Materials Literature
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We perform molecular dynamics simulations of an idealized polymer melt surrounding a nanoscopic filler particle. We show that the glass transition temperature T(g) of the melt can be shifted to either higher or lower temperatures by tuning the interactions between polymer and filler. A gradual change of the polymer dy…
A donor−chromophore−acceptor triad (D−C−A) in which the chromophore is a Pt diimine bis(acetylide) moiety (red), the donor is phenothiazine (blue), and the acceptor is nitrophenyl (green) has been synthesized and studied spectroscopically. Irradiation leads to a charge-separated state that has a 70 ns lifetime as meas…
Optical conductivity measurements on the perovskite-related oxide CaCu3Ti4O12 provide a hint of the physics underlying the observed giant dielectric effect in this material. A low-frequency vibration displays anomalous behavior, implying that there is a redistribution of charge within the unit cell at low temperature.…
We investigate the mechanism of the resonant x-ray scattering on the Ti K edge region of ${\mathrm{YTiO}}_{3}$ using the band structure calculation combined with the local density approximation. A large intensity is obtained for the orbital superlattice spots. The calculated spectra consist of several peaks as a funct…
We have determined the adsorptive capacity of Xe on the different groups of binding sites available to this atom on a sample of single-walled carbon nanotube (SWNT) bundles. The SWNT's used were not treated after production: hence, the caps at the ends of each of the tubes remain intact. By comparing these experimenta…
Substitution of the weakly binding aqua ligand in [Cu(tren)OH2](2+) and [Cu(tpa)OH2](2+) (tren = tris(2-aminoethyl)amine; tpa = tris(2-pyridylmethyl)amine) by a cyano ligand on ferricyanide results in the assembly of heteropolynuclear cations around the cyanometalate core. In water, the reduction of the Fe(III) core t…
The diffusion of deuterated hexane in conformational isomers of a heterogeneous polymer, H 12 MDI (4,4‘-dicyclohexylmethane diisocyanate)/BD (1,4-butanediol)/PTMO (poly(tetramethylene oxide)), was investigated at a fixed hard segment content of 30 wt % and compared to the diffusion of acetonitrile. The effective diffu…
Vibrational study by Raman spectroscopy was made of the layered perovskite compounds of the formula M 2 La 2 Ti 3 O 10 (M = H, Li, Na, K, Rb), K 2 La 2 Ti 3 O 10 ·2H 2 O, and H 2 La 2 Ti 3 O 10 · n H 2 O. The spectral features above 400 cm -1 were similar in all of the unhydrated samples suggesting that the bands orig…
A dinuclear Ru(III) complex, [Ru2Cl2(PPh3)2(μ-Cl)2(μ-salhn)], has been synthesized and characterized by analytical, spectroscopic, magnetic, and X-ray diffractometry. The redox active complex displays two reductions corresponding to RuIII2/RuIIIRuII and RuIIIRuII/RuII2 couples. A weak antiferromagnetic spin coupling i…
31 P and 13 C NMR studies are reported for a smectic A liquid crystal of haxakis[4-dodecyl(4-biphenoxy)]cyclotriphosphazene. In an intense magnetic field, the long axes of the biphenylene fragments and the alkyl chains align along the magnetic field, and the cyclotriphosphazene (ctp) ring-normal points preferentially…
Molecular dynamics (MD) simulations have been performed to study the flexibility of smectite clay minerals. We aim at the quantitative understanding of the mechanical behavior of a single clay layer in a completely exfoliated state. The repeating unit of a clay layer is taken to be a o = 0.52 nm and b o = 0.902 nm wit…
Tensile properties and morphology of tetrafunctional multigraft copolymers are investigated dependent on PS volume fraction and number of branch points. It is found that tetrafunctional multigraft copolymers with 22 vol % PS and seven branch points show a surprising high strain at break of about 2100%, about double th…
Confinement effects on first-order and second-order Raman scattering in nanocrystalline silicon are presented. The average dimension of the nanocrystals has been determined by an analysis of the first-order Raman spectra using the phenomenological phonon confinement model. The second-order acoustic bands 2LA and 2TA d…
First-principles calculations are used to investigate the electronic properties of the surfaces of polyethylene. The calculations support the experimental evidence of a negative electron affinity, with calculated values of -0.17 eV and -0.10 eV for surfaces with chains perpendicular and parallel to the surface normal,…
Dehydroxylation and silanization processes on the silica surface are studied by ab initio molecular dynamics. The (100) and (111) surfaces of β-cristobalite are used as two possible models of the hydroxylated amorphous surface. The activation energy and latent heat for the dehydroxylation reactions of the (100) surfac…
The depletion-induced phase separation in a mixture of colloidal particles (PMMA-latex) and nonadsorbing polymers [poly(styrene)] in a solvent (mixture of tetralin, cis-decalin, and carbon tetrachloride) was investigated in real space with confocal scanning laser microscopy in the initial, intermediate, and final stag…
Heteroatoms of Al and Ti are effectively introduced into the framework of ordered mesoporous silica materials (designated as MAS-7 and MTS-9, respectively) in strong acidic media (pH < 0) by a two-step procedure. MAS-7 shows high catalytic activities for the cracking of both small (cumene) and bulky (1,3,5-tri-isoprop…
The extension of the first-principles generalized pseudopotential theory (GPT) to transition-metal (TM) aluminides produces pair and many-body interactions that allow efficient calculations of total energies. In aluminum-rich systems treated at the pair-potential level, one practical limitation is a transition-metal o…
Comment on PRL v. 86, p. 5084 (2001) [cond-mat/0101016]. We point out that the authors' simulations are consistent with the known theory of steady-state solutions in this system.
The temperature-dependence of the magnetization near the surface of a band-ferromagnet is measured with monolayer resolution. The simultaneous application of novel highly surface-sensitive techniques enables one to deduce the layer-dependent magnetization curves at a Fe(100) surface. Analysis of data is based on a sim…