On the magnetic-field-induced changes in the parameters of phase transitions

Equations describing a change in the thermodynamic parameters of a first-order phase transition in para-and diamagnetic substances under the action of a homogeneous magnetic field are derived. It is shown that the magnetic field effect on the phase transition parameters is negligibly small in the regions of the phase diagram where the P-T curves vary monotonically. However, the applied magnetic field may significantly change the T _f and P _f values in the regions where either P _f (T) or T _f (P) curves exhibit extrema. Substances in which this effect can be observed are indicated.     

The calculation of the parameters of the Mie-Lennard-Jones potential

A method is suggested for self-consistent calculation of the characteristics of interatomic potential of the type of Mie-Lennard-Jones potential, which is based on the lattice parameter, sublimation energy, Debye temperature, and Gr neisen parameter at zero values of temperature and pressure. The method, which takes into complete account the “zero-oscillation” energy, is valid for use with both classical and quantum substances. The results of calculation of the parameters of this potential for Van der Waals crystals demonstrated good agreement with the data of other authors. The parameters of interatomic potential are determined for 70 elements which exhibit the chemical bond of predominantly metallic type. The correlation of the potential parameters with the position of the element in the periodic table is analyzed. The ranges of permitted values of the parameters of the potential are estimated. The parameters of the potential for Rn, T₂, HD, HT, and DT are predicted, and the values of the Debye temperature, Grüneisen parameter, sublimation energy, molar volume, and of the specific surface energy of {100} face are calculated for these crystals. The variation of the parameters of the potential with the variation of the isotopic composition of crystal is estimated.     

The cascade of V. I. Lenin chiryurtsk hydroelectric plants in the dagestan ASSR

Conclusions The Sulak River and its tributaries constitute an extremely important hydropower resource of the Dagestan ASSR. The cascade of 20 hydroelectric plants on this river, which will have a total capacity of 3 million kW and an output of 10 billion kW-h (the Gergegil'sk, Chiryurtsk Nos. 1 and 2. Chirkeisk, and other projected plants), provides an excellent example of the effective utilization of a mountain river for the production of power. Workers, engineers, and technicians! Raise in every possible way the production efficiency! Struggle for a fuller utilization of the reserves and for a more economical use of the labor, material, and financial resources! (From the Appeals of the Central Committee of the CPSU, issued on May 1, 1970) Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 5, pp. 1–5, May, 1970.     

Acousto-optical alcohol meters

The advantages of acousto-optical spectral devices are described. Optical alcohol meters, based on acoustooptical filters for measuring the volume fraction of ethyl alcohol in water-alcohol mixtures and multicomponent alcohol-containing solutions without preliminary distillation of the alcohol from the solution being analyzed are considered. The acousto-optical alcohol meters are based on a spectrophotometer system with a standard mixture in the reference channel, which enables a low measurement error to be obtained when measuring the volume fraction of ethyl alcohol.     

Thermal conductivity of heavy water at high pressures and its dependence on density

We employed the plane horizontal layer method to derive data on the coefficient of thermal conductivity for heavy water, and these data are compared with values for ordinary water.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 56, No. 4, pp. 587–590, April, 1989.     

An Apparatus for Measuring the Electric Conductivity and Thermal EMF of Semiconductors and Their Melts

An apparatus for investigating the thermoelectric characteristics of semiconductors and chemically corrosive semiconductor melts inclined to evaporation and decomposition in a wide temperature range of 300–1300 K is developed and constructed. In contrast to the devices used earlier for this purpose, the electric conductivity and thermal emf are measured in hermetically sealed autoclaves, which, after being evacuated to a pressure of 1.33 × 10^–2 Pa, are filled with spectrally pure argon for preventing the oxidation, evaporation, or decomposition of the substance under study. The errors of the electric-conductivity and thermal-emf measurements at 1000 K do not exceed 4 and 6%, respectively.     

Method of local approximations in thermophysical property calculations: Estimation of errors in derived thermodynamic properties

An algorithm for thermophysical property calculations based on the finiteelement approximation in the thermodynamic plane has been suggested. As an example of using the algorithm, errors in obtaining the compressibility of ethane and its derivatives with respect to reduced density and temperature are discussed.     

Change of Coordination Number during Melting and in the Liquid Phase

A procedure is suggested for the of calculation of the coordination number in a lattice system consisting of (N+ N _v) spherically symmetric cells, where N _vcells are vacant. Atoms of the system interact via the Mie–Lennard-Jones pair potential and may be in localized or delocalized states. Concrete calculations performed for argon reveal good agreement with the experimental data for the solid, liquid, and gas phases, and for phase transitions between them. It is found that, in the region of the solid phase and melting, the delocalization of atoms occurs via the vacancy mechanism, and in the region of boiling and in the gas phase, the delocalization occurs mainly by continuous mass transfer over the entire volume.     

Thermal conductivity and the Wiedemann-Franz relation in melts of indium and gallium antimonides

The thermal and electrical conductivities of indium and gallium antimonides were studied in both solid and liquid states. It is shown that the calculated values of the Lorentz number (L) in InSb and GaSb, unlike in metals, increase with increasing temperature after melting. An anomalous increase in L is consistent with anomalous (for melts) temperature dependences of density, viscosity, and coordination number of these melts at the same temperatures.