of buckled silicon dimers as the ground state reconstruction of the Si(100) surface. Together with the symmetric dimer model of the surface suggested by quantum chemistry calculations on small clusters, these findings…
A simple macroscopic continuum elasticity theory (CET) is used to calculate the structure relaxation of single-wall carbon nanotube (SWNT), an analytic formula is obtained. We also expand an atomic scale three-parameter empirical model [ T. Lenosky {\emph et al.} Nature 355, 333(1992)] in order to correctly describe t…
Vesicles made completely from diblock copolymers-polymersomes-can be stably prepared by a wide range of techniques common to liposomes. Processes such as film rehydration, sonication, and extrusion can generate many-micron giants as well as monodisperse, approximately 100 nm vesicles of PEO-PEE (polyethyleneoxide-poly…
We describe the structural and optical properties of II–VI oxide alloys, MgxZn1−xO and CdyZn1−yO, grown by pulsed-laser deposition. Single-phase alloyed films of (Mg,Zn)O and (Cd,Zn)O with c-axis orientations were epitaxially grown on sapphire (0001) substrates. The maximum magnesium and cadmium concentrations (x=0.33…
Collagen is the most abundant natural protein found in living systems. While there is a whole family of different collagen types, each differing in sequence, the properties that make this protein so attractive as the building blocks for medical devices, are reflected largely by the unique fibrillar structure of the mo…
The catalytic activity of LaFeO 3 perovskite for the gas-phase destruction of chlorinated compounds was investigated; 1,1,2-trichloroethylene in dry and moistened air was selected as the test compound. The catalyst showed good activity and satisfactory stability for prolonged time on stream (>200 h). Experimental data…
We have used X-ray reflectivity and Π-area isotherms to study Langmuir films of a series of second- and third-generation monodendrons with hydrophobic C 12 H 25 alkyl tails at the periphery and hydrophilic COOHCO 2 CH 3 or crown ether groups in the core. Both the limiting molecular areas and the layer thicknesss are c…
The electron-spin g shifts (magnetic moments μ S ) of X 2 Σ + (1π 4 3σ) radicals MX (±) with nine valence electrons are calculated at their equilibrium geometries, using second-order perturbation theory, a Hamiltonian based on Breit−Pauli theory, and correlated (MRCI) wave functions. Eighteen diatomics have been studi…
Taking advantage of the multifunctional characteristics of carbazole along with rational molecular design, a two-dimensional (2-D) carbazole chromophore was synthesized by a facile synthetic route. By doping of the chromophores into an organosoluble poly(ether imide), a series of guest−host NLO polymers were acquired.…