Electrical properties of novel mixed-conducting oxides

Zirconia-titania-yttria oxide solutions are novel mixed-electrical conductors in which both oxygen-ions and electrons are mobile. A determination of their electrical properties is necessary for an evaluation of their potential applications. Single-phase oxide solutions have been prepared and characterized. Phase studies indicates extensive solid solution of titania into zirconia stabilized with 12 mol % yttria. The observed decrease in lattice parameter with increasing titania concentration in these oxide solutions indicates that titanium cations substitute for the zirconium cations in the fluorite lattice. The lattice and grain-boundary electrical conductivities have been determined using impedance spectroscopy at temperatures between 400 and 950 °C.     

Dynamics in a discontinuous field: The smooth Fermi piston

In this paper we examine a version of the Fermi piston with a discontinuous, but nonimpulsive, periodic driving force. The dynamics of a particle moving in one spatial dimension are studied using a combination of numerical and analytical techniques. The configuration space of the particle is divided into two regions of constant acceleration that are of equal magnitude and opposite direction. The point of discontinuity F(t) dividing the regions changes periodically in time. The method of surface-of-section is used to study the phase space (phi(n), v(n)), where phi(n) is the phase of the driving function and v(n) is the velocity of the particle at the nth encounter between the particle and boundary. We show that it is not possible to stochastically drive up the energy indefinitely except for the cases where F is discontinuous, or dF/dt is not finite everywhere. In addition, we find a new mechanism, other than KAM tori, for segmenting the phase space. As in the KAM picture, the central cause of the new behavior is resonance between the natural period of the particle and the period of the driving force. The boundaries to diffusion for continuous driving functions result from parabolic fixed points that span the entire phase range.     

The photoelectron spectra of 4-methylene thiacyclohexane derivatives through-bond interaction

The photoelectron spectra of 4-methylene thiacyclohexane, 4-difluo romethylene thiacyclohexane and trans-2-methylene-6-thiaperhydronaphthalene are described and compared with thiacyclohexabne, difluoromethylene-cyclo hexane and cis-2-methylene-6-thiaperhydronaphthalene.A through bond interaction between the sulphur lone pair and the vinyl-π-system is observed. The results are discussed in relation with the sigma-coupled transition observed in the electronic absorption spectra of the dicyano methylene derivatives by P. Pasman.     

Vibrational spectroscopic studies of some lead silicate glasses

Results are presented of measurements on the infrared and laser Raman spectra of some lead silicate glasses of general formula (PbO)_x(SiO₂)_y.For the infrared spectra, the frequency dependence of the imaginary component of the complex dielectric constant was determined from a Kramers-Krönig analysis of the reflectance spectra of the glasses at normal incidence. Apparently the addition of small amounts of PbO to vitreous silica serves to modify the continuous three-dimensional silica network; whereas in those glasses with a high lead content, the influence of the cation, Pb²⁺, appears to lie between that of network former and network modifier.     

Alkali-metal-intercalated transition metal disulfides: A thermodynamic model

In the lithium-intercalated disulfides, Li_xMS₂, where M = Ti, Ta, a nearly linear compositional variation of the lithium chemical potential is observed throughout the composition range 0 < x < 1.0. For most sodium-intercalated disulfides, chemical potential plateaus are observed between regions exhibiting linear variations of sodium chemical potential. Our thermodynamic model indicates that the two most important factors which determine the compositional variation of the alkali metal chemical potential are the interaction energy between intercalated alkali-metal atoms and the compositional variation of the electron chemical potential. Although these two factors determine the compositional variation of chemical potential in single-phase regions, the existence of two-phase regions in the concentration range x = 0?0.15 are influenced by the energy required to expand the interlayer gap and the configurational entropy.     

Alkali metal intercalation in ternary and multinary compounds

Summary The group-IV,-V and-VI transition metal dichalcogenides are able to rapidly and reversibly incorporate significant concentrations of alkali metal ions (intercalants) within their layer structures. Because of their unusual combination of rapid mobility and high chemical stability for the intercalant, some of the alkali-metal-intercalated dichalcogenides are attractive candidates for high-energy battery electrodes. The structural characteristics of the lithium- and sodium-intercalated TiS₂ compounds, which are the most extensively investigated intercalated materials, are summarized. The chemical stability of intercalants is discussed, with an emphasis on the ternary-phase equilibria, electrochemicalcell voltage and intercalant interaction energies. Some recent investigations with multinary alkali metal intercalation compounds are then described. Paper presented at the ?V International Conference on Ternary and Multinary Compounds?, held in Cagliari, September 14–16, 1982.     

Arylation of Rhodium(II) Azavinyl Carbenes with Boronic Acids

A highly efficient and stereoselective arylation of in situ-generated azavinyl carbenes affording 2,2-diaryl enamines at ambient temperatures has been developed. These transition-metal carbenes are directly produced from readily available and stable 1-sulfonyl-1,2,3-triazoles in the presence of a rhodium carboxylate catalyst. In several cases, the enamines generated in this reaction can be cyclized into substituted indoles employing copper catalysis.