Electron transport in carbynes modified under high pressure

The studies of hopping conductivity in carbynes modified under high pressure are reviewed. Experimental data are presented on the dc and ac conductivities, thermopower, magnetoresistance, and Hall effect. The results obtained are discussed within the framework of a model that takes into account the substantially nonuniform distribution and clusterization of sp² bonds in the carbyne sp matrix.     

C-oriented SrBi2Nb2O9 films grown on YBa2Cu3O7−δ /SrTiO3 and NdGaO3

Epitaxial SrBi₂Nb₂O₉ films were grown by laser ablation on (001)YBa₂Cu₃O_7?δ /(100)SrTiO₃ and (001)NdGaO₃, with c axis normal to the substrate plane. The SrBi₂Nb₂O₉ films were grown in a layer-by-layer regime on NdGaO₃ substrates in 25-Å steps at a condensation temperature of 700 °C. Microinclusions of secondary phases and a-oriented grains were observed to exist on the surface of (001)SrBi₂Nb₂O₉ films grown on (001)YBa₂Cu₃O_7?δ /(100)SrTiO₃. The dielectric permittivity of the SrBi₂Nb₂O₉ films measured along the c axis is 123 (T=300 K, f=100 kHz), and tan δ≈0.04.     

P31 nuclear magnetic relaxation,self-diffusion,and viscosity of tri-n-butylphosphate solutions in inert solvents

Conclusions The joint investigation of spin—lattice relaxation, self-diffusion, and viscosity makes it possible to come to some qualitative conclusions concerning the usefulness of the explicit expressions for correlation times in depicting the concentration dependences of time T₁ in two-component mixtures of liquids. Parameter (T₁)^–1 varies nonlinearly with concentration for chemically noninteracting liquids. However, this cannot serve as an indication of the formation of associations in the solution since possible small conformational changes in the molecule containing the relaxing nuclei will affect the intramolecular contribution to the relaxation because of the strong dependence of this contribution on the effective distance between the dipole-interacting nuclei in complex molecules.The dependence of the conformation of the TBP molecule on the type and concentration of the solvent could also be a cause affecting the reactivity of the extractant and the variation in the distribution coefficients during the extraction of metals with tributyl phosphate solutions.The authors thank T. Ya. Vereshchagina for preparing the solutions and V. E. Samsonov for helping with the measurements.Translated from Zhurnal Strukturnoi Khimii, Vol. 13, No. 6, pp. 1008–1015, November–December, 1972.     

Interaction of iron atoms with the oxidized silicon surface

The room-temperature interaction of iron atoms with the oxidized Si(100)2×1 surface at a coverage from a submonolayer to four monolayers is studied by core-level photoelectron spectroscopy using synchrotron radiation. Computer simulation of the Si 2p core electron spectra demonstrates that iron atoms penetrate beneath the silicon oxide even at room temperature. This process causes the initial silicon phases at the SiO_x/Si interface to disappear; gives rise to a complex ternary phase involving Fe, O, and Si atoms; and favors the formation of a Fe-Si solid solution at the interface.     

Low-temperature anomalies of the Hall coefficient in FeSi

The temperature dependence of the Hall coefficient in the interval 1.8–300 K is investigated in detail in high-quality single-crystal samples of a Kondo insulator — iron monosilicide. It is established that the parameter R _H (T,H=12.5 kOe) changes sign twice in the temperature interval employed, and at temperatures below T _m ≈7 K an anomalous (magnetic) component appears in the angular and field dependences of the Hall voltage. The results of the experimental investigations of R _H (T,H ₀ ) in FeSi are discussed on the basis of the phase diagram in the model of an excitonic insulator. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 10, 774–778 (25 November 1998)     

Problems of classical and quantum-gravitational collapse X. Creation of massless scalar particles by the torsion field

The effect of the creation of massless scalar particles by a cosmological torsion field is considered. It is shown that the particles produced make an initially isotropic universe anisotropic.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 105–109, September, 1978.In conclusion, the authors thank A. A. Grib and S. G. Mamaev for useful discussions, and the participants in the scientific seminar conducted by Prof. D. D. Ivanenko for discussion for the results of this paper.     

Electronic structure of the thiabenzene anion

Chemistry of Heterocyclic Compounds -     

Formation of ultrathin magnetic cobalt films on the Si(111)7 × 7 surface

The phase composition, electronic structure, and magnetic properties of ultrathin cobalt films (no thicker than 20 ?) applied on a Si(111)7 × 7 surface at room temperature are studied by high-resolution photoelectron spectroscopy using synchrotron radiation and magnetic linear dichroism. It is shown that, as the cobalt thickness increases, first interface cobalt silicide and then an island (discontinuous) film of silicon-in-cobalt solid solution form on the silicon surface. A metal cobalt film starts growing after the deposition of a ∼7-?-thick Co layer. It is found that the ferromagnetic ordering of the system, which is characterized by surface magnetization, sets in after the deposition of a ∼6-?-Co layer at the stage of Co-Si solid solution formation.