Materials Literature
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The flow stress of many metals is known to vary more strongly with strain rate epsilon above a critical value epsilon c than below it. An analysis of previous authors' measurements on copper indicates that the value of epsilon c varies systematically with specimen size. An estimate of inertial stress shows that inerti…
Total electron scattering cross sections for C 2 H 4 , C 2 H 6 , C 3 H 6 (propene and cyclopropane) and C 3 H 8 have been measured in the energy range between 4 and 500 eV. Measured results show a remarkable isomer effect and dependence on the geometrical dimension of the molecule.
The locally restricted motion of hydrogen and deuterium which are trapped at Cd acceptors in silicon has been studied by perturbed-angular-correlation spectroscopy. Close Cd-H and Cd-D pairs were identified by their characteristic electric-field gradients. The kinetics of these complexes was extracted directly from th…
Preparation of semiconducting vanadium silicate glasses by the sol-gel route and the results of electrical measurements are reported for the first time. The temperature dependence of the electrical conductivity has been analyzed in terms of small polaron as well as percolation models.
High resolution neutron scattering studies of vibrational spectra (2-800 meV) were carried out on the in -, delta ' and delta -phases of titanium hydride, obtained after high pressure treatment. The observed splitting of the fundamental optic peak in the delta -phase spectrum can be explained by a strong H-H interacti…
Porous silicon membranes have been formed by electrochemical etching through wafers up to 500 μm in thickness. The results show that there is essentially no limit to the thickness of porous silicon layers and that self-supporting porous structures can be formed by this method. In addition, the membranes are structural…
Binary SmFe12 and Sm(Fe,T)12 films, where T =Ti and V, crystallized into the ThMn12-type structure, have been synthesized as sputtered films such that the c axes of the crystallites are oriented perpendicular to the film plane. It has been possible to synthesize Sm(Fe,T)12 films which exhibit a very dominant (002) tex…
Electrical conduction along conducting layers between grains in chemical vapor deposited polycrystalline diamond films has been studied. The dc current-voltage characteristic consists of an ohmic region at low voltages and a highly nonlinear region at high voltages. As-grown films are dominated by the ohmic conduction…
We report on a mean-field thermodynamic analysis of AB random copolymer melts with (backbone) composition correlations that reflect realistic polymerization conditions. Depending on the strength and sign of these correlations, multiple homogeneous phases, periodic mesophases, or disordered mesophases are possible. We…
Explicit formulae are found for the electric field vectors of the ordinary and extraordinary modes produced when plane waves of p or s polarization are incident on an arbitrary face of a uniaxial crystal. The angle of incidence is unrestricted, and the anisotropic medium may be absorbing. The reflection amplitudes r p…
We report on a Raman spectroscopic study of polycrystalline diamond films using a wide range of incident photon energies (1.16–4.82 eV). The scattering intensity of amorphous sp2-bonded carbon is found to vary considerably as a function of the incident photon energy as compared to the strength of the 1332 cm−1 Raman l…
Nucleation, growth, and dissolution of crystals have been studied by stereochemical approach involving molecular recognition at interfaces. A methodology is described for using ;;tailor-made'' additives designed to interact stereospecifically with crystal surfaces during growth and dissolution. This procedure was inst…
Abstract Tensile and impact properties of the ternary system polypropylene (PP)/ethylene propylene diene elastomer (EPDM)/glass fiber (GF) and the corresponding binary systems PP/EPDM blend and PP/GF composite are studied. Results are presented and analyzed as functions of compositional variables, viz., (i) matrix PP/…
Abstract Polymer films were deposited from the plasma polymerization of the mixtures of hydrocarbons, ethane, ethylene, and acetylene, and tetrafluoromethane (CF 4 ) or hexafluoroacetone (HFA). The surface properties, the advancing contact angle of water, and surface energy of the films deposited and the chemical comp…
Hyperfine fields have been calculated by the LMTO-ASA method within the framework of the LSD approximation. The hyperfine field at the Co position in Co 2 TZ changes drastically with the T atom from a positive value for the case T=Ti to a negative value for the case T=Fe. The change occurs mainly in the contribution t…
The temperature-dependent resistivity of the two-dimensional quasicrystals ${\mathrm{Al}}_{65}$${\mathrm{Cu}}_{15}$${\mathrm{Co}}_{20}$ and ${\mathrm{Al}}_{70}$${\mathrm{Ni}}_{15}$${\mathrm{Co}}_{15}$ is studied along the periodic direction (${\mathrm{\ensuremath{\rho}}}_{\mathit{p}}$) and in the quasiperiodic plane (…
A minimum-energy path in strain space has been determined which takes cubic silicon into itself. Energies are computed using the Stillinger-Weber model potential and first-principles total-energy calculations. The energy along this path has an additional minimum corresponding to a crystal structure with a body-centere…
Fluorescence microscopy with polarized excitation allows regions of uniform tilt to be seen within domains of the liquid-condensed phase in monolayers of esters at the air/water interface. Transitions between a tilted and an utilted phase have been observed. Tilt regions within domains form regular six-arm patterns th…
Abstract Poly(vinylidene fluoride) films were γ‐irradiated in the dose range of 1–20 Mrad, resulting in up to 74% gel. The irradiated polymer undergoes both crosslinking and chain scission, about 5 : 3 events, respectively. Swelling measurements indicate an increasing crosslink density with the gel content, already at…
We discovered that an organic radical crystal, p-nitrophenyl nitronyl nitroxide (p-NPNN), is a quasi-1D ferromagnet induced by unpaired electrons on radicals. The magnetization and the susceptibility of the triclinic \ensuremath{\gamma}-phase crystal are very well represented by the Bethe-ansatz solution of the S=1/2…