H.J. Goldsmid. Effect of ionised-impurity scattering on the figure of merit of a bismuth-like thermoelectric material. Journal of
Thermoelectricity. 2006, No.4. - p.5-11.
It has been shown previously that the Seebeck coefficient of a semi-metal or narrow-gap semiconductor can be substantially increased by the introduction of ionised-impurity scattering of the charged carriers. However, this may not lead to an improvement in the thermoelectric figure of merit since there will be a decrease in the electrical conductivity. We show first that there can be a marginal increase in the figure of merit for a material in which there is only one type of charge carrier. We then discuss the case of a zero-gap semiconductor in which the electrons and holes have similar properties and show that, for such a material, the figure of merit can be significantly improved by a certain proportion of ionised-impurity scattering. Finally, we consider a zero-gap conductor with bismuth-like properties, that is for electrons having about the same density-of-states effective mass as holes but an order of magnitude greater mobility. We find that, when ionised-impurity scattering makes almost the same contribution as lattice scattering, the figure of merit may reach a useful level. In fact, if the lattice conductivity can be reduced to a glass-like value, the dimensionless figure of merit may exceed unity. There is evidence that it might be possible to achieve this result for counter-doped bismuth or bismuth-antimony.
P.D. Maryanchuk, E.V. Maistruk. Effect of sulphur and thermal processing on thermoelectric figure of merit of Hg1-xMnxTe1-ySy crystals. Journal of
Thermoelectricity. 2006, No.4. - p.12-17.
In the range of temperatures Ò = 77-300 K and magnetic fields Í = 0.5-6 kOe kinetic coefficients of Hg1-xMnxTe1-ySy crystals (õ ~ 0.001; 0.01 < y < 0.1) were studied prior to and after thermal processing. Thermoelectric figure of merit was obtained from the experimental data. It was established that increased sulphur content in Hg1-xMnxTe1-ySy solid solutions and transformations occurring in the defect subsystem of crystals during their thermal processing in component vapour predetermine high values of thermoelectric figure of merit (Z~ 2•10-3 1/K).
A.I. Medvid. Tåmperature variations of thermoelectric coefficient and deviations from the Wiedemann-Franz law of Fe-Ni-Ti alloy in the martensite-austenite states. Journal of
Thermoelectricity. 2006, No.4. - p.18-27.
Temperature variations of thermoelectric coefficient and the Lorentz number (the latter was calculated from the experimental data of temperature dependences of electric conductivity and thermal conductivity) of Fe-Ni-Ti (N27T3) alloy are investigated in the martensite-austenite states in the temperature range 4.2-1173 K. Correlation between these coefficients is examined and their sensitivity to phase-structural transformations in such systems is analyzed. Peculiarities of titanium effect on the electronic structure of iron-nickel alloys in polycrystalline alpha-(BCC)- and gamma-(FCC)-structural states and their kinetic characteris-tics are discussed. With regard to specific sensitivity of kinetic coefficients and the Lorentz number to different stages of phase-structural transformations in crystals, the ways of updating similar research are proposed.
Yu.V. Stadnyk, V.A. Romaka. Effect of doping intermetallic semiconductor n-ZrNiSn with in acceptor impurities on the value of thermopower factor Z*. Journal of
Thermoelectricity. 2006, No.4. - p.28-37.
Temperature and concentration dependences of electric resistivity and thermoelectric coefficient of heavily doped semiconductor solid solution ZrNiSn1-xInx in temperature and concentration ranges Ò = 80-380 K, õ = 0.005-0.15 have been studied. Possible mechanisms of semiconductor conductivity under different temperatures and acceptor impurity concentrations have been analyzed, conditions for obtaining maximum values of thermopower factor (Z*) in ZrNiSn1-xInx have been determined.
R.R. Kobylyansky. Power characteristics of short-circuited thermoelements. Journal of
Thermoelectricity. 2006, No.4. - p.38-45.
The efficiency and power of short-circuited thermoelement (SCTE) depending on the number of shorting conductors, their resistance, thickness and orientation relative to the temperature gradient are investigated. The optimum parameters of thermoelement ensuring achievement of the maximum efficiency are determined.
V.V. Lysko. Study of errors in measuring electric conductivity of thermoelectric material rod. Journal of
Thermoelectricity. 2006, No.4. - p.46-51.
Computer model for measuring electric conductivity of thermoelectric material rods has been created that allows studying measurement errors due to current density inhomogeneity in a rod. Recommendations as to elimination of the effect of these errors on measurement results have been developed.
L.I. Anatychuk, V.Ya. Mykhailovsky, Î.J. Luste, L.M. Vykhor, I.S. Termena. Thermoelectric modules for gas organic-fueled generators. Journal of
Thermoelectricity. 2006, No.4. - p.52-72.
Efficiency and methods for improving the life and cyclic stability of thermoelectric modules for gas-fueled generators are studied. Constructions and basic characteristics of single- and double-stage modules made of different materials are described. Advantages of the elaborated modules over the existing world analogs are demonstrated.
Yu.N. Lobunets. Analysis of thermoelectric counterflow climatizer efficiency. Journal of
Thermoelectricity. 2006, No.4. - p.73-78.
The circuit of climate control unit using thermoelectric heat pump (THP) with the counterflow of heat-transfer agents is examined. The analysis of its efficiency in the heating and cooling modes is carried out. It is demonstrated that the application of a counterflow circuit ensures considerable decrease in the operating temperature difference on thermoelements and corresponding high efficiency of thermoelectric heat pump over a wide ambient temperature range.
L.I. Anatychuk, O.J. Luste, L.Ya. Kushneryk. Computer control of temperature distribution in tissues at cryosurgery and cryotherapy. Journal of
Thermoelectricity. 2006, No.4. - p.79-83.
Fundamentals of computer technology for temperature distribution control at cryosurgical opera-tions and cryotherapeutical procedures carried out with the use of thermoelectric cryoextractors and probes are described. TCRYO software product implementing this technology is described and its test results are given.
P.D. Mikityuk. Effect of soil surface state on the operating efficiency of thermoelectric generator. Journal of
Thermoelectricity. 2006, No.4. - p.84-88.
Results of research on the efficiency of thermoelectric renewable power sources operated on thermal flows in soil depending on the effect of various factors on the soil surface are given. The necessity of taking into account the state of soil surface in the design is substantiated and optimal operating conditions of such power sources are determined.