Materials Literature
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Excitation spectra of the D45 → 7F emission of Tb3+ were measured in Sc(or In) BO3, and Y (or Gd) BO3, Y3Ga5O12, Sc (or Y) PO4, and Sc2 (or Y2) O3 at room temperature. The 4f–5d excitation band is discriminated from the host lattice excitation band by inspecting the concentration dependences of the excitation spectra.…
Measurements of the nuclear spin-lattice relaxation rate $\frac{1}{{T}_{1}}$ for ${\mathrm{In}}^{115}$, ${\mathrm{Sb}}^{121}$, and ${\mathrm{Sb}}^{123}$ in $n$-type InSb at low temperatures (1.3-4.2\ifmmode^\circ\else\textdegree\fi{}K) are presented as a function of magnetic field $H$ and crystal orientation for sever…
Infrared reflectance and excitation measurements, together with studies of the dependence of the luminescence on excitation intensity and sensitizer concentration, in the fluorides of La, Gd, and Y doped with ${\mathrm{Yb}}^{3+}$ and ${\mathrm{Er}}^{3+}$, ${\mathrm{Ho}}^{3+}$, or ${\mathrm{Tm}}^{3+}$ indicate that inf…
The fcc phases of Pr and Nd have been stabilized at room temperature and at liquid-helium temperatures and both prove to be ferromagnetic. The measured electronic properties of this new phase are discussed in the light of presently accepted phase diagrams. The existence of the fcc phase accounts for a variety of anoma…
Revised intensity relationships for the three common silicon carbide polytypes (6H, 4H and 15R) are presented together with the details of a technique by which pure polytype samples may be prepared.
The anodic oxidation of saturated hydrocarbons on Pt is discussed. Coulombic efficiency for CO 2 production is 100% even for complex fuels. The need to examine adsorption processes in mechanistic studies is emphasized. Such studies reveal three materials in the steady state: CH—β (polymeric), CH—α (alkyl radicals), an…
The corrosion rates of stainless steels 304 and 316, mild steel, nickel, Monel, Inconel and brass were investigated by electrochemical polarization techniques in 5% aerated and deaerated HCl solutions.
The Burgers vectors of the dislocations bounding steps in the stacking fault in Frank dislocation loops in quenched silver and copper-aluminium alloys have been identified by comparison of experimental electron microscope images and images computed using the Head-Humble technique. The steps in the fault are generally…
It has been suggested that the surface region of ordered liquids and, in particular, liquid crystals may extend well into the bulk phase.1 The surface tension of such materials could be expected to reflect changes in bulk properties and should be sensitive to mesophase transitions. In this study the surface tension of…
The Curie temperatures and the electrical resistivity at 4.2°, 78°, and 300°K have been measured for nickel-carbon solid solutions containing up to 1.5 at.% carbon. The resistivity at 4.2°K increases at the rate 3.48±0.06 μΩ cm/at.% carbon; whereas the Curie temperature decreases by ∼30 C°/at.% carbon. The electrical…
Crystalline hexamethylenediammonium adipate (m.p. 197 °C), the one to one salt of hexamethylenediamine and adipic acid, polymerizes at temperatures below its melting point yielding the corresponding polyamide (Nylon 66). Although there is considerable disorientation of the resulting crystalline polymer, two preferred…
Abstract The reactivities of boron, aluminium and silicon nitrides have been compared. Samples of these nitrides have been converted to oxides by being calcined in air. Changes in phase composition, surface area, crystallite and aggregate sizes have been correlated with oxidation time and temperature. Crystallites of…
ABSTRACT High-speed cinephotography has been used to study the movements performed by compound cilia from the segmental gills of Sabellaria and from the abfrontal face of the gill filaments of Mytilus. The two types of cilium have distinctly different beat patterns. Equations are derived which allow the calculation of…
The effects of gegenion on the polymerization of tetrahydrofuran (THF) indicated that the order of stability was PF 6 - ≃ SbF 6 - > BF 4 - ≥ SbCl 6 - . With all gegenions gel permeation chromatography indicated a rapid broadening of the molecular weight distribution before equilibrium conversion was reached. A narrowi…
The damping constant B for the viscous drag on dislocations was measured for NaCl and LiF. A novel technique was employed to improve the accuracy of the measurements, and many specimens were used to check the reproducibility of the results. Measurements of both the attenuation and velocity changes resulting from dislo…
Reflection coefficients of various order diffracted waves are calculated for an echelette grating which finds important use as a component of suboptical resonators. The classical optics approach has been found to be inadequate for deriving reliable results for this configuration. Accurate solution of the boundary valu…
Thin films of the rare-earth alloys of the Co–Sm system with and without the addition of Cu have been found to have exceptionally high coercive forces. A coercive force of 30 000 Oe was realized with Co3.65Cu1.35Sm films, 4000-Å thick prepared at a substrate temperature of 500°C using getter sputtering. This technique…
A number of binary systems have been investigated with p-n-dodecyloxybenzal-p-n-butoxyaniline—a mesomorphic component exhibiting both smectic and nematic phases—and other non-liquid crystalline solutes. When the transition temperatures of such binary systems are plotted against the mole per cent composition of the liq…
Abstract 1,3,3-Trimethylindolino-6′-nitro-benzopyrylspiran (1) exhibits a photoreversible color change which is called “photochromism”. However, it is transformed from a colorless form (A) into a colored form (C) which has a salt-like structure when acid such as malonic acid is added into acetone without irradiation w…
Summary Unit cell dimensions and refractive indices have been determined for synthetic pyroxenes in the system CaMgSi 2 O 6 -CaFeSi 2 O 6 -NaFeSi 2 O 6 , which have been crystallized and annealed on the nickel-bunsenite (Ni-NiO) oxygen buffer curve at 700 °C and a total pressure of 2 kb. The data presented confirms th…