Materials Literature
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The static and dynamic behavior of the Frederiks transition for twist of a uniform planar nematic sample in an external magnetic field has been studied by monitoring the associated conoscopic figure. In particular, the decay of this figure after the field has been switched off is considered in detail in order to obtai…
We report the polarized Raman spectra of vitreous Ge $^{16}\mathrm{O}_{2}$, Ge $^{18}\mathrm{O}_{2}$, $^{70}\mathrm{Ge}$${\mathrm{O}}_{2}$, and $^{74}\mathrm{Ge}$${\mathrm{O}}_{2}$. This yields the $^{16}\mathrm{O}$\ensuremath{\rightarrow}$^{18}\mathrm{O}$ and $^{70}\mathrm{Ge}$\ensuremath{\rightarrow}$^{74}\mathrm{Ge…
The electronic structures of sodium metasilicate (${\mathrm{Na}}_{2}$Si${\mathrm{O}}_{3}$) and the $\ensuremath{\alpha}$ and $\ensuremath{\beta}$ phases of sodium disilicate (${\mathrm{Na}}_{2}$${\mathrm{Si}}_{2}$${\mathrm{O}}_{5}$) are calculated from first principles by the method of linear combination of atomic orb…
We have measured and interpreted the Raman spectra of bulk $\mathrm{Ge}{({\mathrm{S}}_{x}{\mathrm{Se}}_{1\ensuremath{-}x})}_{2}$ glasses for compositions in the range $0\ensuremath{\le}x\ensuremath{\le}0.25$, both at low power levels and at sufficiently high power levels to induce thermally reversible (at $T\ensuremat…
The density of states for thermal vibrations on a fractal is calculated with careful attention paid to the normalization condition. It is found that at the crossover between Debye-type excitations (long wavelength) and "fracton" excitations (short-length scale) the density of states is discontinuous. The size of the d…
Spontaneous photoluminescence (PL) spectra of Cu-doped and undoped $\ensuremath{\epsilon}$-GaSe have been investigated in the temperature range from 80 to 300 K and at low laser-excitation intensity ($P$) from ${10}^{\ensuremath{-}3}$ to 10 W ${\mathrm{cm}}^{\ensuremath{-}2}$. The main modification of the spectra in d…
The magnetic and structural properties of rapidly quenched FePr(BSi) alloys are presented. The samples are usually magnetically soft in the as-quenched state. However, large coercive fields in the range of 5–20 kOe are developed upon heating the samples to a temperature around 700 °C. The best properties have been obt…
In this paper we discuss the properties of optical elements fabricated by holographically recording an ultrahigh spatial-frequency pattern in a photoresist mask followed by reactive ion etching to transfer this pattern into the surface of a quartz substrate. Such optical elements are environmentally durable, potential…
A versatile method for determination of the optical constants is described that can be applied to a variety of coating materials. It is based on the use of an optical thin film synthesis program to adjust the constants of dispersion equations until a good fit is obtained between measured and calculated spectral transm…
An approximate calculation of the total energy of a transition metal as a function of volume and ionic configuration at constant volume obtained by extending the nearly-free-electron theory of the simple metals to include the effects of transition-metal $d$ bands provides a qualitative first-principles prediction of t…
A relationship between the isobaric, isothermal and isochoric lattice Gruneisen parameters has been examined and analysed for several polymers. Relationships between the various parameters describing the thermo-acoustic and nonlinear properties of polymers are developed and their relations with thermo-acoustic data es…
The theory of the transverse magnetophonon effect is developed for inversion layers in semiconducting heterostructures in the presence of a quantising magnetic field perpendicular to the interface. It is assumed that the electrons move in quasi-two-dimensional sub-bands, and that the optic phonons and the polar electr…
The room-temperature triboluminescent spectra of single crystals of CaF 2 :1% Tb, CaF 2 :1% Dy, CaF 2 :1% Sm and CaF 2 :1% Eu have been recorded using a high-gain image intensifier spectrograph. The spectra, obtained as the crystals were cut with a diamond-impregnated circular saw, show significantly more structure th…
A theoretical study of the broadening of magnetic resonance lines due to the dipole interaction in dilute solid solutions of paramagnetic impurities in diamagnetic hosts is presented. The theory takes into account the exchange interaction between impurity ions. Detailed results are presented for the three cubic lattic…
Photoluminescence and cathodoluminescence decay time measurements have been carried out for the H4 (2.499 eV) centre in diamond. The photoluminescence decay time increases progressively from approximately= 19 to 23 ns as the energy of the exciting light is increased from 2.6 to 4.0 eV, and the cathodoluminescence deca…
Article Kristallstruktur der Calcium-Vanadium-Bronze CaxV4+2xV5+2-2xO5 was published on October 1, 1983 in the journal Zeitschrift für Kristallographie - Crystalline Materials (volume 162, issue 1-4).
The effects of surface discharges on dielectric properties of filled and unfilled epoxy resins have been studied. By means of parallel-plate electrodes, sheet samples have been aged through direct and indirect exposure to electric discharges at 15 kV ac 50 Hz voltage in static dry air for time intervals up to 300 hour…
Abstract Graphite electrodes modified chemically with poly(l-valine) and poly(N-acryloyl-l-valine methyl ester) were prepared. They were remarkably more durable than the corresponding dip-coated electrodes when used repeatedly in the electrochemical asymmetric reduction of citraconic acid.
Abstract The in‐plane component of the dielectric constant of chiral smectic p‐decyloxybenzilidene‐p'‐amino‐2‐methylbutyl cinnamate is measured as a function of temperature and magnetic field applied parallel to the smectic layers. The transition from the modulated smectic C* to the uniform smectic C phase is accompan…
Abstract A glow discharge polymerization technique was applied in the preparation of germanium‐containing polymers. The colorless and transparent polymer films formed from tetramethylgermanium (TMG) were investigated by elemental analysis, infrared (IR) spectroscopy, and ESCA. The reaction of TMG was accompanied by th…