Materials Literature
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The ferroelectric (Sm C*)-antiferroelectric (Sm C*A)-reentrant ferroelectric (re Sm C*) phase temperature sequence was observed for systems with competing synclinic-anticlinic interactions. The basic properties of this system are as follows: (i) the Sm C* phase is metastable in the temperature range of the Sm C*A; (ii…
We compute the magnetic shielding tensor within the London approximation and estimate the Knight shift of single-wall carbon nanotubes. Our results indicate that high resolution 13C NMR should be able to separate the metallic and insulator character of the nanotubes since a 11 ppm splitting is predicted from the respe…
The different magnetic behaviors of the ${\mathrm{V}[\mathrm{TCNE}]}_{x}$ $(\mathrm{T}\mathrm{C}\mathrm{N}\mathrm{E}=\mathrm{t}\mathrm{e}\mathrm{t}\mathrm{r}\mathrm{a}\mathrm{c}\mathrm{y}\mathrm{a}\mathrm{n}\mathrm{o}\mathrm{e}\mathrm{t}\mathrm{h}\mathrm{y}\mathrm{l}\mathrm{e}\mathrm{n}\mathrm{e})$ magnet prepared via…
Si-based Er-doped Si nanostructures were fabricated for exploring efficient light emission from Er ions and Si nanocrystallites. High-resolution transmission electron microscopy observations reveal that Si nanocrystallites are spherically embedded in the SiO2 matrix. Energy-dispersive x-ray analysis indicates that the…
Phonon density-of-states curves were obtained from inelastic neutron scattering spectra from the three crystalline phases of uranium at temperatures from 50 to 1213 K. The alpha-phase showed an unusually large thermal softening of phonon frequencies. Analysis of the vibrational power spectrum showed that this phonon s…
Recent magnetization and susceptibility measurements on ${\mathrm{Cu}}_{3}{\mathrm{Cl}}_{6}{(\mathrm{H}}_{2}{\mathrm{O})}_{2}{\mathrm{\ensuremath{\cdot}}2\mathrm{H}}_{8}{\mathrm{C}}_{4}{\mathrm{SO}}_{2}$ by Ishii et al. [J. Phys. Soc. Jpn. 69, 340 (2000)] have demonstrated the existence of a spin gap. In order to expl…
We have demonstrated a route to epitaxial Pb(Zr0.2Ti0.8)O3 on (001) Si that exhibits a uniform piezoelectric response down to nanoscale levels through the utilization of an insulating, single-crystalline SrTiO3 transition layer. These structures, which were grown by a combination of molecular-beam epitaxy and off-axis…
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…