Pi-donor BETS based bifunctional superconductor with polymeric dicyanamidomanganate(II) anion layer: kappa-(BETS)2Mn[N(CN)2]3

Crystals of the bis(ethylenedithio)tetraselenafulvalene (BETS) radical cation salt with dicyanamidomanganate(II) anion, kappa-(BETS)2Mn[N(CN)2]3, were synthesized, which combine conducting and magnetic properties at ambient pressure and are superconducting (Tc approximately/= 5 K) at a moderate pressure of 0.3 kbar.     

Anodic synthesis and properties of polyaminothiazole

The possibility of electrooxidative polymerization of 2-aminothiazole in aqueous and organic media is studied using the cyclic voltammetry method. Anodic synthesis conditions are found that provide the polyaminothiazole conducting film synthesis on platinum and tin dioxide electrodes. IR and electron spectroscopy studies show that the polymer synthesized on the electrode surface contains fragments of π-conjugated bonds that provide optical absorption in the visible region and electrochemical activity of the film. A scheme is suggested for the reactions of oxidative coupling of 2-aminothiazole.     

New multicomponent organic semiconductors based on ET with polymeric Anions: α″-(ET)2N(CN)2·2H2O and α‴-(ET)6(NO3)3·2C2H5O2N3

New multicomponent radical cation salts derived from bis(ethylenedithio)tetrathiafulvalene (ET) were prepared: bis(ethylenedithio)tetrathiafulvalene dicyanamide dihydrate α″-(ET)₂N(CN)₂·2H₂O and bis-(ethylenedithio)tetrathiafulvalene nitrate α?-(ET)₆(NO₃)₃·2C₂H₅O₂N₃ containing two biuret molecules (C₂H₅O₂N₃). The crystal structures of the compounds were determined, and their conducting properties were examined. Both salts have layered structures in which radical cation layers alternate with nonconducting anionic layers. The radical cation layers in the salts α″-(ET)₂N(CN)₂·2H₂O and α?-(ET)₆(NO₃)₃·2C₂H₅O₂N₃ are packed in the α″ and α? fashion, respectively. Anionic layers consist of polymeric chains formed by hydrogen bonding between [N(CN)₂]? anions and water molecules in α″-(ET)₂N(CN)₂·2H₂O or between NO?₃ anions and biuret molecules in α?-(ET)₆(NO₃)₃·2C₂H₅O₂N₃. Both salts show semiconductor conductivity.     

Magnetic and Magnetoelectric Properties of Scandoborate NdSc3(BO3)4

Physics of the Solid State - Trigonal neodymium scandoborate NdSc3(BO3)4 single crystals have been grown by the batch flux method using bismuth trimolybdate and their magnetic and magnetoelectric...     

Three-dimensional numerical simulation of the operation of a rotating-detonation chamber with separate supply of fuel and oxidizer

A three-dimensional numerical simulation of the operation of an annular rotating-detonation chamber (RDC) with separate supply of combustible mixture components, hydrogen and air, is performed, and the calculation results are compared to available experimental data. The model is based on a system of time-dependent Reynolds-averaged Navier-Stokes equations complemented with a turbulence model and continuity and energy equations for a multicomponent reacting gas mixture. The system is solved using a coupled algorithm based on the finite volume method and particle method. Calculations are for the first time performed with allowance for effects of finite rates of turbulent and molecular mixing of the combustible mixture components with each other and with reaction and detonation products. The calculation results compare favorably with the experimental data obtained at the Lavrentyev Institute of Hydrodynamics of the Siberian Branch of the Russian Academy of Sciences.     

Features of the structure, microstructure, and magnetic properties of manganese-aluminum spinels obtained in various thermal treatment conditions

The structural, microstructural, and magnetic properties of aluminum-manganese oxide in the ratio Mn: Al = 1: 1 in the well-crystallized and nanoheterogeneous states have been investigated. This oxide is obtained under various thermal treatment conditions and at different partial pressures of oxygen. The composition and cation distribution of the manganese and aluminum ions in spinel sites are determined. It is shown that the studied compound is a ferrimagnet with the Curie point T _C ≈ 26 K.     

Narrowing the length distribution of Ge nanowires

Synthesis of nanostructures of uniform size is fundamental because the size distribution directly affects their physical properties. We present experimental data demonstrating a narrowing effect on the length distribution of Ge nanowires synthesized by the Au-catalyzed molecular beam epitaxy on Si substrates. A theoretical model is developed that is capable of describing this puzzling behavior. It is demonstrated that the direction of the diffusion flux of sidewall adatoms is size dependent and has a major effect on the growth rate of differently sized nanowires. We also show that there exists a fundamental limitation on the maximum nanowire length that can be achieved by molecular beam epitaxy where the direction of the beam is close to the growth axis.     

Laplace series expansion of the potential of a homogeneous circular torus

The external potential of a homogeneous circular torus is represented by a series expansion in spherical functions (Laplace series). Exact analytical formulas are derived for the coefficients of this series, which can be expressed in terms of Legendre polynomials depending only on the geometrical parameter of the torus. The convergence of the series is proved and the radius of convergence is determined. The resultant expressions are verified numerically.     

On diffusion lengths of Ga adatoms on AlAs(111) and GaAs(111) surfaces

An expression for calculating the effective diffusion length from the measured values of the height and density of nanowhiskers is derived in terms of the diffusion growth model. From experimental data for GaAs nanowhisker MBE growth, the diffusion lengths of Ga adatoms on the GaAs(111) and AlAs(111) surfaces are evaluated. Under typical growth conditions, the value of the Ga diffusion length is found to be about several hundreds of nanometers.