Materials Literature
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The Holt relation d = Kϱ−1/2 between dislocation cell diameter d and average dislocation density ϵ is found to apply to Mo–50wt% Re when K = 4. Comparison with other published dislocation cell data shows that K does not remain constant, but varies from metal to metal. The effect of stacking fault energy on the K value…
Electrical conduction due to thermal activation of electrons from impurity sites is studied in the case of amorphous insulating films of large impurity densities. Considering a two-centre model the central barrier is assumed to be the current-limiting one in the whole field range for the investigation of the influence…
Motion of screw dislocations in b.c.c. lattices at 0 °K has been computer-simulated by applying shear stress on the {110} plane of a model crystal block, using systematically varied interaction potentials between atom rows parallel to the Burgers vector. For all the potentials used, the core of the dislocation moved i…
Aqueous films on terrestrial litter are inhabited by numerous microorganisms; the surfaces of such films are covered by monolayer-forming substances. The spreading pressure of the latter can result in transport of floating and submerged organisms to adjacent water films with clean surfaces. The clean surfaces, produce…
The electron Compton profiles for diamond have been calculated in the impulse approximation from two self-consistent crystalline Hartree-Fock momentum distributions in the [100], [111], [110], [112], and [221] directions. The two calculations use slightly different Gaussian basis sets. The results agree closely with e…
We report our measurements on KIO2F2 and compare these results with the parent MIO3 compounds where M denotes H, Li, etc. Our results show that the nine observed nonlinear coefficients (d's) in these four different crystal systems, composed of IO3− and IO2F2− ions, are geometrically related to only one microscopic bon…
An upper bound to the resistivity of an Einstein solid is calculated using the variational method of Ziman with the usual trial function, and is shown to be proportional to the product of the local-mode specific heat and the temperature. This formula gives an improved fit to the results of recent measurements on the i…
Amorphous Sb films ranging in thickness between 170 and 14 000 \AA{} were prepared at 77\ifmmode^\circ\else\textdegree\fi{}K in three different ways: getter sputtering, evaporation from Sb, and evaporation from PtSb. The electrical resistivity of these various films is well fitted between 30 and 160 \ifmmode^\circ\els…
We present the results of a combined x-ray and neutron diffraction study of the temperature dependence of the "forbidden" (222) reflection in germanium. Integrated intensities were measured from room temperature to 850\ifmmode^\circ\else\textdegree\fi{}C with x rays and to 904\ifmmode^\circ\else\textdegree\fi{}C with…
The radiative lifetimes for a number of electronic states of the alkaline earth monohalide molecules MX, where M denotes Ca, Sr, or Ba and where X denotes F, Cl, Br, or I, have been determined directly from the rate of fluorescence decay with time using a pulsed dye laser as an excitation source. The measured lifetime…
The pressure-volume relationships for EuSe, EuS, YbSe, and YbS have been obtained from high-pressure x-ray-diffraction studies to nearly 300 kbar. Like EuTe, EuSe and EuS exhibit normal compression and undergo the NaCl-to-CsCl-type transition at about 145 and 215 kbar. The compression curves of YbSe and YbS are anomal…
A calculation of the diamagnetism of graphite including the effects of trigonal warping of the Fermi surfaces has been performed using Fukuyama's formulation of the diamagnetism of Bloch electrons. Inclusion of the trigonal warping increases the diamagnetism by about 13% at low temperatures and reduces it by about 1%…
The auxospore wall of Melosira nummuloides C. A. Agardh is composed of two distinct parts, an organic layer and a layer of siliceous scales. Similar scales are reported from other species of the genus and their mode of formation is described. The possible phylogenetic significance of the two wall layers is discussed w…
The heat capacity of amorphous germanium, measured between 2 and 30 K using a thermal-relaxation technique, is about 50% greater than that of crystalling germanium, but has a similar temperature dependence. We infer an amorphous phonon density of states at low frequencies given by the TA crystalline density of states,…
Comparison of ultraviolet-photoemission, valence-orbital spectra (as well as high-resolution, x-ray photoemission, N-core-level spectra) of TTF-TCNQ, neutral TCNQ, and ${\mathrm{K}}^{+}$ ${(\mathrm{TCNQ})}^{\ensuremath{-}}$ indicates a large amount of charge transfer in TTF-TCNQ. The spectra for this complex show stro…
The effect of pressure on the lattice parameter of magnetite has been determined at room temperature up to 320 kbar by means of X ray diffraction employing a diamond anvil high-pressure cell. By using the Birch-Murnaghan equation with a (∂KT/∂P)T∣P=0 value of 4 ± 0.4 the isothermal bulk modulus at zero pressure was ca…
The high-field electrical properties of several groups of transition-metal phosphate glasses have been examined, especially those based on V, Fe, Cu and Mo ions, and pure and doped tungstates. Conductivity measurements have been carried out under DC and pulse conditions at fields up to approximately 10 6 V cm -1 but b…
Photoemission energy distributions for $20<~h\ensuremath{\nu}<~50$eV for semiconducting Fe${\mathrm{S}}_{2}$ (fool's gold) show a narrow, \ensuremath{\sim}1 eV wide, localized uppermost valence level, whereas the corresponding levels of semiconducting Ni${\mathrm{S}}_{2}$ are broad (\ensuremath{\sim}3.5 eV) and…
The structure of the hexamethylenetetramine 14N nuclear quadrupole resonance line has been studied in detail on a powdered sample at 77°K. An improved, frequency-stabilized spectrometer, interfaced to a digital computer, was used in resolving fine details of the experimental lineshape. The line shape could be fitted b…
The complete ligand-field, Coulomb interelectronic repulsion, and spin-orbit interaction matrices have been derived for the d 5 electron configuration within octahedral (O h ) and tetrahedral (T d ) symmetry. The calculations were performed in both the weak-field and strong-field coupling schemes and complete agreemen…