372595872

JPRS-UMS-92-003 16 March 1992

ANALYSIS, TESTING

11

in carbon materials has a grcater effect on their electric conductivity than a similar change in their macroporos-ity. A simple and sound method of assessing the electric conductivity of crystalline grains along the basal piane of the macroisotropic carbonized materials is proposed. The electric conductivity of GMZ-type carbonized materials is virtually the same as that of calcinated coke-based graphites. Figures 3; references 14:8 Russian; 6 Western.

Investigation of Thermoelectric Materials Based on Solid Solutions of Bi2Te₃-Bi₂Se₃ and Sb₂Te₃-Bi₂Te₃ Systems Doped With Copper and Nickel 927D0068H Moscow IZVESTIYA AKADEMII NAUK SSSR: SERIYA NEORGANICHESKIYE MATERIAŁY in Russian Vol 27 No 12, Dec 91 pp 2533-2535

[Article by A.A. Mageramov, A.T. Tilavoldiyev, S.Sh. Kakhramanov, A.M. Muydinov, Fergana State Teachers College imeni Ulugbek]

UDC 536.212.2+537.322.8

[Abstract] The shortcomings of Bi₂Te₃- and Sb₂Te₃-based materials used in thermocouples and thermal converters and ways of overcoming them by doping these compositions with copper and nickel are discussed and the efTect of copper and nickel on the properties of solid Solutions is examined. To this end, the properties of a Bi₂Te_{2 88}Se_{0 12} solid solution doped with copper and nickel are investigated; in so doing, the copper concen-tration was varied within 0.1-0.05% by mass. The depen-dence of the thermoelectric coefficient a, electric con-ductivity a, efficiency z, and compressive strength of ®*2Te₂.88Seo.i2 ^and Sb₁₅Bi₀.5Te₃ solid Solutions is ana-lyzed and tabulated and the temperaturę dependence of electric conductivity a, thermal conductivity k, and efficiency z of the former solid solution is plotted. It is shown that an increase in the copper concentration alone hardens the alloy but its thermoelectromotive force decreases. Doping with nickel makes it possible to obtain hardened thermoelectric materials with both p- and n-type conduction. Figures 1; tables 1; references 3.

Interrelation Between Conductirity,

Thermoelectric Coefficient, and Magnetic Susceptibility of Semiconductor Melts

927D0068G Moscow IZYESTIYA AKADEMII NAUK SSSR: SERIYA NEORGANICHESKIYE MATERIAŁY in Russian Vol 27 No 12, Dec 91 pp 2523-2526

[Article by V.M. Glazov, A.I. Faradzhov, Moscow Electronic Engineering Institute]

UDC 621.315.532

[Abstract] The interrelation between the electric conduc-tivity a, thermoelectric coefficient a, and magnetic susceptibility % of certain molten semiconductors, primarily bismuth-selenium systems, are studied and the difficul-ties of calculating these values are addressed. The corre-lation of the values of a, a, and x plotted as a function of temperaturę for a Bi₂Se₃ melt is investigated. It is shown that experimental data may be used to assess certain melt parameters and thus obtain valuable data on the electron spectrum characteristics of semiconductor melts. For-mulas for computing the conductivity, thermoelectric coefficient, and magnetic susceptibility in the diffusive transfer region are derived; an analysis demonstrates that given a weak electron scattering, these formulas do not differ from those describing metallic melts. Figures 1; references 8: 7 Russian, 1 Western.

Lu-Lu₂S₃ System

927D0068D Moscow IZVESTIYA AKADEMII NAUK SSSR: SERIYA NEORGANICHESKIYE MATERIAŁY in Russian Vol 27 No 12, Dec 91 pp 2511-2515

[Article by O.V. Andreyev, N.N. Parshukov, Tyumen State University]

UDC 546.669’221:003.63

[Abstract] An attempt is madę to fili in the gaps in the study of phase equilibria in the Lu-Lu₂S₃ system and plot geometrical images of the high-temperature section of the Lu-Lu₂S₃ system’s constitution diagram T-x-projection. LyuM-1 lutetium and especially pure OSCh 14-4 sulfur are used in the experiments. Samples with a sulfur concentration of 40-59.5% are synthesized in two stages; the resulting ingots and sinters are then annealed at 1,870 or 2,070K for 25 or 15 min, respec-tively. The phase equilibrium is demonstrated by inves-tigating the microstructure and phase composition of samples quenched at various stages. As expected, the Lu-Lu₂S₃ system constitution diagram is similar to that of a Gd-Gd₂S₃ system and shows that two congruently melting phases are formed in the structure: LuS and Lu₂S₃. The concentration dependence of the microhard-ness and lattice celi constant of a LuS-based solid solution for Lu-Lu₂S₃ system samples annealed and quenched at 1,870K is examined and diffraction pat-tems of samples annealed and quenched at 1,870K are plotted. It is shown that in addition to the two congruently melting phases, two eutectic phases are also formed in the Lu-Lu₂S₃ system. Figures 3; references 9: 6 Russian; 3 Western.

Structure and Electric Properties of Rapidly Quenched InSb Foils and InSb-InBi System Solid Solutions

927D0068C Moscow IZYESTIYA AKADEMII NAUK SSSR: SERIYA NEORGANICHESKIYE MATERIAŁY in Russian Vol 27 No 12, Dec 91 pp 2505-2507

[Article by V.G. Shepelevich, Belarus State University imeni V.I. Lenin]