Materials Literature
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In order to study the magnetic excitation behaviors in colossal magnetoresistance manganites, a magnon-phonon interacting system is investigated. Sudden broadening of magnon linewidth is obtained when a magnon branch crosses over an optical phonon branch. Onset of the broadening is approximately determined by the magn…
The band gap energy as well as the possibility of cross luminescence processes in alkaline-earth dihalide crystals have been calculated using the ab initio Perturbed-Ion (PI) model. The gap is calculated in several ways: as a difference between one-electron energy eigenvalues and as a difference between total energies…
The electrical properties of LiNbO3 ceramic pellets were investigated by impedance spectroscopy in the temperature range of 450–800 °C. Impedance data are presented in the Nyquist plot which, in addition to the separation of grain and grain boundary contributions, allows the determination of the relaxation frequency o…
In this article, we show how the well-known one-phonon confinement model can be improved to determine the diameter of silicon nanocrystalline spheres from the optical phonon wave-number shift, even using a physical-meaning weighting function. We show that the fundamental parameter is the knowledge of the phonon disper…
Measurements by atomic force microscopy are reported for (100) and (110) surfaces of ${\mathrm{SrTiO}}_{3}$ monocrystals prepared with different oxidizing and reducing conditions at elevated temperatures (800--1000 \ifmmode^\circ\else\textdegree\fi{}C). The morphology of the surfaces turns out to be drastically altere…
Large wavelength shifts have been measured in the reflectivity spectra of Bragg mirrors etched in porous silicon after exposure of the mirrors to vapor from organic solvents. The shift in the Bragg wavelength of the mirror arises from refractive index changes, induced by capillary condensation of the vapor in the meso…
We have studied systematically the chemical trends of the band-gap pressure coefficients of all group IV, III-V, and II-VI semiconductors using first-principles band-structure method. We have also calculated the individual ``absolute'' deformation potentials of the valence-band maximum (VBM) and conduction-band minimu…
1 H NMR spectra for solutions prepared by dissolution of [CpCr(CO) 3 ] 2 and [Cp*Cr(CO) 3 ] 2 in toluene in the temperature range 190−390 K are interpreted in terms of thermodynamic and kinetic parameters for dissociation of the diamagnetic dimers into the paramagnetic monomers CpCr(CO) 3 and Cp*Cr(CO) 3 . There is no…
Suspensions of poly(2-ethylhexyl acrylate) in supercritical CO 2 formed by dispersion polymerization with a poly(dimethylsiloxane)-based surfactant were sprayed to form uniform films. The viscosity reduction of the dispersed phase caused by dissolved CO 2 is crucial for atomization to produce fine droplets, and for co…
The 515 kHz ultrasound-initiated reduction of AuCl 4 - to Au(0) was examined as a function of the concentration of various surface-active solutes. The amount of AuCl 4 - reduced in the presence of ethanol, propan-1-ol, and butan-1-ol was found to be dependent on the surface excess of the alcohol at the gas/solution in…
We present results of small-angle neutron scattering (SANS) investigations into the characteristics of charged poly(amidoamine) (PAMAM) dendrimer solutions in deuterium oxide. The study shows that ionic strength, surface charge density, and concentration are the crucial parameters controlling the degree of structural…
Recent simulations suggest that the presence of filler particles in a phase separating blend can induce the development of composition waves having the symmetry of the filler particles. We investigate these predictions through atomic force microscopy (AFM) measurements on ultrathin ( L ≈ 100 nm) polystyrene and poly(v…
Significant enhancements in the electrocatalytic oxidation of HCOOH are obtained on deliberately stepped platinum surfaces with (111) terraces and (100) monatomic steps when bismuth is deposited on terrace and/or step sites. The bismuth-modified surfaces with higher step densities/narrower terrace widths exhibit highe…
Hydrous aluminosilicate glasses of composition NaAlSi 8 O 18, NaAlSi 3 O 8, NaAlSi 2 O 6, and NaAlSiO 4 have been studied with 1 H MAS, and 1 H/ 27 Al, and 1 H/ 23 Na TRAPDOR NMR spectroscopy. Two different environments for molecular water were identified. Three 1 H OH resonances (1.5, ca. 3.5, and 5−6 ppm) are observ…
The cubic mesoporous silica molecular sieves MCM-48 have been obtained as an energetically favorable mesophase via a synthesis route using the surfactant mixtures between alkyltrimethylammonium bromides and polyoxyethylene alkyl ethers, with sodium silicate as the silica source. The MCM-48 mesophase was stable under t…
In a previous work [ Macromolecules 1998, 31, 6426] the preparation technique of a latex of poly(β-hydroxyoctanoate) (PHO) obtained from Pseudomonas oleovorans grown at high cell density on sodium octanoate was presented. The resulting films displayed typical properties of thermoplastic elastomer. Depending on the exp…
Electronic energy transfer from [Cr(ox) 3 ] 3- (ox = oxalate) in three-dimensional (3D) anionic oxalate networks to encapsulated [Cr(bpy) 3 ] 3+ (bpy = 2,2‘-bipyridine) cations at 1.5 K was investigated by time-resolved luminescence spectroscopy. Two series of mixed crystals of nominal compositions [NaAl 1 - x Cr x (o…
Unsymmetrical porphyrazines, M[pz(H)(2)(R)(6)], with three substituted pyrroles (substituents, R = -NMe(2), propyl, or 4-tert-butylphenyl) at the periphery and one unsubstituted pyrrole have been synthesized from inexpensive and readily available materials. Linstead crossover macrocyclization of 8 with 9, 11, and 12 g…
The ligand field in HBr results in the splitting of the Br 3d orbitals into the 3d (d x 2 - y 2 , d xy ), 3d (d xz , d yz ), and 3d (d z 2 ) orbitals. In core ionized HBr, the stronger spin-orbit splitting removes the remaining degeneracies and results in five different Br 3d eigenstates from linear combinations of th…
The molecular hyperpolarizabilities and electronic properties of some azulene-containing chromophores have been investigated by employing AM1/FF and ZINDO/S-CI approaches. The calculation results show good agreement with the experimental values. It is found that the nonalternant azulene ring can be regarded as a more…