Archive ‘ Technology and Physical Chemistry

Fundamentals of general description of technologies

Vladimir Romanenko, Galina Nikitina
St-Petersburg State University of Technology and Design, North-West Institute of Printing, Russia
North-West Branch of the Academy of Information Technologies in Education, Russia,

Basic concepts of general theory of technologies are presented. The technology denotes as a set of scheduled actions which could be exactly described. These actions transform the input goods, stuffs or services into output ones. Input, transformation and output construct basic technology triad. The matrix description of each of this triad parts is the best form for theoretical analysis of technology. Three types of streams build all interactions inside the technology area and outside too. These streams are: the stream of material, the stream of energy and the stream of information. All possible technologies of our World build so called technological sphere which is the significant part of noosphere. The areas on which this zone can be divide are also discussed. The coefficient of uncertainty of output production is the main value which allows to find location of borders between the principal parts of the technological zone.

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Sizes of crystallites as a function of cooling rate

A.S. Bakin, V.N. Romanenko, J. Schilz, G.V. Nikitina, and D.I. Ivanov

The effective function model of phase transitions (1) has been applied to the process of crystallisation of the segregating solid solutions PblxSnxTe and Gel xSix in order to determine the values of the maximum sizes of crystallites and the effective diffusion coefficients for the liquid phase.

The model has already been checked in a number of investigations (2) and the references herein), but verification of the maximum possible size of a crystallite Lmjx for a binary system that undergoes a certain rate of temperature drop w is still lacking. The theory obtains the simple relation (3):

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Vladimir Romanenko, Vladimir Bystrov, Viktor Zherdev, Khafiz Mellekh

Saint-Petersburg State University of Architecture and Civil Engineering ( 4, 2-nd Krasnoarmeiskaya at., St-Peteraburg, 198005, Russia ).

Two types of building and housing testing instruments are described in this report. The first one based on the semiconductor conductivity changes of the small point, linear or planar probe. Dependence of CdP2 optical properties is the base of the second instrument groupe. Principles of the first group instruments work is represented on the Current from the source E heated special small heater #. Heater temperature is measured with the aid of thermoiesistor R. TYansformed value of resistor resistivity may be seen on the special screen S or on the digital/analogous display. In some constructions thermoresistor may be changed for thermocouple.

The heater and the thermoresibior are assembled in a small probe. Globe form is the usual form of this assemble. The amount of globe is no more than 1-3 mm in diameter. Power and measuring wires run throw small metall tube. Its diameter is no more than 3-5 mm ( The length of the tube is no less than 100 mm. Different -planar and cilindrical – geometries are also possible. The theory of such a probe measuring is described in[l].

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M.Dvinyaninov, V.N.Romanenko

Solidification features of high purity substances used as temperature reference points have bean considered using analytical and numerical methods. The cases of planar and cylindrical solidification are studied. A series of peculiarities is first revealed being of a certain practical interest. Calculated results are compared with available experimental data of other authors.

Аналитически и численно изучаются особенности кристаллизации особо чистых веществ, применяемых для создания реперов температурной шкалы. Изучены два случая — плоской и цилиндрической кристаллизации. При этом впервые обнаружен ряд особенностей, представляющих определенный практический интерес. Результаты расчетов сравнены с имеющимися экспериментами других авторов.

Directional solidification (DS) is widely used in many scientific and technological fields, such as crystal growth, purification, temperature reference points etc. In many cases, it is necessary to know the impurity redistribution at DS in various conditions (phase transition rate, physical properties of materials, layers width, sample geometry etc).

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V.Romanenko, Ya.Sergeeva, D.Ivanov, I.Saunin

Saint-Petersburg State University of Architecture and Civil Engineering, 4, 2-nd Krasnoarmeiskaya st., Saint-Petersburg, 198005, Russia *Saint-Petersburg Electrotechnical University, 5 Prof. Popova st., Saint-Petersburg, 197022, Russia

Semiconductor AIVBVI compounds are of great interest for applications in infrared techniques [1]. Study of growing and electrical properties of PbS and PbTe thin films on silicon substrates are presented in this work.

Samples were prepared by vacuum condensation of PbS and PbTe on substrates using the «hot wall» technique [2]. To provide a proper structure perfectness of layers, the intermediate buffer layers of CaF2 and BaF2 were preliminary grown on the silicon substrate. Growth conditions are shown in the Table below.

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Bulk growth of silicon – germanium solid solutions

This paper provides an overview of the technology for growing bulk silicon-germanium solid solutions and of the structural properties of the solidified materials.

It is an attempt to summarize and value the methods and efforts applied to the controlled crystallization of silicon germanium melts which were employed during the last four decades.

The especially high degree of segregation makes the system sensitive to small changes of growth conditions, which leads to inhomogeneities and strain. The future availability of homogeneous, low-defect Si-Ge crystals through the whole composition range is briefly discussed

V.Romanenko, G.Nikitina
Department of Physics, St.-Petersburg State University of Architecture and Civil Engineering, 4,2-nd Krasnoarmeiskaya St., 198005, St.-Petersburg, Russia. Department of Physics, St.Petersburg Technological Institute, 26 Moskovskii Ave., 198013, St.-Petersburg, Russia.
Methods for determing distribution coefficients and solubility curves based on analysis of effective distribution coefficients are examined. Examples are given for Ge-impurity, Ge-Si and InSb-GaSb systems. For Те, Pb, Sn, Sb, Se impurities in Bi, influence of current density on distribution coefficient when d.c. flows through the solid/liquid interface has been investigated. For the same case, magnetic field effect on this dependence has been studied. A method to determine the volatile impurity distribution is described.

It has been used to determine distribution coefficients of Zn, Те and Sm in GaAs. It is shown that analysis of distribution coefficients in complex systems allows to determine the chemical form in which an impurity enters the crystal matrix. The method has been used to study the behaviour of impurities in Bi2Te3. It is shown that impurities introduced into Bi2Te3 in the form of halides may partially dissociate in the melt. The phenomenon of maxima arising on concentration curves during the solidification of complex systems is described.

Analysis of that phenomenon has shown that choosing initial conditions for the crystallization of an epitaxial layer, one can control the shape of the composition distribution curve as a function of the epilayer thickness. Use of additional feeding of the liquid phase to determine the physico-chemical system parametrs has been considered. Making use of the methods developed, solubility curves of Dy, Gd and Sm in GaAs have been found. The second of proposed methods has been used for the analysis of GaAs-impurity systems. The so-called thermal arrest process is described. It allows to find the impurity distribution coefficient without measuring its concentration in the solid phase. The method has been checked for the case of In impurity in GaAs.

Department of Physics, Saint-Petersburg State University of Architecture and Civil Engineering
(4, 2-nd Krasnoarmeiskaya st., St.-Petersburg, 198005, Russia)
Small semiconductor sensors have some advantages in air quality and thermal conditions of interioir apartments control. The main of these sensor’s advantages are small sizes and universality. Some sensors are produced on Sn02 films. It is possible to detect air pollutions of different kind with these sensor’s help. Some problems with results interpretation may be overcome with the help of new instrumental constructions described in the report.
Seria of thermophysical sensors described in the report permits to study humidity, air flows velocities, thermoflows throw walls and ceelings behaviours and some other valuable housing parameters. These sensors construction is based on special type of point thermoresistors disposed in the end of the thin tube. Some technical data of described sensors are discussed. Results of the sensor usage in appartment parameters control for cold climate conditions are described.