Materials Literature
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We study a recently proposed nonlinear evolution equation describing the collective step meander on a vicinal surface subject to the Bales-Zangwill growth instability [O. Pierre-Louis et al., Phys. Rev. Lett. (80), 4221 (1998)]. A careful numerical analysis shows that the dynamically selected step profile consists of…
The decay properties of the one-particle Green function in real space and imaginary time are systematically studied for solids. I present an analytic solution for the homogeneous electron gas at finite and at zero temperature as well as asymptotic formulas for real metals and insulators that allow an analytic treatmen…
We use an atom-atom potential between carbon atoms to obtain an interaction potential between nanotubes (assumed rigid), thereby calculating the cohesive energy of a bunch of nanotubes in hexagonal two dimensional packing. The model proposed is quite similar to our earlier work on fullerenes and organic molecular crys…
Transparent films of CuScO2+x have been prepared which show p-type electrical conductivity. The temperature dependence of the conductivity indicates semiconducting behavior with an apparent room temperature activation energy of 0.11 eV. The highest room temperature conductivity observed was 30 S cm−1. Films 110 nm thi…
Single-walled carbon nanotubes show linear elasticity under hydrostatic pressure up to 1.5 GPa at room temperature. The volume compressibility, measured by in situ synchrotron x-ray diffraction, has been determined to be 0.024 GPa (-1). Theoretical calculations suggest that single-walled carbon nanotubes are polygoniz…
The oxygen-binding behaviors of five cobalt(II) meso -tetrakis(substituted phenyl)porphyrin complexes [CoTPP, CoT(2-Cl)PP, CoT(4-Cl)PP, CoT(4-MeO)PP, and CoT(2,4-2MeO)PP] in chloroform solution were investigated using a UV−visible spectrophotometer. It shows that the substituents and the fifth ligand in the cobalt(II)…
Unusually rigid π-stacked porphyrin−spacer−quinone systems have been synthesized using an approach that enables extensive control over the nature of electronic interactions between donor, aromatic spacer, and acceptor. This new class of porphyrin-based structures is distinct from related assemblies designed to probe e…
Bis-benzamidines were studied as linkers for the formation of gold nanoparticle assemblies on planar gold surfaces modified with ω-mercaptohexadecanoic acid. In situ ellipsometry, external reflection Fourier transform spectroscopy, and atomic force microscopy showed that the packing density and order of the bis-benzam…
New diazacrown-appended cholesterol gelators 1 and 2 were synthesized, and their gelation ability was evaluated in organic solvents. Very surprisingly, 1 + acetic acid gel results in spherical vesicles with two distinct sizes 200 and 2500 nm in diameter. In particular, the smaller vesicles are linked linearly, which i…
The ZrW 2 O 8 family of materials has been shown to display the unusual property of an isotropic bulk contraction in volume as a function of temperature. We report here on negative thermal expansion properties and oxygen migration at very low temperatures in ZrW 2 - x Mo x O 8 phases. ZrWMoO 8 shows significant negati…
Various ternary blends of HDPE, PS, and PMMA were prepared in one step using a Brabender mixer. When HDPE is the major component, as in this case, the morphology consists of a HDPE matrix, a PS dispersed phase and PMMA subinclusions within the dispersed PS, as predicted by the spreading coefficients. SEM observation a…
The techniques for seeding of a desired polymorph during crystallisation from solutions are reviewed. The basic information about the type of polymorphism needed to consider seeding strategies is discussed first. The development of seeding strategies is facilitated by certain data on the system. Their relevance as wel…
We report the first theoretical estimate of the nuclear-spin dephasing time T_2 owing to the spin interaction with the two-dimensional electron gas, when the latter is in the integer quantum Hall state, in a two-dimensional heterojunction or quantum well at low temperature and in large applied magnetic field. We estab…
We present a study of resonant vibrational coupling between adsorbates and an elastic substrate at low macroscopic coverages. In the first part of the paper we consider the situation when adsorbates form aggregates with high local coverage. Based upon our previously published theory, we derive formulas describing the…
We propose using short-period superlattices as substrates to control the vibrational relaxation dynamics of adsorbate overlayers. The mass modulation of superlattices creates both band gaps and large spectral enhancements in the phonon density of states. These modifications can dramatically alter the coupling between…
Deposition of low surface energy plasma polymer layers onto microroughened PTFE substrates is found to give rise to high repellency toward polar and nonpolar probe liquids. This behavior has been interpreted in terms of Wenzels theory and the Cassie−Baxter relationship.
We discuss dynamic hydrophobicity from the perspective of the force required to move a water droplet on a surface and argue that the structure of the three-phase contact line is important. We studied the wettability of a series of silicon surfaces that were prepared by photolithography and hydrophobized using silaniza…
Sodium Bismuth Titanate, Na 0.5 Bi 0.5 TiO 3 (NBT), has the perovskite structure, general formula ABO 3 . This is one of a limited number 1 of perovskite compounds were substitution occurs at the A-cation site, the vast majority substituting on the B-site. NBT was first described by Smolenskii and co-workers 2 , and d…
A method for particle sizing using a commercial spectrophotometer is presented, based on a Rayleigh−Gans−Debye treatment of the wavelength dependence of turbidity. The finite acceptance angle of the spectrophotometer has been taken into account and shown to be potentially advantageous. The method has been used to moni…
The order−disorder and order−order transitions (ODT and OOT) of a series of mixtures of a compositionally asymmetric polystyrene- block -polyisoprene- block -polystyrene copolymer (SIS) ( f PS = 0.131) and low molecular weight PS homopolymers with different molecular weights have been investigated by using transmissio…