Materials Literature
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The crystal structures of the isomorphous salts MI6[Mo7O24],4H2O (M = NH4 or K) have been refined by three-dimensional X-ray diffraction methods. Unit cell dimensions of these monoclinic compounds, space group P21/C with Z= 4, are, ammonium salt: a= 8·3934 ± 0·0008, b= 36·1703 ± 0·0045, c= 10·4715 ± 0·0011 Å, β= 115·9…
The spinels are one of the most extensive series of related chemical compounds known. The mineral spinel Mg 2+ Al 2 3+ O 4 2- can be modified by substitution by a wide range of divalent and trivalent cations to replace Mg 2+ and Al 2 3+ respectively. The spinel crystal structure is physically flexible which leads to a…
This study is part of a programme to determine the diffusion behaviour of the principal constituents of Type 316 stainless steel. Chromium diffusion plays an important role in the oxidation behaviour of stainless steels and both lattice and grain-boundary diffusion rates have been measured. Lattice diffusion in the te…
There are two important mechanisms which produce image contrast in the electron microscope.
SUMMARY Temperature gradients in high speed steel tools used to turn iron, titanium and nickel have been measured using a method based on the structural changes in high speed steel heated to temperatures over 560°C. The relationship between temperature gradient, cutting speed and feed rate have been demonstrated throu…
The theory described in the preceding paper is extended to include intramolecular reactions in A—A + B—B type polymerisations. The extension is described in a general way and a limiting form is applied to previously published data giving total ring fractions during the formation of linear polyurethanes. The interpreta…
The subsolidus miscibility gap for the TiO 2 ‐SnO 2 system was redetermined. The critical temperature, 1430°C, is intermediate between that determined by Padurow, 1330°C, and that determined by Garcia and Speidel, 1475°C. Although the phase boundary is slightly asymmetric (the critical composition occurs at 47 mol% Ti…
Electron diffraction patterns are routinely obtained in the electron microscope and are used to gain quantitative information on the following.
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)…