Synthesis of CN<Subscript>x</Subscript> nanotubes using catalysts prepared from zinc and nickel bimaleates

Nitrogen-containing carbon nanotubes have been prepared via acetonitrile (CH₃CN) pyrolysis at 850°C catalyzed by nanoparticles produced by the thermal decomposition of zinc and nickel bimaleates and their solid solutions. The synthesized samples have been characterized by transmission electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. The results demonstrate that increasing the zinc content of catalyst nanoparticles reduces the yield of carbon nanotubes and increases the nitrogen content of the material. The high synthesis temperature gives rise to zinc vaporization, which influences the growth process, increasing the nanotube diameter, reducing the wall thickness, and lowering the structural perfection of the graphite layers.     

Terahertz emission at impurity electrical breakdown in Si(Li)

Terahertz electroluminescence caused by impurity-induced breakdown in lithium-doped silicon crystals is studied. The spectrum of the terahertz emission exhibits lines corresponding to intracenter electronic transitions between excited states of the impurity and sublevels of the ground state of the lithium donor. The spectrum also shows a background signal, which, apparently, is a manifestation of the effects due to heating at electric excitation.     

Simultaneous estimation of liquid level and density based on the maximum likelihood method

This paper considers the operation algorithm of a hydrostatic level sensor in a liquid of unknown density which is based on the determination of the moment when the level crosses the pressure sensor and provides increased accuracy of density and level measurements compared to available methods. The algorithm was synthesized on the basis of the maximum likelihood method. The algorithm was analyzed and experimental data are given.     

Origin of an absorption band peaked at 5560 cm−1 and related to divacancies in Si1−x Gex

It is found that two types of centers are formed in Si_1?x Ge_x single crystals as a result of irradiation with fast electrons: divacancies (V ₂) characteristic of silicon and the V ₂ ^* centers; the latter are complexes of divacancies V ₂ with germanium atoms (V ₂Ge). It is shown that an absorption band peaked at about 5560 cm^?1 is a superposition of two absorption bands that correspond to the above centers. The V ₂ divacancies diffuse during isochronous heat treatment and interact with germanium atoms, thus giving rise to additional V ₂ ^* centers. The latter have a higher thermal stability than the V ₂ centers do, and their annealing temperature increases with increasing content of germanium.     

Structural and electrical properties of the Ge x Si1−x /Si heterojunctions obtained by the method of direct bonding

The results of studying the structural and electrical properties of structures produced by the method of direct bonding of Ge _x Si_1?x and Si wafers are reported. The wafers were cut from the crystals grown by the Czochralski method. Continuity of the interface and the crystal-lattice defects were studied by X-ray methods using synchrotron radiation and by scanning electron microscopy. Measurements of the forward and reverse current-voltage characteristics of the p-Ge _x Si_1?x /n-Si diodes made it possible to assess the effect of the crystallattice defects on the electrical properties of heterojunctions. Satisfactory electrical parameters suggest that the technology of direct bonding is promising for the fabrication of large-area Ge _x Si_1?x /Si heterojunctions.     

Manifestation of clustering of Ge atoms in the spectra of electron spin resonance of Si1 ? xGex alloys (0 < x < 0.057)

The electron spin resonance (ESR) at phosphorus dopants in the P-doped Si_1−x Ge _x alloys (0 < x < 0.057) with the concentration of phosphorus in the range 10¹⁵–10¹⁶ cm⁻³ is studied at temperatures from 3 to 30 K. The ESR spectra of the alloys (x > 0) are compared to the ESR spectra of similar silicon samples (x = 0). It is found that, from the smallest Ge content x = 0.008, the ESR spectra contain two additional lines. It is assumed that these lines are due to phosphorus dopants located in clusters with higher Ge content. It is found that an increase in the Ge content in the alloys up to x = 0.024 yields only an increase in the concentration of such clusters. At x ≥ 0.024, the Ge content increases with x both inside and outside the clusters. Original Russian Text ? A.I. Veinger, A.G. Zabrodskiĭ, T.V. Tisnek, S.I. Goloshchapov, N.V. Abrosimov, 2007, published in Fizika i Tekhnika Poluprovodnikov, 2007, Vol. 41, No. 6, pp. 687–693.     

Dynamics of jet flows in a vortex tube

The results of experimental studies of the pressure gradient field near the axis are presented, and the change in the pitch of the screw structure of gas flows is determined.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 53, No. 6, pp. 906–911, December, 1987.     

Automatic Precision Apparatus for Measuring Electromotive Force

The results of the development at the Siberian Scientific Research Institute of Metrology of automatic precision apparatus for use as the Mongolian national standard of the unit of electromotive force are presented. The apparatus has been investigated and certified at the D. I. Mendeleev All-Union Scientific Research Institute of Metrology.     

Similarity of high-temperature gas-cooled reactor technologies and designs in Russia and USA

Historical information concerning the development of high-temperature gas-cooled reactors in the USA and Russia is presented. The reactor facilities MHTGR (USA), VG-400 (Russia), VGM (Russia), GT-MGR (Russia, USA), and at the Fort St. Vrain nuclear power plant (USA) are described. The US programs for developing innovative high-temperature nuclear reactor technologies are examined. It is shown that the Russian and US technological developments for the fuel, reactor system, energy conversion system, and fission-product transport are similar.