Materials Literature
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A simple formula in closed form is proposed for the thermal accomodation coefficient from which the accommodation coefficient of a monatomic gas—solid system may be calculated from certain basic parameters of the system. The formula α(T)=1−exp(−T0/T)+α(∞) tanh{[(MT)1/2/α(∞)](a/λ)} exp(−T0/T)is obtained from considerat…
This paper reports measurements of the shift with hydrostatic pressure and uniaxial stress of the temperature for a metal-to-semiconductor transition in ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$; of the change with pressure and uniaxial stress of the resistivity in the metallic phase and the activation energy for condution…
The nucleation of droplets of polyethylene, polyethylene oxide, polyoxymethylene, nylon 6, poly (3,3-bis-chloromethyloxacyclobutane), isotactic polypropylene, and isotactic polystyrene, suspended in silicone oil, has been investigated. Under conditions of slow cooling (0.1°C/min), two different phenomena were observed…
The elastic moduli of hexagonal beryllium oxide, zinc sulfide, and cadmium selenide at 25°C have been determined by measuring ultrasonic wave velocities in the 20- to 50-MHz frequency range. The data are compared with other literature data and discrepancies are discussed. The adiabatic bulk modulus, volume compressibi…
A statistical model for the reflection of scalar plane waves from a rough surface leads to a plane wave in the direction of specular reflection and to a contribution with a finite angular spread about that direction, depending on the tangential correlation of the surface asperities. Based upon on this result, a new se…
The electron Hall mobility has been measured in semiconducting SrTi${\mathrm{O}}_{3}$ over the temperature range from 1.6 to 550\ifmmode^\circ\else\textdegree\fi{}K. Electron concentrations in the range from 1\ifmmode\times\else\texttimes\fi{}${10}^{17}$ to 2.5\ifmmode\times\else\texttimes\fi{}${10}^{19}$ ${\mathrm{cm…
Precision x-ray measurements of the motions of the atoms in LaCo${\mathrm{O}}_{3}$ every 50\ifmmode^\circ\else\textdegree\fi{}C from room temperature to 1000\ifmmode^\circ\else\textdegree\fi{}C indicate that the crystal space group is $R\overline{3}c$ below 375\ifmmode^\circ\else\textdegree\fi{}C and $R\overline{3}$ a…
Results of measurements on the thermoelectric power of pure nickel, pure iron, and four dilute iron alloys are presented. They strongly suggest that, in iron, magnon drag is dominant over a wide temperature range, and provide the first indication of this mechanism in a ferromagnetic metal.
A general investigation into the green luminescence of hexavalent uranium in calcium fluoride has been made in the temperature range 5 to 300\ifmmode^\circ\else\textdegree\fi{}K. Two types of spectra have been found, due to different centers. Absorption spectra for these were also observed. The luminescent spectrum ha…
We have measured the attenuation of 100- and 260-Mc/sec longitudinal acoustic waves in $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ (corundum) containing a few ppm of ${\mathrm{Ni}}^{3+}$, and have compared our data with previous measurements at 2 Mc/sec. The attenuation as a function of temper…
The fluorescence intensities and lifetimes of various no-phonon lines in ruby samples with 2.1 and 0.94% ${\mathrm{Cr}}^{3+}$ were studied from 13 to 700\ifmmode^\circ\else\textdegree\fi{}K. The temperature dependences of the intensities of numerous lines were used to determine the energy levels of two pair systems. T…
Measurements of the Jahn-Teller splittings of the $^{5}T_{2g}(^{5}D)\ensuremath{\rightarrow}^{5}E_{g}(^{5}D)$ optical transition of divalent iron in the near infrared are reported for Fe${\mathrm{F}}_{2}$, KFe${\mathrm{F}}_{3}$, KMg${\mathrm{F}}_{3}$:${\mathrm{Fe}}^{2+}$, FeSi${\mathrm{F}}_{6}$:6${\mathrm{H}}_{2}$O, F…
The optical absorption of substitutional ${\mathrm{Fe}}^{2+}$ impurities in natural single crystals of cubic ZnS has been measured in the far infrared (10 to 100 ${\mathrm{cm}}^{\ensuremath{-}1}$) at temperatures from 4 to 25\ifmmode^\circ\else\textdegree\fi{}K. Several absorption peaks are identified with electric- a…
Three-dimensional growth of large populations of cells in vitro has been observed in the interstices of a matrix consisting of collagen-coated cellu lose sponge. The growth of Walker tumor 256 in this composite matrix is com pared with that found in a matrix composed of either cellulose sponge alone or collagen sponge…
The electronic energy levels of ${\mathrm{U}}^{4+}$ in ZrSi${\mathrm{O}}_{4}$ have been obtained from the absorption spectra of oriented single crystals. This host was chosen because of the relatively high (${D}_{2d}$) symmetry of the ${\mathrm{Zr}}^{4+}$ site occupied by the ${\mathrm{U}}^{4+}$ ion. Spectra were obta…
A spin-$\frac{3}{2}$ ferromagnetic iron compound is reported. The ferromagnet is bis-($N,N$-diethyldithiocarbamato) ${\mathrm{iron}}^{\mathrm{III}}$ chloride, and has a Curie temperature of 2.5\ifmmode^\circ\else\textdegree\fi{}K. Extensive susceptibility, ESR, and M\"ossbauer data are presented which establish conclu…
The polarized emission and absorption spectra of single crystals of yttrium vanadate doped with ${\mathrm{Eu}}^{+3}$ were measured and analyzed. The spectra are consistent with the ${D}_{2d}$ site symmetry of the ${\mathrm{Eu}}^{+3}$ ion in this lattice, and no significant violation of the appropriate electric- and ma…
Abstract Es wird über die Syntheses hochmolekularer, thermoplastischer, glasklarer und vorwiegend amorpher Copolyharnstoffe mit periodisch wiederkehrender Harnstoffbindung in der Hauptvalenzkette berichtet. Unverzweigte aliphatische Diamine wurden mit steigenden Mengen von Diaminen cokondensiert, die Ätherbrücken oder…
Abstract Durch Reaktivierung der kurzlebigen Vanadiumkontakte mit Hexachlorcyclopentadien wird eine bessere Katalysatornutzung und damit eine größere Wirtschaftlichkeit bei der Herstellung von Äthylen/Propylen‐Copolymerisaten erzielt. Hexachlorcyclopentadien wirkt dadurch reaktivierend, daß es das bei der Umsetzung vo…
"Plastics as Corrosion-Resitant Materials." British Corrosion Journal, 2(2), p. 78