The Maximums of Power Factor, Figure of Merit of alloy SixGe1-x and Some Other Thermoelectric (*)(**) | Chapter 8 | Current Perspective to Physical Science Research Vol. 6

In this article, the issue of determining the maximums of power factor (PF) and figure of merit (ZT) of SixGe1-x alloy of n- and p-type conductivity with different compositions is investigated. This issue is discussed also for other thermoelectrics based on literature data. It is shown that for the values of the Seebeck coefficient in the interval (1-4)10-4V/K, (PF)max corresponds to the minimum of the specific electrical conductivity. The interdependence of these thermoelectric parameters has a regular character. The dependence of maximums of figure of merit on thermoelectric quality factor (B) for thermoelectric SixGe1-x of n- and p-type conductivity has been considered. For all samples, (ZT)max appear at about 900°C. The (ZT)max – σ' (universal electrical conductivity) dependence allows us to assume with sufficient accuracy the mentioned maxima for other values of σ' (that is, for SixGe1-x with other relative compositions as well. Thus, σ' can be used to predict of (ZT)max. With this approach, is not required coefficient of thermal conductivity (kL). σ'S2 – S independence is also considered (S – Seebeck coefficient). Experimental points and the averaged curve for a large number of samples calculated from the data of literature match well. The middle part of this dependence (1∙10-4≤S≤2.5∙10-4 V∙K-1) is well described by theparabolic empirical expression. And in the range 0≤S≤6∙10-4V∙K-1the equation of exponential type should be used. Experimental points in coordinates σ'− BS/S2are well located on a straight line for all x in n- and p-SixGe1-xexcept of some points for p-Si0.7Ge0.3. The dependence σ'− BS/S2have the form of a straight line with a slope of 1.347∙108 Sim∙W-1∙K-2.

Author(s) Details:

Irakli Nakhutsrishvili,
Institute of Cybernetics of Georgian Technical University, Georgia.

Zurab Adamia,
Tbilisi State University, Georgia and University of Georgia, Georgia.

Giorgi Kakhniashvili,
Institute of Cybernetics of Georgian Technical University, Georgia.

Please see the link here: https://stm.bookpi.org/CPPSR-V6/article/view/13265