EXPRESS METHODS FOR ANALYSING THERMO-ELECTRIC MATERIALS AND CONVERTER CHARACTERISTICS

Abstract

Objectives. Recently, there has been a sharp increase in research interest in thermoelectricity (TE) and its applications. New designs for thermoelectric converters (TEC) are being proposed and a large number of new thermoelectric materials (TEM) with a thermoelectric figure of merit Z = a 2 s / k enhanced by the nanotechnological (NT) method are obtained. (Here a , s and k are the coefficient of thermal electromotive force (EMF), the specific electrical conductivity and the thermal conductivity, respectively). As a result, the need for a sharp increase in the labour productivity of researchers working in the thermoelectric (TE) industry has emerged, especially when determining the characteristics of thermoelectric materials and thermoelectric converters, as well as when processing an increased volume of literature data. The aim of the present work is to develop a set of methods for rapid analysis of the characteristics of thermoelectric materials and thermoelectric converters, allowing the labour productivity of researchers working in the TE industry to be increased. Methods. The problem was solved by selecting well-known methods for studying TEM and TEC, based on nonstationary measurement principles and computer calculations, as well as creating new methods. Results. The result of the work was an expansion of the capabilities of the established thermal probe and Harman methods used to measure the Z parameter and its components (a , s and k). The Harman method is expanded to multistage modules, allowing for the passive compensation of thermal losses when measuring in air (the switching of thermocouples (TP) in “head to head” mode). Methods for estimating the Eg – the band gap width of the TEM – according to the curves Z = f (T , as well as the calculation of the TEC using the Lenz rule, are developed. A method is proposed for diagnosing the “phonon glass electron crystal” (PGEC) phase ( 1 ~ l ph / a << λ e / a / a) by determining the mean free paths of phonons l ph and electrons λe. (Here, a = 3 nm is the shortest interatomic distance). The method of autoelectrochemical alloying of thermoelectric materials, as well as diagnostics of nanostructures (NS), is developed by determining the “physical property-NS identity period x ” dependencies. Examples of the developed technique using for analysing the characteristics of thermoelectric materials and thermoelectric converters are given. Conclusion The possibility of a sharp increase in the labour productivity of researchers working in the TE industry is indicated. Acknowledgment. The work was carried out according to the state task No. 007-00129-18-00.