Li5ReN4, ein Lithium–Nitridorhenat(VII) mit anti‐Flußspat‐Überstruktur

Li₅ReN₄, a Lithium Nitridorhenate(VII) with Anti Fluorite Superstructure At 673 K Li₃N reacts with Re powder under N₂ to pale yellow, microcrystalline Li₅ReN₄. The structure determination is based on X‐ray powder data: Spacegroup Pmmn (No. 59), Z = 2, a = 6.719(1) Å, b = 6.627(1) Å, c = 4.893(1) Å. The compound crystallizes in an anti‐type of a fluorite superstructure. In comparison to the aristo‐type – CaF₂ – in Li₅ReN₄ tetrahedral interstices of a ccp nitrogen partial structure are unoccupied. The distribution of these vacancies is related with its orthorhombic distortion. Under aspects of crystal chemistry the tetragonally crystallizing compounds Li₆MN₄ with M = Mo, W result by partially filling up such vacancies.     

Relativistic effect of pseudospin symmetry and tensor coupling on the Mie-type potential via Laplace transformation method

A relativistic Mie-type potential for spin-1/2 particles is studied. The Dirac Hamiltonian contains a scalar S（r） and a vector V（r） Mie-type potential in the radial coordinates, as well as a tensor potential U（r） in the form of Coulomb potential. In the pseudospin（p-spin） symmetry setting Σ = Cps and Δ = V（r）, an analytical solution for exact bound states of the corresponding Dirac equation is found. The eigenenergies and normalized wave functions are presented and particular cases are discussed with any arbitrary spin–orbit coupling number κ. Special attention is devoted to the caseΣ = 0 for which p-spin symmetry is exact. The Laplace transform approach（LTA） is used in our calculations. Some numerical results are obtained and compared with those of other methods.     

Photoelectric studies of gallium monosulfide single crystals

Photoconductivity (PC) studies were carried out on GaS single crystals prepared from melt by directional solidification. We studied the effect of light intensity, applied voltage on both the PC and the lifetime of carriers. The V-I characteristics and the absorption spectra were checked for different sample thickness. The present investigation was extended to study the spectral distribution of the photocurrent for GaS. It was found that the photocurrent curves are practically independent of the bias voltage. The energy gap for GaS was found to be 2.5 eV.     

Nanoparticulate cathode thin films with high electrochemical activity for low temperature SOFC applications

Nanocrystalline La_0.6Sr_0.4Co_0.2Fe_0.8O_3 − δ (LSCF) and La_0.25Ba_0.25Sr_0.5Co_0.2Fe_0.8O_3 − δ (LBSCF) with a high specific surface area (~ 40 m²/g) were synthesized by spray pyrolysis. The as prepared powder was characterized by X-ray diffraction, nitrogen adsorption, and high-resolution electron microscopy. Water-based dispersions of pure LSCF, LBSCF and mixtures containing gadolinium doped ceria (GDC) with agglomerate sizes of approx. 50 nm were prepared by application of ultrasonic energy. Spin coating was employed to prepare porous thin films. The thickness of the films (≤1 μm) was more than 10–20 times lower than conventional cathode layers. The interfacial polarization resistances of LBSCF cathodes are 19, 38, and 101 mΩ cm² at 650, 600, and 550 °C, respectively. The high performance is attributed to the nanometer-sized grain dimensions, the nanoporosity, and the large specific surface area within the cathode layer. The novel approach of preparing nanoparticulate thin film cathodes suggests strong benefit for Micro Solid Oxide Fuel Cells operating below 500 °C.     

One-pot solvent-free synthesis of 2,3-dihydro-2-substituted-1H-naphtho[1,2-e][1,3]oxazine derivatives using Fe3O4@nano-cellulose/TiCl as a bio-based and recyclable magnetic nano-catalyst

Molecular Diversity - The present study describes an efficient and environmentally benign protocol for the synthesis of 2,3-dihydro-2-substituted-1H-naphtho[1,2-e][1,3]oxazine derivatives....     

Analysis of a Drop-Push Model for Percolation and Coagulation

In this article, we study a type of a one dimensional percolation and coagulation model whose basic features include a sequential dropping of particles on a substrate followed by their transport via a pushing mechanism. Particles are dropped onto a one dimensional lattice and carry out a random walk until they encounter an empty site where they become stuck. In such a model, calculating the probability of coalescence of two arbitrary clusters of particles, we embed a certain coalescence process, called the additive Marcus-Lushnikov process, which converges to a particular solution of the Smoluchowski equation. Throughout, we study the asymptotic behavior of the arrangement of empty sites and of the total displacement of all particles as well as the partial displacement of some particles, when the number of sites and of the particles tend to infinite.     

Catalytic reduction of organic dyes at gold nanoparticles impregnated silica materials: influence of functional groups and surfactants

Gold nanoparticles (Au NPs) in three different silica based sol–gel matrixes with and without surfactants are prepared. They are characterized by UV–vis absorbance and transmission electron microscopic (TEM) studies. The size and shape of Au NPs varied with the organo-functional group present in the sol–gel matrix. In the presence of mercaptopropyl functionalized organo-silica, large sized (200–280 nm) spherical Au NPs are formed whereas in the presence of aminopropyl functionalized organo-silica small sized (5–15 nm) Au NPs are formed inside the tube like organo-silica. Further, it is found that Au NPs act as efficient catalyst for the reduction of organic dyes. The catalytic rate constant is evaluated from the decrease in absorbance of the dye molecules. Presence of cationic or anionic surfactants greatly influences the catalytic reaction. The other factors like hydrophobicity of the organic dyes, complex formation of the dyes with anionic surfactants, repulsion between dyes and cationic surfactant, adsorption of dyes on the Au NPs also play important role on the reaction rate.