Materials Literature
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Recently M. Tokunaga has published two interesting papers (J. Phys. Soc. Jpn. 56 (1987) 1653; 57 (1988) 4275) that relate the fluctuating polarizations p c in the paraelectric phases of ferroelectrics (estimated from the Curie constants determining the dielectric susceptibilities) and the spontaneous polarizations P S…
The translational diffusion coefficient D of long enough polymer chains without excluded volume is studied on the basis of the discrete helical worm-like (HW) chain with partially fluctuating (orientation-dependent) hydrodynamic interaction (HI). In order to evaluate D(∞) in the long time limit, which corresponds to d…
We present band-structure calculations of ${\mathrm{SnTaS}}_{2}$, an intercalation compound in which the Sn atoms have a very uncommon linear coordination by two S atoms and an unusual formal valency ${\mathrm{Sn}}^{1+}$. The Sn 5${p}_{x}$ and 5${p}_{y}$ states show strong metal-metal bonding in the intercalant planes…
We report the observation of 1/frequency magnetization noise in toroidal strip-wound cores of amorphous ferromagnetic alloys at liquid-helium temperatures and in the frequency range 0.1 Hz–1 kHz. The materials tested are Co-based alloys, and exhibit very low magnetostriction and good soft magnetic properties. The expe…
Layer Korringa-Kohn-Rostoker (LKKR) approaches that calculate interlayer scattering using a plane-wave basis set cannot treat systems in which the interplanar spacing becomes small. This problem is most acute at band energies at which electronic lifetimes are long and the scattering strong. Taking a face-centered-cubi…
The important role atomic hydrogen plays in the low-temperature and pressure deposition of diamond has renewed interest in the dissociation processes of hydrogen. Following a method originally developed by Langmuir and co-workers, the voltage-current characteristics of refractory filaments in vacuum and reduced-pressu…
The charge-transfer mechanism in 1,4 cis-polyisoprene is studied using solid state 13C NMR spectroscopy as a function of doping level of iodine. The CP/MAS NMR data show that the concentration of double bonds decreases as a consequence of doping. The overall results are consistent with previous observations and indica…
A solgel process is described to produce Ta(2)O(5) films as short wavelength antireflective (AR) coatings for silicon. The AR coatings were optimized for 370 nm by controlling the acid catalyzed hydrolysis of Ta(OC(2)H(5))(5), the spin coating parameters, and the heat treatment process (rapid thermal processing (RTP)…
The application of the algorithm of Zeiger and McEwen to the analysis of noisy photon correlation data is investigated. For the particular case where the data are sampled at equidistant time intervals a complete solution is given allowing reliable reconstruction of the spectrum of exponential decay rates without any a…
Cristallisation dans Cc avec a=17,250, b=9,767 et c=17,106 A, β=110,9 o , Z=32; affinement jusqu'a R=0,0289. La structure consiste en tetraedres PO 4 discrets lies par des tetraedres ZnO 4 et LiO 4 deformes de sorte que trois tetraedres differents partagent un sommet. Bien que des couches de tetraedres paralleles a (0…
Cristallisation dans Cm avec a=8,129, b=16,051 et c=3,5390 A, β=100,94 o , Z=2; affinement jusqu'a R=0,038. La structure contient des ions Ca 2+ coordines octaedriquement par des atomes O et F et des anions (BO 3 ) 3− qui sont principalement responsables de l'effet de generation d'harmonique secondaire
From 15 K to room temperature, dielectric and pyroelectric properties have been measured in six ferroelectric niobate single crystals with tungsten-bronze (TB) structure. Dielectric and pyroelectric experiments show that in the three kinds of ferroelectric niobate single crystals ${\mathrm{Sr}}_{1\mathrm{\ensuremath{-…
ZnS thin films were deposited with and without ion assisted deposition onto substrates held at temperatures ranging from -120 to 50 degrees C. Effects on chemical and crystalline composition, film microstructure, refractive index, stress, and waveguide losses were investigated. We observed that minimum stress and mini…
With an ultralow load indenter the hardness H and the Young’s modulus E of amorphous hydrogenated carbon and silicon films, prepared under different conditions, were determined. The values of the hardness of a-C:H, corrected for the elastic recovery, are about 1/3 of the values measured by the Knoop method. The result…
We show by transport properties and electron-microscopy measurements that a polytype of ${\mathrm{NbS}}_{3}$ undergoes a Peierls transition at 340 K. Similarly to other transition-metal trichalcogenides and tetrachalcogenides, ${\mathrm{NbS}}_{3}$ exhibits charge-density-wave transport for temperatures below the phase…
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.
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, \…
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 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…
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…