Materials Literature
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The luminescence of the unactivated and Bi3+- and Eu3+-activated compounds ABO4 (A is Sc, In; B is P, V, Nb) is reported and compared with the luminescence of the corresponding rare-earth and yttrium compounds. The ScNbO4 shows a weak, blue emission, ScVO4 a blue-green, and InVO4 a green emission. The other host latti…
When a hydrostatic pressure is applied to a metal containing particles or inclusions of different elastic constant, the local shear stresses which develop can be large enough to cause the interface between the particle and the metal matrix to emit dislocations. We have measured the pressure (from which we calculate th…
Abstract Die reinen Phasen oxydierter Nickelhydroxide, die auf der Nickelhydroxidelektrode im alkalischen Akkumulator auftreten können, wurden hergestellt, ihre kristallographischen Daten und ihr chemisches Verhalten untersucht und Umwandlungsbedingungen ermittelt.
The adhesion properties of polymers are known to be influenced by both intermolecular forces operative at the interface and the rheological history of both bonding and unbonding. Recent adsorption and viscoelastic theories of adhesion and cohesion are implemented in a comprehensive examination of these phenomena. Eigh…
Abstract Low temperature gaseous plasmas of ammonia or nitrogen–hydrogen mixtures contain NH 2 groups, or precursors thereof, formed in the plasma, which experimental evidence strongly suggests, can add to various polymer surfaces. The plasmas were established in the 0.3–1.5 torr range by radiofrequency (13.56 MHz) e…
An experiment is described which confirms the theory of the distortion of a cholesteric structure by a magnetic field. Field effects in a sample of p-azoxyanisole doped with cholesteryl acetate were viewed directly with a microscope, and the pitch of the helical structure was measured as a function of field strength.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDiamagnetic susceptibility exaltation in hydrocarbonsHyp J. Dauben Jr., James Dennis Wilson, and John L. LaityCite this: J. Am. Chem. Soc. 1969, 91, 8, 1991–1998Publication Date (Print):April 1, 1969Publication History Published online1 May 2002Published inissue 1 April 1969…
Recently, electromigration has been identified as a potential wear-out failure mode for semiconductor devices employing metal film conductors of inadequate cross-sectional area. A brief survey of electromigration indicates that although the effect has been known for several decades, a great deal of the processes invol…
If the distance between atoms in a crystalline lattice is increased, an energy gap appears, which in a divalent material will separate occupied from unoccupied states of an electron. In a non-crystalline substance, a minimum is expected in the density of states (a ‘pseudogap’). An approximate theoretical estimate is g…
Abstract By using a high speed rotating mirror camera combined with a microscope, the rapid initial lengthening of twins and their subsequent broadening have been studied. In zinc, twins of up to 1·9 mm appeared in crystal surfaces within 1 μs and subsequently the tips of such twins were observed to move at up to 780…
The fluorescence efficiency of tetracene single crystals may be enhanced by as much as 38% in a magnetic field $H>2000$ G. The enhancement is anisotropic with respect to the orientation of $H$ in the $\mathrm{ab}$ plane. It is shown that a magnetically sensitive coupling of singlet states to a double-triplet-excito…
The glass-transition temperature of water (T(g)) has been calculated by use of the Tammann-Hesse viscosity equation with the viscosity equal to 10(13) poise at T(g). The derived value of T(g),162 +/- 1 degrees K, is significantly higher than previous estimates.
The absorption spectrum of blue, γ-irradiated CaF2: Y3+ crystals shows several bands in the visible region whose intensity is roughly proportional to the yttrium concentration. Bleaching into the individual bands indicates that more than one center is responsible for the whole spectrum. Inconsistent color response of…
Measurements of quantum yield of Al–Al2O3 films were made at photon energies between 7 and 22 eV. The photoelectric threshold for intrinsic photoemission from amorphous Al2O3 appeared to be about 8 eV. Approximately 1 eV was estimated for the electron affinity of Al2O3. The yield of anodic oxide film on aluminum at 10…
Experiments on directed atom motions in $\ensuremath{\beta}\ensuremath{-}\mathrm{Zr}$ have been carried out with a view to bringing additional experimental evidence to bear on the current conflicting theories of the anomalous diffusion behavior in this and other bcc refractory metals. Thermomigration and electromigrat…
Optical scattering data have been used to investigate molecular order in certain cholesteric mixtures. When films of these materials are deposited on a reflecting substrate, their colors can be shifted by several thousand angstroms for any condition of illumination and observation by a mechanical disturbance. The disp…
A model descriptive of the growth of precipitates which nucleate at grain boundaries and grow pre ferentially along them (grain-boundary allotriomorphs) is studied. The sequential processes during growth are presumed to be volume diffusion of solute to the grain boundary, transport along the grain boundary to the prec…
The efficiency of production of electrons emitted by the Auger process from the surface of a solid irradiated with a beam of electrons in the energy region below 2 keV is estimated. It is shown that the probability of photon production is negligible and that to a first approximation the optimum primary energy required…
The ternary alloy MnAlGe has been studied by diffraction techniques using both neutrons and x rays. The unit cell is found to be tetragonal with a0 = 3.914±0.001 Å and c0 = 5.933±0.001 Å. The space group is D4h7-P4/nmm. The intensities in the neutron-diffraction patterns agree with a ferromagnetic spin alignment of th…
N,N-Dimethyl formamide (DMF) and N,N-diphenyl formamide (DPF) complexes of six lanthanide perchlorates of the composition M(DMF) 8 (ClO 4 ) 3 and M(DPF) 6 (ClO 4 ) 3 where M = La, Ce, Pr, Nd, Sm, or Y have been prepared and characterized. The infrared spectra show that the amide is bonded to the metal through oxygen.…