Materials Literature
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The valence states of Fe and the charge compensation by oxygen vacancies of Fe57-doped BaTiO3 are studied by the Mössbauer effect and gravimetry as a function of O2 partial pressure. By preparational and analytical effort, it is ensured that the dopant homogeneously substitutes Ti4+ in the BaTiO3 lattice (up to 1.2 mo…
The perovskites Pb(Sc1/2Nb1/2)O3 and Pb(Sc1/2Ta1/2)O3 can be obtained in a disordered state by means of a synthesis at high temperature (1250 to 1500°C). Ordering of the trivalent and pentavalent ions occurs during annealing at lower temperatures. The kinetics of this ordering process are investigated by means of X-ra…
Electro-optical measurements of the electric field along solid insulator/vacuum interfaces have been made to determine the mechanisms associated with fast (ns) insulator flashover. Data showing the temporal and spatial performance of the insulator surface fields prior to and at flashover are presented. The results sho…
By modifying the surface plasma mode on a bare metal surface with an ultrathin film deposited on the metal, we measured the film thickness by attenuated total reflection (ATR). Various factors causing measurement errors are estimated with numerical examples. As a result, for example, it is shown that for some thicknes…
The vibrational averaging theory of Kern and Matcha is extended, at the harmonic level of approximation, to the case where the molecular property under investigation can itself lead indirectly to a perturbation of the vibrational levels of the molecule. It is found that contributions arising from this perturbation can…
The observation of a frequency-dependent conductivity ($\ensuremath{\sigma}$) and dielectric constant ($\ensuremath{\epsilon}$) in Nb${\mathrm{Se}}_{3}$ is reported. In both charge-density-wave phases a strong frequency dependence and huge dielectric constant are observed below 100 MHz, with greatest effects observed…
The heat capacities of LaNi5, α-LaNi5H0.36, and β-LaNi5H6.39 were measured from 5 to 300 °K, and in the case of LaNi5 also from 300 to 350 °K. Various special techniques and unusual circumstances involved in the measurements and calculations are described. A slight enhancement of the heat capacity of β-LaNi5H6.39 was…
While thin films of TiN and TaN are good diffusion barriers in contact structures which use nickel or gold as a top layer, they show poor barrier properties if aluminum is used as a top layer. It is shown in this letter that stable high-temperature contacts on silicon semiconductor devices can be produced by using int…
Optical spectra of the elpasolite hexachloride compounds Cs2NaLnCl6, where Ln represents one of the lanthanide ions, are analyzed with a crystal-field Hamiltonian of Oh symmetry. Crystal-field parameters, Bnm, are found that minimize the rms deviation between calculated and experimental energy levels for Ln=Ce, Pr, Nd…
The complete determination of the crystal structure of solid nitromethane has been obtained from single crystal x-ray diffraction and neutron powder diffraction data. The structure is orthorhombic, space group P212121 with a=5.1832 Å, b=6.2357 Å, c=8.5181 Å at T=4.2 K, and Z=4. Two models were used to describe the the…
Extensive electrical resistivity and Seebeck-coefficient measurements are reported for ${({\mathrm{V}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x})}_{2}{\mathrm{O}}_{3}$ single-crystal alloys in the range $0\ensuremath{\le}x\ensuremath{\le}0.1$. For $0\ensuremath{\le}x\ensuremath{\le}0.005$ a metal-insulator transition is enc…
Theoretical studies of the vibrational excitations of charged solitons in polyacetylene are reported. Two strongly infrared active modes, derived from bulk optical phonons, are associated with these defects and we suggest the presence of a third, as yet unobserved, infrared-active mode in the acoustic phonon regime.
The in situ temperature coefficient of resistance of palladium films in the thickness range 25-370 AA is reported. The Fuchs theoretical curve agrees with experimental alpha versus t curve for a specularity parameter p=0.88. The thickness dependence of the temperature coefficient of resistance gives the bulk mean free…
The effects of oxidation on the electrical conduction of low- and high-density polyethylene (LD-PE and HD-PE) have been studied. It has been found that oxidation enhances the carrier mobility in LD-PE, but lowers that in HD-PE. A qualitative explanation of these opposing effects is given, based on the assumption that…
The behaviour of systems which exhibit both commensurate and incommensurate phases is studied for a discrete lattice model. Close to the lock-in transition the incommensurate phase is shown to be well described by a soliton theory in which the solitons may be pinned to the lattice. This pinning effect leads to a 'devi…
The Raman spectra of the layer-type magnetic materials of formula (CH 2 ) n (NH 3 ) 2 CuCl 4 , n=2, 3 and 5, have been measured at various temperatures above and below their respective magnetic ordering temperatures and in a magnetic field up to 10 kOe. For all three crystals, the Raman spectra excited at energies ran…
For pt.I see ibid., vol.13, p.4671 (1980). The theory of boundary scattering of phonons in crystals of small size that also display substantial point-defect scattering is summarised. It is then applied to the analysis of the previously presented experimental results on Ge 30 Si 70 at 300K and 600K and on Ge 70 Si 30 a…
The thermal conductivity of polycrystalline Ge 30 Si 70 has been determined at and above room temperature for samples having a wide range of porosity and mean grain diameter. It has been established that the thermal conductivity at 300K is completely dominated by the lattice contribution and that its value varies line…
Radiological surveys at some former uranium ore processing facilities have indicated the presence of significant quantities of 219 and its daughters. Due to the extremely short half-life of actinon, it has traditionally been assumed that its activity is negligible in comparison with 222Rn. This paper discusses the pro…
Ralf Conrad, Wolfgang Seiler; Photooxidative production and microbial consumption of carbon monoxide in seawater, FEMS Microbiology Letters, Volume 9, Issue 1,