Materials Literature
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Machine learning (ML) is transforming all areas of science. The complex and time-consuming calculations in molecular simulations are particularly suitable for an ML revolution and have already been profoundly affected by the application of existing ML ...Read More
Single crystals of pure copper oriented for single slip were fatigued in air at room temperature at low constant plastic strain amplitudes in the range 0·1 % ≤ e p≤ 0·6%. After a few thousand cycles the specimens entered what appeared to be an equilibrium state which contained two phases: a hard and almost inactive ‘m…
Absorption and reflection spectra of β-Ga 2 O 3 are measured with polarized light in the wavelength region near its absorption edge. The crystals of β-Ga 2 O 3 are grown by using a Ga/HCl/O 2 /Ar vapor reaction system. The platelike crystals of β-Ga 2 O 3 have (100), (010), and (001) surfaces, and the major surface is…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTechnique for the determination of absolute emission quantum yields of powdered samplesMark S. Wrighton, David S. Ginley, and David L. MorseCite this: J. Phys. Chem. 1974, 78, 22, 2229–2233Publication Date (Print):October 1, 1974Publication History Published online1 May 2002…
Using a formalism developed by Stroh (1962), a simple image force theorem for a dislocated anisotropic bicrystal is derived. An extension of the Stroh formalism, shows that the prelogarithmic energy factors depend only on the crystallographic directions of the dislocation line and its Burgers vector relative to each m…
The elastic properties of copper have been compiled and reviewed. Polycrystalline elastic constants included are: Young's modulus, the shear modulus, the bulk modulus, and Poisson's ratio. Single-crystal constants of second-, third-, and fourth-order are included. Over 200 references to the experimental literature are…
Optical and x-ray observations of polyethylene have been made at high pressures and temperatures using a gasketed diamond-anvil cell. The experiments confirm the existence of the high-pressure phase previously postulated by Bassett and Turner. The new phase is hexagonal, with orthohexagonal lattice parameters of a = 8…
Abstract Native cellulose has been shown to consist of a crystalline array of parallel chains, based on the X‐ray diffraction data for specimens from the sea alga Valonia ventricosa . The unit cell is monoclinic with dimensions a = 16.34 Å, b = 15.72 Å, c = 10.38 Å (fiber axis), and β = 97.0°. The space group is P2 1…
This review discusses the physical properties of nematic, cholesteric, and smectic liquid crystals. Molecular theories of the liquid crystal phases are discussed and the molecular field theories of the phase transitions between the various liquid crystal phases are presented. The elastic theory and hydrodynamics of li…
We show core-electron energy spectra determined by means of (soft) x-ray photoelectron spectroscopy and appearance potential spectroscopy to be closely related for $2p$ electrons in iron and nickel. An earlier comparison for the first transition-series elements had indicated a systematic difference between appearance-…
In a new technique for studying electron collisions, the electrons are confined by electromagnetic fields and exposed to a known low density of atoms or molecules. Collisions rates are measured by electron diffusion in the trap. The use of spin-oriented atoms allows triplet and singlet contributions to be separated. R…
The dislocation velocity, , on prismatic planes of monocrystalline MgZn2 has been determined by etching as a function of applied stress, τ, chemical composition within the homogeneity range, and temperature, T, between 340 und 456°C. The results are interpreted in terms of a double kink mechanism, where
Doping processes of silicon carbide crystals with scandium are investigated. It is shown that the scandium solubility in SiC is limited within the 1800 to 2600°C temperature range and amounts to (2 to 3) × 1017 cm−3. On doping silicon carbide crystals with scandium the VLS growth mechanism is possible. The luminescenc…
Ionic force parameters for a soft sphere model have been derived from the known crystal structures and thermodynamic lattice energies of alkaline earth halides. Polarization of the chloride, bromide, and iodide ions has been taken into account by a simple shell-core model. The derived parameters are capable of reprodu…
The reflectivities of single crystals of Mo${\mathrm{O}}_{2}$ and oriented films of Cr${\mathrm{O}}_{2}$ grown on rutile substrates have been measured from 0.1 to 6 eV. A Kramers-Kronig analysis has been performed to obtain the dielectric functions and optical conductivities. A rise in the absorption coefficient above…
Anomalous EPR line intensities observed in the photoexcited triplet state of porphyrins at 100°K are discussed. A kinetic model consisting of the singlet ground state and the first excited triplet state is developed. The EPR signal intensities are expressed in terms of the kinetic rate constants and are given as linea…
An experimental study of the microwave properties of pure crystals of the organic salt tetrathiofulvalene-tetracyanoquinodimethan (TTF-TCNQ) is presented. Included are electron spin resonance and a complete study of the dielectric function, ${\ensuremath{\epsilon}}_{1}\ensuremath{-}i{\ensuremath{\epsilon}}_{2}$, from…
The effect of pressure on the solubility of CaCO 3 (calcite), CaF 2 , and SrSO 4 in water was investigated for temperatures between 0 and 35 °C for pressures up to 1000 atm. It was found that for SrSO 4 at 0 °C, and at 22 °C above 500 atm, and CaCO 3 the high pressure solubility products were appreciably lower than th…
Methyl 5-bromolevulinate (30%) is obtained directly by brominating levulinic acid in methanol. The synthesis of 5-aminolevulinic acid over the 5-phthalimido ester thus becomes a three-step one.
Transformation formulas have been derived for conversions between the various conventional systems for reporting zero field splitting data using the Hamiltonian H = D [Sz2 − (1/3)S(S + 1)] + E(Sx2−Sy2). It is recommended that all future work be reported in the standard system corresponding to the range −1≤3E/D≤0.