Materials Literature
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The equilibration of spherical micelles formed by polystyrene−poly(2-vinylpyridine) (PS−PVP) diblock copolymers in toluene is studied by means of cryo electron microscopy. The evolution of the micelles in order to reach the equilibrium state involves the transformation of their structure and size and requires a consid…
Manganese-based perovskites have been successfully synthesized using deposition by aqueous acetate solution (DAAS). This novel technique, which has the potential for depositing large area thin films with high throughput and low cost, involves the preparation of stoichiometric mixtures of metal−acetate precursor soluti…
We have synthesized metallocene−porphyrazine (pz) complexes, as shown, and find them to be highly electroactive with five reversible redox couples. X-band EPR measurements of the (2H)−Mo(V) complex indicate that spin delocalization from the Mo(V) to the pz−dithiolene is significantly greater than for classical dithiol…
A new chiral ligand (H(2)L) based on the condensation of diaminocyclohexane and 4-(diethylamino)salicylaldehyde is reported along with its nickel(II) and manganese(III) complexes. These compounds all crystallize in noncentrosymmetric space groups. Crystal data are as follows. For the ligand (C(28)H(40)N(4)O(2)): monoc…
The mixed functionality pyrazole/phenol ligand (2-hydroxyphenyl)bis(pyrazolyl)methane, L1OH, has been used to prepare a series of linear trimetallic systems with the general structural motif [M(3)(L1O)(4)](2+), where M = Mn(2+), Co(2+), Ni(2+), Cu(2+), and Zn(2+). Each of these complexes has been structurally characte…
Several polyoxyethylene-substituted perylene-3,4,9,10-tetracarboxyldiimides have been synthesized and characterized. Relative to other known perylene diimide derivatives, all of the present compounds have much lower melting points and much greater solubility in common solvents. Most of these compounds possess liquid c…
The effect of pressure on the relaxation processes in poly(propylene glycol) of number-average molecular weights 400 and 4000 g mol -1 (PPG-400 and PPG-4000) has been investigated using dielectric spectroscopy as well as thermal conductivity and heat capacity measurements. The relaxations associated with segmental mot…
The effect of an inclined substrate on heteroepitaxial diamond has been investigated on 4° off β-SiC(001) tilted around the [1̄10] axis. Homogeneous macro steps with (001) terraces are observed in the [1̄10] direction forming a vicinal angle of 3°–4° from the (001) surface reflecting the substrate inclination. The sel…
A remarkably low turn-on field of about 1 V/μm has been observed in electron field emission from planar SiC/Si heterostructures formed by high dose C implantation into Si using a metal vapor vacuum arc ion source. An implant energy of 35 keV was used to a dose of 1.0×1018 ions/cm2 with subsequent annealing in nitrogen…
Graphite samples are heated in a diamond anvil cell with a CO2 laser above 11 GPa. A light transparent phase has appeared after heating, which is quenchable at ambient conditions. The Raman spectrum shows that the phase is a fine-grained cubic diamond. Images by a high resolution transmission electron microscope indic…
We show that NMR chemical shift spectroscopy could help to identify the crystalline phases of hard carbon nitride compounds. To this purpose we compute the NMR chemical shifts of defect zinc-blende, cubic, $\ensuremath{\alpha}\ensuremath{-}$, $\ensuremath{\beta}\ensuremath{-}$, and graphitic ${\mathrm{C}}_{3}{\mathrm{…
Accurate determination of thermal parameters of microbolometer-based sensors is of considerable interest for many applications. The most important parameters are thermal time constant, heat capacitance and thermal conductance. In this work, we have developed a technique to measure all three quantities using a single e…
The dynamics of addition polymerization-induced phase separation in a liquid crystal solvent is examined via confocal microscopy in systems where the final morphology consists of nematic liquid crystal domains suspended in a cross-linked polymer matrix. For low polymer concentrations, we observe unusually rapid hydrod…
Magnetization measurements of a ${\mathrm{Gd}}_{0.5}{\mathrm{Ba}}_{0.5}{\mathrm{CoO}}_{3}$ perovskitelike compound have revealed an anomalous behavior at ${T}_{i}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}240\mathrm{K}$ and ${T}_{C}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}277\mathrm{K}$ that correspo…
Spatially resolved electron energy loss spectroscopy is used to characterize the cross-sectional structure of highly tetrahedral amorphous carbon films, particularly concentrating on the ${\mathrm{sp}}^{2}$ bonded surface layer. The surface layer is shown to be due to subsurface conversion from ${\mathrm{sp}}^{2}$ to…
Ring torsion effects on optical excitation properties in poly(para-phenylene) (PPP) and polyaniline (PAN) are investigated by extending the Shimoi-Abe model [Synth. Met. 78, 219 (1996)]. The model is solved by the intermediate exciton formalism. Long-range excitons are characterized, and the long-range component of th…
X-ray resonant scattering at the $K$-edge of transition-metal oxides is shown to measure the orbital order parameter, supposed to accompany magnetic ordering in some cases. Virtual transitions to the $3d$ orbitals are quadrupolar in general. In cases with no inversion symmetry, such as ${\mathrm{V}}_{2}{\mathrm{O}}_{3…
We propose that glass-forming liquids are intrinsically under the influences of both fluctuating interactions and random fields well-known in the field of spin systems. This is due to the frustration between the isotropic and anisotropic parts of effective intermolecular interactions. Our model indicates the existence…
We study dendritic microstructure evolution using an adaptive grid, finite element method applied to a phase-field model. The computational complexity of our algorithm, per unit time, scales linearly with system size, allowing simulations on very large lattices. We present computations on a ${2}^{17}\ifmmode\times\els…
Silicon nanowires have been synthesized in high yield and high purity by using a high-temperature laser-ablation method with growth rates ranging from 10 to 80 μm/h. Transmission electron microscopic investigation shows that the nanowires are crystalline Si, and have diameters ranging from 3 to 43 nm and length up to…