Materials Literature
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The pyrolysis of tetraiodopyrrole in an inert atmosphere at temperatures from 120-700° yields black, infusible, amorphous polymers insoluble in solvents. Depending on the pyrolysis temperature, iodine may be present in the polymers as iodine of substitution and as chemisorbed molecular iodine, which is very tenaciousl…
Viscosities of synthetically hydrated obsidians have been measured by the falling-sphere technique at two values of the H2O content. At 4.3 per cent H2O, by weight, the common logarithm of the viscosity in poises ranges from 6.51 at 800°C to 5.88 at 900°C, and at 6.2 per cent H2O from 6.54 at 700°C to 5.25 at 850°C. T…
The frequency-dependent complex dielectric constant $\ensuremath{\epsilon}(\ensuremath{\omega})={\ensuremath{\epsilon}}_{1}+i{\ensuremath{\epsilon}}_{2}$ and associated functions are derived in the range 0 to 22 eV by application of the Kramers-Kronig relations to existing reflectance data for clean Al surfaces. The r…
The oxidation of molybdenum and tungsten was investigated mass spectrometrically at temperatures between 1500° and 2600°K and oxygen pressures between 10—4 and 10—2 Torr. The principal products of oxidation were found to be the gaseous dioxide and trioxide, MO2(g) and MO3(g) (M=Mo or W). The trioxide is the more impor…
The vapor above heated lithium oxide (Li2O) has been investigated mass spectrometrically and by infrared matrix-isolation spectroscopy. The vapor composition and Knudsen effusion rates were measured as functions of temperature, and the matrix spectra of the principal lithium oxide species—Li2O, LiO, Li2O2—identified a…
Received 30 September 1963DOI:https://doi.org/10.1103/PhysRevLett.11.458©1963 American Physical Society
The small signal dielectric coefficient of triglycine sulfate (TGS) and K${\mathrm{D}}_{2}$P${\mathrm{O}}_{4}$ has been determined as a function of frequency, temperature, and dc bias field in both the ferro- and paraelectric regions. The data for TGS are found to agree with a heuristic model involving a Gaussian dist…
We have measured the near infrared absorption, Zeeman effect, and electron spin resonance of ${\mathrm{Cu}}^{2+}$ ions introduced as a substitutional impurity into single-crystal ZnO. From the $g$ values of the lowest ${\ensuremath{\Gamma}}_{6}$ component of the ${T}_{2}$ state (the ground state), ${g}_{\mathrm{II}}=0…
Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation John L. Kropp, Maurice W. Windsor; Enhancement of Fluorescence Yield of Rare‐Earth Ions by Heavy…
Room-temperature reflectivity measurements in the wavelength range 1 to 140 \ensuremath{\mu} have been made on corundum and ruby. Classical oscillator analysis of the data shows that the optical lattice modes with dipole moment vibrating perpendicular to the $C$ axis occur at 15.7, 17.6, 22.6, 26.0 \ensuremath{\mu}. T…
The high pressure phases of the mercury and cadmium sulfides. selenides, and tellutrides have been determined by means of x-raiy diffraction patterns obtained while the materials are under presssure.
Abstract Under a large tensile stress the atoms in a solid may slide past one another or they may pull apart. The great contrast between ductile solids such as gold and brittle ones such as diamond has led to a widely held belief that yielding and fracture are independent processes, each occurring at its own character…
Abstract A primitive theory is developed for treating magnetic substances where exchange interaction is com parable with crystal field effects. The properties primarily considered are the Curie temperature and the saturation magnetization at 0°K ; the possibility of anisotropic exchange effects is considered briefly.…
Ferrites are essentially a class of semiconductors showing ferromagnetic properties. Their high resistivity combined with high permeabilities make them useful for a variety of applications practically covering every field in electronics and communications. A brief review of the principles of ferromagnetism in ferrites…
Abstract Abhängigkeit der Reduktionsgeschwindigkeit vom Gesamtdruck und Partialdruck des Wasserstoffes, der Temperatur, der Korngröße und der Struktur des Erzes. Deutung der gefundenen Abhängigkeiten durch ein Modell, bei dem Gastransport und Diffusion von Eisenionen im Wüstit gemeinsam geschwindigkeitsbestimmend sind.
Abstract A variety of metal alkyls have been found to be catalysts for preparing a polyester from terephthalaldehyde via the Tischenko reaction. The polymer was examined by infrared spectra, x‐ray diffraction patterns, and differential thermal analysis, and is apparently a crystallizable random 50 : 50 copolymer compo…
Abstract Das Gleichgewicht zwischen WO 3(fest) und H 2 O (gas) wurde bei Temperaturen zwischen 400–850°C mit der Mitführungsmethode untersucht. Zur Bestimmung der überführten Substanz wurde ein photometrisches Analysenverfahren und die Neutronenaktivierungsanalyse verwandt.
Abstract Microinterferometry was applied as a quantitative method for determining the transversal distribution of graft concentration instead of the usual determination of an overall graft concentration of the radiation‐induced polypropylene–styrene graft copolymer. Since polystyrene has a higher refractive index than…
The concept of Markov chains has been employed to derive the degree-of-polymerization distribution, the over-all composition, and the compositional distribution for copolymers containing any number of different monomers. The results are then used to obtain explicit expressions for systems of two monomers. It is shown…
The asymptotic value of the isothermal thermomagnetic figure of merit is obtained for a two-band multivalleyed semiconductor or semimetal where the concentration of holes and electrons is equal. The bismuth band structure is used as a specific model. It is shown that at strong magnetic fields the isothermal Nernst coe…