Materials Literature
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Transmission electron microscopy (TEM) has been widely used to study point defect clusters in metals following quenching and irradiation. As a result of this work considerable progress has been made in our understanding of the nucleation, morphology, and growth of clusters and this paper reviews the current state of t…
Photochromic (Z)-1-methylpropylidene(diphenylmethylene)succinic anhydride undergoes photochemical conrotatory ring closure and thermal disrotatory ring closure reactions to form red 1,8a-dihydronaphthalene intermediates (1,8a-DHNs) which undergo a facile thermal 1,5-H shift to yield colourless 1,2-DHNs. Yellow (E)-3,5…
Abstract Electrically polarized and unpolarized films of polyacrylonitrile (PAN) have been investigated by both infrared attenuated total reflection (ATR) and thermally stimulated discharge (TSD). ATR analysis of PAN films has been aimed at explaining the molecular origin of thermally stimulated currents, and conseque…
Dielectric measurements of the ceramic samples of Bi2MoO6 show that this crystal is ferroelectric with the Curie temperature Tc ≈ 570°C. According to the empirical relation between cation shift and ferroelectric Curie temperature the approximate magnitude of Mo6+ cations displacement equal to Δz = 0.21 Å.
Single crystals of Ca 3 (VO 4 ) 2 with diameters up to 25 mm and lengths of 60 mm have been grown by the Czochralski technique from a stoichiometric melt. Elastic, thermoelastic, piezoelectric, linear electrooptic, dielectric and pyroelectric properties have been measured. Ca 3 (VO 4 ) 2 exhibits much smaller elastic…
Treatment of the phaeofarnesins (4) isolated from the Chlorobium chlorophylls-660 (ex. Chloropseudomonas ethylicum) with sulphuric acid in methanol gives the methyl phaeophorbides (1) which can be dehydrated by refluxing in benzene in the presence of acid to afford the 2-vinyl derivatives (2); prolonged refluxing give…
Procedures are described for the quantitative determination of the asbestos and α-quartz contents of bulk samples by use of X-ray powder diffractometry. The method gives satisfactory results for several different types of asbestos and for mixtures of two or more different types. Problems with sample grinding and prefe…
Electron microscopy observations show that in the ordered alloy Ni 3V, perfect 1/ 2[112] dislocations are dissociated into three 1/ 6[112] partial dislocations bounding an intrinsic-extrinsic pure stacking fault pair (i.e. without any wrong first neighbour bonds); from this an evaluation of stacking fault energies can…
Polystyrene without additional compounds was treated in a laboratory oven at elevated temperatures (200 degrees, 350 degrees, 500 degrees C) under slight air flow (0.7 l/min). The thermal degradation products appearing in different phases (gases, vapors, aerosols) were collected and analyzed by methods of chromatograp…
A variety of configurations of coupled dislocations straddling a polygon wall were revealed by the etch hillock technique on the (001) surface of white tin. Observations indicated that: (1) Both coupled dislocations and wall dislocations move to the same [100] direction under an applied stress; (2) Their slip plane is…
The intensities of 90 normal and 93 satellite x-ray reflections of the modulated intermediate phase of NaNO2 were measured 0.2 K. above the Curie temperature. The least agreement between the observed and calculated structure factors has been obtained by assuming that the antiferroelectric phase of NaNO2 is both amplit…
The nature of recent international research collaboration is described. Breakdown data obtained on a wide variety of air clearances are comprehensively summarised; the effects of the polarity and shape of the testing impulse, the geometry of the electrodes and the condition of the atmosphere are considered separately.…
Abstract Studies were carried out to determine the crystalline elastic modulus E 1 along the chain axis for the α‐form of nylon‐6 [poly(ε‐caprolactam)] by X‐ray diffraction. To obtain an inherent E 1 value of this polymer the problem was solved that different orders of meridional reflections give different E 1 values.…
Solutions apparently containing Ni[C 6 F 5 ) 2 are obtained by reaction of anhydrous NiBr 2 with [C 6 - F 5 ]MgBr in THF. The addition of different ligands to these solutions gives four-coordinate nickel(II) complexes of the type (C 6 F 5 ) 2 NiL 2 [L = PEt 3 PBu 3 , PPh 3 AsPh 3 SbPh 3 , OPPh 3 OAsPh 3 , p-Dioxane].…
Sliding friction experiments were conducted with pyrolytic boron nitride in sliding contact with itself and various metals. Auger emission spectroscopy was used to monitor transfer of pyrolytic boron nitride to metals and metals to pyrolytic boron nitride. Results indicate that the friction coefficient for pyrolytic b…
Abstract Untersuchungen der Lochfraßbeständigkeit einer großen Anzahl von Zr‐Legierungen in verschiedenen Lösungen durch elektrochemische Methoden ergaben, daß durch Zusätze von Va‐ und VIa‐Metallen, vor allem aber von Ti, die Lochfraßanfälligkeit des Zr vermindert werden kann. Lokalelementbildende Metalle verschlecht…
Abstract The dielectric constant ϵ′ and the dielectric loss ϵ″ for cellulose fiber were measured over a frequency band 0.2 to 10 Mc/sec and a temperature range from −20 to 80°C. Also, the variation of the dielectric behavior with relative humidity was measured at 25°C. From these data, both the specific resistivity R…
Chemisorption of oxygen on the surface of the grains of ZnO powder layers mainly controls the photoconductivity. The adsorption of oxygen ions is regarded as a chemical reaction at the interface and involves oxygen from the gas atmosphere and electrons from the metal oxide. The changes in the conductivity of ZnO-layer…
A study has been made of the effect of hydrostatic pressure, ranging from 1 to 300 atm. (0·102 to 30·6 N.mm−2) on the corrosion of copper in sea water at pH 7·8 and at a temperature of 10°c. The experimental technique ensured that the content of dissolved oxygen in the sea water was virtually constant over the pressur…
The properties of an even homologous series of alkoxy benzoic acids have been investigated in the crystalline and mesomorphic states by means of thermal microscopy, x-ray scattering and dilatometry. Structural parameters such as inter-lamellar distance d, and the molar volume Vm were studied as a function of the numbe…