372595891

JPRS-UMS-92-003 16 March 1992

PREPARATIONS

33

Efficiency of the Absorption of Radiation Point Defects by Pores Surrounded by Impurity Atmospheres

927D0089B Moscow FIZIKA 1KHIMIYA OBRABOTK1MATERIALOV in Russian No 6,

Nov-Dec 91 (manuscript received 16 Aug 90) pp 12-18

[Article by S.B. Kislitsin, Yu.S. Pyatiletov, and N.I. Yedemskiy, Alma-Ata]

UDC 621.039.531

[Abstract] The authors of the study examined the effects of the formation of equilibrium atmospheres of intersti-tial impurity atoms on the efficiency of the absorption of radiation point defects by vacancy and gas-filled pores in metals with a body-centered crystal structure irradiated under various conditions. Specifically, they performed a mathematical analysis of the following: the equilibrium impurity atmospheres close to pores, the concentrations of point defects close to pores surrounded by an impurity atmosphere, and the efficiency of absorption of point defects by pores surrounded by impurity atmospheres. The analysis performed led the authors to conclude that as a result of the formation of impurity atmospheres around vacancy and gas-filled pores, each porę becomes a sink with a preference for absorbing either titanium interstitial atoms or vacancies. Vacancy pores with an impurity atmosphere mainly absorb interstitial atoms, whereas gas-filled pores with a gas pressure excceding 2y/r_u mainly absorb vacancics. The application of extemal tensile or compressive stresses does not change these absorption preferences; however, it does change the values of the absorption efficiency (YJ and the porę preference parameter (BJ. Figures 4; references 10: 8 Russian, 2 Western.

Use of Cryogenic Technology To Produce Powders

927D0049J Moscow FIZIKA I KHIMIYA OBRABOTKI MATERIALOV in Russian No 3, May-Jun 91 (manuscript recei\ed 26 Jun 89) pp 121-123

[Article by A.F. Alckseyev, K.K. Palekha, S.G. Ponomar-chuk, L.V. Chemyak, and V.Ya. Shlyuko, Kiev]

UDC 621.762.2

[Abstract] The authors of the study examined the various process variables affecting the dispersivity powders pro-duced by cryogenic technology. A1₂(S0₄)₃ x 18H₂0 with a purity grading of good was used as the starting materiał to prepare the Solutions. Solutions containing between 0.025 and 0.65 moles A1₂(S0₄)₃ x 18H₂0 per liter (obtained by diluting a saturated solution) were used to study the effect of concentration on specific surface. Tests revealed that decreasing the concentration of the starting Solutions results in an increase in the specific surface of the resultant powder. The experiments also established that increasing the ratę at which the starting solution is cooled results in an increase in specific surface. A “hard” sublimation drying regimen was found to result in a specific surface of 92 m²/g, whereas a “moderate” regimen resulted in a specific surface of 116 m²/g. Derivative thermogravimetric analysis of the decomposition process of granules of sublimation-dried aluminum sulfate indicated that the process is completed at a temperaturę of about 1,000° within 60 to 90 min-utes. A sharp decrease in specific surface was found to occur in the temperaturę interval from 1,050 to 1,200°, and it remained virtually unchanged upon further heating to 1,300°. At a temperaturę of 1,050°, average particie size ranged from 0.5 to 1 x 10'⁸ m; at 1,300°, it ranged from 1 to 3 x 10'⁷ m. The studies performed confirmed that cryogenic technology can indeed be used to produce powders with a high specific surface and that specific surface may be controlled within a broad interval of starting water-and-salt solution concentrations, cooling rates, and heat treatment conditions. Figures 2; references 4 (Russian).

Preparation and X-Ray Phase Analysis of Thin Zinc Arsenide Films

927D0068B Moscow IZYESTIYA AKADEMII NAUK SSSR: SERIYA NEORGANICHESKIYE MATERIAŁY in Russian Vol 27 No 12, Dec 91 pp 2499-2500

[Article by N.S. Zhalilov, G.S. Yuryev, S.F. Marenkin, General and Inorganic Chemistry Institute imeni N.S. Kumakov at the USSR Academy of Sciences]

UDC 539.27:546.48’19+546.47’18

[Abstract] Interest in Zn₃As₂ compounds is due to their use as a component of Zn₃As₂-Cd₃As₂ solid Solutions and an analogue of CdTe-HgTe solid Solutions. Zn₃As₂ films for the study are prepared from Zn₃As₂ single crystals; 24x10x05 mm vitreous and leucosapphire wafers are used as the substrate. Thin Zn₃As₂ films are produced in a VUP-5 all-purpose vacuum chamber and their thickness is measured under a MII-4 interference microscope. The resistivity, Hall concentration, and carrier mobility of the films are measured in weak constant electric and magnetic fields. The results dem-onstrate that vacuum deposition can be used to produce amorphous and crystalline Zn₃As₂ films. At substrate temperatures above 300°C, the films consist primarily of [224] oriented crystalline grains. An analysis demon-strates that the electric properties of the films are close to the properties of Zn₃As₂ single crystals. Diffraction pattems of Zn₃As₂ films are plotted. Figures 2; tables 1; references 7: 2 Russian; 5 Western.

ZnSe Production by Self-Propagating High-Temperature Synthesis Method and ZnSe Properties

927D0068E Moscow IZVESTIYA AKADEMII NAUK SSSR: SERIYA NEORGANICHESKIYE MATERIAŁY in Russian Vol 27 No 12, Dec 91 pp 2516-2519

[Article by S.V. Kozitskiy, D.D. Polishchuk, V.P. Pisar-skiy, S.V. Zubritskiy, N.M. Kompanichenko, I.S. Chaus,