Materials Literature
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The current understanding of the theory of the atomic photoelectric effect is reviewed for incident photon energies above 10 keV, complementing the earlier review of Fano and Cooper (1968) at lower energies. The theoretical developments of the last two decades are of two types: (1) analytic results giving insight into…
The mean square of the electron-density gradient, 〈|grad η|2〉 in isotropic structures is shown to be proportional to the fourth moment of the SAXS intensity distribution in reciprocal space ∫s4I(s)ds, as well as to the second derivative of the correlation function in the origin. In the case of two-phase structures wit…
In the previous paper a practical method has been applied for an analysis of non-isothermal crystallization in terms of data of isothermal crystallization. The fundamental equation was written on the assumption of the isokinetic conditions in the following form: where X(t) is the degree of phase transformation at time…
A complete study of the lattice-dynamical behavior of the ferroelectric tetragonal perovskite PbTi${\mathrm{O}}_{3}$ has been carried out using Raman spectroscopy. The temperature dependence of all the long-wavelength mode frequencies are determined. We show that a damped-harmonic-oscillator model with a frequency-ind…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTConformational analysis of the sugar ring in nucleosides and nucleotides. Improved method for the interpretation of proton magnetic resonance coupling constantsC. Altona and M. SundaralingamCite this: J. Am. Chem. Soc. 1973, 95, 7, 2333–2344Publication Date (Print):April 1,…
Thin films of Wo3 deposited on quartz substrates at room temperature have been shown to be amorphous in structure. The optical absorption spectra of the amorphous and crystalline films have been measured in the temperature range 110° to 500°K. The fundamental absorption edge of an amorphous film occurs at 3800 Å which…
Chemical analyses of clays, shales and slates from different parts of the world and from different sedimentological environments have been collected, together with analyses of the most common minerals found in these sediments. It is shown how these chemical compositions are distributed within a triangular diagram with…
The structure of potassium niobate KNbO 3 in the ferroelectric tetragonal phase has been determined at 270 degrees C by neutron diffraction. The atomic displacements along (001) from the cubic perovskite positions are Delta (K)=-0.030+or-0.035 AA, Delta (Nb)=0.064 AA, Delta (O I )=-0.095+or-0.012 AA and Delta (O II )=…
Abstract In the preceding Part I of this investigation a relation was derived among the measured failure energy, θ, the energy dissipated viscoelastically during joint separation, and an intrinsic failure energy θ0, for various rubber-to-polymer substrate joints. For some joints, θ0 was equal to the thermodynamic work…
Abstract Die 1,3‐Dithiolderivate 8 – 11 Red lassen sich zu den stabilen Radikalionen 8 – 11 Sem oxidieren, deren Elektronen‐ und EPR‐Spektren vermessen wurden. 8 – 11 bilden nach Red + Ox K 2 Sem in Acetonitril ein reversibles zweistufiges Redoxsystem mit K = 10 6 –10 7 . Der Einfluß von Alkyl‐ und Benzo‐Substitution…
New organic compounds of positive dielectric anisotropy giving nematic liquid crystals at room temperature, either as the pure compounds or in admixture, are described. These materials are of improved stability, and function well in electro-optical devices based on the twisted-nematic or cholesteric-nematic phase-chan…
This letter cites previous work carried out on the method contained in Misell's (1973) letter, and points out accomplishments and problems that exist in connection with it.
Voids were produced in nickel by protons and Ni++ ions at 500°C. Methods for an accurate determination and quantitative description of the shape of voids are discussed. The voids thus produced in Ni are prominently cubo-octahedral with 100% truncation, or octahedral with partial {100} truncation, and occasionally cubi…
The lattice thermal conductivity in high-concentration harmonic isotopically disordered mixed crystals is calculated within the coherent-potential approximation from the appropriate Kubo formula using the energy current operators of Hardy. The infrared divergence in harmonic systems is eliminated by restriction to fin…
The Raman spectrum of LiO2 in argon matrices has been observed using 4880 Å excitation. The intraionic (O–O)− mode was observed as a sharp intense band at 1097 cm−1; the symmetric interionic (Li+–O2−) mode was recorded as a weaker broad feature at 694 cm−1. Oxygen-18 and lithium-6 substitution confirmed these vibratio…
$2s$ and $3s$ core-electron exchange splittings have been measured for a number of transition-metal compounds. It is found that the $2s$ splittings agree roughly with values from Hartree-Fock calculations, whereas measured $3s$ splittings are smaller by about a factor of 2. This discrepancy is tentatively linked to co…
A deep-defect level in a semiconductor is simulated by a cluster of host atoms surrounding the defect. The system is then treated as a "large molecule," the energy levels and wave functions for the entire cluster being obtained using molecular-orbital techniques. As examples, the substitutional nitrogen-atom impurity…
The amino acid L-tyrosine (C9H11NO3) and its salt L-tyrosine hydrochloride (C9H11NO3·HCl) crystallize respectively in the space groups P212121, a=6.913(3) Å, b=21.118(10) Å, c=5.832(3) Å, and P21, a=11.083(5) Å, b=9.041(4) Å, c=5.099(3) Å, β=91.82(3) Å. Both structures have been refined by neutron diffraction techniqu…
Dispersion curves for lattice vibrations propagating along the five major symmetry directions in a single crystal of rubidium have been measured using inelastic neutron scattering. Care has been taken to identify spurious peaks in the neutron groups and to correct for effects of instrumental resolution. The results, a…
We have been able to extend the dielectric theory of ionicity to include such $d$-electron systems as the noble-metal halides (e.g., CuCl, AgBr, etc.), $AB$ transition-metal compounds (e.g., ScN, MnS, FeO, NiO, etc.), ${A}_{m}{B}_{n}$ crystals (e.g., Zr${\mathrm{F}}_{4}$, Ti${\mathrm{O}}_{2}$, ${\mathrm{Cr}}_{2}$${\ma…