Materials Literature
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Abstract When tested in tension, a cross‐linked epoxy resin can be made to exhibit shear yielding. A modified von Mises criterion, τ = τ 0 − μ P describes the yielding behavior of the same resin under a biaxial stress system, indicating that the flow of the material is pressure sensitive. Butadien‐acrylonitrile elasto…
The relationship between crystallisation and melting behaviour of copolymers and their morphology has been the subject of intensive discussion. One of the main points of interest is the distribution of the noncrystallizable units within the partially crystalline systems. For the explanation of physical properties of c…
The basic phenomena involved in double-pumped phosphors with energy transfer are described and discussed. The role played by successive multiple transfers as well as cooperative processes giving rise to antistokes fluorescence is emphasized for the different kinds of doping which have been used. The field of the diffe…
Abstract The differential scanning calorimeter (Perkin‐Elmer DSC‐1) is used to characterize the cure of a general‐purpose polyester during isothermal and scanning experiments. The technique is based on a new proposed model for the kinetics of isothermal cure. The model yields results which are in good agreement with e…
Abstract Conventional optical microscopy and, more particularly, a range of electron microscopic techniques have been adapted to identify the nature, and examine the chemical consequences, of emergent structural imperfections in single crystals of a number of anisotropic solids. Detailed studies have been carried out…
The operative slip systems, and the strain hardening behaviour in tension of single crystals of β′-AgMg (CsCl structure) has been investigated in the temperature range from 25 to 298 °K; a few compressive experiments are also reported. It is shown that β′-AgMg crystals deform by slip on the {112} 〈111〉, {110} 〈111〉, {…
The magnetic structures of antiferromagnetic manganese pyrophosphate and copper pyrophosphate have been determined by single crystal neutron diffraction techniques. There have been two previous determinations of the structure of manganese pyrophosphate. The discrepancy between these results is explained by postulating…
The low-temperature size effects in the phonon-drag thermopower and electrical and thermal conductivities of bismuth, measured under identical experimental conditions on a tuningfork sample of arm thicknesses 2.8 and 1.2 mm, are reported. The thin arm has the highest positive thermopower and a plateau is observed for…
Crystals of calcium fluorophosphate ${\mathrm{Ca}}_{10}$${(\mathrm{P}{\mathrm{O}}_{4})}_{6}$${\mathrm{F}}_{2}$ have been grown from melts of various compositions. Optical and ESR measurements have been performed on samples before and after various treatments such as a uv irradiation and a thermal quench. Two kinds of…
Longitudinal and transverse relaxation times of 119Sn have been measured as a function of temperature in liquid SnCl4 and SnI4. For SnCl4, T1 is a monotonically decreasing function of temperature and is dominated mechanistically by spin-rotation over the entire liquid range. In SnI4, T1 passes through a maximum near 1…
A new form of Cu 3 V 2 O 8 was prepared at 30 kbar and 900 °C. The unit cell has dimensions a = 6.2493(9), b = 7.9936(9), c = 6.3776(10) Å, β = 111.49(1)°, and the space group is P2/c. The crystal structure, refined by least-squares to a final R = 0.054, using 848 reflections, is similar to that of Mg 3 V 2 O 8 . Chai…
free path 1(k) will be parallel to k, and hence one may write 1 =7~V, OH 'e(rd ~/m )/(~d&')
In a molecular beam apparatus, a thermal beam of aluminum atoms (≈ 1700°K) intersects an uncollimated thermal beam of ozone molecules (300°K) and the resulting visible chemiluminescence is recorded with a 1 m scanning monochromator. The chemiluminescence spectrum consists of (1) the AlO B 2Σ+−X 2Σ+ blue-green system f…
Raman scattering and exciton luminescence and absorption have been studied in high-purity single-crystal ${\mathrm{Cu}}_{2}$O at liquid-helium temperature using 4880-\AA{} laser excitation. The Raman-active mode has been unambiguously identified at 515 ${\mathrm{cm}}^{\ensuremath{-}1}$, and the first observation made…
Surface modes play an important role in a solid's response to external disturbances. A charged particle on approaching or leaving the surface may suffer inelastic scattering owing to its coupling with these modes. The scattering rate is calculated in the Born approximation for two instances: (i) in metals, where the s…
The linear-combination-of-atomic-orbitals (LCAO) model of the preceding paper for the cubic-SrTi${\mathrm{O}}_{3}$ band structure is applied to predict the effect of the 110 \ifmmode^\circ\else\textdegree\fi{}K phase transition on the SrTi${\mathrm{O}}_{3}$ conduction bands. In this cubic-to-tetragonal structural tran…
The temperature and frequency dependence of conductivity, dielectric properties, infrared absorption, and electron-paramagnetic-resonance data are presented for semiconducting phosphate glasses based on oxides of Ti, V, Mn, Fe, Co, Ni, Cu, Mo, and W. The vanadate system is examined in a range of compositions, most of…
The nonrelativistic augmented-plane-wave (APW) method has been applied to calculate the electronic band structures for several cubic perovskite-type compounds, including KNi${\mathrm{F}}_{3}$, SrTi${\mathrm{O}}_{3}$, KMo${\mathrm{O}}_{3}$, and KTa${\mathrm{O}}_{3}$. These calculations involve ad hoc crystal potentials…
A theory is outlined of the aligning action of sound on nematic liquid crystals. It is based on sound-induced stresses and forces and identifies four contributions to the transverse stress. Formulas for the threshold sound intensities of a few simple deformations are given.
Experiments to reveal the influence of water concentration in obsidian upon the annealing rate of fission tracks showed that a 2.2% H2O obsidian would lose 70% of its tracks in 1 m.y. if held at 30°C. Data obtained at three temperatures (227°, 253°, and 282°C) give the possibility of extrapolations to geologically sig…