Materials Literature
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Numerous measurements of saturation magnetization of Fe and Ni are reported. Saturation magnetization is determined by consideration of all contributions in the change of magnetization in high magnetic fields, i.e., internal demagnetizing fields, homogeneous rotations, and paramagnetic terms. The value found for the a…
Mössbauer spectra of CoFe2O4 show that this spinel is not completely inverse and that the degree of inversion depends on the heat treatment of the material. The magnetic moments of the slowly cooled and the quenched material are 3.4 and 3.9 μB per unit chemical formula, respectively, and the Néel temperatures are 798°…
Received 21 November 1967DOI:https://doi.org/10.1103/PhysRevLett.20.209©1968 American Physical Society
The X-ray scattering produced by a distribution of two-dimensional lattices with preferred orientation, a problem which arises e.g. in the study of anisotropic structures of non-graphitic C atoms, is given a rigorous theoretical treatment for infinite and perfect lattices and approximations are given for finite and im…
Takagi's theory is used to calculate the propagation of X-rays in perfect and nearly perfect crystals. In the general case, the equations have to be solved on a computer. The principle of the calculation is given. It has been applied to the case where an incident plane wave is collimated by a slit. The separation of w…
The Reciprocity Theorem of scattering theory is shown to hold generally for electrons scattered elastically in an absorbing medium, and also for inelastically scattered electrons, to a certain approximation. Two scattering symmetry conditions are defined by applying the theorem to crystals having mirror symmetry paral…
Abstract A new model is proposed to describe the large recoverable extensions which can be observed with high polymers below their glass transition points. The model consists of a Hookean spring in series with an Eyring dashpot and rubber elasticity spring in parallel. Conventional stress-strain curves for cellulose n…
In the analysis of spin structures a `natural' point of view looks for the set of symmetry operations which leave the magnetic structure invariant and has led to the development of magnetic or Shubnikov groups. A second point of view presented here simply asks for the transformation properties of a magnetic structure…
A binuclear ion ([NH(3))5RuN(2)Ru(NH(3))(5)](5)+ is formed by the direct reaction of N(2) with an aqueous solution of (NH(3))(5)RuOH(2)(2+) at room temperature. The binuclear ion is also formed by the reversible reaction of (NH(3))5RuOH(2)(2+) with (NH(3))(5)RuN(2)(2+). Solid [(NH(3))(5)RuN(2)Ru(NH(3))(5)] (BF(4))(4)…
The infrared absorption spectrum of KH2PO4, KD2PO4, and KH2AsO4 single crystals has been measured from 3000-1000 cm−1 over a temperature range from 20°-300°K. Three broad absorptions are found at 2670, 2360, and 1720 cm−1 which are associated with the hydrogen bonds. The two upper frequencies are stronger for light po…
Mössbauer spectra of naturally occurring mineral chalcopyrite have been studied over a temperature range 300°–448°K. The spectra showed a typical pattern of six absorption lines due to the internal magnetic field. The Q.S. have values which are independent of temperature whereas the magnitudes of the internal magnetic…
Measurements of the galvanomagnetic properties of single-crystal graphite were made at 4.2\ifmmode^\circ\else\textdegree\fi{}K in pulsed magnetic fields up to 160 kG. With the magnetic field parallel to the $c$ axis, the transverse magnetoresistance is approximately proportional to the magnetic field strength, and the…
Absolute-reflectance measurements of single-crystal Re${\mathrm{O}}_{3}$ in the spectral range 0.2-22 eV are analyzed by Kramers-Kronig relations to give the real and imaginary parts of the dielectric constants. The dielectric constant is characteristic of free-electron behavior below the sharp plasma edge at 2.1 eV,…
Potassium nitrite frequently contains significant nitrate impurity, detectable by vibration spectroscopy. Analyses based independently on infrared and Raman band intensities permit a quantitative determination of the nitrate impurity. Reassignment of some previously reported vibrational frequencies is discussed.
Shock-wave compression measurements from 20 to 300 kbar are reported for hexagonal boron nitride. A phase transition occurs at 122 kbar and 230°C in good agreement with static data. The volume decrease is approximately 19% and the estimated slope of the phase line for the solid–solid transition is −3.6 × 10−2kbar °C−1…
Frequency assignments for the vibrational modes of species Bu in CaWO4 and CaMoO4 are made. Bu modes are both infrared inactive and Raman inactive in unstrained material, but become infrared active and exhibit Eu characteristics under xz or yz shear strain and Au characteristics under xy shear strain. In the present p…
The infrared spectra of rare earth acetates have been studied to examine the metal-acetate bonding. The thermal decomposition of rare earth acetates as well as lead and copper acetates have been investigated in detail by employing thermogravimetric analysis and differential thermal analysis. Thermal decomposition of c…
The temperature dependence of the resistance of iron has been measured in the range 1 to 4.2\ifmmode^\circ\else\textdegree\fi{}K. Single-crystal iron specimens 100 to 300 \ensuremath{\mu} in diameter with residual resistance ratios up to 2100 were used in the experiments. The dominant temperature dependence in this ra…
The exact eigenvalue spectrum and thermodynamic properties of the spin Hamiltonian $\mathcal{H}=2|J|\ensuremath{\Sigma}\stackrel{\frac{N}{2}}{i=1}({\mathrm{S}}_{2i}\ifmmode\cdot\else\textperiodcentered\fi{}{\mathrm{S}}_{2i\ensuremath{-}1}+a{\mathrm{S}}_{2i}\ifmmode\cdot\else\textperiodcentered\fi{}{\mathrm{S}}_{2i+1})…
Received 20 November 1967DOI:https://doi.org/10.1103/PhysRevLett.20.59©1968 American Physical Society