The fluorite-related anion-excess structure of CeN0.222O0.667F1.333: Ordering of defect clusters

This investigation presents the preparation of CeN_0.222O_0.667F_1.333 by a solid-state reaction from a mixture of CeN:CeF₃:CeO₂ = 1:2:1.5 and its structural investigation. The samples were annealed at 900°C in platinum tubes for different times. The basic structure found by powder neutron diffraction is anion-excess fluorite-related. The unit cell is an orthorhombic distortion of the cubic fluorite cell and has the space group Abm2. The lattice constants are a = 577.71(2) pm, B = 572.76(5) pm, and c = 573.32(6) pm. The structure refined by Rietveld analysis shows that [1:0:2]- defect clusters are present. In samples prepared by longer annealing times an ordering of these clusters to larger aggregates, i.e., toward the vernier phases, was observed. This was deduced from full profile analysis without refining a structural model by comparing the instrumental resolution curves of several models.     

Estimate of the temperature field in a compressible medium

Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 1, pp. 23–26, January–February, 1992.     

Deposition of amorphous hydrogenated semiconductors by magnetron assisted silane decomposition

Magnetron assisted silane decomposition (MASD) is proposed as a method for deposition of a-Si:H and its alloys. In this method a silane containing gas mixture is passed through the magnetron plasma near a target and decomposed there. The deposition rate in the case of the c-Si target is increased 3 times compared to magnetron sputtering and film properties are changed. a-SiSn:H is obtained with a Sn target.     

A novel detection scheme for vibration monitoring using optical techniques

An all-fibre interferometer which allows the measurement of the movement (speed and distance) of a vibrating body is presented. An electronic signal processing scheme is used and this is contrasted with the measurement of velocity through an optical processing technique, which is however, more complex and expensive to implement. The overall simplicity of the electronic technique, the low cost of components and the use of an all-fibre arrangement make this an attractive system to implement where the more limited information available is sufficient for monitoring purposes.     

On a duel with time lag and arbitrary accuracy functions

This paper deals with a two-person zero-sum game called duel with the following structure: Each of two players I and II has a gun with one bullet and he can fire his bullet at any time in [0, 1], aiming at his opponent. If I or II fires at timex, he hits his opponent with probabilityp (x) orq(x), respectively. The gun of I is silent, and hence, II does not know whether his opponent has fired or not, and the gun of II is noisy with time lagt, wheret is a positive constant,i.e., if II fires at timex then I knows it at timex +t. Further, if I hits II without being hit himself before, the payoff is 1; if I is hit by II without hitting II before, the payoff is ?1; if they hit each other at the same time or both survive, the payoff is 0. This paper gives optimal strategy for each player and the value of the game.     

Azine bridged silver coordination polymers: Powder X-ray diffraction route to crystal structure determination of silver benzotriazole

In continuation of our interest in solid-state structures of silver complexes of photographic importance, the structure for silver benzotriazole (AgBZT), has now been obtained. The preferred method for solving crystal structures is via single-crystal X-ray diffraction (XRD). However, for some materials, growing single crystals of appropriate size and quality is often difficult or even impossible. AgBZT is an example of such a silver complex with poor solubility. The usual routes to preparing single crystals using recrystallization from a cooperating solvent resulted in polycrystalline powder samples. We propose a crystal structure for AgBZT, solved from synchrotron X-ray powder diffraction data, using a direct-space Monte Carlo simulated annealing approach. AgBZT crystals are monoclinic, (P2₁/c), with unit cell dimensions, a=14.8052(3) Å, b=3.7498(4) Å, c=12.3495(12) Å, and β=114.200(6)°. The AgBZT complex is constructed from all three of the Benzotriazole (BZT) nitrogens bonding to a separate silver atom. As a consequence of this bonding mode, the structure is a highly cross-linked, coordination polymer.     

Assembly and Photophysics of Ternary Luminescent Lanthanide Molecular Complex Systems

In this paper, according to the molecular fragment principle, a series of eight ternary luminescent lanthanide complex systems were assembled, and whose compositions were determined with elemental analysis and infrared spectrum: Ln(MA)₃(L)·H₂O, where Ln = Sm, Eu, Tb, Dy; HMA = α‐methylacrylic acid; L = 1,10‐phenanthroline (phen), 2,2′‐bipyridine (bipy). The photophysical properties of these functional molecular systems were studied with ultraviolet‐visible absorption spectrum, and fluorescence excitation and emission spectrum. It was found that the heterocylic compounds (phen and bipy) act as the main energy donor and luminescence sensitizer for their suitable energy match and effective energy transfer to the emission energy level of Ln³⁺ ions. MMA ligand was only used as the terminal structural ligand to influence the luminescence. Especially terbium complex systems show the strongest luminescence for the optimum energy match and transfer between phen (bipy) and Tb³⁺ ion.     

High-quality hydroxyapatite coating on biocompatible materials by laser-assisted laser ablation method

A new method for high-quality hydroxyapatite (HAp) coating is developed, the laser-assisted laser ablation method. In this method, two lasers are used. One is used for ablation of a HAp target. The other, the assist laser, is used to irradiate a Ti substrate surface. The effects of the assist laser irradiation are to anneal the HAp coating and to improve its adhesive strength to the Ti substrate. The quality of the HAp coating depends on the delay time of the assist-laser irradiation. HAp coatings obtained at a delay time of 10 microseconds or more are more amorphous. It was confirmed that the amorphous part of a coating dissolves in simulated body fluid, while the crystalline part does not. The value of the Ca/P ratio in a coating obtained at a delay time of a few microseconds is close to the stoichiometric value. PACS 81.16.Mk     

Solubility diagrams of the potassium iodide-water-N,N-dimethylformamide and iodine-iodide-water-N,N-dimethylformamide systems at 25°C

The solubility diagrams of the potassium iodide-water-N,N-dimethylformamide (DMFA) and iodine-iodide-water-N,N-dimethylformamide systems were studied at 25°C by the method of sections. The systems are characterized by three-phase equilibria of the peritonic and eutonic types, respectively. Potassium iodide in the I₂-KI-/H₂O-DMFA (95: 5 wt %)/ system was found to salt in crystalline iodine. The selected composition of the H₂O-DMFA mixed solvent possessed a higher iodine-solving ability compared with pure mixture components.