Materials Literature
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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…
Abstract Abundant authigenic K-feldspar is present in continental sandstones of the Lower Cretaceous Areado Formation in Sao Francisco Basin, central Brazil. Feldspar authigenesis occurred in two major episodes. (1) In the Early Cretaceous K-feldspar precipitated as overgrowths, healing of microfractures, and replacem…
Annealed metallic bilayers consisting of Cu/Al/SiO2 are studied from the perspective of providing both surface passivation and diffusion barrier/adhesion promoter function for advanced copper based metallization. Upon annealing this bilayer film at 400 °C or higher, enough Al dissolves into the Cu to provide substanti…
In this study, we have demonstrated that boron carbide, an extremely hard and wear-resistant material, can be deposited with hot filament-activated chemical vapor deposition (HFCVD). There are several benefits to using a hot filament system, including a high deposition rate and a relatively low substrate temperature w…
When a binary alloy is directionally solidified, a two-phase mushy dendritic zone is often formed. Interdendritic convection of the melt may occur, and is coupled with compositional convection of the residual melt. If fluid flow velocities are high enough, local melt-back of the dendrites may occur, leading to channel…