Low loss nematic liquid crystal cored fiber waveguides
Nematic LC material in the aligned state scatters light strongly, but in low loss LC cored fiber waveguides it scatters less and has enhanced recovery time.
Materials Literature
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Calculation of grain-boundary segregation in Ni-Cu alloys
The equilibrium segregation at symmetric twist grain boundaries in Ni-Cu alloys is computed with use of Monte Carlo simulations combined with the Daw-Baskes embedded-atom method. These simulations include both compositional rearrangements and atomic displacements. The boundaries studied are the \ensuremath{\Sigma}5, \…
Surface chemistry of metastable oxygen. II. Destruction of O2(a 1Δg)
The loss rate O2(a 1Δg) on a variety of surfaces has been investigated. At 300 K, the most rapid deactivants are Cu, Ag, and Co, with Fe, Ni, Pt, and Pd being somewhat less active. Numerous metals exhibit very low activity, including Al, Au, and W. Quite different temperature dependences were observed among the metals…
Neutron powder-diffraction studies of lithium, sodium, and potassium metal
Neutron powder-diffraction measurements have been performed on polycrystalline lithium and sodium specimens at 80 and 20 K and on potassium metal at 80 and 10 K. Lithium is bcc (body-centered cubic) at room temperature and undergoes a martensitic structural phase transformation to a 9R (samarium-type) form at low temp…
Formation and characterization of grain-oriented VO2 thin films
Grain-oriented films of VO2 have been prepared to characterize the effects of film orientation on electrical and optical switching performance. This oriented growth has been achieved by lattice matching to (0001) sapphire, and results in intergranular structures favorable to rapid propagation of the monoclinic-tetrago…
Large displacement transducers based on electric field forced phase transitions in the tetragonal (Pb0.97La0.02) (Ti,Zr,Sn)O3 family of ceramics
Several properties associated with the field-induced phase change between the antiferroelectric and ferroelectric states in tetragonal (Pb0.97 La0.02 )(Sn,Ti,Zr)O3 antiferroelectric ceramic family were investigated for high-strain displacement transducer applications. The longitudinal field-induced strain accompanying…
u parameters for the wurtzite structure of ZnS and ZnO using powder neutron diffraction
ZnS cristallise dans P6 3 mc avec a=8227 et c=6,2607 A, Z=2; affinement jusqu'a R=0,017. ZnO cristallise dans P6 3 mc avec a=3,2501 et c=5,2071 A, Z=2 affinement jusau'a R=0,012. Les atomes Zn occupent la position speciale 2(b) avec les coordonnees 1/3, 2/3, Os et O occupent egalement la position speciale 2(b) avec le…
Dissolution of Si(100) layers in NaOH aqueous solutions
NaOH solution has been used to study the dissolution rates on boron-doped Si(100) wafers as a function of molarity (0.02 to 10 M) and temperature in the range from 30 degrees C to boiling point. For dissolution at boiling point, two distinct ranges of solution normalities have been observed. For M<or=4.5, the dissolut…
Simulation of plastic deformation in a two-dimensional atomic glass by molecular dynamics IV
Abstract Plastic deformation in a structurally well-relaxed two-dimensional atomic glass was simulated by a computer molecular dynamics approach. The simulation, which was carried through yielding and to substantial plastic strains, demonstrated that the principal mechanism of plastic strain production is by local par…
Specimen inertia in high strain-rate compression
Previous theories of the inertial contribution to measured stress in dynamic compression of cylindrical specimens have been extended to allow for anvil motion as well as specimen strain. A numerical model has been developed to estimate the inertial stress from this theory, and it was found that the new term can have t…
Radiation Chemistry of Polymers
Changes in the properties of polymer materials caused by absorption of high-energy radiation result from a variety of chemical reactions subsequent to the initial ionization and excitation. A number of experimental procedures may be used to measure, directly or indirectly, the radiation chemical yields for these react…
The Effects of Radiation on High-Technology Polymers
Changes in the properties of polymer materials caused by absorption of high-energy radiation result from a variety of chemical reactions subsequent to the initial ionization and excitation. A number of experimental procedures may be used to measure, directly or indirectly, the radiation chemical yields for these react…
ChemInform Abstract: A Structural Study of 12 H‐BaFeO2.93
ChemInformVolume 20, Issue 50 Physical Inorganic Chemistry ChemInform Abstract: A Structural Study of 12 H-BaFeO2.93 M. PARRAS, M. PARRAS Dep. Quim. Inorg., Fac. Cienc. Quim., Univ. Complutense, E-28040 Madrid, SpainSearch for more papers by this authorM. VALLET-REGI, M. VALLET-REGI Dep. Quim. Inorg., Fac. Cienc. Quim…
Benthic marine diatoms of Caja de Muertos Island, Puerto Rico
A taxonomic study of the benthic marine diatoms from Caja de Muertos Island is reported in this paper. One hundred eighty-five taxa were observed. Twenty-one of these taxa represent new records for Puerto Rico and twenty-two taxa are new records for the Caribbean Sea. The genera represented by the greatest number of t…
Microphase separation in block copolymers
We introduce a microscopic model for the phase separation in block copolymers and carry out Monte Carlo simulations in two dimensions. We find that the equilibrium structure function satisfies a scaling relation with ${D}_{\mathrm{eq}}$, the thickness of the microdomains. We also find that ${D}_{\mathrm{eq}\mathrm{\en…
Lattice dynamics of BaTiO3in the cubic phase
The authors have calculated the phonon dispersion curves of barium titanate (BaTiO 3 ) in the cubic phase. A nonlinear shell model is used, in which the fourth-order anharmonic core-shell interaction of the oxygen ion is considered within a self-consistent phonon approximation. The temperature dependence of the ferroe…
Electrically controlled surface bistability in nematic liquid crystals
The use of obliquely SiO evaporated glass plates at grazing incidence and controlled thickness gives a surface twofold degenerate oblique orientation for the nematic liquid-crystal MBBA (p-methoxy-benzylidine-p-n-butyl-aniline). Using a horizontal electric field and the linear flexoelectric coupling, one can switch th…
Monte Carlo study of a monolayer of hard oblate spheroids
The constant-NPT Monte Carlo method of statistical mechanics has been used to study a monolayer of hard oblate spheroids. The spheroids are free to rotate, but their centres are confined to a plane. Order parameters, configurational free energy, and singlet orientation distributions are calculated. It is found that or…
Asymptotic behaviour of the effective dielectric constants of composite materials
Abstract Asymptotic formulae are derived for the effective dielectric constants of composites containing densely packed spherical inclusions with dielectric constants differing greatly from that of the background. The asymptotic results are obtained by treating the influence of nearest-neighbouring inclusions analytic…
Structure of a Three-Dimensional, Microporous Molybdenum Phosphate with Large Cavities
The synthesis, single-crystal x-ray structural characterization, and sorption properties of a microporous molybdenum phosphate, (Me(4)N)(1.3)(H(3)O)(0.7)[Mo(4)O(8)(PO(4))(2)] . 2H(2)O (Me, methyl), are presented. The three-dimensional framework is built up from Mo(4)O(8)(4+) cubes and PO(4)(3-) tetrahedra that are con…