Materials Literature
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Exploration of the generality of the recently discovered reaction whereby certain organic molecules can be inserted between the metallic layers of the superconductors tantalum disulfide and niobium disulfide revealed that a large variety of organic and inorganic molecules can penetrate between the crystalline layers o…
The voltage dependence of the surface conduction current in pure and oxidized polyethylene has been investigated at various relative humidities and at room temperature. The surface conductivity of pure polyethylene has been confirmed to be less than 10 -19 mho at near saturated water vapour pressure at 25 degrees C. I…
Polycrystalline ferrites of compositions NiFe 2-x Mn x O 4 with x=0.02 and 0.05 were obtained by a conventional ceramic technique. Neutron diffraction measurements of the oxygen parameter u and X-ray diffraction measurements of the cell dimension a of the samples are presented. The u parameter of either sample is not…
Single crystals of ${\mathrm{K}}_{2}$Pt${(\mathrm{CN})}_{4}$${\mathrm{Br}}_{0.3}$\ifmmode\cdot\else\textperiodcentered\fi{}${({\mathrm{H}}_{2}\mathrm{O})}_{n}$ show a Drude-type optical reflectivity for light polarized parallel to the crystal axis. The energy of the plasma edge indicates a metallic density of free car…
Six measurements of $^{114}\mathrm{In}$ diffusion in single crystals of 99.999% pure Al have been made in the range 440-660 \ifmmode^\circ\else\textdegree\fi{}C. A least-mean-squares analysis of the data leads to the expression $D=1.16{e}^{\frac{\ensuremath{-}(1.27\mathrm{eV})}{\mathrm{kT}}}$ ${\mathrm{cm}}^{2}$${\mat…
The difficulty of making electrical contact to, and obtaining meaningful data from, strongly anisotropic layer structures is discussed and clarified for MoS 2 . An analysis of this anisotropy is presented and used to explain experimental results obtained from natural crystals of molybdenite.It is shown that annealed c…
Two experiments of the successive vaporization type, five mass spectrometric vaporization experiments, and two isomolecular exchange reaction experiments were undertaken to resolve discrepancies in the thermodynamics of the titanium—oxygen system. The first two types of experiments confirmed that Ti3O5(s) is the congr…
Neutron double-differential cross sections of four polycrystalline samples of $\mathrm{Zr}{\mathrm{H}}_{x}$ with hydrogen-to-zirconium ratios ($x$) of 0.54, 1.03, 1.56, and 2.00 have been measured with high-energy resolution by downscattering of neutrons from initial energies of 171.5 and 244.8meV. Clear evidence of s…
The second-order optical susceptibilities of III-V and II-VI compounds are calculated on the basis of a charge-transfer model and shown to be in close agreement with the experimental values. The importance of the $d$-electron contributions to the determination of the sign of the nonlinear susceptibilities of polar sem…
The infrared spectra of polycrystalline LiBH 4 and LiBD 4 have been recorded in the region 4000–50 cm −1 at 80 °K. Raman spectra of polycrystalline samples were also recorded at this temperature. The spectra of the [Formula: see text]and [Formula: see text]lattice vibrations are consistent with symmetrically equivalen…
The static dielectric constant $\ensuremath{\epsilon}$ of KTa${\mathrm{O}}_{3}$ has been measured from 4 to 300K and at pressures up to 26kbar. The temperature ${T}_{1}$ at which $\ensuremath{\epsilon}$ deviates from a Curie-Weiss law, attributed to quantum effects, is found to increase with increasing pressure with a…
The method of tight binding has been applied to calculate the energy band structure of the lithium fluoride crystal. As initial approximations to the ultimate self-consistent---field (SCF) calculations, two different overlapping atomic potentials were employed, one formed by a superposition of the potential of the neu…
We have observed strong anharmonic coupling between the pseudospin "tunneling" mode and an optical mode of ${\ensuremath{\beta}}_{2}$ symmetry in the paraelectric phase of cesium dihydrogen arsenate. At temperatures above ${T}_{c}=143$ \ifmmode^\circ\else\textdegree\fi{}K this interaction is manifest as an antiresonan…
Photoemission and secondary electron emission (SEE) measurements have been used to investigate the band structure of graphite. The energy distribution curves obtained from both types of measurements reveal identical features for those transitions to conduction-band states occurring up to 5 eV above the vacuum level. T…
Using both infrared and laser Raman techniques the low temperature vibrational spectra of KBH 4 , KBD 4 , NaBH 4 , and NaBD 4 have been recorded. The spectra of the external lattice vibrations are consistent with the following borohydride ion site symmetries: T d for potassium borohydride and D 2d for sodium borohydri…
Some electronic defects and the associated photoelectronic processes in Th${\mathrm{O}}_{2}$ are analyzed by utilizing the data from thermoluminescence (TL) and EPR measurements on a number of rare-earth-doped and undoped single crystals from various sources. (The EPR measurements were made by others.) Some fluorescen…
For the first time, phosphorescence has been observed from and clearly assigned to the molecular triplet of several metallophthalocyanine (Pc) molecules. The Pc's of Pt, Pd, Cu, Zn, and Cd have O–O bands in solution (77°K) at the extraordinarily low energies of 10 590, 10 100, 9390, 9150, and 9120 cm−1, respectively,…
Using a simple Hamiltonian of the tight-binding type, rigorous bounds are derived for the density of states of a tetrahedrally bonded solid. These include inner bounds which define a band gap between occupied and unoccupied states. The derivation uses only the assumed perfect coordination of nearest neighbors, and so…
The energy distribution and angular dependence of secondary electrons generated by the impact of 100–2000-eV electrons on He, N2, and O2 and by the impact of 500-eV electrons on Ne, Ar, Kr, Xe, H2, NO, CO, H2O, NH3, CH4, C2H2, and CO2 have been measured over the 4–200-eV range. The measurements were made in a crossed-…
Dispersion relations of phonons propagating along three symmetry directions in calcium oxide have been measured by the triple axis neutron spectrometer method. The experimental results have been interpreted in terms of a shell model showing that the electronic polarizability of both ions must be taken into considerati…