Materials Literature
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Free-ion and crystal-field energy parameters for trivalent lanthanide ions (Ln3+) in Cs2NaLnCl6 and Cs2NaYCl6 are presented and discussed. Spin-correlated crystal-field parameters are determined for those systems for which sufficient data are available. The superposition model is used to compare the crystal-field inte…
Magnetization measurements and neutron diffraction experiments were carried out on (Ba 1- x Sr x ) 2 Zn 2 Fe 12 O 22 in a field applied parallel to the c -plane. Spins in the (T 1/2 ST 1/2 ) block are observed to be bunched in the form of ferrimagnet. Five magnetic phases appear with increasing field : helix with a sm…
The lengths and the thermal expansion values of the glass ceramic Zerodur show a reversible dependence on the thermal history within two temperature intervals. Typical effects associated with this dependence are, for example, isothermal length changes within and permanent length changes below the temperature intervals…
We have studied the structure and morphology of the useful high-temperature/high-strength polymer polyaryletherketone (PEEK) by transmission electron microscopy and three-dimensional electron diffraction after finding suitable solvents (α-chloronaphthalene and benzophenone) that allowed casting of the required ultrath…
The surface compositions of polystyrene (PS)/poly(vinyl methyl ether) (PVME) blends have been investigated using x-ray photoelectron spectroscopy (XPS). The XPS results demonstrate that there are significant differences between the composition of the surfaces (e.g., outmost ∼6 nm) and the bulk of both miscible and imm…
Any molecular system explores significantly different regions of the potential-energy hypersurface as the system is found, respectively, in the solid and liquid phases. We study in detail the multidimensional geometry of these different regions with molecular-dynamics calculations for 256 simple atoms in a fixed volum…
Finite size effects have been observed at low temperatures for electrons confined to semiconductor microcrystallites embedded in a simple borosilicate glass. Luminescence data reveal large electronic energy shifts relative to bulk energy levels which can be used to calculate the confinement energy of the localized ele…
The best available energy level data for the cubic Cs2NaLnCl6 and Cs2NaYCl6:Ln3+ (doped) systems are collected together and summarized. These data are analyzed in terms of a parametric model which assumes an octahedral (Oh) site symmetry for the Ln3+ ions and a 4 f N ‘‘free-ion’’ Hamiltonian similar to that used previ…
Recent Raman spectra of Matson, Sharma, and Philpotts on g-${\mathrm{xM}}_{2}$O\ensuremath{\cdot}(100-x)${\mathrm{SiO}}_{2}$ for M=all alkalies and x=5n, n=1,...,6, are analyzed theoretically. The selective enhancement of certain bands by alkali addition is explained naturally by alkali intercalation along cluster int…
The preparation of n-MoSe2/p-WSe2 heterojunctions by epitaxial growth of WSe2 (Eg=1.16 eV) on MoSe2 (Eg=1.06 eV) substrates is reported. The two semiconductors are nearly lattice matched along their hexagonal (001) base plane with Δa/a=0.25%. Diode capacitance-voltage measurements show that the band edges of MoSe2 and…
The effect of Co2O3 additions on the characteristics of electric field-current density was investigated at high current densities. With the increase of mole % of Co2O3, the onset of voltage upturn descends to lower current density due to the decrease in the conductivity in ZnO grains. This is confirmed by impedance me…
The size distribution of nodules on the surface of polypropylene films crystallized from the glass and subsequently annealed was studied. The origin of the nodule was the crystallite produced by the growth of many nuclei which were generated on crystallization from the glass and survived on annealing. The surviving nu…
is species-dependent.
The near-edge structure of the 2p absorption edges of the complete series of the 3d transition metals has been investigated by high-resolution electron-energy-loss spectroscopy. Structures in the spectra were observed that could not be resolved in previous studies. The data are compared with single-particle calculatio…
A theory is presented for the x-ray absorption spectra of materials characterized by bandwidths which are somewhat larger than the (quasiatomic) electron correlation energies. Assuming that an empty-band approximation is appropriate for nearly empty bands we show that the problem is much akin to the well-known Coulomb…
We introduce a ''generalized dual method'' for generating quasicrystal structures with arbitrary orientational symmetry in two and three dimensions.Received 22 August 1985DOI:https://doi.org/10.1103/PhysRevB.32.5547©1985 American Physical Society
A new method for obtaining surface-conductive polymer systems, related to the reticulate doping technique, is presented. The surface layer of a non-conductive macromolecular material doped with 0.2-1.0 wt.% of a conductive charge-transfer complex is treated with solvent vapour to induce precipitation of the initially…
The breakdown voltage in diluted SF 6 was studied at elevated temperatures up to 4000K. The measurements were carried out in a diaphragm shock tube behind the reflected shock wave. The temperature dependence of the electric strength of pure and diluted SF 6 may be described by two factors E c =E c0 ( rho / rho 0 ) chi…
The anchoring energy at the interface between the nematic liquid crystal 4-$n$-pentyl-4\ensuremath{'}-cyanobiphenyl (5CB) and a glass plate treated by oblique evaporation of SiO is studied by measurement of the torque exerted on the surface by the nematic subject to an orienting magnetic field. The anchoring energy is…
The AC conductivity sigma ( omega ) and dielectric constant epsilon ' of lithium niobate single crystals have been measured along the ferroelectric c-axis in the temperature range 77-700K and in the frequency region 0.1-100 kHz. At low temperatures, below 400K, the AC conductivity can be expressed as sigma ( omega )=A…