Materials Literature
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The effects of transient and steady−state illumination on the electrical properties of single−crystal cuprous oxide have been investigated in the temperature range from 230 to −20 °C. For samples equilibrated well within the region of Cu2O stability, conduction was governed by an acceptor level at 0.4 eV above the val…
Abstract The R AMAN spectra of solid polycristalline samples of peroxides of alkali metals, alkaline earths, and two group II transition metals have been measured. The OO stretch vibration produces an intense band in the expected frequency region of 750 to 850 cm −1 . The observation of a weak band at 815 cm −1 indic…
A model and procedures are described which permit the calculation of optical and e.s.r. spectra and magnetic susceptibilities of pn, dn, or fn electron systems for any basis chosen as free-ion terms and/or states relating to a molecule of any geometry. Ligand fields are parameterized within the angular-overlap model.…
Abstract Der Vergleich der Komplexreihen LMo(CO) 4 , LMo(CO) 3 PBu 3 und LMo(CO) 2 (PBu 3 ) 2 [L = t‐C 4 H 9 NCHCHNt‐C 4 H 9 (DAB); 2,2′‐Bipyridyl (bpy)] und ihrer paramagnetischen Monoanionen zeigt, daß die π‐Akzeptorfähigkeit von bpy nur etwa halb so groß ist wie die von DAB. Das ergibt sich aus den Spindichten…
The normalB-Hcurves of several types of steel are shown to be approximated by the equationH= (k_{1} e^{k_{2}B^{2}} + k_{3}) B. The reluctivity (H/B) and its derivative with respect toBare given by simple equations that are especially useful in the finite element method of analyzing steel magnetic circuits.
Calcite and/or aragonite were formed from calcium bicarbonate solutions containing sodium sulfate, sodium chloride and magnesium chloride of various concentrations. Sodium, chloride and sulfate contents of synthetic calcite or aragonite were measured. Sodium and chloride ions are incorporated into aragonitic calcium c…
The mechanical behavior ("shape memory") associated with martensitic solid-state transformation in nearly equiatomic Ni-Ti alloy (55-Nitinol) has been studied. Potential dental and medical applications for 55-Nitinol (55% Ni, 1.5% Co, balance Ti, by weight) and for 60-Nitinol (60% Ni, by weight) have been suggested.
Abstract Corona‐treated polyethylene films have been reported to exhibit strong self‐adhesion when joined together under conditions of heat and pressure that give no adhesion with untreated films. The present study of this effect has shown that the adhesion is completely destroyed by the application of any hydrogen‐bo…
The ordering reactions in iron–silicon alloys have been studied by transmission electron microscopy in the composition range 10–17 at.-%Si and the temperature range 535–822°C. It has been found that: <list list-type="order"> <list-item>The A2 → B2 ordering reaction appears to occur homogeneously (i.e. in the non-class…
A steric model of the smectic-$C$ phase is presented, with molecules assumed to have a symmetric zig-zag shape (this kind of molecular gross shape may arise from obliquely placed end chains). The interaction between such molecules depends on mixed tensors ${\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\nu}}}^{3}{\s…
The number of wool and acrylic fibres transferred to various articles of clothing during simulated contacts has been studied. The variation of the number of fibres transferred from a new wool sweater with area of contact is described and repeated contacts over the same area were found to cause the transfer of some fib…
Abstract Considerable confusion exists in the literature concerning the glass temperature, T g , of many highly crystalline polymers, in particular, linear polyethylene (PE), poly(vinyl fluoride) (PVF), poly(vinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), poly(oxymethylene) (POM), and poly(ethylene oxide)…
Abstract Characteristic features of isothermal growth, thickening, and melting behavior of melt grown single crystals of low molecular weight poly (ethylene oxide) fractions are presented and discussed in terms of their relevance to basic concepts of polymer crystal growth. Measurements of growth (G) and thickening ra…
Treatment of crude meso-tetraphenylporphyrin with 2,3-dichloro-5,6-dicyanobenzoquinone affords a high recovery of ‘chlorin-free’meso-tetraphenylporphyrin (1), the excess of quinone and its transformation products being easily removed by adsorption on alumina. This new procedure is also applied to the purification of m…
The oxide films produced by anodic oxidation of gold and platinum have been studied by X-ray photoelectron spectroscopy. The change in the amount of each species present, with electrode potential, has been investigated. It is demonstrated that X-ray reduction occurs for these systems but that it can be minimised by a…
The ultraviolet and visible reflectance spectra (52 000–15 000 cm–1) of high surface area MgO (250–300 m2 g–1) and CaO (100–200 m2 g–1) have been studied in vacuo and in the presence of O2, N2O, CO2 and H2O. The effect of outgassing MgO and CaO at increasing temperatures (773–1073 K) is to develop u.v. absorption band…
New, efficient, vitroceramic hosts for rare earth luminescence are discussed. Their applications to infrared up‐conversion are emphasized. Optimized compositions lead to an efficiency nearly twice as high as commercially available LaF 3 : Yb : Er . As for infrared to blue efficiency, these vitroceramics are among the…
Data on the structure and chemistry of the iron sulphides are collated. Corrosion of ferrous metals by the iron sulphides and soluble sulphide, including corrosion by the sulphate-reducing bacteria, is reviewed. Corrosion mechanisms are discussed.
In the last 10 years an extensive research and development effort has been made to implement the catalytic removal of noxious constituents from automotive exhaust. This effort is finally coming to fruition as this paper is going into print. Vehicles sold in the United States in 1975 will be, in a significant proportio…
The compounds Ce 1 − x Ln x O 2 − x / 2 ( Ln = lanthanoid element ) have been synthesized and the emf and resistivity measurements have been carried out between 400° and 1000°C. It is found that charge carriers of conduction in these compounds are oxygen ions above 600°C; the oxygen transference number being above 0.9…