Materials Literature
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The linear and nonlinear optical response properties of crystalline DEANST, N,N-diethyl-4-(2-nitroethenyl) phenylamine, have been computed rigorously, using a large set of input data including modified neglect of differential overlap (MNDO) and ab initio theoretical estimates of molecular polarizability α and hyperpol…
The title compound, a new polymorphic phase of dicobalt diphosphate, Co2P2O7, was prepared by hydrothermal methods. The structure contains CoO6 coordination octahedra and P2O7 radicals. The CoO6 radicals, connected by edge sharing, form six-membered rings, which are further interconnected to form two-dimensional zigza…
Poly(silylenemethylene)s of the types [SiMeRCH2]n and [SiHRCH2]n were prepared by the ring-opening polymerization (ROP) of 1,3-disilacyclobutanes (DSCBs) containing n-alkyl substituents, such as C2H5, n-C3H7, n-C4H9, n-C5H11, and n-C6H13, or a phenyl group on the Si. These new polymers include a monosilicon analog of…
The nature of the insulating ground state in quasi-two-dimensional organic conductor lambda-(BETS)_2GaX_zY_{4-z}, where the existence of a spin gap is suggested by susceptibility measurement, has been studied theoretically. Hartree-Fock calculations at absolute zero temperature show that if the on-site Coulomb interac…
Spontaneous emission and absorption in an aggregate of π-conjugated oligomers are studied theoretically. Each oligomer is taken as a ring of N carbon atoms with average bond length a, and is treated using the Hückel Hamiltonian with bond alternation parameter δ. Coulombic interactions between rings are treated to firs…
New phthalide-containing bisphenols, phenolphthalein-N-(3-methylanilide) (3-PMA), and phenolphthalein-N-(4-methylanilide) (4-PMA), were synthesized from phenolphthalein and m- and p-toluidines. These bisphenols were polycondensed with terephthaloyl chloride (TPC) using an interfacial or solution polymerization techniq…
The frequencies, widths, and shapes of the one-phonon Raman spectra of isotopically enriched and highly isotopically disordered $\ensuremath{\alpha}$-Sn samples have been measured. The isotopically enriched samples show a frequency inversely proportional to the square root of the mass, in agreement with the harmonic a…
The conductance of single-shell carbon nanotubes is numerically calculated in the effective-mass approximation by treating scattering from impurities exactly. The magnetic-field dependence of the conductance depends sensitively on the mean free path. When the mean free path is sufficiently large, undoped metallic nano…
The miscibility and thermal properties of polyethylene oxide(PEO)/oligoester resin (OER) blends and PEO/crosslinked polyester (PER) blends were studied by differential scanning calorimetry (DSC). The effect of quenching process on the crystallization behavior of PEO for these two systems were investigated and discusse…
The crystal structure of antiferroelectric PbZrO 3 was re-examined by high resolution powder neutron diffraction. The structure obtained with assumed modulations associated with the lattice vibrational modes Σ 3 ( T O ) and R 25 x y is almost the same as that obtained previously with the same assumptions. However, one…
We present a microstructure-dependent anisotropic infrared-optical dielectric function model for mixed-phase polycrystalline material from which we derive the transverse and longitudinal-optical modes observable in thin films. Infrared ellipsometry over the wavelength range from 700 to $3000{\mathrm{cm}}^{\mathrm{\ens…
Effects of hydrostatic pressure on the magnetic and transport properties have been investigated for melt-grown crystals of ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ with a finely-controlled doping level $x$ near the metal-insulator phase boundary. Application of pressure affects the critica…
The degree of overheating of a melt often plays a significant role in determining its supercooling behavior and thus the nucleation and growth of crystals and their qualities. However, the relationship between the level of melt overheating and the resulting degree of supercooling is far from being understood. It is de…
The single-particle excitation spectra of cupric oxide (CuO) are calculated by using the three-body scattering approximation on a multiorbital tight-binding model. Multiplet structures are fully taken into account. The Hartree-Fock solutions are modified by making a self-energy correction due to multiple scattering be…
The concept of the drawing of a molecular network has been employed to derive a total network draw ratio from the combination of the two deformations occurring in the production of poly(butylene terephthalate), PBT, fibers by the consecutive processes of melt spinning and cold drawing. The mechanical properties of PBT…
A new cyclosilicate, calcium yttrium cyclosilicate, crystallizes in space group C2/c. Ca and Y atoms are in eight-, seven- and sixfold coordination sites between the layers of ternary SiO4 rings (Si3O9). The structural formula can be expressed as (Ca0.89Y0.11)2 (Ca0.54Y0.46)2 (Ca0.14Y0.86) (Si3O9)2.
The structures of Sr2SnO4 ( I 4/ mmm , a 4·0528(1), c 12·5852(5) Å) and Ba2SnO4 (I 4/ mmm , a 4·1428(1), c 13·2993(4) Å) have been refined from neutron powder diffraction data by the Rietveld method. The results show the SnO6 polyhedra are not regular octahedra but are either elongated or compressed along the c direct…
Computer simulations on the display characteristics of chiral-homeotropic liquid crystal cells are performed. This normally black display mode exhibits an excellent contrast ratio, nearly achromatic light transmission, and low operation voltage. The optimal twist angle for suppressing the wavelength and voltage depend…
The tensile properties of polyether-based polyurethane (PU) filaments decrease with increasing chlorine concentrations as well as with treatment times. Fourier transform infrared (FTIR) results show the formation of quinoid, azo, and aldehyde groups in the chlorine-treated PU, and increased hydrogen bonding between th…
Large magnetic contributions to the low-temperature specific heats of rare-earth metaphosphate (R 2 O 3 ) 0.25 (P 2 O 5 ) 0.75 glasses have been observed. These effects result from electronic transitions between 4 f levels multiply split due to local disorder, which also give rise to a strong electronic contribution t…