Ultrapurification of <Superscript>76</Superscript>Ge-enriched GeH<Subscript>4</Subscript> by distillation

⁷⁶Ge-enriched germane has been ultrapurified by low-temperature distillation. The nature and concentration of molecular impurities in the germane samples were determined by gas chromatography/mass spectrometry, high-resolution Fourier transform IR spectroscopy, and gas chromatography. The distillate contains no more than 10⁻⁵ mol % hydrocarbons, 10⁻⁴ mol % carbon dioxide, 10⁻³ to 10⁻¹ mol % digermane and trigermane, and <3 × 10⁻⁵ mol % other impurities. A distinctive feature of the impurity composition of the isotopically enriched germane samples is the presence of silicon tetrafluoride and sulfur hexafluoride impurities.     

Molecular analysis of isotopically enriched <Superscript>28</Superscript>SiF<Subscript>4</Subscript> and <Superscript>28</Superscript>SiH<Subscript>4</Subscript> prepared from it

We have developed analytical techniques for the determination of impurities in isotopically enriched ²⁸SiH₄ and ²⁸SiF₄. The impurities in SiF₄ were first determined by IR spectroscopy, and those in SiH₄, by gas chromatography/mass spectrometry. High-sensitivity determination of organic impurities in SiH₄ and SiF₄ was performed by gas chromatography. SiF₄ was found to contain C₁–C₄ hydrocarbons, hexafluorodisiloxane (Si₂F₆O), hydrogen fluoride, trifluorosilanol (SiF₃OH), fluorosilanes, water, and carbon oxides. The impurities identified in SiH₄ include C₁–C₄ hydrocarbons, disilane (Si₂H₆), inorganic hydrides, Si₂H₆O, alkylsilanes, and fluorinated and chlorinated organics. The detection limits of IR spectroscopy were 3 × 10^?3 to 5 × 10^?5 mol %, those of gas chromatography/mass spectrometry were 8 × 10^?6 to 10^?8 mol %, and those of gas chromatography were 6 × 10^-6 to 2 × 10^?7 mol %.     

Precision methods of nondestructive control of thermophysical properties

We examine original solutions for two-dimensional problems of nonsteady heat conduction in the case of an orthotropic half-space with discontinuous mixed boundary conditions; these are used to develop new methods of controlling thermophysical properties in a nondestructive manner.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 57, No. 6, pp. 999–1005, December, 1989.     

Impurities in monosilanes synthesized by different processes

Using high-resolution IR spectroscopy, we have compared the impurity compositions of monosilane (SiH₄) fractions enriched in impurities in the process of cryofiltration and low-temperature distillation of monosilanes derived from silicon tetrafluoride (SiF₄) and trichlorosilane (SiCl₃H). The results demonstrate that the more volatile impurities present in both monosilanes are methane (CH₄) and carbon dioxide (CO₂), whereas the impurities specific to the fluoride-derived monosilane are SiF₄, SiF₃H, and SiF₂H₂. The less volatile impurities common to both monosilanes are ethane (C₂H₆), disiloxane (Si₂H₆O), and disilane (Si₂H₆); the impurities specific to the fluoride-derived monosilane are tetrafluoroethylene (C₂F₄) and monofluorosilane (SiFH₃); and those specific to the chloride-derived monosilane are hydrogen chloride (HCl) and the chlorosilanes SiClH₃, SiCl₂H₂, and SiCl₃H.     

An inverse Laplace transformation for solving heat-conduction problems with discontinuous boundary conditions of the second kind

An inverse Laplace transformation is found for a class of functions encountered in heat-conduction problems with discontinuous boundary conditions.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 50, No. 5, pp. 852–859, May, 1986.     

Gas-Sprayed Tin Powders

A gas-dynamic technology has been developed for obtaining tin powder by spraying molten metal and equipment has been built for this purpose. The powder (grain size <100 m) is distinguished by the stability of its parameters, including the granulometric composition. This is achieved by keeping the technological parameters stable throughout the metal spraying process. Those parameters have been calculated and then refined on the basis of results obtained from experimental research on the process of spraying liquid metal. A constant molten metal consumption is ensured by a special dosing device. Its design and operation are described and the parameters of the powders produced are given.     

Thermochemical purification of sulfur from hydrocarbons

The behavior of carboniferous impurities during thermochemical purification of sulfur was studied. The integral absorption coefficient for the IR absorption band at 2920 cm^-1, related to aliphatic hydrocarbons, was determined. The detection limit for aliphatic hydrocarbons in sulfur was evaluated to be 2 x 10^-5 wt % (3σ criterion).     

Asymptotic analysis of the effect of parameters on the natural virration frequencies of elastic systems

Institute of the Mechanics of Metal-Polymer Systems, Academy of Sciences of the Belorussian SSR, Gomel'. V. I. Lenin Belorussian State University, Minsk. Translated from Problemy Prochnosti, No. 2, pp. 90–95, February, 1989.     

Local heating of an unbounded orthotropic plate through a circular and annular domain

The regularities of temperature field development in an unbounded orthotropic plate heated through circular and annular domains by an arbitrary heat flux of density q(r, ) are established.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 57, No. 5, pp. 837–849, November, 1989.     

Fine Purification of Sulfur from Carbon by High-Temperature Oxidation

Using high-temperature oxidation, the residual carbon content of high-purity sulfur was reduced to 10^–5wt %. The effects of the oxidation temperature and duration on the efficiency of the process were studied. The results are used to elucidate the mechanism for the removal of carboniferous impurities in the course of purification.