Materials Literature
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It has been traditional to interpret the strength of ceramics in terms of the mean grain size. This paper investigates, critically, the use of strength vs mean grain size{sup {minus}1/2} plots and shows them to be inconsistent with fracture mechanisms theory. It is suggested that strength be plotted against maximum gr…
Abstract To study the effect of potassium titanium oxyoxalate on the esterification reaction of terephthalic acid (TPA) and ethylene glycol (EG) in the first tank reactor of TPA/EG continuous esterification, experiments at various addition rates of potassium titanium oxyoxalate were made in the pilot plant. Potassium…
Large (5 × 3 × 3 cm3) crystals of the organic nonlinear optical material MBA-NP have been prepared by growth from solution, in an optically and structurally highly perfect state. Oriented cut and polished specimens were examined by the Maker fringe technique at a wavelength of 1·064 µm. Analysis of the data yielded d…
A commercial ceria‐stabilized tetragonal zirconia polycrystal is shown not to degrade at low temperatures. Slight strength decrease is found for elevated‐temperature treatments, which is not related to formation of the monoclinic phase. A possible mechanism to explain the behavior based upon the ferroelastic nature of…
Small loops and stacking fault tetrahedra of sizes 1 to 10 nm were created during irradiation of copper with 14 MeV neutrons at room temperature. The electrical resistivity of these defect clusters has been investigated using a combination of resistivity and electron microscopy techniques. The dislocation specific res…
Polycrystalline samples of SrMe/sub 2/Fe/sub 16/O/sub 27/ (SrMe/sub 2-/W) with Me/sup 2+/=Zn, Co, Ni, Mn, Mg, Cu, and Sr/sub 2/Zn/sub 2/Fe/sub 28/O/sub 46/ (SrZn-X) hexagonal ferrites have been prepared by the chemical coprecipitation method. The main steps of W- and X-phase formation have been evidenced by means of M…
Nonlinear optical crystals appear very attractive due to their potential applications in optical signal processing. We have investigated several strategies in order to get efficient organic nonlinear optical crystals having enhanced quadratic responses and, more particularly, high efficiencies for second harmonic gene…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTWhole-pattern approach to structure refinement problems of fibrous materials: application to isotactic polypropyleneA. Immirzi and P. IannelliCite this: Macromolecules 1988, 21, 3, 768–773Publication Date (Print):March 1, 1988Publication History Published online1 May 2002Pub…
The potassium selenostannate(IV) K 4 Sn 3 Se 8 has been prepared by methanolothermal reaction of K 2 CO 3 with elemental Sn and Se at 190 °C and its structure established by X-ray structural analysis. The unit cell contains isolated [Sn 3 Se 8 ] 4- anions consisting of a central SnSe 4 -tetrahedron edge-bridged to two…
The conductivity of a random-resistor model, recently proposed for dispersed ionic conductors, is calculated using the effective-medium approximation. The results are compared with Monte Carlo simulations (MCS) for two- and three-dimensional systems. This simple analytical approach describes satisfactorily both the te…
Abstract Raman spectra of some indo‐, thia‐ and selena‐carbocyanine dyes have been measured. The bands are assigned to the modes associated with the methine chain, end chromophore and methyl/ethyl group based on a comparison of the positions of the bands for a series of dyes with similar structures and those for 1,2,3…
Das bekannte, äußerst reaktive [18]Annulen 1 und das hypothetische Isomer 2 sollten sich durch CH 2 ‐ und CHCH‐Gruppen als innere bzw. äußere Brücken stabilisieren lassen. Die entsprechenden Kohlenwasserstoffe 3 bzw. 4 sind nicht bekannt, obwohl sie als Bindeglieder zwischen den nicht‐natürlichen Annulenen und dem Po…
Abstract The KAHR model of structural relaxation has been extended to include the effects of pressure upon the retardation times of glass‐forming materials. The previously used methodology is applied with a continuous distribution of retardation times of the fractional exponential form. Several forms of the pressure d…
Unterschiedlich sind die Antworten auf die Titelfrage für beide Verbindungen: Bei 1 wird im Kristall bei 100 K röntgenographisch die Struktur beobachtet, die dem Übergangszustand des freien Moleküls zwischen den beiden möglichen Valenztautomeren entspricht.Dagegen enthält der Kristall von 2 Moleküle mit deutlich recht…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAffinity of grain deformation in mesomorphic block polymers submitted to simple elongationR. Seguela and J. Prud'hommeCite this: Macromolecules 1988, 21, 3, 635–643Publication Date (Print):March 1, 1988Publication History Published online1 May 2002Published inissue 1 March 1…
A new type of information on the distribution of electron density in crystals of biological macromolecules is proposed. This is a quasihistogram of the image of the function of electron density distribution at a finite resolution. It is shown how this information should be used to restore the values of low-angle struc…
Abstract Blends of 50/50 natural rubber (NR) and styrene‐butadiene rubber (SBR) are vulcanized using several conventional and semi‐EV systems. The cure characteristics and vulcanizate properties are compared. The quantity and quality of crosslinks in each case are deciphered by chemical probes to correlated them with…
The dc electrical conductivity of MgO‐doped Cr 2 O 3 and the defect models with the defect structure of a sesquioxide were investigated as a function of oxygen partial pressure, temperature, and dopant content. The electrical conductivity of MgO‐doped Cr 2 O 3 is increased with oxygen partial pressure and temperature.…
This article demonstrates the stable levitation of single small gas bubbles in water in a downward directed visible laser beam. The natural upward buoyancy of the bubbles was counteracted by the optical radiation pressure of the light beam, whose optical power ranged from 1–3.5 W. The sizes of the levitated bubbles ra…
The dependence of the saturation polarization, the Curie temperature, the anisotropy field strength, and the intrinsic coercivity of sintered Nd-Fe-TM-B magnets on the concentration of metals, such as Al, Cr, Mn and Cu, was examined. The relation of the intrinsic coercivity to the anisotropy field strength and localiz…