Photostimulated phenomena in relaxors

The action of illumination on the conducting and dielectric properties of lead magnoniobate was investigated. The photostimulated currents were examined and the spectral dependence of photoconductivity in the region of diffuse phase transition was obtained. It was found that the illumination affects the dielectric properties and that its action is memorized at temperatures below room temperature. The role of defect states in the formation of relaxor properties is discussed on the basis of the obtained data.     

Structure of a nonequilibrium high-frequency discharge

The problem for a one-temperature plasma is considered with allowance for the finite ionization rate. It is shown that in the developed nonequilibrium case the leading effect of ambipolar electron diffusion and ionization lag lead to a qualitatively different picture as compared with the equilibrium case. In particular, the heat release zone covers only a relatively small leading part of the ionization zone with a relatively low (n_e n_ef) electron concentration.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 161–169, May–June, 1989.The authors thank A. A. Barmin and A. G. Kulikovskii for useful discussions.     

Effect of the introduction of certain additives to the CO + H2 mixture and the scheme for the formation of alcohols higher than C1

The effect of additions of certain alcohols (methanol, ethanol, 2-propanol, and 2-butanol) to the synthesis gas on the distribution of the products during the hydrogenation of CO to alcohols at zinc-chromium oxide catalysts, promoted by various amounts of K₂O, was studied. The results demonstrate the fundamental applicability of the principal theories of chain growth proposed by other authors for copper-containing catalysts. However, it was shown that the probability of -addition is lower while that of -addition is higher at the zinc-chromium-potassium catalysts than at copper-containing catalysts, and the calculated amounts of isobutanol obtained from the data for ethanol and propanols do not agree with the experimental data. It was found that there is an isomeric transition from the secondary alcohols (2-propanol, 2-butanol) to the primary alcohols at the surface of the catalyst, and this can evidently change the normal course of chain growth in the alcohols. It can be concluded that the activity of the alcohol added to synthesis gas in reaction with other C-fragments present on the surface of the catalyst increases with increase in the number of carbon atoms in the alcohol.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 4, pp. 501–505, July–August, 1990.     

ACID SODIUM SALT OF 1H-PYRAZOLE-3,4,5- TRICARBOXYLIC ACID: SYNTHESIS,CRYSTAL STRUCTURE AND FEATURES OF INTRAMOLECULAR BONDS

Journal of Structural Chemistry - The oxidation reaction of 3,3′,5,5′-tetramethyl-1H,1′H-4,4′-bipyrazole in the HNO3–Fe3+ system unexpectedly resulted in the formation...     

The effect of clay morphology on water relaxation

The frequency dependence of the permittivity of water in calcium kaolinite (clay) is measured. It is shown that two mechanisms contribute to dipole relaxation of water. One refers to water in the free volume of pores in the clay. The other is associated with bound water covering the porous surface. Experimental data are treated in terms of a fractal model of the medium. The frequency dependence of the permittivity in a wide range of water content in the clay is accounted for theoretically.     

Component desorption effect on the material catalyticity in high-temperature multicomponent gases

The distinctive features of the formation of the catalyticity of materials with respect to atom recombination on the material surface are investigated for mixtures of different high-temperature gases under conditions of hypersonic atmospheric flight or bench setups. It is shown that in general the catalyticity constants (heterogenous recombination probabilities) of individual components determined experimentally in dissociated flows of “pure” gases are improperly used for calculating the heat fluxes to material surfaces in multicomponent gas flows, owing to differences in the occupation of the surface by atoms in pure gases and mixtures. This effect must be taken into account in interpreting the experimental data which so far have been the only source of information on material catalyticity in gas mixtures. Otherwise, the results of calculations of the heat transfer to hypersonic flight vehicles could turn out to be invalid. Examples of the possible effect of ignoring this factor on the calculated heat fluxes are presented.     

Laser-fluorescent determination of traces of cobalt in dry residues of solutions with atomization in a hot hollow cathode

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 52, No. 3, pp. 359–363, March, 1990.