Materials Literature
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Interplanar interactions were analysed for metal bridged phthalocyanine dimers, [NBu4] [M(III)Pc2] (M = Y, Yb and Lu), by using zero field splitting (ZFS) parameters in the T1 states. The observed ZFS D and a triplet lifetime decreased remarkably due to dimerization. From a comparison of D between the monomer and the…
Abstract This work describes the effect of solvent precipitation on the crystallization behavior and morphology of nylon 6,6. We found that solvent precipitation of nylon 6,6 induces elevated crystallization temperatures upon cooling from the melt ( T mc ) and highly nucleated morphologies that rival those induced by…
The formation and evolution of the gap states formed with increasing Cs concentration in thin sexiphenyl (6P) films is followed with ultraviolet photoemission spectroscopy (UPS). Two distinct doping regimes are apparent, experimental considerations suggest that in the lower-doping bipolaron-like (dianionic 6P 2- ) sta…
Quasielastic neutron scattering experiments have been carried out to study the thermally activated rotational process of the NH4+ ion in the perovskite family NH4MF3 (M=Mg, Zn, Mn and Cd). The activation energies of this process in the high- and low-temperature structural phases have been obtained, and range from 44.8…
The optical absorption spectrum of NiO is measured at low temperatures and energies between 7000 and 30000 cm -1 . An assignment to cubic crystal field components of the 3d 8 configuration of Ni 2+ is proposed. The fine structure of the A band, showing two sharp lines at the lowest energies, 7811 and 7852 cm -1 , is e…
Upconversion luminescence of Er3+ in the chloride glass system has been investigated in ZnCl2-BaCl2-KCl-ErCl3 and CdCl2-BaCl2-KCl-ErCl3 glasses. Under 800 nm excitation, the glasses gave upconversion luminescence with barely detectable red (around 660 nm), very intense green (around 525–560 nm), and considerably inten…
Freely-suspended films of smectic liquid crystals can be regarded as membranes consisting of a stack of an integral number of molecular (smectic) layers with the layer planes being parallel to the two free surfaces. Because of their variable thickness (between thousands and only two layers) and the large variety of ph…
Magnesium grain boundary diffusion rates in forsterite aggregates have been experimentally determined from 1000° to 1300°C and 0.1 MPa to 10 GPa. The samples are fine‐grained (mean linear intercept of 4.3 μm) hot‐pressed aggregates. The technique employs a 26 Mg‐enriched surface layer and depth profiling using an ion…
Abstract Liquid crystalline polyurethane elastomers (LCPUE) have been synthesized by a two‐step block copolymerization reaction. The main‐chain LCPUEs are based on two biphenyl‐type mesogenic diol chain extenders (HB 2 and HB 6 ), a poly(tetramethylene oxide) (PTMO) soft segment, and different diisocyanates, icluding…
The stabilities of salt-finger and plume convection, two major flows characterizing the fluid dynamics of NH 4 Cl solutions cooling from below, are investigated by theoretical and experimental approaches. A linear stability analysis is implemented to study theoretically the onset of salt-finger convection. Special emp…
Structural information on the pair distribution function g 2 (r) for single-component disordered systems is usually obtained from the experimental structure factor S(k) measured by diffraction techniques. Complementary short-range information can be provided by the analysis of the extended X-ray absorption fine struct…
The site-specified tunneling spectroscopy on $1T\ensuremath{-}\mathrm{T}\mathrm{a}{\mathrm{Sa}}_{2}$ at 77 K and room temperature indicated a wide opening of energy gap at the Fermi level at 77 K. The gap at the Fermi level was attributed to the Mott localization in the commensurate charge density wave (CDW) phase. Th…
High current YBa2Cu3O7−δ (YBCO) thick films on flexible nickel substrates with textured buffer layers were fabricated. Highly textured yttria-stabilized-zirconia buffer layers were deposited by using ion beam assisted deposition (IBAD). Pulsed laser deposited YBCO films were not only c-axis oriented with respect to th…
The second harmonic spectrum of ${\mathrm{Cr}}_{2}$${\mathrm{O}}_{3}$ is studied in the 1.7-2.9 eV spectral range as a function of temperature. Below the N\'eel temperature ${T}_{N}=307.5$ K a nonlinear electric susceptibility ${\ensuremath{\chi}}_{\mathrm{ijk}}^{e}(c)$ appears, which changes sign under the time-rever…
A Schottky contact consisting of a semiconducting ferroelectric material and a high work function metal shows a bistable conduction characteristic. An on/off ratio of about 2 orders of magnitude was obtained in a structure consisting of a 0.2 \ensuremath{\mu}m ferroelectric PbTi${\mathrm{O}}_{3}$ film, a Au Schottky c…
We have formed strained dielectric superlattices of BaTiO3 (BTO) and SrTiO3 (STO) by a pulsed laser deposition technique. A large strain of 400–500 MPa is introduced at the interface between the BTO and STO layers. A large dielectric constant of 900 was observed with a stacking periodicity of 2 unit cells/2 unit cells…
An atomic structure model for a 25 degrees [001] symmetric tilt grain boundary in SrTiO(3) has been determined directly from experimental data with the use of high-resolution Z-contrast imaging coupled with electron energy loss spectroscopy. The derived model of the grain boundary was refined by bond-valence sum calcu…
The structure of a protein triple helix has been determined at 1.9 angstrom resolution by x-ray crystallographic studies of a collagen-like peptide containing a single substitution of the consensus sequence. This peptide adopts a triple-helical structure that confirms the basic features determined from fiber diffracti…
A novel concept for performing stoichiometric and catalytic chemical transformations has been developed that is based on the limited miscibility of partially or fully fluorinated compounds with nonfluorinated compounds. A fluorous biphase system (FBS) consists of a fluorous phase containing a dissolved reagent or cata…
We consider a "cluster picture" to explain the structure and formation of quasicrystals. Quasicrystal ordering is attributed to a small set of low-energy atomic clusters which determine the state of minimum free energy. The nature of the ground state as $T\ensuremath{\rightarrow}0$, depending upon the clusters and clu…