Thermodynamically stable fractal-like domain structures in magnetic films

A fractal-like structure of the domain boundaries was revealed in “overcritical” uniaxial Permalloy magnetic films. The fractal dimension of domain boundaries at the film surfaces was determined as a function of the film thickness. It is shown that the phase transition between the two possible types of fractal-like structures is accompanied by a jump in fractal dimension.

     

Polymorphism of biperiodic stripe domain structures

Magnetic-field-induced polymorphism of biperiodic stripe domain structures of films with a positive anisotropy constant and easy axis parallel to the normal to the surface is studied. A symmetry classification of the observed types of domain structures is performed, and the phase diagram of the films in the (H _⊥, H _∥) plane, where H _⊥ and H _∥ are, respectively, the components of the magnetic field vector perpendicular and parallel to the normal to the surface, is determined. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 9, 701–706 (10 May 1998)     

Analogue of the Kapitza pendulum based on a compass arrow in an oscillating magnetic field

Magnetic analogues of the Kapitza pendulum have been implemented in systems formed by one or two compass arrows in an oscillating magnetic field. The complete state diagrams for the systems studied have been determined. It is experimentally confirmed that two dynamically stabilized equilibrium states coexist in the system of two magnetic arrows.     

Solvent effects in the polymerization of propylene catalyzed by octahedral complexes

The effect of solvents (toluene, dichloromethane, and hexane) was studied on the polymerization of propylene with the octahedral complexes bis(trimethylsilyl)benzamidinate titanium dichloride(a), bis(acetylacetonate) titanium dichloride(b), and bis(diethylamino) titanium di‐2‐(diphenylphosphanylamino)pyridine as catalytic precursors and methylalumoxane as the cocatalyst. For comparison, the polymerization was also performed in plain liquid propylene without the addition of any solvent. The obtained polymers were fractionated by refluxing hexane. The activity of the complexes and the molecular weights and tacticities of the whole polymers and their different fractions were the studied parameters. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4505–4516, 2005     

Field-induced phase transitions in magnetooptical films with a small positive anisotropy constant

We study phase transitions induced by a static magnetic field in magnetically uniaxial films with a small positive anisotropy constant. The phase diagram of these objects is determined in the H _∥-H _⊥ plane, where H _∥ and H _⊥ are, respectively, the components of the magnetizing field along and perpendicular to the surface normal. The stability boundary is located for all of the main types of domain configurations observed: a simple stripe domain structure, a stripe domain structure with periodic bending by surface distortions in the profile of the domain walls, and hexagonal lattices of cylindrical magnetic bubbles. Zh. éksp. Teor. Fiz. 111, 283–297 (January 1997)     

Features of the α-γ transition in a low-pressure rf argon discharge

It is found that the region for the stable existence of the aregime of a radio-frequency (rf) discharge is bounded not only on the moderate-pressure side, but also on the low-pressure side. One feature of the α-γ transition in a low-pressure rf discharge is that the criterion for breakdown of the electrode sheath is not satisfied. It is shown that at low pressures the α-γ transition of an rf argon discharge takes place abruptly and exhibits hysteresis. At intermediate pressures the α-γ transition is continuous and lacks jumps; negative differential conductivity appears, double layers form, and nonmonotonic behavior of the plasma density is observed at the center of the discharge. The role of stochastic (collisionless) electron heating in sustaining an rf discharge at intermediate gas pressures is discussed. Zh. Tekh. Fiz. 68, 52–60 (May 1998)     

Nonlinear magnetoelectric effects in an isotropic disordered dielectric in nonuniform fields

Theoretical analysis allowing experimental observation of nonlinear magnetoelectric effects in isotropic disordered dielectric in nonuniform electric and magnetic fields is carried out.     

Order-disorder-order phase transitions between metastable modifications of biperiodic stripe domain structures

Magnetooptic methods were used to observe the existence of magnetic-field-induced order-disorder-order phase transitions between metastable modifications of biperiodic stripe domain structures in magneto-uniaxial iron garnet films having a low positive anisotropy constant. It is shown that the loss of long-range order in the system in a certain range of variation of the field is caused by the loss of correlation between the quasi-harmonic surface distortions of the profile of neighboring domain walls.     

Oxidative dehydrogenation of ethylbenzene over a charcoal catalyst

The oxidative dehydrogenation of ethylbenzene over a charcoal catalyst has been studied by the pulse technique. The styrene yields for the oxidation of ethylbenzene by gaseous oxygen and upon the interaction of ethylbenzene with oxygen adsorbed on charcoal are shown to be the same.

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Interaction of closo-decaborate anion B10H 10 2− with iminium salts

The interaction of closo-decaborate anions with iminium salts, either formed in situ or introduced into the reaction as individual compounds, has been studied. The reaction leads to products with an exopolyhedral boron-nitrogen bond. The formation of compounds with exopolyhedral boron-chlorine and boron-carbon bonds is also possible. The crystal structures of [NMe₂(CH₂Cl)]₂B₁₀H₈ and 3-CH₃-2,8-[NMe₂(CH₂Cl)]₂-7-ClB₁₀H₆ have been studied.