Inelastic neutron scattering study of the lattice dynamics of LaCoO3

The lattice dynamics of lanthanum cobaltite is investigated using the coherent inelastic neutron scattering technique in a temperature range from 10 to 536 K, in which two phase transitions are observed: a change in the Co spin state and a metal-insulator phase transition. The measurements were performed using an IN8 high flux thermal neutron triple-axis spectrometer (ILL, Grenoble). Temperature changes in the phonon dispersion curves caused by the rearrangement of the electron and spin subsystems are found.     

Microscopic structure of <Superscript>126</Superscript>Ba in IBM terms

The yrast band of the nonaxially deformed ¹²⁶Ba nucleus is described by the Hamiltonian of the interaction boson model. Its parameters are calculated on the basis of a microscopic theory within a spherical mean field, and residual interactions that include pairing and multipole factorized forces. Each state of the yrast band is considered independently of others, allowing us to study variations in the superfluid properties of the nucleus and the quasiparticle structure of collective D phonons with spin. The calculations are performed in an expanded configuration space that includes the collective D phonon states, and noncollective states in which an additional phonon of positive parity whose spin assumes values of 0 to 6 is present along with the D phonons. It is shown that the collective Hamiltonian parameters cannot be reproduced without considering the effect of the noncollective states.     

The low-temperature macroscopic phase separation in La<Subscript>0.5</Subscript>Ba<Subscript>0.5</Subscript>CoO<Subscript>3 − δ</Subscript> cobaltite

La_0.5Ba_0.5CoO_2.87 has been characterized with neutron and synchrotron powder diffraction and magnetization measurements. This compound was shown to have a cubic crystal structure at temperatures above 200 K whereas slightly above the Curie point T _c ∼ 170 K the structural separation into two different pseudocubic phases gradually develops upon cooling. The structural transformation is reversible. At 2 K the sample consists of G-type antiferromagnetic oxygen-poor and ferromagnetic oxygen-rich phases (approximately 33 and 66%, respectively).     

Effect of hydrothermal conductivity on thermal resistance of porous materials

Results of experimental study for dependency of thermogradient coefficient on moisture in porous material have been presented. These experimental data were used for estimating the effect of hydrothermal conductivity on heat transfer.     

Platinum- and palladium-containing carbon nanomaterials as catalysts for hydrogenation and hydrogenating amination

The catalytic activity of the carbon nanomaterials containing platinum and palladium in the model reactions of liquid-phase hydrogenation of nitrobenzene and hydrogenating amination was investigated. The catalytic systems based on nanodiamonds are more efficient than platinum-containing fullerene black, multi-walled nanotubes, and carbon nanofibers.     

Study of damage in plastics by optical methods

Conclusion Inclined exposure to radiation, coupled with measurement of the intensity of light fluxes transmitted in the forward direction and reflected from crazes and subsequent interpretation of the results of the measurements using a model that assumes one-time reflection and the presence of a certain functional dependence of the refractive index of the craze along its length, is the most effective of the optical methods that we examined for the investigation of the damage sustained by transparent polymers prone to craze formation. Based on a series of similar analyses, it is possible to evaluate the variation in such craze parameters as total length, form, and degree of loosening in the fatigue process.Translated from Mekhanika Kompozitnykh Materialov, No. 6, pp. 1081–1090, November–December, 1991.     

Reaction of 4,5-dimethyl-2-(2-oxo-1,2-diphenylethoxy)-1,3,2-dioxaphospholane with hexafluoroacetone: formation of isomeric caged phosphoranes with phosphorus–carbon and phosphorus–oxygen bonds

Russian Chemical Bulletin - 4,5-Dimethyl-2-(2-oxo-1,2-diphenylethoxy)-1,3,2-dioxaphospholane bearing the carbonyl group at the γ-position to the phosphorus atom reacted with hexafluoroacetone...     

The Role of Interphase Interactions in Electrosynthesis of Composites Based of Graphene Oxide and Poly-<Emphasis Type="Italic">o</Emphasis>-Phenylenediamine

The formation of the composite of reduced graphene oxide (RGO) with poly-o-phenylenediamine (PPD) on the surface of SnO₂-coated conducting glasses (CG) is studied by the methods of voltammetry, atomic force microscopy (AFM), electron microscopy (SEM) with energy-dispersive X-ray spectroscopic (EDXS) microanalysis, and electron spectroscopy, When a CG with deposited graphene oxide is placed into aqueous solution of o-phenylenediamine (OPD), the monomer is strongly fixed in the GO matrix, as confirmed by EDXS data. The further redox interaction in the two-phase system GO–OPD initiates polymerization of OPD in the GO film. When anodic polarization in switched on, the oxidation and the further polymerization of OPD go on, while GO is reduced to RGO as a result of mediated reaction to yield the RGO–PPD composite even in the absence of cathodic polarization. The electron spectra of composites reveal the presence of an absorption band close to absorption of individual PPD. According to AFM and SEM data, OPD incorporated into the composite structure keeps RGO from being folded in acidic media. As the time of impregnation increases, the degree of reduction of GO to RGO changes, which is reflected in the surface morphology and the amount of monomer in the composite (RGO–PPD)-1. The coating becomes black, which is typical of RGO, and its conductivity increases by 4–5 orders of magnitude.     

Synthesis and electrochemical properties of nanocomposites containing poly(3,6-bis(phenylamino)-2,5-dichlorobenzoquinone and multiwalled carbon nanotubes

The method of synthesizing nanocomposites based on multiwalled carbon nanotubes and a new polymer poly(3,6-bis(phenylamino)-2,5-dichlorobenzoquinone) containing polyaniline chains with electroactive substituents in the N-position is developed, and the electrochemical properties of the composites are studied. The in situ oxidative polymerization of N-substituted aniline performed in the presence of multiwalled carbon nanotubes makes it possible to design an organized, effective structure of the conducting composite material with enhanced electrochemical capacity and stable capacity parameters during long cycling in protic (1 mol/L H₂SO₄) and aprotic (1 mol/L LiClO₄ in propylene carbonate) electrolytes.