INVESTIGATION OF KINETIC CHARACTERISTICS OF SENSITIVE ELEMENTS OF THERMOCONVERTERS BASED ON Ti1-xMoxCoSb

Abstract

Mathematical modeling and experimental measurements of the kinetic and energy characteristics of the sensitive elements of thermo converters based on the thermometric material Ti1-xMoxCoSb in the temperature range 80-400 K was carried out. Previous studies of the electrophysical, energetic, and structural properties of thermometric materials obtained by doping the TiCoSb semi-Heisler phase with Ni and V atoms respectively have shown that they are inherent in the stable and reproducible characteristics at 4.2–1000 K. It was revealed that the results of modeling the thermometric characteristics of the sensitive elements based on TiCo1-xNixSb and Ti1-xVxCoSb did not agree with the experimental results. This made impossible to use the mentioned materials for the manufacturing the sensitive elements of resistance thermometers and thermoelectric transducers. Modeling of Electronic Structure of Ti1-xMoxCoSb Thermometric Material with help of The Korringa–Kohn–Rostoker (KKR) Green Function Method in Coherent Potential Approximation and Local Density Approximation using AkaiKKR and SPR-KKR Software of the exchange-correlation potential with the parameterization of Moruzzi-Janak-Williams have envisaged that the substitution of Ti at Mo generates structural defects of the donor nature in the crystal (Mo has more 3d electrons than in Ti), and in the bandgap near the conduction band εC impurity donor level (zone) 2 D ε . Measurements of the electrokinetic characteristics of Ti1-xMoxCoSb Вимірювальна техніка та метрологія. Том 80, вип. 3, 2019 р. 29 thermometric materials determined the presence of high-temperature activation sites on the specific resistance of ln(ρ(1/T)), indicating the location of the Fermi level εF in the Forbidden Zone of a Semiconductor, which is possible under the condition of generating acceptors that capture free electrons, reducing their concentration, and slowing the movement of the Fermi level to the level of the conductivity zone. Thus, doping the TiCoSb compound with the Mo admixture produces the generation of structural defects of the acceptor and donor natures in the crystal. Mechanisms of electrical conductivity of sensing elements of thermo converters are established.