Materials Literature
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CdSe nanocrystals in solution and films can enter a metastable state in which the highly luminescent nanocrystals become dark. This change, which we attribute to a surface transformation, can be caused by heating or by changing the environment of the nanocrystals at room temperature. The metastable transformation is r…
We report on temperature dependence of excitonic photoluminescence (PL) from ZnO/(Mg, Zn)O multiple quantum wells (MQWs). Two kinds of MQWs having different barrier heights grown by laser molecular-beam epitaxy showed significantly different temperature dependences of PL spectra; in ZnO/Mg0.27Zn0.73O MQWs, the PL peak…
We have synthesized novel crystalline ropes of "polygonized" single-wall carbon nanotubes (SWCNTs). The tubes exhibit rounded-hexagonal cross sections in contrast to the earlier observations of nearly circular tubes. To investigate the structural characteristics of the lattice of SWCNTs we have performed extensive mol…
Anodic aluminum oxide (AAO) templates were fabricated by anodizing Al films. After the Co catalyst had been electrochemically deposited into the bottom of the AAO template, carbon nanotubes (CNTs) were grown by the catalytic pyrolysis of C2H2 at 650 °C. Overgrowth of CNTs on the AAO templates was observed. The diamete…
The static friction between crystalline surfaces separated by a molecularly thin layer of adsorbed molecules is calculated using molecular dynamics simulations. These molecules naturally lead to a finite static friction that is consistent with macroscopic friction laws. Crystalline alignment, sliding direction, and th…
Aiming to settle the controversial observations for halogen-bridged binuclear transition-metal (MMX) complexes, finite-temperature Hartree-Fock calculations are performed for a relevant two-band Peierls-Hubbard model. Thermal, as well as quantum, phase transitions are investigated with particular emphasis on the compe…
The low-temperature properties of the so-called ``charge-ordered'' state in 50% doped perovskite manganites are described from the viewpoint of the magnetic spin ordering. In these systems, the zigzag antiferromagnetic ordering, combined with the double exchange physics, effectively divides the whole sample into the o…
A theoretical study of the subpicosecond fragmentation of C60 clusters in response to ultrafast laser pulses is presented. We simulate the laser excitation and the consequent nonequilibrium relaxation dynamics of the electronic and nuclear degrees of freedom. The first stages of the nonequilibrium dynamics are dominat…
We investigate the limits of high energy transport in multiwalled carbon nanotubes (MWNTs). In contrast to metal wires, MWNTs do not fail in the continuous, accelerating manner typical of electromigration. Instead, they fail via a series of sharp, equally sized current steps. We assign these steps to the sequential de…
Article Refinement of the crystal structure of heptasilver(I) tetraseleniogermanate(IV) selenide iodide, Ag7GeISe5 was published on April 1, 2001 in the journal Zeitschrift für Kristallographie - New Crystal Structures (volume 216, issue 1-4).
Cs 4 SiTe 4 , cubic, P43n (No. 218), a = 15.081(2) , V = 3430.0 3 , = 8, Rgi(F) = 0.032, wR,ef<F 2 ) = 0.057, =293 .
Low density polyethylene (LDPE) and polyvinyl acetate (PVAc) blends containing different weights percentages of PVAc, were prepared. Polyethylene graft Maleic anhydride (PE-g-MA) containing 0.4 mole% of anhydride groups was used as compatibility booster in the blends. FTIR helped confirming the blend formation. Improv…
The optical properties of Tb3+/Ce3+ doped zeolites are elucidated with emphasis on ultraviolet (UV) and vacuum ultraviolet (VUV) excitation and luminescence. Ce3+ sensitized Tb3+ emission with quantum yields of 85 % may be obtained at 330 nm excitation. Low absorptivity at 254 nm due to low Ce3+ concentrations or low…
The chiral structure of liquid crystalline phases arises due to the intrinsic chirality of the constituent mesogens. While it is seemingly straightforward to quantify the macroscopic chirality by using, for instance, the cholesteric pitch or the optical rotatory power, it is not as simple to quantify the chirality of…
The crystallization and lamellar morphology of isotactic polypropylene (ipp) have been investigated by thermal analysis and electron microscopy. When ipp samples are crystallized above 132°C, no β-phase was detected and the samples consisted of pure α-spherulites and those showing double melting endotherms, the occurr…
The morphology of thermoplastic polyolefins (TPOs) has a profound effect on their paintability. Paint molecules can penetrate an amorphous surface easier than a crystalline one. The effects of the compression molding processing conditions, such as molding temperature and cooling rate, on the crystallinity of TPOs were…
In this work we have analysed the light scattering pattern produced by the cellulose derivative based PDLC type cells [1-5] when illuminated at normal incidence by a laser light beam. The voltage dependence of the scattering pattern was obtained along with the voltage dependence of the cells' transmission coefficient.…
Single crystals of (Sb0.75Bi0.25)2-xMnxTe3 (x = 0.0–0.05) were characterized by X-ray diffraction, measurements of reflectance in the plasma resonance frequency region, Hall coefficient, electrical conductivity, and Seebeck coefficient. It was found that Mn atoms in the crystal structure of Sb1.5Bi0.5Te3 behave like a…
It is shown that the softening of the acoustic mode and the ensuing ferroelastic phase transition are due to the linear-quadratic interaction between the symmetric and antisymmetric deformations, which is presently neglected in the literature. An expression is obtained which can be used to predict the phase transition…
Self-assembly of preformed aluminosilicate nanoclusters in the presence of templating micella provides a route to strongly acidic, hydrothermally stable mesoporous aluminosilicates with ordered hexagonal structures (MAS-5). Results show that the materials are similar to Beta zeolite and are highly active for the catal…