Materials Literature
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Pervasive alteration is a common feature of metamict minerals. Previous studies of metamict niobium-tantalum-titanium oxides and electron microprobe analyses of altered areas in metamict yttrialite document the leaching of uranium, thorium, and rare earth elements. These data suggest that glasses may not provide a sta…
Over 300 small-scale experiments have been performed to investigate the interaction that sometimes occurs when hot liquid metal is poured into a container of water. IN these experiments molten tin was used. The violence of each interaction was classified by measuring the ratio of the mass of comminuted tin to the orig…
The crystal structure of (CH3NH3)2MnCl4 (MAMC) is determined by neutron diffraction at 188 K in the low temperature tetragonal phase (P42/ncm). The sequence of structural phase transitions of MAMC can be discussed in terms of NH …︁ Cl bridges between NH3 and certain Cl−-ions. The order of the room temperature orthorh…
The $\ensuremath{\omega}$ phase transformation in Zr-Nb alloys has been studied by measuring x-ray and M\"ossbauer diffuse scattering from single crystals with compositions ranging from 8- to 30-wt% Nb. We present an extensive two-dimensional mapping of the x-ray diffuse scattering for all compositions. The distinct f…
Mean free paths for electrons in bulk jellium are calculated for electrons with energies from a few hundred to a few thousand eV and for values of ${r}_{s}$ for 1.5 to 5 where ${r}_{s}$ is the average distance between valence electrons measured in units of the Bohr radius. Account is taken of exchange and correlation…
Optical absorption, reflectivity, and photoconductivity in the near-uv range (1950-3200 \AA{}) of a thin film of hexagonal boron nitride were measured. The main absorption peak was observed at 6.2 eV. A sharp fall at about 5.8 eV was attributed to the direct band gap. The temperature dependence of the band gap was fou…
It is pointed out that the recent observation of localized holes and electrons at low temperatures after optical excitation of chalcogenide glasses by Bishop et al. is consistent with a model previously proposed for lone-pair amorphous semiconductors. The model uses the existence of these localized states to provide a…
Abstract Mit Hilfe der Röntgendiffraktometrie werden die Phasengleichgewichte des Systems MgO ‐MgC12 ‐ H 2 Obei 25°C sowie die Reaktionen, die zur Bildung der Gleichgewichtsphasen 5 Mg(OH)2°C MgClg ° 8 H 2 O und 3 Mg(OH)2°C MgClg ° 8 H 2 O führen, untersucht.
From light scattered by director modes in the smectic-$A$ phase of cyanobenzylidene octyloxyaniline (CBOOA) and octyloxy cyanobiphenyl (80CB) we deduce that the restoring force for phase fluctuations in the smectic order parameter vanishes as ${({T}_{c}\ensuremath{-}T)}^{0.33}$ as the nematic phase is approached. In C…
Abstract Thermolysis of p-acetylphenyl 3-guaiazulenecarboxylate (1) results in loss of the ester group. In contrast, thermolysis of phenyl 3-guaiazulenecarboxylate (2) or p-methoxyphenyl 3-guaiazulenecarboxylate (3) gives (i) loss of the ester group, (ii) loss of the 1-methyl group with concomitant rearrangement of th…
A new stylus with which it is possible to measure both the steep and shallow sides of diffraction grating grooves is described. The relations between the ruling tool profile and the groove profiles have been investigated and it is shown that the included angle of grating grooves may be considerably less than that of t…
A device is described which illustrates how physical principles learned in the classroom can find industrial application. This device is the thermoelectric metal sorter which operates on the principle of the Seebeck effect.
The thermal decomposition of dialkyl tert-butylperoxy phosphates, in the presence and absence of solvents, yields the corresponding dialkyl phosphate, acetone, methanol, 2,2-dimethoxypropane, and methyl isopropenyl ether as the primary products. Prolonged heating of the product mixture produces trialkyl phosphates, (R…
Nuclear spin relaxation-time measurements of the cesium nuclei in the perovskite crystal CsPb${\mathrm{Cl}}_{3}$ are reported for the temperature range 300-430 K. The data exhibit the characterisitic anomaly which is expected to occur in the civinity of the structural phase transitions. Comparison of these data with c…
Analytically pure single crystals of polymeric sulfur nitride (polythiazyl), (SN) x, suitable for solid state studies were prepared by the spontaneous room temperature polymerization of single crystals of pure S 2 N 2 . The polymer is relatively inert to oxygen and water. A single-crystal x-ray study revealed that an…
Electrothermal atomic absorption spectrometry has five major advantages for measurements of trace metals in biological materials, in comparison to measurements by conventional flame atomic absorption analysis: (1) Trace metal contamination is minimized by avoidance of preliminary chemical extractions and additions of…
The production of light upon the electron transfer reaction of electrogenerated radical ions of tetraarylpyrroles [aryl = anisyl (TAP), phenyl (TPP), tolyl (TTP), p‐chloro‐phenyl (TCPP)], tetraphenylfuran (TPF), and tetraphenylthiophene (TPT) in systems containing these compounds alone in acetonitrile solutions or in…
High-speed streak and framing photography of surface flashover across solid insulators in vacuum is reported. Experiments were performed with direct and impulse voltages. It is shown that the initial propagation of a visible arc across an alumina surface in vacuum occurs at a speed greater than 109cm . s-1. It is show…
This paper presents a progress report on a continuing investigation into the voltage endurance of cast and molded resins, particularly cast epoxy resins. The relation of gas cavity size to the observable discharge magnitude and the stress level on the resin at which discharges can be expected to occur within internal…
Abstract As a preliminary step to studies on the regeneration of active carbon, its wet oxidation has been followed in order to obtain information about the different parameters involved: agitation, temperature and pressure. The oxidation reaction takes place in the liquid phase and it does not proceed at significant…