Materials Literature
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A phenomenological band-theoretic model for photoelectric emission which includes the effects of energy loss due to phonon scattering is developed. The model is applicable near threshold when the optical absorption depth is large compared to the phonon scattering length of hot electrons, and is particularly useful for…
Studies of the infrared-pumped visible luminescence of NaYF4 : Yb, Er show it to have at least twice the visible output of YF3 : Yb, Er when pumped with a narrow-band excitation source at the optimum frequency. It is also free from saturation effects until very intense excitation levels are reached. The mechanism for…
Vacuum-deposited films now replace the familiar ``rubbing'' process in substrate preparation for liquid-crystal cells. Films deposited at an angle provide an oriented surface for alignment of nematic liquid crystals far better than the well-known ``rubbed'' plate. The oblique deposit causes a film growth in a preferre…
The ac conductivity of scandium-oxide thin films in the audio-frequency range at temperatures between 4 and 295 K has been measured. The frequency-dependent component of the conductivity was found to obey an equation of the form ${\ensuremath{\sigma}}_{1}(\ensuremath{\omega})=A{\ensuremath{\omega}}^{s}$, where $\ensur…
The optical absorption spectrum of Tm 3+ in TmVO 4 has been studied to obtain information on the cooperative Jahn-Teller phase transition which occurs in this material at 2.14+or-0.04 K. The temperature dependence of the absorption lines below 2.14 K was in good agreement with the predictions of molecular field theory…
The adsorption of di- and tri-methylamine has been studied at 280 and 276°K, respectively, on a range of silica gels and on silica–alumina. Adsorption–desorption isotherms and isothermal calorimetric heats of adsorption were measured. Heats of adsorption for di-methylamine on silica gel varied from 29.0 kcal/mol at θ…
A phase diagram of the semiconducting uniaxial ferroelectric antiferromagnetic Fe1-xS covering the available experimental evidence is given.
Two aminoacylases [EC 3. 5. 1] from Mycobacterium smegmatis were purified as single protein components, based on analysis by ultracentrifugation and electrophoresis. The enzyme, “short acyl aminoacylase” which exhibited hydrolytic activity toward N-short chain fatty acyl amino acids, had a sedimentation coefficient s2…
In an investigation of X-ray counting circuits the fundamental quantity governing component interaction and system counting efficiency was the pulse duration associated with a single counting event. Theoretical expressions governing the behaviour of counting systems consisting of two components were derived assuming e…
The radiation-induced bulk polymerization of liquid hexamethylcyclotrisiloxane has been achieved. Appreciable yields of polymer from octamethylcyclotetrasiloxane liquid have also been obtained. These results were achieved on “ultra-dry” monomers and are interpreted in terms of an ionic polymerization mechanism.
The thermodynamics of a water‐vapor‐E‐glass system were studied by adsorption‐isotherm analysis. The seven isotherms completed were Brunauer type IV with permanent hysteresis. The first adsorbed water layer could not be removed by pumping, indicating permanent hydrolysis. Application of heat removed the remaining wate…
Abstract The methods of Hermans and Weidinger and of Wakelin et al. (the correlation and integral methods) were used to determine the degree of crystallinity in poly(ethylene terephthalate) (PET) fibers. A standarization of cutting of the amorphous background scattering in PET fibers, indispensable for the method of H…
The crystal structure of Ca(H2AsO4)2 (triclinic, PT, with two formula units per cell) has been refined by single-crystal neutron-diffraction analysis to give an R value of 0.025 over 930 independent neutron reflexions. For the non-hydrogen atoms, bond lengths, angles and thermal parameters agree very closely with the…
Abstract Interlayer K was extracted with sodium tetraphenylboron solution from a powdered sericite heated to the temperature of dehydroxylation and quenched to room temperature. By this procedure, sericite of the 2 M 1 type was changed to an interstratified mineral. The X-ray diffraction properties of this interstrati…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemical studies of closo-1,5-dicarbapentaborane(5)Anton B. Burg and Thomas J. ReillyCite this: Inorg. Chem. 1972, 11, 8, 1962–1964Publication Date (Print):August 1, 1972Publication History Published online1 May 2002Published inissue 1 August 1972https://pubs.acs.org/doi/10.…
Gold films are used as an alloying flux to form 5 μ thick indium film seals at temperatures below 300°C. Pyrex was sealed to quartz, ULE, CER-VIT, Irtran 2, Ge, GaAs, Invar, Kovar, Al, and Cu. The seals can also be used as current feedthroughs and graded seals.
The structure of ferroelectric tetragonal KTN (KTaxNb1 - xO3 with x = 0.56), which is isomorphous with BaTiO3, has been determined by neutron diffraction. The atomic displacements from the cubic perovskite positions are δ(K) = 0.012 ± 0.003, δ(Ta,Nb) = 0.0003, δ(O(1)) = -0.010 ± 0.001 and δ(O(2)) = δ(O(3)) = -0.011 ±…
Transmission electron microscopy and selected area electron diffraction have been used to study the structural changes produced in thin (0001) crystals of NbSe2 and MoS2 by intercalation with sodium in ammonia solution. Three distinct superlattice structures have been identified, one, with orthorhombic symmetry, assoc…
Abstract Rare earth carbonates which give the same X-ray powder diffraction pattern as tengerite were prepared by heating aqueous solutions containing rare earth chlorides and ammonium trichloroacetate. Y, Er, Ho, and Gd gavee xactly the same X-ray powder pattern as tengerite, while Nd and Sm were similar to tengerite…
The room temperature Gd3+ EPR spectrum in SrF2 containing Ce3+ as a second dopant exhibits three types of symmetry sites: cubic, trigonal, and tetragonal. Relative intensities of the spectra from these sites have been determined as a function of the Ce3+ codopant level in crystals having nominally 0.1 molar % of Gd3+.…