On the application of a single‐crystal κ‐diffractometer and a CCD area detector for studies of thin films

A multipurpose six‐axis κ‐diffractometer, together with the brilliance of the ESRF light source and a CCD area detector, has been explored for studying epitaxial relations and crystallinity in thin film systems. The geometrical flexibility of the six‐axis goniometer allows measurement of a large volume in reciprocal space, providing an in‐depth understanding of sample crystal relationships. By a set of examples of LaAlO₃ thin films deposited by the atomic layer deposition technique, the possibilities of the set‐up are presented. A fast panoramic scan provides determination of the crystal orientation matrices, prior to more thorough inspection of single Bragg nodes. Such information, in addition to a broadening analysis of families of single reflections, is shown to correlate well with the crystallinity, crystallite size, strain and epitaxial relationships in the thin films. The proposed set‐up offers fast and easy sample mounting and alignment, along with crucial information on key features of the thin film structures.     

Dynamic properties of zirconium dioxide refractories

The results of static and dynamic tests for three groups of ceramic materials based on zirconium dioxide ZrO₂ and for zirconium dioxide concrete are reported. The static and dynamic tests were performed according to the conventional procedure and Kolsky procedure, respectively. The ceramic samples were obtained using different manufacturing technologies and had different initial densities and porosities. In the experiments, static and dynamic strain curves were obtained and strength characteristics were determined. The dynamic strength properties of ceramics and concrete are shown to depend on the stress growth rate. The dynamic curves of ceramics are compared with those of structural and zirconium dioxide concretes.     

Special and extreme triple shock-wave configurations

Triple shock-wave configurations in steady supersonic flows of an inviscid perfect gas are considered. Triple configurations with special intensities of shock waves and extreme ratios of various flow parameters behind these configurations are determined. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 4, pp. 39–53, July–August, 2006.     

Synthesis of CF<Subscript>3</Subscript>-substituted 1,2,3,4-tetrahydroisoquinolines and 1,2,3,6-tetrahydropyridines

A three-step method for the preparation of CF₃-substituted 1,2,3,4-tetrahydroisoquino-lines and 1,2,3,6-tetrahydropyridines has been suggested. The first step includes alkylation of isoquinoline or 4-methylpyridine at the nitrogen atom with the formation of salts, which are involved into the reaction with Grignard reagent or lithium triethylborohydride to give enamines. The enamines undergo nucleophilic trifluoromethylation upon the action of Me₃SiCF₃ under acidic conditions.     

Excitons in heteroepitaxial CdSe/CdS structures

X-ray diffractometry and low-temperature exciton spectroscopy are used to study heteroepitaxial CdSe/CdS layers grown at temperatures of 350–485 °C by MOCVD. The high-temperature samples are found to display the exciton and x-ray diffraction spectra characteristic of hexagonal Wurtzite (W) structures, while the low-temperature samples display the features characteristic of the cubic structure of sphalerite (ZB). A number of the samples have x-ray spectra characteristic of structures with stacking faults (SF), which represent a separate crystalline phase in the structures studied here. It is found that the individual crystalline phases are spatially separated. Fiz. Tverd. Tela (St. Petersburg) 40, 887–889 (May 1998)     

XPS study of the oxidation of nanosize Ni/Si(100) films

The XPS (X-ray photoelectron spectroscopy) study of nickel oxide nanolayers obtained by magnetron sputtering of the metal and its subsequent oxidation in air at different temperatures (400°C and 1000°C) was performed. Silicon(100) was used as a substrate. Surface of the initial Ni/Si structure was shown to contain not only Ni metal, but also the NiO oxide. Annealing at 400°C results in a complete oxidation of the metal film. At a high-temperature annealing (1000°C), nickel interacts both with oxygen and silicon substrate to form NiSi silicide and a composite Ni-Si-O phase in transition layer. Electronconductivity of NiO films is determined by intercrystallite barriers. Activation energies of film electroconductivity in model gases (O₂, Ar, H₂) were found.     

On the invertibility of differential operators of the second order

We present sufficient conditions for the invertibility of a second-order differential operator with variable coefficients in the space L_p.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 47, No. 3, pp. 411–413, March, 1995.This paper was partially supported by the International Science Foundation, Grant No. ZA000.