Materials Literature
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Abstract The reaction between pyrroles and benzaldehyde in refluxing acetic acid gives meso ‐tetraphenylporphins and chlorins. The initial condensations give a porphyrinogen which undergoes an acid catalyzed autoxidation to porphyrin via a porphodimethene. The chlorin is shown to be derived from the reduction of porph…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMagnetic resonance studies of some low-spin d5 tris diimine complexesRichard E. DeSimone and Russell S. DragoCite this: J. Am. Chem. Soc. 1970, 92, 8, 2343–2352Publication Date (Print):April 1, 1970Publication History Published online1 May 2002Published inissue 1 April 1970h…
Abstract Selectivity of a number of vermiculites, montmorillonites and micas for K and Cs ions was determined by sorption of these ions from equilibrium solutions of diverse concentrations. The selectivity coefficients were related to the layer charge density and the area of the frayed edges in layer silicates. Montmo…
The Raman scattering in crystalline polyethylene, deuterated polyethylene, and n-paraffins has been investigated as a function of temperature. Crystal-field splitting of the A1G methylene bending mode observed at room temperature increases at − 160°C in both polyethylene and deuterated polyethylene. No splitting of th…
A glass with composition 0.265 B 2 O 3 ‐0.405 BaO‐0.33 Fe 2 O 3 (mole ratio) was prepared by a fast‐quenching technique. When it is heat‐treated, this glass exsolves up to ∼45 wt% BaFe 12 O 19 as the only magnetic phase. Magnetic measurements of glasses heated at various temperatures show that superparamagnetic, singl…
Abstract The nature of interstratification in mixed-layer illite-montmorillonites has been investigated by comparison of diffraction patterns of ethylene glycol and ethylene glycol monoethyl ether treated samples with calculated one-dimensional diffraction profiles. The calculated profiles take into account the effect…
Abstract The demand for graphites with specific properties and for an improvement in the economics of graphite production in recent years has led to an increased interest in catalytic graphitisation. At the present time, however, there is no review available of published studies and this paper attempts to make good th…
Various transport studies have been carried out on amorphous and crystalline GeTe films of 80 Å to 10 μ thickness. Crystalline GeTe has a low resistivity (∼10−4 Ω·cm at 300°K) which increases with temperature slowly and nearly linearly at low temperatures (below ∼300°K) and rapidly at higher temperatures. The hole con…
The forming process, by which changes are brought about in the electronic conduction of thin films of various binary amorphous oxides and halides, is first described, and experimental evidence is put forward which contradicts an earlier theory of the forming process in gold-silicon monoxide-metal structures. A theory…
A new theory is presented for calculating the structure of finite nuclei from the nucleon-nucleon interaction. The essential features of the reaction matrix in finite nuclei are obtained from nuclear-matter theory through the local-density approximation. The resulting density- and energy-dependent effective interactio…
A new definition for work of adhesion Wa is applied to computationally define the dispersion γs d and polar γs d components of the solid surface tension γs = γs d + γs d for twenty-five low energy substrates. These calculated surface properties are correlated with surface composition and structure. Surface dipole orie…
By introducing trivalent ions Me3+ into brucite-like layers Me(II)(OH)2, layer ions [Me(II)1-xMe(III)x(OH)2)x+ can be obtained. In these layer ions the charge compensation of an O2--ion by the metal ions is in the average 1+x/2 , leaving only a bond strength of 1-x/2 for the O–H bond, i. e. the charge of H+ must partl…
Several polywater samples were prepared by the standard methods and have the same physical and spectroscopic properties as those made in other laboratories. However, a variety of chemical analyses show high concentrations of impurities which may account for many of the anomalous properties.
It was reasoned that in normal ferroelastic crystals, if their prototypic (or peraelastic) phase transitions are of the second kind, the dependence of the spontaneous strain on temperature T should be proportional to ( T c - T ) 1/2 right below the transition temperature T c and the T dependence of the elastic complia…
The homogeneous composition range and magnetic properties of the hexagonal Laves-Phase compound, CO 2+ x Ti 1- x ( x >0), have been determined by X-ray diffraction and magnetic studies. X-ray diffraction studies show that the MgNi 2 -type structure is stable in a narrow composition range from about 29 to 31.3 at.% Ti…
The Hall effect and resistivity have been measured as a function of temperature for lightly Zn-doped GaAs of better quality than previously available. Analysis of the Hall coefficient data yields activation energies which change with doping level. These results, along with earlier results on more heavily doped samples…
Vapor deposition simulation programs have been developed using Monte Carlo methods to determine the molecular dynamics of condensation, evaporation, and migration on the lattice. The simulation methods employed in the programs are developed in detail. The principle application will be to systems that permit a comparis…
Some consequences of the symmetry change associated with the vanadium dioxide metal-semiconductor transition are derived. A free-energy expansion in the ionic displacements has been used. The effect of a $〈101〉$ zone-edge phonon instability and strain effects have been included. The symmetry arguments have been carrie…
Measurements of the ac and dc resistivity in the temperature range of 77-750\ifmmode^\circ\else\textdegree\fi{}K and of the optical transmission and reflectance have been made on amorphous Ge films of 1000-\AA{} to 7-\ensuremath{\mu} thickness prepared by thermal evaporation. The resistivity of amorphous Ge films at r…
The magnetic field generated by the magnetization has been calculated for films with arbitrarily rough surfaces for the case in which the magnetization is uniform throughout the film. Simple results are obtained on the assumption that the film surface is not too ``ragged,'' i.e., for the case in which the inclination…